Waning of vaccine effectiveness against moderate and severe covid-19 among adults in the US from the VISION network: test negative, case-control study

Evaluating the impact of extended dosing intervals on mRNA COVID-19 vaccine effectiveness in adolescents

BACKGROUND

Extending the dosing interval of a primary series of mRNA COVID-19 vaccination has been employed to reduce myocarditis risk in adolescents, but previous evaluation of impact on vaccine effectiveness (VE) is limited to risk after second dose.

METHODS

We quantified the impact of the dosing interval based on case notifications and vaccination uptake in Hong Kong from January to April 2022, based on calendar-time proportional hazards models and matching approaches.

RESULTS

We estimated that the hazard ratio (HR) and odds ratio (OR) of infections after the second dose for extended (28 days or more) versus regular (21-27 days) dosing intervals ranged from 0.86 to 0.99 from calendar-time proportional hazards models, and from 0.85 to 0.87 from matching approaches, respectively. Adolescents in the extended dosing groups (including those who did not receive a second dose in the study period) had a higher hazard of infection than those with a regular dosing interval during the intra-dose period (HR 1.66; 95% CI 1.07, 2.59; p = 0.02) after the first dose.

CONCLUSIONS

Implementing an extended dosing interval should consider multiple factors including the degree of myocarditis risk, the degree of protection afforded by each dose, and the extra protection achievable using an extended dosing interval.

Effect of metabolic dysfunction-associated steatotic liver disease on BNT162b2 immunogenicity against the severe acute respiratory syndrome coronavirus 2 omicron variant

BACKGROUND AND AIM

We aimed to investigate the effect of metabolic dysfunction-associated steatotic liver disease (MASLD) on three-dose BNT162b2 immunogenicity to the omicron variant.

METHODS

Adult recipients of three doses of BNT162b2 were prospectively recruited between May and December 2021. The serology of the neutralizing antibody by live virus microneutralization (vMN) to the omicron variant was measured at baseline, day 180, and day 360 after the first dose. The primary outcome was seroconversion (vMN titer ≥ 10) at day 360. Exposure of interest was MASLD, defined as hepatic steatosis (controlled attenuation parameter ≥ 248 dB/m on transient elastography) plus at least one of five cardiometabolic risk factors. Subjects with prior COVID-19 were excluded. A multivariable logistic regression model was used to derive the adjusted odds ratio of seroconversion with MASLD by adjusting for age, sex, antibiotic use, and proton pump inhibitor use.

RESULTS

One hundred forty-eight BNT162b2 recipients (male: 48 [32.4%]; median age: 51.0 years [interquartile range, IQR: 44.5-57.3]) were recruited. The median time from the first dose to the third dose was 8.5 months (IQR: 7.9-8.9). MASLD subjects had a lower seroconversion rate than non-MASLD ones (89.6% vs 99.0%; P = 0.007). MASLD was the only independent risk factor for seroconversion (adjusted odds ratio: 0.051, 95% confidence interval: 0.002-0.440). Subgroup analysis of immunogenicity at 4 months after the third dose shows significantly lower vMN titer (13.06 [IQR: 7.69-22.20] vs 33.49 [IQR: 24.05-46.53]; P = 0.004) and seroconversion rate (76.9% vs 97.4%; P = 0.016) in MASLD than non-MASLD subjects, but not within 4 months from the third dose (vMN titer: 46.87 [IQR: 33.12-66.02] vs 41.86 [IQR: 34.47-50.91], P = 0.240; seroconversion rate: 94.3% vs 100%, P = 0.131).

CONCLUSION

Metabolic dysfunction-associated steatotic liver disease was a risk factor for poorer immunogenicity to the omicron variant, with a more pronounced waning effect compared among three-dose BNT162b2 recipients.

The Effect of COVID-19 Vaccination on Outpatient Antibiotic Prescribing in Older Adults: A Self-Controlled Risk-Interval Study

BACKGROUND

Coronavirus disease 2019 (COVID-19) vaccination has been associated with reduced outpatient antibiotic prescribing among older adults with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We assessed the impact of COVID-19 vaccination on outpatient antibiotic prescribing in the broader population of older adults, regardless of SARS-CoV-2 infection status.

METHODS

We included adults aged ≥65 years who received their first, second, and/or third COVID-19 vaccine dose from December 2020 to December 2022. We used a self-controlled risk-interval design and included cases who received an antibiotic prescription 2-6 weeks before vaccination (pre-vaccination or control interval) or after vaccination (post-vaccination or risk interval). We used conditional logistic regression to estimate the odds of being prescribed (1) any antibiotic, (2) a typical "respiratory" infection antibiotic, or (3) a typical "urinary tract" infection antibiotic (negative control) in the post-vaccination interval versus the pre-vaccination interval. We accounted for temporal changes in antibiotic prescribing using background monthly antibiotic prescribing counts.

RESULTS

469 923 vaccine doses met inclusion criteria. The odds of receiving any antibiotic or a respiratory antibiotic prescription were lower in the post-vaccination versus pre-vaccination interval (aOR, .973; 95% CI, .968-.978; aOR, .961; 95% CI, .953-.968, respectively). There was no association between vaccination and urinary antibiotic prescriptions (aOR, .996; 95% CI, .987-1.006). Periods with high (>10%) versus low (<5%) SARS-CoV-2 test positivity demonstrated greater reductions in antibiotic prescribing (aOR, .875; 95% CI, .845-.905; aOR, .996; 95% CI, .989-1.003, respectively).

CONCLUSIONS

COVID-19 vaccination was associated with reduced outpatient antibiotic prescribing in older adults, especially during periods of high SARS-CoV-2 circulation.

Social Vulnerability and Compliance With World Health Organization Advice on Protective Behaviors Against COVID-19 in African and Asia Pacific Countries: Factor Analysis to Develop a Social Vulnerability Index

BACKGROUND

COVID-19 protective behaviors are key interventions advised by the World Health Organization (WHO) to prevent COVID-19 transmission. However, achieving compliance with this advice is often challenging, particularly among socially vulnerable groups.

OBJECTIVE

We developed a social vulnerability index (SVI) to predict individuals' propensity to adhere to the WHO advice on protective behaviors against COVID-19 and identify changes in social vulnerability as Omicron evolved in African countries between January 2022 and August 2022 and Asia Pacific countries between August 2021 and June 2022.

METHODS

In African countries, baseline data were collected from 14 countries (n=15,375) during the first Omicron wave, and follow-up data were collected from 7 countries (n=7179) after the wave. In Asia Pacific countries, baseline data were collected from 14 countries (n=12,866) before the first Omicron wave, and follow-up data were collected from 9 countries (n=8737) after the wave. Countries' socioeconomic and health profiles were retrieved from relevant databases. To construct the SVI for each of the 4 data sets, variables associated with COVID-19 protective behaviors were included in a factor analysis using polychoric correlation with varimax rotation. Influential factors were adjusted for cardinality, summed, and min-max normalized from 0 to 1 (most to least vulnerable). Scores for compliance with the WHO advice were calculated using individuals' self-reported protective behaviors against COVID-19. Multiple linear regression analyses were used to assess the associations between the SVI and scores for compliance to WHO advice to validate the index.

RESULTS

In Africa, factors contributing to social vulnerability included literacy and media use, trust in health care workers and government, and country income and infrastructure. In Asia Pacific, social vulnerability was determined by literacy, country income and infrastructure, and population density. The index was associated with compliance with the WHO advice in both time points in African countries but only during the follow-up period in Asia Pacific countries. At baseline, the index values in African countries ranged from 0.00 to 0.31 in 13 countries, with 1 country having an index value of 1.00. The index values in Asia Pacific countries ranged from 0.00 to 0.23 in 12 countries, with 2 countries having index values of 0.79 and 1.00. During the follow-up phase, the index values decreased in 6 of 7 African countries and the 2 most vulnerable Asia Pacific countries. The index values of the least vulnerable countries remained unchanged in both regions.

CONCLUSIONS

In both regions, significant inequalities in social vulnerability to compliance with WHO advice were observed at baseline, and the gaps became larger after the first Omicron wave. Understanding the dimensions that influence social vulnerability to protective behaviors against COVID-19 may underpin targeted interventions to enhance compliance with WHO recommendations and mitigate the impact of future pandemics among vulnerable groups.

Knowledge of the Serological Response to the Third BNT162b2 Vaccination May Influence Compliance of Healthcare Workers to Booster Dose

BACKGROUND

Previous studies showed that the fourth SARS-CoV-2 vaccine dose has a protective effect against infection, as well as against severe disease and death. This study aimed to examine whether knowledge of a high-level antibody after the third dose may reduce compliance to the fourth booster dose among healthcare workers (HCWs).

METHODS

We conducted a prospective cohort study among HCWs vaccinated with the first three doses at Rambam Healthcare Campus, a tertiary hospital in northern Israel. Participants underwent a serological test before the fourth booster vaccine was offered to all of them, with results provided to participants. The population was divided into two groups, namely those with antibodies below 955 AU/mL and those with 955 AU/mL and higher, a cutoff found protective in a previous study. Multiple logistic regression was carried out to compare the compliance to the fourth booster between the two groups, adjusted for demographic and clinical variables.

RESULTS

After adjusting for the confounding variables, the compliance was higher in those with antibody levels below 955 AU/mL (OR = 1.41, p = 0.05, 95% CI 1.10-1.96). In addition, male sex and age of 60 years and above were also associated with higher vaccination rates (OR = 2.28, p < 0.001, 95% CI 1.64-3.17), (OR = 1.14, p = 0.043, 95% CI 1.06-1.75), respectively.

CONCLUSIONS

Knowledge of the antibody status may affect compliance with the booster dose. Considering waning immunity over time, reduced compliance may affect the protection of HCWs who declined the fourth dose.

