Durability of the Single-Dose Ad26.COV2.S Vaccine in the Prevention of COVID-19 Infections and Hospitalizations in the US Before and During the Delta Variant Surge

Vaccine effectiveness of JCOVDEN single-dose against COVID-19 hospitalisation in Europe: An id.DRIVE test-negative case-control study

BACKGROUND

JCOVDEN (Ad26.COV2.S), a viral-vector vaccine, was granted conditional marketing authorisation in the European Union for the prevention of COVID-19 in early 2021. We present JCOVDEN single-dose vaccine effectiveness (VE) estimates against COVID-19 hospitalisation.

METHODS

The id.DRIVE (previously COVIDRIVE) COVID-19 VE study is an ongoing European non-interventional, multi-centre study with a test-negative case-control design. Study participants were adults ≥ 18 years old, hospitalised with severe acute respiratory infection between 1 May 2021 and 28 February 2023. Estimated as a single measure over the entire study period, VE was stratified by risk group, time since vaccination intervals (14 days-12 weeks, 12-to-25 weeks, 25-to-52 weeks, >52 weeks), SARS-CoV-2 variant and calendar time categories. All estimates were adjusted for symptom-onset date, age, sex, and number of pre-defined chronic conditions.

RESULTS

Overall, VE was 55.6 % (95 % CI 23.6; 74.2) for a median time since vaccination of 146 days. For 18- to 49-year-olds, VE was 61.6 % (95 % CI 16.2; 82.4), 57.7 % (95 % CI 3.4; 81.5) for 50- to-64-years-olds, and 40.8 % (95 % CI -6.0; 66.9) for ≥ 65-year-olds. Most precise estimates were obtained for time since vaccination 12-to- 25-week interval (59.2 % [95 % CI 25.0; 77.8]) and for the calendar time period 1 Aug 2021 -30 Nov 2021 (Delta predominant; 51.2 % [95 % CI 21.7; 69.6]).

CONCLUSION

The JCOVDEN single-dose protected against COVID-19 hospitalisation. It is effective for at least six months, with VE estimates comparatively lower in the older age groups. Results had low to medium levels of certainty and are to be interpreted with caution.

Balancing fairness and efficiency in dynamic vaccine allocation during major infectious disease outbreaks

The outbreak of novel infectious diseases presents major public health challenges, highlighting the urgency of accelerating vaccination efforts to reduce morbidity and mortality. Vaccine allocation has become a crucial societal concern. This paper introduces a dynamic vaccine allocation model that considers demand uncertainty and vaccination willingness, focusing on the trade-off between fairness and efficiency. We develop a multi-period dynamic vaccine allocation model, evaluating optimal strategies over different periods. The model addresses structural differences among vaccination groups, strategy selection, dynamic demand, and vaccination willingness. Our findings suggest that prioritizing efficiency in the initial outbreak stages may lead to inequitable distribution, causing adverse social impacts, while overemphasizing fairness can undermine overall utility. Therefore, we propose a dynamic optimization-based strategy balancing fairness and efficiency at different pandemic stages. Our results indicate that allocation strategies should shift from efficiency to fairness as the pandemic evolves to enhance vaccine utility. Additionally, macro-level interventions like reducing free-rider behavior and increasing vaccination convenience can improve total vaccine utility. This study offers new perspectives and methodologies for dynamic vaccine allocation, highlighting the trade-off between fairness and efficiency, providing crucial insights for policy formulation and pandemic response.

Economic burden of cardiorespiratory hospitalizations associated with respiratory syncytial virus among United States adults in 2017-2019

Morbidity and mortality caused by respiratory syncytial virus (RSV) in older adults and those with underlying health conditions can be potentially alleviated through vaccination. To assist vaccine policy decision-makers and payers, we estimated the annual economic burden of RSV-associated cardiorespiratory hospitalizations among insured US adults aged ≥18 y in the Merative MarketScan claims database from September through August of 2017-2018 and 2018-2019. Negative binomial regression models were used to estimate the number of RSV-associated cardiorespiratory hospitalizations using MarketScan-identified cardiorespiratory diagnosis codes in the presence or absence of RSV circulation per weekly laboratory test positivity percentages from the Centers for Disease Control and Prevention. This number was multiplied by mean cardiorespiratory hospitalization costs to estimate total costs for RSV-associated cardiorespiratory hospitalizations. Number and cost for International Classification of Diseases (ICD)-coded RSV hospitalizations were quantified from MarketScan. In 2017-2018 and 2018-2019, respectively, 18,515,878 and 16,462,120 adults with commercial or Medicare supplemental benefits were assessed. In 2017-2018, 301,248 cardiorespiratory hospitalizations were observed; 0.32% had RSV-specific ICD codes, costing $44,916,324, and 5.52% were RSV-associated cardiorespiratory hospitalizations, costing $734,078,602 (95% CI: $460,826,580-$1,103,358,799). In 2018-2019, 215,525 cardiorespiratory hospitalizations were observed; 0.34% had RSV-specific ICD codes, costing $33,053,105, and 3.14% were RSV-associated cardiorespiratory hospitalizations, costing $287,549,472 (95% CI: $173,377,778-$421,884,259). RSV contributes to substantial economic burden of cardiorespiratory hospitalizations among US adults. Modeling excess risk using viral positivity data provides a comprehensive estimation of RSV hospitalization burden and associated costs, compared with relying on ICD diagnosis codes alone.

An observational post-authorization study to assess the effectiveness of a single dose Ad26.COV2.S for the prevention of COVID-19 using real-world data

Background

The goal of this FDA-committed, post authorization study was to assess the real-world effectiveness of Ad26.COV2.S in preventing observed COVID-19 disease in individuals in the United States interacting with the healthcare system who were vaccinated according to the national immunization recommendations.

Methods

The study cohort consisted of individuals ≥18 years in the U.S. between March 1, 2021 and July 31, 2022. Two exposure groups were considered: those who received a single dose of COVID-19 Ad26.COV2.S vaccine and individuals who were unvaccinated. Individuals eligible for the referent group, defined as those who were unvaccinated, were identified through exact matching on age, sex, location, and Gagne comorbidity score. Propensity-score (PS) matched Cox proportional hazards models were used to evaluate COVID-19 related outcomes.

Results

A total of 478,162 vaccinated, and 1,897,759 risk set sampled (RSS) and PS-matched unvaccinated referent individuals were included. The vaccine effectiveness (VE) against any observed COVID-19 disease was 20% (95% CI, 19 to 21%). VE increased as the outcome severity increased. The VE against COVID-19 related hospitalizations was 43% (95% CI, 40 to 45%). VE was highest, 53% (95% CI, 42 to 61%), against all-cause mortality temporally associated with COVID-19. The results of subgroup analyses generally showed a similar pattern as the main analyses with VE increasing in parallel with seriousness of outcomes, albeit with lower VE in groups thought to be at higher risk of COVID-19.

Discussion

This population-representative cohort study in U.S. clinical practice showed that a single dose of Ad26.COV2.S is effective for at least 12 months against several COVID-19 related outcomes. Individuals who were vaccinated with a single dose of Ad26.COV2.S were at lower risk for developing COVID-19, for being hospitalized for COVID-19, and for all-cause mortality temporally associated with COVID-19 compared to unvaccinated individuals in the U.S. during Alpha, Delta, and Omicron BA.1, BA.2, BA.212.1, and BA.5 variants circulation.

Prevalence of Genital Herpes and Antiviral Treatment

BACKGROUND

Genital herpes is a common sexually transmitted infection caused by the herpes simplex virus. Contemporary US population-based epidemiologic data on genital herpes are limited. This study aimed to provide nationally representative estimates of genital herpes prevalence and treatment using a large US health insurance claims database.

METHODS

This observational cohort study used administrative claims data from HealthVerity. Crude and age- and sex-standardized prevalence rates of genital herpes and recurrent genital herpes were calculated for the years 2019 to 2021. The distribution of patients with prevalent genital herpes who received episodic or suppressive antiviral therapy was also estimated.