Immunogenicity of the Monovalent Omicron XBB.1.5-Adapted BNT162b2 COVID-19 Vaccine in People Living with HIV (PLWH)

While SARS-CoV-2 has transitioned to an endemic phase, infections caused by newly emerged variants continue to result in severe, and sometimes fatal, outcomes or lead to long-term COVID-19 symptoms. Vulnerable populations, such as PLWH, face an elevated risk of severe illness. Emerging variants of SARS-CoV-2, including numerous Omicron subvariants, are increasingly associated with breakthrough infections. Adapting mRNA vaccines to these new variants may offer improved protection against Omicron for vulnerable individuals. In this study, we examined humoral and cellular immune responses before and after administering adapted booster vaccinations to PLWH, alongside a control group of healthy individuals. Four weeks following booster vaccination, both groups exhibited a significant increase in neutralizing antibodies and cellular immune responses. Notably, there was no significant difference in humoral immune response between PLWH and the healthy controls. Immune responses declined rapidly in both groups three months post vaccination. However, PLWH still showed significantly increased neutralizing antibody titers even after three months. These findings demonstrate the efficacy of the adapted vaccination regimen. The results suggest that regular booster immunizations may be necessary to sustain protective immunity.

Safety, Immunogenicity, and Effectiveness of Chinese-Made COVID-19 Vaccines in the Real World: An Interim Report of a Living Systematic Review

Background: Several COVID-19 vaccines were developed and approved in China. Of these, the BIBB-CorV and CoronaVac inactivated whole-virion vaccines were widely distributed in China and developing countries. However, the performance of the two vaccines in the real world has not been summarized. Methods: A living systematic review based on findings from ongoing post-licensure studies was conducted, applying standardized algorithms. Articles published between 1 May 2020 and 31 May 2022 in English and Chinese were searched for in Medline, Embase, WanFang Data, medRxiv, bioRxiv, arXiv, SSRN, and Research Square, using SARS-CoV-2, COVID-19, and vaccine as the MeSH terms. Studies with estimates of safety, immunogenicity, and effectiveness from receiving the BIBB-CorV or CoronaVac vaccine that met the predefined screening criteria underwent a full-text review. The Joanna Briggs Institute's Critical Appraisal Checklist and the Cochrane risk of bias were used for assessment of the quality. A random-effects meta-regression model was applied to identify the potential impact factors on the vaccines' effectiveness. Results: In total, 32578 articles were identified, of these, 770 studies underwent a full-text review. Eventually, 213 studies were included. The pooled occurrence of solicited and unsolicited adverse events after any dose of either vaccine varied between 10% and 40%. The top five commonly reported rare adverse events were immunization stress-related responses (211 cases, 50.0%), cutaneous responses (43 cases, 10.2%), acute neurological syndrome (39 cases, 9.2%), anaphylaxis (17 cases, 4.0%), and acute stroke (16 cases, 3.8%). The majority (83.3%) recovered or were relieved within several days. The peak neutralization titers against the ancestral strain was found within 1 month after the completion of the primary series of either vaccine, with a GMT (geometric mean titer) of 43.7 (95% CI: 23.2-82.4), followed by a dramatic decrease within 3 months. At Month 12, the GMT was 4.1 (95% CI: 3.8-4.4). Homologous boosting could restore humoral immunity, while heterologous boosting elicited around sixfold higher neutralization titers in comparison with homologous boosting. The effectiveness of receiving either vaccine against death and severe disease was around 85% for both shortly after the primary series. At Month 12, the protection against death did not decline, while the protection against severe disease decreased to ~75%. Conclusions: Both the BIBP-CorV and CoronaVac inactivated vaccines are safe. Sustained vaccine effectiveness against death was determined 12 months after the primary series, although protection against severe disease decreased slightly over time. A booster dose could strengthen the waning effectiveness; however, the duration of the incremental effectiveness and the additional benefit provided by a heterologous booster need to be studied.

Willingness to get vaccinated initially and yearly against COVID-19 and its association with vaccine hesitancy, vaccine knowledge and psychological well-being: a cross-sectional study in UK adults

OBJECTIVES

This study explores the association between vaccine hesitancy, vaccine knowledge and psychological well-being with (1) receipt of/willingness to receive an initial vaccine against COVID-19, and (2) willingness to get vaccinated yearly against COVID-19. The importance of different vaccine attributes (eg, vaccine technology, effectiveness, side effects) to choose a specific COVID-19 vaccine was also assessed.

DESIGN

Cross-sectional survey administered during May to June 2021 on vaccine hesitancy, vaccine knowledge, psychological well-being, willingness to receive COVID-19 vaccines, sociodemographics and COVID-19-related factors.

SETTING

UK.

PARTICIPANTS

A self-selected sample of 1408 adults.

OUTCOME MEASURES

Receipt of/willingness to receive COVID-19 vaccine for the first time and yearly.

RESULTS

Receipt of/willingness to receive a vaccine against COVID-19 initially and yearly were high (97.0% and 86.6%, respectively). Vaccine hesitancy was negatively associated with receipt of/willingness to receive vaccine initially/yearly (adjusted OR (aOR)=0.09, 95% CI 0.04 to 0.26, p<0.001/aOR=0.05, 95% CI 0.03 to 0.09, p<0.001). Vaccine knowledge and psychological well-being were positively associated with willingness to receive a yearly vaccine (aOR=1.81, 95% CI 1.43 to 2.29, p<0.001 and aOR=1.25, 95% CI 1.02 to 1.51, p=0.014, respectively), and general vaccine knowledge also with receipt of/willingness to receive vaccine initially (aOR=1.69, 95% CI 1.18 to 2.42, p=0.004). Vaccine effectiveness was the most important attribute for participants to choose a specific COVID-19 vaccine.

CONCLUSIONS

Improving vaccine knowledge and emphasising vaccine efficacy may minimise vaccine hesitancy and increase COVID-19 vaccine uptake.

Deviation from the recommended schedule: optimal dosing interval for a two-dose vaccination programme

Optimizing vaccination impact during an emerging disease becomes crucial when vaccine supply is limited, and robust protection requires multiple doses. Facing this challenge during the early stages of the COVID-19 vaccine deployment, a pivotal policy question arose: whether to administer a single dose to a larger proportion of the population by deferring the second dose, or to prioritize stronger protection for a smaller subset of the population with the established dosing interval from clinical trials. Using a delay-differential model and considering waning immunity and distribution capacity, we compared these strategies. We found that the efficacy of the first dose significantly influences the impact of delaying the second dose. Even for a relatively low efficacy of the first dose, a delayed strategy may outperform vaccination with the recommended dosing interval in reducing short-term hospitalizations and deaths despite increase in infections. The optimal delay, however, depends on the specific outcome measured and timelines within which the vaccination strategy is evaluated. We found transition lines for the relative reduction of infection, hospitalization and death below which vaccination with the recommended schedule is the preferred strategy. In a realistic parameter space, our results highlight scenarios in which the conclusions of previous studies are invalid.

Duration of effectiveness of the COVID-19 vaccine in Japan: a retrospective cohort study using large-scale population-based registry data

BACKGROUND

Most evidence of the waning of vaccine effectiveness is limited to a relatively short period after vaccination.

METHODS

Data obtained from a linked database of healthcare administrative claims and vaccination records maintained by the municipality of a city in the Kanto region of Japan were used in this study. The study period extended from April 1, 2020, to December 31, 2022. The duration of the effectiveness of the COVID-19 vaccine was analyzed using a time-dependent piecewise Cox proportional hazard model using the age, sex and history of cancer, diabetes, chronic obstructive pulmonary disease, asthma, chronic kidney disease, and cardiovascular disease as covariates.

RESULTS

Among the 174,757 eligible individuals, 14,416 (8.3%) were diagnosed with COVID-19 and 936 (0.54%) were hospitalized for COVID-19. Multivariate analysis based on the time-dependent Cox regression model with reference of non-vaccine group revealed a lower incidence of COVID-19 in the one-dose group (hazard ratio, 0.76 [95% confidence interval, 0.63-0.91]), two-dose (0.89 [0.85-0.93]), three-dose (0.80 [0.76-0.85]), four-dose (0.93 [0.88-1.00]), and five-dose (0.72 [0.62-0.84]) groups. A lower incidence of COVID-19-related hospitalization was observed in the one-dose group (0.42 [0.21-0.81]), two-dose (0.44 [0.35-0.56]), three-dose (0.38 [0.30-0.47]), four-dose (0.20 [0.14-0.28]), and five-dose (0.11 [0.014-0.86]) groups. Multivariable analyses based on the time-dependent piecewise Cox proportional hazard model with reference of non-vaccine group revealed significant preventive effects of the vaccine for 4 months for the incidence of COVID-19 and ≥ 6 months for hospitalization.

CONCLUSIONS

Vaccine effectiveness showed gradual attenuation with time after vaccination; however, protective effects against the incidence of COVID-19 and hospitalization were maintained for 4 months and ≥ 6 months, respectively. These results may aid in formulating routine vaccination plans after the COVID-19 pandemic.

Evaluating the impact of extended dosing intervals on mRNA COVID-19 vaccine effectiveness in adolescents

Extending the dosing interval of a primary series of mRNA COVID-19 vaccination has been employed to reduce myocarditis risk in adolescents, but previous evaluation of impact on vaccine effectiveness (VE) is limited to risk after second dose. Here, we quantified the impact of the dosing interval based on case notifications and vaccination uptake in Hong Kong from January to April 2022. We estimated that the hazard ratio (HR) and odds ratio (OR) of infections after the second dose for extended (28 days or more) versus regular (21-27 days) dosing intervals ranged from 0.86 to 0.99 from calendar-time proportional hazards models, and from 0.85 to 0.87 from matching approaches, respectively. Adolescents in the extended dosing groups (including those who did not receive a second dose in the study period) had a higher hazard of infection than those with a regular dosing interval during the intra-dose period (HR: 1.66; 95% CI: 1.07, 2.59; p = 0.02) after the first dose. Implementing an extended dosing interval should consider multiple factors including the degree of myocarditis risk, the degree of protection afforded by each dose, and the extra protection achievable using an extended dosing interval.

Prior COVID-19 Diagnosis, Severe Outcomes, and Long COVID among U.S. Adults, 2022

Given the increase in COVID-19 emergency department visits and hospitalizations during the winter of 2023-2024, identifying groups that have a high prevalence of COVID-19 cases, severity, and long-term symptoms can help increase efforts toward reducing disparities and prevent severe COVID-19 outcomes. Using data from the 2022 National Health Interview Survey (n = 27,651), we assessed the prevalence of COVID-19 outcomes (prior diagnosis, moderate/severe COVID-19, and long COVID) by sociodemographic characteristics and factors associated with each COVID-19 outcome. Approximately one third of adults reported a prior COVID-19 diagnosis (30.7%), while one half (51.6%) who had COVID-19 reported moderate or severe symptoms, and one fifth (19.7%) who had COVID-19 symptoms reported long COVID. The following were associated with higher odds of moderate/severe COVID-19 and long COVID: havinga high-risk condition (aOR = 1.20, OR = 1.52); having anxiety or depression (OR = 1.46, OR = 1.49); having a disability (OR = 1.41, OR = 1.60); and having a food insecurity (OR = 1.37, OR = 1.50) compared to a lack of these conditions. Having two or more COVID-19 vaccinations was associated with lower odds of a COVID-19 diagnosis (OR = 0.75), moderate/severe COVID-19 (OR = 0.86), and long COVID (OR = 0.82). Improving vaccination coverage and reducing disparities in COVID-19 outcomes could advance health equities and protect against future resurgence of disease.

Temporal changes to adult case fatality risk of COVID-19 after vaccination in England between May 2020 and February 2022: a national surveillance study

OBJECTIVES

Risk of death after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has fallen during the pandemic, largely due to immunity from vaccination. In England, the timing and extent of this reduction varied due to staggered eligibility during the primary vaccination campaign, based on age and clinical risk group. Duration of protection is less well understood. Our objective was to estimate the case fatality risk (CFR) by vaccination status and time since last dose during a period of widespread community testing, to better understand the impact of coronavirus disease 2019 (COVID-19) vaccination and duration of protection.

DESIGN

SARS-CoV-2 cases diagnosed between May 2020 and February 2022 were linked to vaccine records from the National Immunisation Management System. CFR was calculated as the proportion of cases that died of COVID-19 per the death certificate, aggregated by week of specimen and stratified by 10-year age band and vaccination status.

SETTING

England, UK.

PARTICIPANTS

A total of 10,616,148 SARS-CoV-2 cases, aged ≥18 years, recorded by England's laboratory reporting system.

MAIN OUTCOME MEASURES

Case fatality risk of COVID-19, stratified by age band and vaccination status.

RESULTS

Overall, a reduction in CFR was observed for all age bands, with a clear temporal link to when the age group became eligible for primary vaccination and then the first booster. CFR increased with age (0.3% 50-59 years; 1.2% 60-69; 4.7% 70-79; 16.3% 80+) and was highest in the unvaccinated - albeit a reduction was observed over time. The highest CFR was seen in the unvaccinated 80+ group prior to vaccination rollout (30.6%). CFR was consistently lowest in vaccinated populations within 6 months of last dose, yet increased after over 6 months elapsed since last dose, across all age bands.

CONCLUSIONS

COVID-19 CFR reduced after vaccination, with the lowest CFR seen across all age bands when vaccinated up to 6 months prior to specimen date. This provides some evidence for continued booster doses in older age groups.

Remdesivir is Associated with Reduced Mortality in Patients Hospitalized for COVID-19 Not Requiring Supplemental Oxygen

Background

Remdesivir has demonstrated benefit in some hospitalized patients with coronavirus disease 2019 (COVID-19) on supplemental oxygen and in nonhospitalized patients breathing room air. The durability of this benefit across time periods with different circulating severe acute respiratory syndrome coronavirus 2 variants of concern (VOC) is unknown. This comparative effectiveness study in patients hospitalized for COVID-19 and not receiving supplemental oxygen at admission compared those starting remdesivir treatment in the first 2 days of admission with those receiving no remdesivir during their hospitalization across different VOC periods.

Method

Using a large, multicenter US hospital database, in-hospital mortality rates were compared among patients hospitalized for COVID-19 but not requiring supplemental oxygen at admission between December 2020 and April 2022. Patients receiving remdesivir at hospital admission were matched 1:1 to those not receiving remdesivir during hospitalization, using propensity score matching. Cox proportional hazards models were used to assess 14- and 28-day in-hospital mortality rates or discharge to hospice.

Results

Among the 121 336 eligible patients, 58 188 remdesivir-treated patients were matched to 17 574 unique patients not receiving remdesivir. Overall, 5.4% of remdesivir-treated and 7.3% in the non-remdesivir group died within 14 days, and 8.0% and 9.8%, respectively, died within 28 days. Remdesivir treatment was associated with a statistically significant reduction in the in-hospital mortality rate compared with non-remdesivir treatment (14-day and 28-day adjusted hazard ratios [95% confidence interval], 0.75 [0.68-0.83] and 0.83 [0.76-0.90], respectively). This significant mortality benefit endured across the different VOC periods.

Conclusions

Remdesivir initiation in patients hospitalized for COVID-19 and not requiring supplemental oxygen at admission was associated with a significantly reduced in-hospital mortality rate. These findings highlight a potential survival benefit when clinicians initiated remdesivir on admission across the dominant variant eras of the evolving pandemic.

Protecting the vulnerable: addressing the COVID-19 care needs of people with compromised immunity

While the general population regained a certain level of normalcy with the end of the global health emergency, the risk of contracting COVID-19 with a severe outcome is still a major concern for people with compromised immunity. This paper reviews the impact of COVID-19 on people with immunocompromised status, identifies the gaps in the current management landscape, and proposes actions to address this unmet need. Observational studies have demonstrated that people with immune dysfunction have a higher risk of COVID-19-related hospitalization and death, despite vaccination, than the general population. More research is needed to define the optimal prevention and treatment strategies that are specific to people with immunocompromised status, including novel vaccination strategies, monoclonal antibodies that provide passive immunity and complement suboptimal vaccination responses, and improved and safer antiviral treatment for COVID-19. Preventive measures beyond vaccination alone are urgently needed to protect this vulnerable population.

Global COVID-19 Pandemic Outcomes: A Cross-Country Comparison Study of Policy Strategies

This paper explores global COVID-19 treatment and containment strategies in 108 countries worldwide, specifically the correlation between COVID-19 deaths and the countries' vaccination rates. Comparison of data across states, provinces, territories, and countries relied upon a common method to evaluate data regarding the impact of COVID-19 policies in the last three years. Data from nine different databases were analyzed to determine if there were correlations between the percentage of countrywide COVID-19 deaths/population and countries' percent vaccinated. Secondary outcome measures include the effect of other variables on COVID-19 death rates per country population, including health expenditures and annual income per capita, COVID-19 tests per 1000 people, stringency index (a measure of each country's containment strategies), hydroxychloroquine/ivermectin scores (measure country use), hypertension, obesity, diabetes, and geographic locations. COVID-19 vaccination rates ranged from 0-99% in 108 countries. Bivariate analysis demonstrates the following independent variables to correlate with COVID-19 deaths/population (Spearman correlation coefficient, p value): countrywide COVID-19 vaccination rates (moderate relationship, r=0.39, P < .001); healthcare expenditures per capita per annum (US dollars) (moderate relationship, r=0.46, P < .001), net annual income per capita (moderate relationship, r=0.50, P < .001), COVID-19 tests per 1000 country population (moderate relationship, r=0.36, P < .003); stringency index per country (moderate relationship, r=0.28, P < .003); hydroxychloroquine index (negative relationship, r= 0.15, P = .125); and ivermectin index (negative relationship, r=0.23 P = .018). The authors found that the higher the percentage of a country's vaccination rate, stringent containment strategies, mass testing, etc., moderately correlated with higher COVID-19 death rates/population. Future studies are required to explore the findings of this study fully.

Screening Strategies to Reduce COVID-19 Mortality in Nursing Homes

Importance

Nursing home residents continue to bear a disproportionate share of COVID-19 morbidity and mortality, accounting for 9% of all US COVID-19 deaths in 2023, despite comprising only 0.4% of the population.

Objective

To evaluate the cost-effectiveness of screening strategies in reducing COVID-19 mortality in nursing homes.

Design and Setting

An agent-based model was developed to simulate SARS-CoV-2 transmission in the nursing home setting. Parameters were determined using SARS-CoV-2 virus data and COVID-19 data from the Centers for Medicare & Medicaid Services and US Centers for Disease Control and Prevention that were published between 2020 and 2023, as well as data on nursing homes published between 2010 and 2023. The model used in this study simulated interactions and SARS-CoV-2 transmission between residents, staff, and visitors in a nursing home setting. The population used in the simulation model was based on the size of the average US nursing home and recommended staffing levels, with 90 residents, 90 visitors (1 per resident), and 83 nursing staff members.

Exposure

Screening frequency (none, weekly, and twice weekly) was varied over 30 days against varying levels of COVID-19 community incidence, booster uptake, and antiviral use.

Main Outcomes and Measures

The main outcomes were SARS-CoV-2 infections, detected cases per 1000 tests, and incremental cost of screening per life-year gained.

Results

Nursing home interactions were modeled between 90 residents, 90 visitors, and 83 nursing staff over 30 days, completing 4000 to 8000 simulations per parameter combination. The incremental cost-effectiveness ratios of weekly and twice-weekly screening were less than $150 000 per resident life-year with moderate (50 cases per 100 000) and high (100 cases per 100 000) COVID-19 community incidence across low-booster uptake and high-booster uptake levels. When COVID-19 antiviral use reached 100%, screening incremental cost-effectiveness ratios increased to more than $150 000 per life-year when booster uptake was low and community incidence was high.

Conclusions and Relevance

The results of this cost-effectiveness analysis suggest that screening may be effective for reducing COVID-19 mortality in nursing homes when COVID-19 community incidence is high and/or booster uptake is low. Nursing home administrators can use these findings to guide planning in the context of widely varying levels of SARS-CoV-2 transmission and intervention measures across the US.

Factors affecting motivation for receiving a booster dose of the COVID-19 vaccine among Japanese university students and staff: a cross-sectional questionnaire survey

Understanding the factors that influence people's decisions regarding vaccination is essential to promote vaccination. We aimed to clarify the motivations for receiving booster vaccines. We conducted a paper-based questionnaire distributed during January-February 2022 involving students and faculty staff who received the first COVID-19 vaccination at the mass vaccination program during June-September 2021 at Keio University. A total of 1725 participants were enrolled, and all completed the survey. Among these, 64.9% reported a significant adverse event (AEs) affecting daily life after the second vaccine. "Fear of severe COVID-19 illness" (72.6%) was the most common reason for getting vaccinated, followed by "concern of infecting others" (68.4%) and "fear of COVID-19 infection itself" (68.3%). Television emerged as the most influential source of information (80%), followed by university information (50.2%) and social networking sites (42.8%). Multivariate analysis revealed "fear of severe COVID-19 illness", "fear of COVID-19 infection itself", and "trust in the efficacy and safety of the vaccines in general" were significantly correlated with willingness to receive paid vaccinations. The severity of AEs and source of information were not related to participants' willingness to receive booster vaccinations. Participants with positive reasons for vaccination were more likely to accept a third dose.

Poor durability of the neutralizing response against XBB sublineages after a bivalent mRNA COVID-19 booster dose in persons with HIV

We estimated the dynamics of the neutralizing response against XBB sublineages and T cell response in persons with HIV (PWH) with previous AIDS and/or CD4 < 200/mm3 receiving the bivalent original strain/BA.4-5 booster dose in fall 2022. Samples were collected before the shot (Day 0), 15 days, 3, and 6 months after. PWH were stratified by immunization status: hybrid immunity (HI; vaccination plus COVID-19) versus nonhybrid immunity (nHI; vaccination only). Fifteen days after the booster, 16% and 30% of PWH were nonresponders in terms of anti-XBB.1.16 or anti-EG.5.1 nAbs, respectively. Three months after, a significant waning of anti-XBB.1.16, EG.5.1 and -XBB.1 nAbs was observed both in HI and nHI but nAbs in HI were higher than in nHI. Six months after both HI and nHI individuals displayed low mean levels of anti-XBB.1.16 and EG.5.1 nAbs. Regarding T cell response, IFN-γ values were stable over time and similar in HI and nHI. Our data showed that in PWH, during the prevalent circulation of the XBB.1.16, EG.5.1, and other XBB sublineages, a mRNA bivalent vaccine might not confer broad protection against them. With a view to the 2023/2024 vaccination campaign, the use of the monovalent XBB.1.5 mRNA vaccine should be urgently warranted in PWH to provide adequate protection.

Waning effectiveness of mRNA COVID-19 vaccines against inpatient and emergency department encounters

In the United States, most real-world estimates of COVID-19 vaccine effectiveness are based on data drawn from large health systems or sentinel populations. More data is needed to understand how the benefits of vaccination may vary across US populations with disparate risk profiles and policy contexts. We aimed to provide estimates of mRNA COVID-19 vaccine effectiveness against moderate and severe outcomes of COVID-19 based on state population-level data sources. Using statewide integrated administrative and clinical data and a test-negative case-control study design, we assessed mRNA COVID-19 vaccine effectiveness against SARS-CoV-2-related hospitalizations and emergency department visits among adults in South Carolina. We presented estimates of vaccine effectiveness at discrete time intervals for adults who received one, two or three doses of mRNA COVID-19 vaccine compared to adults who were unvaccinated. We also evaluated changes in vaccine effectiveness over time (waning) for the overall sample and in subgroups defined by age. We showed that while two doses of mRNA COVID-19 vaccine were initially highly effective, vaccine effectiveness waned as time elapsed since the second dose. Compared to protection against hospitalizations, protection against emergency department visits was found to wane more sharply. In all cases, a third dose of mRNA COVID-19 vaccine conferred significant gains in protection relative to waning protection after two doses. Further, over more than 120 days of follow-up, the data revealed relatively limited waning of vaccine effectiveness after a third dose of mRNA COVID-19 vaccine.

The impact of the 2022 spring COVID-19 booster vaccination programme on hospital occupancy in England: An interrupted time series analysis

Regular booster vaccination programmes help protect the most vulnerable from COVID-19 and limit pressure on health systems. Existing studies find booster doses to be effective in preventing hospital admissions and deaths but focus on individual effects, failing to consider the population impact of incomplete vaccination coverage and seasonal patterns in disease transmission. We estimated the effectiveness of the 2022 spring booster vaccination programme, available for those aged 75 years and older, residents in care homes, and adults with weakened immune systems, on COVID-19 hospital bed occupancy in England. Booster vaccine coverage in the eligible population increased rapidly in the months after rollout (from 21st March 2022), flattening out just below 80% by July 2022. We used interrupted time series analysis to estimate a 23.7% overall reduction in the rate of hospital occupancy for COVID-19 following the programme, with a statistically significant benefit in the 6-12 weeks following rollout. In the absence of the programme, we calculate that a total of 380,104 additional hospital bed-days would have been occupied by patients with COVID-19 from 4th April to 31st August 2022 (95% CI: -122,842 to 1,034,590). The programme delayed and shortened the duration of the peak while not reducing its magnitude. In sensitivity analyses adjusting the start of the post-intervention period or removing the rate of COVID-19 infection in the over 60s from the model, the effect of the spring booster programme on hospital bed occupancy remained similar. Our findings suggest that timing is a critical consideration in the implementation of COVID-19 booster programmes and that policymakers cannot rely on intermittent booster vaccination of high-risk groups alone to mitigate anticipated peaks in hospital pressure due to COVID-19 epidemics.

Comparing frequency of booster vaccination to prevent severe COVID-19 by risk group in the United States

There is a public health need to understand how different frequencies of COVID-19 booster vaccines may mitigate the risk of severe COVID-19, while accounting for waning of protection and differential risk by age and immune status. By analyzing United States COVID-19 surveillance and seroprevalence data in a microsimulation model, here we show that more frequent COVID-19 booster vaccination (every 6-12 months) in older age groups and the immunocompromised population would effectively reduce the burden of severe COVID-19, while frequent boosters in the younger population may only provide modest benefit against severe disease. In persons 75+ years, the model estimated that annual boosters would reduce absolute annual risk of severe COVID-19 by 199 (uncertainty interval: 183-232) cases per 100,000 persons, compared to a one-time booster vaccination. In contrast, for persons 18-49 years, the model estimated that annual boosters would reduce this risk by 14 (10-19) cases per 100,000 persons. Those with prior infection had lower benefit of more frequent boosting, and immunocompromised persons had larger benefit. Scenarios with emerging variants with immune evasion increased the benefit of more frequent variant-targeted boosters. This study underscores the benefit of considering key risk factors to inform frequency of COVID-19 booster vaccines in public health guidance and ensuring at least annual boosters in high-risk populations.

Durability of the Effectiveness of Heterologous COVID-19 Vaccine Regimens in Thailand: Retrospective Cohort Study Using National Registration Data

BACKGROUND

The durability of heterologous COVID-19 vaccine effectiveness (VE) has been primarily studied in high-income countries, while evaluation of heterologous vaccine policies in low- and middle-income countries remains limited.

OBJECTIVE

We aimed to evaluate the duration during which the VE of heterologous COVID-19 vaccine regimens in mitigating serious outcomes, specifically severe COVID-19 and death following hospitalization with COVID-19, remains over 50%.

METHODS

We formed a dynamic cohort by linking records of Thai citizens aged ≥18 years from citizen vital, COVID-19 vaccine, and COVID-19 cases registry databases between May 2021 and July 2022. Encrypted citizen identification numbers were used to merge the data between the databases. This study focuses on 8 common heterologous vaccine sequences: CoronaVac/ChAdOx1, ChAdOx1/BNT162b2, CoronaVac/CoronaVac/ChAdOx1, CoronaVac/ChAdOx1/ChAdOx1, CoronaVac/ChAdOx1/BNT162b2, BBIBP-CorV/BBIBP-CorV/BNT162b2, ChAdOx1/ChAdOx1/BNT162b2, and ChAdOx1/ChAdOx1/mRNA-1273. Nonimmunized individuals were considered for comparisons. The cohort was stratified according to the vaccination status, age, sex, province location, month of vaccination, and outcome. Data analysis employed logistic regression to determine the VE, accounting for potential confounders and durability over time, with data observed over a follow-up period of 7 months.

RESULTS

This study includes 52,580,841 individuals, with approximately 17,907,215 and 17,190,975 receiving 2- and 3-dose common heterologous vaccines (not mutually exclusive), respectively. The 2-dose heterologous vaccinations offered approximately 50% VE against severe COVID-19 and death following hospitalization with COVID-19 for 2 months; however, the protection significantly declined over time. The 3-dose heterologous vaccinations sustained over 50% VE against both outcomes for at least 8 months, as determined by logistic regression with durability time-interaction modeling. The vaccine sequence consisting of CoronaVac/CoronaVac/ChAdOx1 demonstrated >80% VE against both outcomes, with no evidence of VE waning. The final monthly measured VE of CoronaVac/CoronaVac/ChAdOx1 against severe COVID-19 and death following hospitalization at 7 months after the last dose was 82% (95% CI 80.3%-84%) and 86.3% (95% CI 83.6%-84%), respectively.

CONCLUSIONS

In Thailand, within a 7-month observation period, the 2-dose regimens could not maintain a 50% VE against severe and fatal COVID-19 for over 2 months, but all of the 3-dose regimens did. The CoronaVac/CoronaVac/ChAdOx1 regimen showed the best protective effect against severe and fatal COVID-19. The estimated durability of 50% VE for at least 8 months across all 3-dose heterologous COVID-19 vaccine regimens supports the adoption of heterologous prime-boost vaccination strategies, with a primary series of inactivated virus vaccine and boosting with either a viral vector or an mRNA vaccine, to prevent similar pandemics in low- and middle-income countries.

Enhancing Immunological Memory: Unveiling Booster Doses to Bolster Vaccine Efficacy Against Evolving SARS-CoV-2 Mutant Variants

A growing number of re-infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in previously immunized individuals has sparked discussions about the potential need for a booster vaccine dosage to counteract declining antibody levels and new strains. The protective immunity produced by vaccinations, and past illnesses relies on immunological memory. CD4 + T cells, CD8 + T cells, B cells, and long-lasting antibody responses are all components of the adaptive immune system that can generate and maintain this immunological memory. Since novel mutant variants have emerged one after the other, the world has been hit by repeated waves. Various vaccine formulations against SARS-CoV-2 have been administered across the globe. Thus, estimating the efficacy of those vaccines against gradually developed mutant stains is the essential parameter regarding the fate of those vaccine formulations and the necessity of booster doses and their frequency. In this review, focus has also been given to how vaccination stacks up against moderate and severe acute infections in terms of the longevity of the immune cells, neutralizing antibody responses, etc. However, hybrid immunity shows a greater accuracy of re-infection of variants of concern (VOCs) of SARS-CoV-2 than infection and immunization. The review conveys knowledge of detailed information about several marketed vaccines and the status of their efficacy against specific mutant strains of SARS-CoV-2. Furthermore, this review discusses the status of immunological memory after infection, mixed infection, and vaccination.

Natural products from Streptomyces spp. as potential inhibitors of the major factors (holoRdRp and nsp13) for SARS-CoV-2 replication: an in silico approach

The COVID-19 pandemic caused unprecedented damage to humanity, and while vaccines have been developed, they are not fully effective against the SARS-CoV-2 virus. Limited targeted drugs, such as Remdesivir and Paxlovid, are available against the virus. Hence, there is an urgent need to explore and develop new drugs to combat COVID-19. This study focuses on exploring microbial natural products from soil-isolated bacteria Streptomyces sp. strain 196 and RI.24 as a potential source of new targeted drugs against SARS-CoV-2. Molecular docking studies were performed on holoRdRp and nsp13, two key factors responsible for virus replication factor. Our in silico studies, K-252-C aglycone indolocarbazole alkaloid (K252C) and daunorubicin were found to have better binding affinities than the respective control drugs, with K252C exhibiting binding energy of - 9.1 kcal/mol with holoRdRp and - 9.2 kcal/mol with nsp13, and daunorubicin showing binding energy at - 8.1 kcal/mol with holoRdRp and - 9.3 kcal/mol with nsp13. ADMET analysis, MD simulation, and MM/GBSA studies indicated that K252C and daunorubicin have the potential to be developed as targeted drugs against SARS-CoV-2. The study concludes that K252C and daunorubicin are potential lead compounds that might suppress the inhibition of SARS-CoV-2 replication among the tested microbial compounds and could be developed as targeted drugs against COVID-19. In the future, further in vitro studies are required to validate these findings.

Humoral immune response in people living with HIV after administration of SARS-CoV-2 vaccine CoronaVac or BNT162b2 or CoronaVac/BNT162b2 booster sequence: A cross-sectional study

BACKGROUND

The evidence of SARS-CoV-2 vaccine effectiveness in people living with HIV (PLWH) is limited. This study evaluated the humoral immune response to CoronaVac™ (virus inactivated) and BNT162b2 (mRNA- based) vaccines in PLWH and HIV-negative controls, with and without a booster sequence.

METHODS

We conducted a cross-sectional study on PLWH and HIV-negative controls who received CoronaVac or BNT162b2, with a subgroup receiving a CoronaVac/BNT162b2 booster. Blood samples were collected 4-6 months after primary vaccination and tested for anti-SARS-CoV-2 protein S (aSAb) and neutralizing antibodies (NtAb) using validated assays. Immune response was evaluated by age, sex, previous COVID-19 history, and CD4 + cell count.

FINDINGS

One hundred and eighty nine participants were enrolled with 161 (85%) being PLWH. Among participants without previous known COVID-19, median aSAb levels were significantly lower in PLWH who received CoronaVac compared to BNT162b2 (32 U/mL vs. 587 U/mL, p < 0.001), with similar results in HIV-negative controls. NtAb presence was also significantly lower after CoronaVac compared to BNT162b2 (30% vs. 93%, p < 0.001). The booster sequence group showed a significant increase in aSAb titers in both PLWH and HIV-negative controls (from 33 U/ml to 2500 U/ml, p < 0.001), and NtAb positivity increased from 20% to 95 % in PLWH, and 27% to 100% in HIV-negative controls. Prior COVID-19 led to significantly higher post-vaccine antibody titers particularly in the BNT162b2 group. PLWH with CD4 + count < 200 cells/mL showed a weaker immune response to both vaccines.

INTERPRETATION

CoronaVac resulted in a weaker immune response in both PLWH and HIV-negative controls compared to BNT162b2, particularly in immunosuppressed PLWH without prior COVID-19. Hybrid immunity and heterologous booster vaccination increased antibody levels.

FUNDING

Local funding.

Going Forward: Potential Impact of Protein-Based COVID-19 Vaccination Coverage on Population Outcomes and Costs in the United States

Policymakers in the United States (US) recommend coronavirus disease 2019 (COVID-19) vaccination with a monovalent 2023-2024 vaccine formulation based on the Omicron XBB.1.5 variant. We estimated the potential US population-level health and economic impacts of increased COVID-19 vaccine coverage that might be expected with the availability of a protein-based vaccine with simpler storage requirements in addition to messenger ribonucleic acid (mRNA) vaccines. A Markov model was developed to estimate 1-year COVID-19-related costs, cases, hospitalizations, and deaths with and without the availability of a protein-based vaccine option. The model population was stratified by age and risk status. Model inputs were sourced from published literature or derived from publicly available data. Our model estimated that a five-percentage-point increase in coverage due to the availability of a protein-based vaccine option would prevent over 500,000 cases, 66,000 hospitalizations, and 3000 COVID-19-related deaths. These clinical outcomes translated to 42,000 quality-adjusted life years (QALYs) gained and an incremental cost-effectiveness ratio of USD 16,141/QALY from a third-party payer perspective. In sensitivity analyses, outcomes were most sensitive to COVID-19 incidence and severity across age groups. The availability of a protein-based vaccine option in the US could reduce hospitalizations and deaths and is predicted to be cost-effective.

Effectiveness of a Fourth COVID-19 mRNA Vaccine Dose Against the Omicron Variant in Solid Organ Transplant Recipients

BACKGROUND

The effectiveness of booster doses of COVID-19 vaccines in solid organ transplant recipients is unclear. We conducted a population-based matched cohort study using linked administrative healthcare databases from Ontario, Canada to estimate the marginal vaccine effectiveness of a fourth versus third dose of the BNT162b2 and mRNA-1273 vaccines against clinically important outcomes (ie, hospitalization or death) and infection during the era of the Omicron variant.

METHODS

We matched 3120 solid organ transplant recipients with a third COVID-19 vaccine dose (reference) to 3120 recipients with a fourth dose. Recipients were matched on the third dose date (±7 d). We used a multivariable Cox proportional hazards model to estimate the marginal vaccine effectiveness with outcomes occurring between December 21, 2021 and April 30, 2022.

RESULTS

The cumulative incidence of COVID-19-related hospitalization or death was 2.8% (95% confidence interval [CI], 2.0-3.7) in the third dose group compared with 1.1% (95% CI, 0.59-1.8) in the fourth dose group after 84 d of follow-up (P < 0.001). The adjusted marginal vaccine effectiveness was 70% (95% CI, 47-83) against clinically important outcomes and 39% (95% CI, 21-52) against SARS-CoV-2 infection.

CONCLUSIONS

Compared with a third dose, a fourth dose of the COVID-19 vaccine was associated with improved protection against hospitalization, death, and SARS-CoV-2 infection during the Omicron era. Results highlight the importance of a booster COVID-19 vaccine dose in solid organ transplant recipients.

Development of COVID-19 vaccine policy - United States, 2020-2023

COVID-19 vaccines represent a great scientific and public health achievement in the face of overwhelming pressures from a global pandemic, preventing millions of hospitalizations and deaths due to COVID-19 vaccines in the United States. Over 675 million doses of COVID-19 vaccines have been administered in the United States, and over 80% of the U.S. population has had at least 1 dose of a COVID-19 vaccine. Over the course of the COVID-19 pandemic in the United States, over one million people died from COVID-19, and over six million were hospitalized. It has been estimated that COVID-19 vaccines prevented more than 18 million additional hospitalizations and more than 3 million additional deaths due to COVID-19 in the United States. From the beginning of the COVID-19 pandemic in 2020 through June 2023, ACIP had 35 COVID-19 focused meetings and 24 votes for COVID-19 vaccine recommendations. ACIP had the critical task of rapidly and thoroughly reviewing emerging and evolving data on COVID-19 epidemiology and vaccines, as well as making comprehensive population-based recommendations for vaccine policy and considerations for implementation through a transparent and evidence-based framework. Safe and effective COVID-19 vaccines, recommended through transparent policy discussions with ACIP, remain the best tool we have to prevent serious illness, hospitalization and death from COVID-19.

Effectiveness and durability of a second COVID-19 booster against severe outcomes among older people in Norway: a population-based cohort study comparing mono- and bivalent booster doses

BACKGROUND

Evidence on the durability of the protection of a fourth dose of a monovalent or bivalent messenger ribonucleic acid (mRNA) vaccine against coronavirus disease 2019 (COVID-19) among older people during the predominant Omicron period is needed.

METHODS

We performed a population-based cohort study in Norway covering the time from 1 July 2022 to 15 January 2023, including individuals ≥75 years of age who had received at least a third dose. Using Cox proportional hazard models on severe COVID-19-associated outcome measures and all-cause mortality, we estimated the vaccine effectiveness of mono- and bivalent vaccines, comparing fourth- to third-dose recipients (>24 weeks ago). Vaccine status was included as a time-varying covariate and models were adjusted for potential confounders.

RESULTS

We included 408 073 individuals. A fourth dose with either monovalent or bivalent mRNA vaccine showed increased protection against COVID-19-associated mortality relative to a third dose in individuals ≥75 years of age. We estimated a protective effect for the bivalent BA.1 vaccine [adjusted hazard ratio (aHR) 0.08, 95% CI 0.02-0.32] relative to the bivalent BA.4-5 (aHR 0.27, 95% CI 0.14-0.56) and a monovalent dose (aHR 0.34, 95% CI 0.26-0.45) 2-9 weeks after vaccination compared with recipients with a third dose >24 weeks ago. The increased protective effect waned with no added protection for the monovalent vaccine after 33 weeks compared with a third dose.

CONCLUSIONS

Our results indicate an increased protective effect of a fourth dose against severe outcomes compared with a third dose, with decreasing effect with time since the last dose.

Airway and Systemic Immune Responses Following the Third COVID-19 Vaccination in COPD Patients

Introduction

Booster vaccinations are required to maintain protection against COVID-19. COPD patients are at higher risk of developing severe illness following SARS-CoV-2 infection. Previous cross-sectional analysis after the second COVID-19 booster showed similar immune responses in COPD patients and controls, but pre-vaccination samples were not available. This longitudinal study evaluated systemic and airway immune responses in COPD patients using samples obtained pre- and post-third COVID-19 vaccination.

Methods

Twelve COPD patients were recruited, with plasma, nasal and sputum (n = 10) samples collected pre-vaccination and 4- and 14-weeks post vaccination. Samples were analyzed for anti-spike IgA and IgG and cellular immunity. The ability of plasma and nasal samples to block ACE2-spike protein interaction was assessed for Wild type, Delta, and Omicron spike variants.

Results

Vaccinations increased anti-spike IgG in plasma (p < 0.001), nasal (IgG p < 0.001) and sputum (p = 0.002) samples, IgA in plasma (p < 0.001) and blood cellular immunity (p = 0.001). Plasma and nasal anti-spike IgA levels correlated (rho: 0.6, p = 0.02), with similar results for IgG (rho: 0.79, p = 0.003). Post-vaccination nasal (p = 0.002) and plasma (p < 0.001) samples were less effective at blocking Omicron spike binding to ACE2 compared to the Wild type spike variant.

Discussion

Airway and systemic immune responses against SARS-CoV-2 increased in COPD patients following a third COVID-19 vaccination. Nasal and systemic responses in COPD patients were less effective against Omicron variant compared to previous variants.

Inactivated vaccine effectiveness against symptomatic COVID-19 in Fujian, China during the Omicron BA.2 outbreak

Objective

More than 90% of the Chinese population have completed 2 doses of inactivated COVID-19 vaccines in Mainland China. However, after China government abandoned strict control measures, many breakthrough infections appeared, and vaccine effectiveness against Omicron BA.2 infection was uncertain. This study aims to investigate the real-world effectiveness of widely used inactivated vaccines during the wave of Omicron variants.

Methods

Test-negative case-control study was conducted in this study to analyze the vaccine effectiveness against symptomatic disease caused by the Omicron variant (BA.2) in Fujian, China. Conditional logistic regression was selected to estimate the vaccine effectiveness.

Results

The study found the vaccine effectiveness against symptomatic COVID-19 is 32.46% (95% CI, 8.08% to 50.37%) at 2 to 8 weeks, and 27.05% (95% CI, 1.23% to 46.12%) at 12 to 24 weeks after receiving booster doses of the inactivated vaccine. Notably, the 3-17 years group had higher vaccine effectiveness after 2 doses than the 18-64 years and over 65 years groups who received booster doses.

Conclusion

Inactivated vaccines alone may not offer sufficient protection for all age groups before the summer of 2022. To enhance protection, other types of vaccines or bivalent vaccines should be considered.

Potential contribution of vaccination uptake to occupational differences in risk of SARS-CoV-2: analysis of the ONS COVID-19 Infection Survey

OBJECTIVES

To assess variation in vaccination uptake across occupational groups as a potential explanation for variation in risk of SARS-CoV-2 infection.

DESIGN

We analysed data from the UK Office of National Statistics COVID-19 Infection Survey linked to vaccination data from the National Immunisation Management System in England from 1 December 2020 to 11 May 2022. We analysed vaccination uptake and SARS-CoV-2 infection risk by occupational group and assessed whether adjustment for vaccination reduced the variation in risk between occupational groups.

RESULTS

Estimated rates of triple vaccination were high across all occupational groups (80% or above), but were lowest for food processing (80%), personal care (82%), hospitality (83%), manual occupations (84%) and retail (85%). High rates were observed for individuals working in health (95% for office based, 92% for those in patient-facing roles) and education (91%) and office-based workers not included in other categories (90%). The impact of adjusting for vaccination when estimating relative risks of infection was generally modest (ratio of hazard ratios across all occupational groups reduced from 1.37 to 1.32), but was consistent with the hypothesis that low vaccination rates contribute to elevated risk in some groups.

CONCLUSIONS

Variation in vaccination coverage might account for a modest proportion of occupational differences in infection risk. Vaccination rates were uniformly very high in this cohort, which may suggest that the participants are not representative of the general population. Accordingly, these results should be considered tentative pending the accumulation of additional evidence.

Post COVID-19 Symptoms Among Infected Vaccinated Individuals: A Cross-Sectional Study in Saudi Arabia

INTRODUCTION

Multiple studies investigated the endurance and occurrence of symptoms three months after SARS-CoV-2 infection. This study examines the possible effects of COVID-19 vaccination on the persistence of post-recovery symptoms.

PATIENTS AND METHODS

A cross-sectional survey was conducted in Saudi Arabia to evaluate 14 prevalent long COVID-19 symptoms among vaccinated individuals. Patients self-reported their acute COVID-19 experience, demographic information, chronic conditions, vaccine history, and persistent symptoms.

RESULTS

Of the 484 patients, four respondents were excluded from the study as they had not received the vaccine, and 111 (23.1%) were vaccinated but did not get infected and were also excluded. The remaining 369 (76.9%) reported COVID-19 and a vaccination and thus they were included in the study. The occurrence of post-COVID-19 symptoms was reported in 59 (16.1%) for ≤ 3 months, 202 (54.8%) experienced persistent symptoms 3-6 months, and 108 (29.1%) reported symptoms lasting > 6 months. In relation to age group, persistent symptoms 3-6 months after recovery was more common in those > 50 years and symptoms lasting > 6 months were more common in 30-50 years of age (p < 0.001). Persistence of symptoms for  3-6 months was more common in those who were infected prior to vaccination compared to those who were infected after vaccination (P < 0.001). Of the included patients, 323 (87.5%) rated their health as good, 41 (11.1%) considered it fair, and 5 (1.4%) described their well-being as poor or terrible.

CONCLUSION

The study provides information of persistent symptoms in vaccinated individuals who had recovered from COVID-19 and highlights the need for targeted interventions to alleviate post-COVID-19 symptoms. The study is limited by its reliance on self-reported data and potential selection bias. Future research is needed to understand the mechanisms underlying persistent symptoms in vaccinated individuals and to identify effective interventions for long COVID.

Comparative Effectiveness of Bivalent (Original/Omicron BA.4/BA.5) COVID-19 Vaccines in Adults

The emergence of Omicron variants coincided with declining vaccine-induced protection against SARS-CoV-2. Two bivalent mRNA vaccines, mRNA-1273.222 (Moderna) and BNT162b2 Bivalent (Pfizer-BioNTech), were developed to provide greater protection against the predominate circulating variants by including mRNA that encodes both the ancestral (original) strain and BA.4/BA.5. We estimated their relative vaccine effectiveness (rVE) in preventing COVID-19-related outcomes in the US using a nationwide dataset linking primary care electronic health records and pharmacy/medical claims data. The study population (aged ≥18 years) received either vaccine between 31 August 2022 and 28 February 2023. We used propensity score weighting to adjust for baseline differences between groups. We estimated the rVE against COVID-19-related hospitalizations (primary outcome) and outpatient visits (secondary) for 1,034,538 mRNA-1273.222 and 1,670,666 BNT162b2 Bivalent vaccine recipients, with an adjusted rVE of 9.8% (95% confidence interval: 2.6-16.4%) and 5.1% (95% CI: 3.2-6.9%), respectively, for mRNA-1273.222 versus BNT162b2 Bivalent. The incremental relative effectiveness was greater among adults ≥ 65; the rVE against COVID-19-related hospitalizations and outpatient visits in these patients was 13.5% (95% CI: 5.5-20.8%) and 10.7% (8.2-13.1%), respectively. Overall, we found greater effectiveness of mRNA-1273.222 compared with the BNT162b2 Bivalent vaccine in preventing COVID-19-related hospitalizations and outpatient visits, with increased benefits in older adults.

Effectiveness of the live zoster vaccine during the 10 years following vaccination: real world cohort study using electronic health records

OBJECTIVES

To assess the effectiveness of live zoster vaccine during more than 10 years after vaccination; and to describe methods for ascertaining vaccine effectiveness in the context of waning.

DESIGN

Real world cohort study using electronic health records.

SETTING

Kaiser Permanente Northern California, an integrated healthcare delivery system in the US, 1 January 2007 to 31 December 2018.

POPULATION

More than 1.5 million people aged 50 years and older followed for almost 9.4 million person years.

MAIN OUTCOME MEASURE

Vaccine effectiveness in preventing herpes zoster, postherpetic neuralgia, herpes zoster ophthalmicus, and admission to hospital for herpes zoster was assessed. Change in vaccine effectiveness by time since vaccination was examined using Cox regression with a calendar timeline. Time varying indicators were specified for each interval of time since vaccination (30 days to less than one year, one to less than two years, etc) and adjusted for covariates.

RESULTS

Of 1 505 647 people, 507 444 (34%) were vaccinated with live zoster vaccine. Among 75 135 incident herpes zoster cases, 4982 (7%) developed postherpetic neuralgia, 4439 (6%) had herpes zoster ophthalmicus, and 556 (0.7%) were admitted to hospital for herpes zoster. For each outcome, vaccine effectiveness was highest in the first year after vaccination and decreased substantially over time. Against herpes zoster, vaccine effectiveness waned from 67% (95% confidence interval 65% to 69%) in the first year to 15% (5% to 24%) after 10 years. Against postherpetic neuralgia, vaccine effectiveness waned from 83% (78% to 87%) to 41% (17% to 59%) after 10 years. Against herpes zoster ophthalmicus, vaccine effectiveness waned from 71% (63% to 76%) to 29% (18% to 39%) during five to less than eight years. Against admission to hospital for herpes zoster, vaccine effectiveness waned from 90% (67% to 97%) to 53% (25% to 70%) during five to less than eight years. Across all follow-up time, overall vaccine effectiveness was 46% (45% to 47%) against herpes zoster, 62% (59% to 65%) against postherpetic neuralgia, 45% (40% to 49%) against herpes zoster ophthalmicus, and 66% (55% to 74%) against admission to hospital for herpes zoster.

CONCLUSIONS

Live zoster vaccine was effective initially. Vaccine effectiveness waned substantially yet some protection remained 10 years after vaccination. After 10 years, protection was low against herpes zoster but higher against postherpetic neuralgia.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT01600079; EU PAS register number EUPAS17502.

Long-term Real-world Protection Afforded by Third mRNA Doses Against Symptomatic Severe Acute Respiratory Syndrome Coronavirus 2 Infections, Coronavirus Disease 19-related Emergency Attendances and Hospitalizations Amongst Older Singaporeans During an Omicron XBB Wave

BACKGROUND

Literature on long-term real-world vaccine effectiveness of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) booster vaccines (up to and beyond 360 days) is scarce. We report estimates of protection against symptomatic infection, emergency department (ED) attendances and hospitalizations up to and beyond 360 days post-receipt of booster messenger RNA (mRNA) vaccines among Singaporeans aged ≥60 years during an Omicron XBB wave.

METHODS

We conducted a population-based cohort study including all Singaporeans aged ≥60 years with no documented prior SARS-CoV-2 infection who had previously received ≥3 doses of mRNA vaccines (BNT162b2/mRNA-1273), over a 4-month period during transmission of Omicron XBB. We reported the adjusted incidence-rate-ratio (IRR) for symptomatic infections, ED attendances and hospitalizations at different time-intervals from both first and second boosters, using Poisson regression; with the reference group being those who received their first booster 90 to 179 days prior.

RESULTS

In total, 506 856 boosted adults were included, contributing 55 846 165 person-days of observation. Protection against symptomatic infections among those who received a third vaccine dose (first booster) waned after 180 days with increasing adjusted IRRs; however, protection against ED attendances and hospitalizations held up, with comparable adjusted IRRs with increasing time from third vaccine doses (≥360 days from third dose: adjusted IRR [ED attendances] = 0.73, 95% confidence interval [CI] = .62-.85; adjusted IRR [hospitalization] = 0.58, 95% CI = .49-.70).

CONCLUSIONS

Our results highlight the benefit of a booster dose in reducing ED attendances and hospitalizations amongst older adults aged ≥60 years with no documented prior SARS-CoV-2 infection, during an Omicron XBB wave; up to and beyond 360 days post-booster. A second booster provided further reduction.

Understanding low COVID-19 booster uptake among US adults

BACKGROUND

Vaccinations against SARS-CoV-2 have consistently been shown to reduce the risk of severe COVID-19 disease. However, uptake of boosters has stalled in the United States at less than 20% of the eligible population. The objective of this study was to assess the reasons for not having obtained a bivalent booster within an existing COVID-19 cohort.

METHODS

A total of 2196 adult participants from the Arizona CoVHORT, a population-based cohort in the United States established in May 2020, who had received at least one dose of the COVID-19 vaccine, responded to surveys administered between February 13 and March 29, 2023 querying receipt of a bivalent booster and if not, the reasons for not receiving it. Descriptive statistics were employed, including frequencies of responses by participant characteristics, and multivariable logistic regression was used to assess the association between participant characteristics and selected themes for not having received the bivalent booster.

RESULTS

The most commonly reported reason for not having been boosted was a prior SARS-CoV-2 infection (39.5%), followed by concern about vaccine side effects (31.5%), believing that the booster would not provide additional protection over the vaccines already received (28.6%), and concern about booster safety (23.4%) or that it would not protect from SARS-CoV-2 infection (23.1%). For themes related to reasons for not having been boosted, those 60 years of age or older were less likely to select items related to knowledge (OR: 0.24; 95% CI: 0.11-0.55) or logistical concerns (OR: 0.09; 95% CI: 0.03-0.30) about the vaccine; while those reporting Hispanic ethnicity were more likely to convey concerns about logistics than those reporting non-Hispanic ethnicity (OR: 2.15; 95% CI: 1.08-4.30). Finally, compared to college graduates, those with some college or technical school were significantly more likely to select items related to the risks and benefits of the bivalent vaccine not being clear as reasons for not having been boosted (OR: 2.41; 95% CI: 1.69-3.43).

CONCLUSIONS

Improvement in booster uptake is necessary for optimal public health in the United States. The development of vaccines against SARS-CoV-2 occurred at an unprecedented speed, but vaccine uptake remains among the greatest current public health challenges as updated boosters continue to be developed and made available to the public. Interventions to improve vaccination rates require a variety of approaches.

Mechanistic modeling projections of antibody persistence after homologous booster regimens of COVID-19 vaccine Ad26.COV2.S in humans

Mechanistic model-based simulations can be deployed to project the persistence of humoral immune response following vaccination. We used this approach to project the antibody persistence through 24 months from the data pooled across five clinical trials in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-seronegative participants following vaccination with Ad26.COV2.S (5 × 1010 viral particles), given either as a single-dose or a homologous booster regimen at an interval of 2, 3, or 6 months. Antibody persistence was quantified as the percentage of participants with detectable anti-spike binding and wild-type virus neutralizing antibodies. The projected overall 24-month persistence after single-dose Ad26.COV2.S was 70.5% for binding antibodies and 55.2% for neutralizing antibodies, and increased after any homologous booster regimen to greater than or equal to 89.9% for binding and greater than or equal to 80.0% for neutralizing antibodies. The estimated model parameters quantifying the rates of antibody production attributed to short-lived and long-lived plasma cells decreased with increasing age, whereas the rate of antibody production mediated by long-lived plasma cells was higher in women relative to men. Accordingly, a more pronounced waning of antibody responses was predicted in men aged greater than or equal to 60 years and was markedly attenuated following any homologous boosting regimen. The findings suggest that homologous boosting might be a viable strategy for maintaining protective effects of Ad26.COV2.S for up to 24 months following prime vaccination. The estimation of mechanistic modeling parameters identified the long-lived plasma cell pathway as a key contributor mediating antibody persistence following single-dose and homologous booster vaccination with Ad26.COV2.S in different subgroups of recipients stratified by age and sex.

Protection of COVID-19 Vaccination Against Hospitalization During the Era of Omicron BA.4 and BA.5 Predominance: A Nationwide Case-Control Study Based on the French National Health Data System

Background

Knowing the duration of effectiveness of coronavirus disease 2019 (COVID-19) booster doses is essential to providing decision-makers with scientific arguments about the frequency of subsequent injections. We estimated the level of protection against COVID-19-related hospitalizations (Omicron BA.4-BA.5) over time after vaccination, accounting for breakthrough infections.

Methods

In this nationwide case-control study, all cases of hospitalizations for COVID-19 identified in the comprehensive French National Health Data System between June 1, 2022, and October 15, 2022, were matched with up to 10 controls by year of birth, sex, department, and an individual COVID-19 hospitalization risk score. Conditional logistic regressions were used to estimate the level of protection against COVID-19-related hospitalizations conferred by primary and booster vaccination, accounting for history of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

Results

A total of 38 839 cases were matched to 377 653 controls; 19.2% and 9.9% were unvaccinated, respectively, while 68.2% and 77.7% had received ≥1 booster dose. Protection provided by primary vaccination reached 45% (95% CI, 42%-47%). The incremental effectiveness of booster doses ranged from 69% (95% CI, 67%-71%; ≤2 months) to 22% (95% CI, 19%-25%; ≥6 months). Specifically, the second booster provided an additional protection compared with the first ranging from 61% (95% CI, 59%-64%; ≤2 months) to 7% (95% CI, 2%-13%; ≥4 months). Previous SARS-CoV-2 infection conferred a strong, long-lasting protection (51% ≥20 months). There was no incremental effectiveness of a second booster among individuals infected since the first booster.

Conclusions

In the era of Omicron BA.4 and BA.5 predominance, primary vaccination still conferred protection against COVID-19 hospitalization, while booster doses provided an additional time-limited protection. The second booster had no additional protection in case of infection since the first booster.

COVID Vaccination as a Strategy for Cardiovascular Disease Prevention

PURPOSE OF REVIEW

Cardiovascular (CV) disease is a known complication of SARS-CoV-2 infection. A clear benefit of COVID-19 vaccination is a reduction mortality; however, COVID-19 vaccination may also prevent cardiovascular disease (CVD). We aim to describe CV pathology associated with SARS-CoV-2 infection and describe how COVID-19 vaccination is a strategy for CVD prevention.

RECENT FINDINGS

The risks and benefits of COVID-19 vaccination have been widely studied. Analysis of individuals with and without pre-existing CVD has shown that COVID-19 vaccination can prevent morbidity associated with SARS-CoV-2 infection and reduce mortality. COVID-19 vaccination is effective in preventing myocardial infarction, cerebrovascular events, myopericarditis, and long COVID, all associated with CVD risk factors. Vaccination reduces mortality in patients with pre-existing CVD. Further study investigating ideal vaccination schedules for individuals with CVD should be undertaken to protect this vulnerable group and address new risks from variants of concern.

COVID-19 vaccine effectiveness in children by age groups. A population-based study in Galicia, Spain

BACKGROUND

Studies on vaccine effectiveness (VE) against COVID-19 in the pediatric population are outgoing. We aimed to quantify VE against SARS-CoV-2 in two pediatric age groups, 5-11 and 12-17-year-old, while considering vaccine type, SARS-CoV-2 variant, and duration of protection.

METHODS

A population-based test-negative control study was undertaken in Galicia, Spain. Children 5-11-year-old received the Comirnaty® (Pfizer, US) vaccine, while those aged 12-17-year-old received the Comirnaty® (Pfizer, US) or SpikeVax® (ModernaTX, Inc) vaccine. Participants were categorized into unvaccinated (0 doses or one dose with <14 days since vaccination), partially vaccinated (only one dose with ≥14 days, or two doses with <14 days after the second dose administration), and fully vaccinated (two doses with ≥14 days after the second injection). Adjusted odds ratios (OR) and their 95% confidence intervals (CI) were estimated using multiple logistic regression models. VE was calculated as (1-OR) * 100. Stratified and sensitivity analyses were performed.

RESULTS

In the fully vaccinated 5-11-year-old children, VE against the Omicron variant was 44.1% (95% CI: 38.2%-49.4%). In the fully vaccinated 12-17-year-old individuals, VE was 83.4% (95% CI: 81.2%-85.3%) against Delta and 74.8% (95% CI: 58.5%-84.9%) against Omicron. Comirnaty® and SpikeVax® vaccines showed a similar magnitude of VE against Delta [Comirnaty® VE: 81.9% (95% CI: 79.3%-84.1%) and SpikeVax® VE: 85.3% (95% CI: 81.9%-88.1%)]. Comirnaty® (Pfizer, US; VE: 79.7%; 95% CI: 50.7%-92.4%) showed a slightly higher magnitude of protection against Omicron than SpikeVax® (ModernaTX, Inc), yet with an overlapping CI (VE: 74.3%; 95% CI: 56.6%-84.9%). VE was maintained in all age subgroups in both pediatric populations, but it declined over time.

CONCLUSIONS

In Galicia, mRNA VE was moderate against SARS-CoV-2 infections in the 5-11-year-old populations, but high in older children. VE declined over time, suggesting a potential need for booster dose schedules.

mRNA vaccines against respiratory viruses

PURPOSE OF REVIEW

The successes of the coronavirus disease 2019 (COVID-19) mRNA vaccines have accelerated the development of mRNA vaccines against other respiratory pathogens. The aim of this review is to highlight COVID-19 mRNA vaccine advances and provide an update on the progress of mRNA vaccine development against other respiratory pathogens.

RECENT FINDINGS

The COVID-19 mRNA vaccines demonstrated effectiveness in preventing severe COVID-19 and death. H7N9 and H10N8 avian influenza mRNA vaccines have demonstrated safety and immunogenicity in phase 1 clinical trials. Numerous seasonal influenza mRNA vaccines are in phase 1-3 clinical trials. Respiratory syncytial virus (RSV) mRNA vaccines have progressed to phase 2-3 clinical trials in adults and a phase 1 clinical trial in children. A combined human metapneumovirus and parainfluenza-3 mRNA vaccines was found to be well tolerated and immunogenic in a phase 1 trial among adults and trials are being conducted among children. Clinical trials of mRNA vaccines combining antigens from multiple respiratory viruses are underway.

SUMMARY

The development of mRNA vaccines against respiratory viruses has progressed rapidly in recent years. Promising vaccine candidates are moving through the clinical development pathway to test their efficacy in preventing disease against respiratory viral pathogens.

COVID-19

COVID-19, the illness caused by SARS-CoV-2, became a worldwide pandemic in 2020. Initial clinical manifestations range from asymptomatic infection to mild upper respiratory illness but may progress to pulmonary involvement with hypoxemia and, in some cases, multiorgan involvement, shock, and death. Older adults, pregnant persons, those with common comorbidities, and those with immunosuppression are at greatest risk for progression. Vaccination is effective in preventing symptomatic infection and reducing risk for severe disease, hospitalization, and death. Antiviral treatment and immunomodulators have been shown to benefit certain patients. This article summarizes current recommendations on prevention, diagnosis, management, and treatment of COVID-19.

Rural-Urban Disparities in Hospital Admissions and Mortality Among Patients with COVID-19: Evidence from South Carolina from 2021 to 2022

Although rural communities have been hard-hit by the COVID-19 pandemic, there is limited evidence on COVID-19 outcomes in rural America using up-to-date data. This study aimed to estimate the associations between hospital admissions and mortality and rurality among COVID-19 positive patients who sought hospital care in South Carolina. We used all-payer hospital claims, COVID-19 testing, and vaccination history data from January 2021 to January 2022 in South Carolina. We included 75,545 hospital encounters within 14 days after positive and confirmatory COVID-19 testing. Associations between hospital admissions and mortality and rurality were estimated using multivariable logistic regressions. About 42% of all encounters resulted in an inpatient hospital admission, while hospital-level mortality was 6.3%. Rural residents accounted for 31.0% of all encounters for COVID-19. After controlling for patient-level, hospital, and regional characteristics, rural residents had higher odds of overall hospital mortality (Adjusted Odds Ratio - AOR = 1.19, 95% Confidence Intervals - CI = 1.04-1.37), both as inpatients (AOR = 1.18, 95% CI = 1.05-1.34) and as outpatients (AOR = 1.63, 95% CI = 1.03-2.59). Sensitivity analyses using encounters with COVID-like illness as the primary diagnosis only and encounters from September 2021 and beyond - a period when the Delta variant was dominant and booster vaccination was available - yielded similar estimates. No significant differences were observed in inpatient hospitalizations (AOR = 1.00, 95% CI = 0.75-1.33) between rural and urban residents. Policymakers should consider community-based public health approaches to mitigate geographic disparities in health outcomes among disadvantaged population subgroups.

Mesenchymal Stem Cells in the Treatment of COVID-19

Since the emergence of the coronavirus disease 2019 (COVID-19) pandemic, many lives have been tragically lost to severe infections. The COVID-19 impact extends beyond the respiratory system, affecting various organs and functions. In severe cases, it can progress to acute respiratory distress syndrome (ARDS) and multi-organ failure, often fueled by an excessive immune response known as a cytokine storm. Mesenchymal stem cells (MSCs) have considerable potential because they can mitigate inflammation, modulate immune responses, and promote tissue regeneration. Accumulating evidence underscores the efficacy and safety of MSCs in treating severe COVID-19 and ARDS. Nonetheless, critical aspects, such as optimal routes of MSC administration, appropriate dosage, treatment intervals, management of extrapulmonary complications, and potential pediatric applications, warrant further exploration. These research avenues hold promise for enriching our understanding and refining the application of MSCs in confronting the multifaceted challenges posed by COVID-19.

Pseudotyping Improves the Yield of Functional SARS-CoV-2 Virus-like Particles (VLPs) as Tools for Vaccine and Therapeutic Development

Virus-like particles (VLPs) have been proposed as an attractive tool in SARS-CoV-2 vaccine development, both as (1) a vaccine candidate with high immunogenicity and low reactogenicity and (2) a substitute for live virus in functional and neutralization assays. Though multiple SARS-CoV-2 VLP designs have already been explored in Sf9 insect cells, a key parameter ensuring VLPs are a viable platform is the VLP spike yield (i.e., spike protein content in VLP), which has largely been unreported. In this study, we show that the common strategy of producing SARS-CoV-2 VLPs by expressing spike protein in combination with the native coronavirus membrane and/or envelope protein forms VLPs, but at a critically low spike yield (~0.04-0.08 mg/L). In contrast, fusing the spike ectodomain to the influenza HA transmembrane domain and cytoplasmic tail and co-expressing M1 increased VLP spike yield to ~0.4 mg/L. More importantly, this increased yield translated to a greater VLP spike antigen density (~96 spike monomers/VLP) that more closely resembles that of native SARS-CoV-2 virus (~72-144 Spike monomers/virion). Pseudotyping further allowed for production of functional alpha (B.1.1.7), beta (B.1.351), delta (B.1.617.2), and omicron (B.1.1.529) SARS-CoV-2 VLPs that bound to the target ACE2 receptor. Finally, we demonstrated the utility of pseudotyped VLPs to test neutralizing antibody activity using a simple, acellular ELISA-based assay performed at biosafety level 1 (BSL-1). Taken together, this study highlights the advantage of pseudotyping over native SARS-CoV-2 VLP designs in achieving higher VLP spike yield and demonstrates the usefulness of pseudotyped VLPs as a surrogate for live virus in vaccine and therapeutic development against SARS-CoV-2 variants.

Application of a life table approach to assess duration of BNT162b2 vaccine-derived immunity by age using COVID-19 case surveillance data during the Omicron variant period

BACKGROUND

SARS-CoV-2 Omicron variants have the potential to impact vaccine effectiveness and duration of vaccine-derived immunity. We analyzed U.S. multi-jurisdictional COVID-19 vaccine breakthrough surveillance data to examine potential waning of protection against SARS-CoV-2 infection for the Pfizer-BioNTech (BNT162b) primary vaccination series by age.

METHODS

Weekly numbers of SARS-CoV-2 infections during January 16, 2022-May 28, 2022 were analyzed by age group from 22 U.S. jurisdictions that routinely linked COVID-19 case surveillance and immunization data. A life table approach incorporating line-listed and aggregated COVID-19 case datasets with vaccine administration and U.S. Census data was used to estimate hazard rates of SARS-CoV-2 infections, hazard rate ratios (HRR) and percent reductions in hazard rate comparing unvaccinated people to people vaccinated with a Pfizer-BioNTech primary series only, by age group and time since vaccination.

RESULTS

The percent reduction in hazard rates for persons 2 weeks after vaccination with a Pfizer-BioNTech primary series compared with unvaccinated persons was lowest among children aged 5-11 years at 35.5% (95% CI: 33.3%, 37.6%) compared to the older age groups, which ranged from 68.7%-89.6%. By 19 weeks after vaccination, all age groups showed decreases in the percent reduction in the hazard rates compared with unvaccinated people; with the largest declines observed among those aged 5-11 and 12-17 years and more modest declines observed among those 18 years and older.

CONCLUSIONS

The decline in vaccine protection against SARS-CoV-2 infection observed in this study is consistent with other studies and demonstrates that national case surveillance data were useful for assessing early signals in age-specific waning of vaccine protection during the initial period of SARS-CoV-2 Omicron variant predominance. The potential for waning immunity during the Omicron period emphasizes the importance of continued monitoring and consideration of optimal timing and provision of booster doses in the future.