RESULTS

From 2019 to 2021, the standardized prevalence of genital herpes and recurrent genital herpes ranged from 236 to 280 cases per 100,000 person-years and 81 to 98 cases per 100,000 person-years, respectively. The prevalence of genital herpes was highest among those aged 25 to 29 years (prevalence range, 497-582 years), female patients (prevalence range, 348-404 years), and those with a history of HIV infection (prevalence range, 1608-2080 years). The prevalence of recurrent genital herpes was also highest in these groups. From 2019 to 2021, two-thirds of patients (65%-68%) with prevalent genital herpes received antiviral medications; the majority received episodic therapy (80%) rather than suppressive therapy (20%).

CONCLUSIONS

The burden of genital herpes and recurrent genital herpes in the United States is substantial, with the highest rates observed in young adults, women, and immunocompromised individuals. About two-thirds receive antiviral treatment each year.

Incidence of Herpes Zoster and Postherpetic Neuralgia and Herpes Zoster Vaccination Uptake in a US Administrative Claims Database

Background

The objective of this study was to estimate the annual incidence rates of herpes zoster (HZ) and postherpetic neuralgia (PHN) among individuals aged ≥19 years and the proportion who received HZ vaccination among those aged ≥50 years.

Methods

This observational cohort study was conducted with administrative claims data from HealthVerity and included insured individuals across the US. Crude and US age- and sex-standardized incidence rates of HZ and PHN were calculated from 1 January 2019 to 31 May 2022 by calendar year in persons aged ≥19 years. Outcomes were defined as ≥1 ICD-10 diagnosis code for HZ or PHN. Analyses were stratified by age, sex, and immunocompromised status. Among those aged ≥50 years, the proportion who received 1 or 2 doses of recombinant zoster vaccine (Shingrix) or 1 dose of Zostavax was calculated.

Results

Standardized annual incidence rates from 2019 to 2021 were 542 to 685 per 100 000 person-years for HZ and 35 to 38 per 100 000 person-years for PHN. Rates were highest among females, older adults, and individuals who were immunocompromised. From 1 January 2019 to 31 May 2022, 4.3% and 9.0% of persons aged ≥50 years received 1 and 2 doses of Shingrix, respectively, and 0.2% received 1 dose of Zostavax.

Conclusions

In this US claims database analysis, HZ and PHN were more frequent among older adults, females, and individuals who were immunocompromised. Between 1 January 2019 and 31 May 2022, 9% of persons aged ≥50 years received 2 doses of the Shingrix vaccine. Greater efforts are needed to increase vaccine uptake against HZ, especially for those at highest risk.

Current Progress, Challenges and Prospects in the Development of COVID-19 Vaccines

The COVID-19 pandemic has resulted in over 772 million confirmed cases, including nearly 7 million deaths, according to the World Health Organization (WHO). Leveraging rapid development, accelerated vaccine approval processes, and large-scale production of various COVID-19 vaccines using different technical platforms, the WHO declared an end to the global health emergency of COVID-19 on May 5, 2023. Current COVID-19 vaccines encompass inactivated, live attenuated, viral vector, protein subunit, nucleic acid (DNA and RNA), and virus-like particle (VLP) vaccines. However, the efficacy of these vaccines is diminishing due to the constant mutation of SARS-CoV-2 and the heightened immune evasion abilities of emerging variants. This review examines the impact of the COVID-19 pandemic, the biological characteristics of the virus, and its diverse variants. Moreover, the review underscores the effectiveness, advantages, and disadvantages of authorized COVID-19 vaccines. Additionally, it analyzes the challenges, strategies, and future prospects of developing a safe, broad-spectrum vaccine that confers sufficient and sustainable immune protection against new variants of SARS-CoV-2. These discussions not only offer insight for the development of next-generation COVID-19 vaccines but also summarize experiences for combating future emerging viruses.

Predicting Vaccine Effectiveness for Hospitalization and Symptomatic Disease for Novel SARS-CoV-2 Variants Using Neutralizing Antibody Titers

The emergence of new virus variants, including the Omicron variant (B.1.1.529) of SARS-CoV-2, can lead to reduced vaccine effectiveness (VE) and the need for new vaccines or vaccine doses if the extent of immune evasion is severe. Neutralizing antibody titers have been shown to be a correlate of protection for SARS-CoV-2 and other pathogens, and could be used to quickly estimate vaccine effectiveness for new variants. However, no model currently exists to provide precise VE estimates for a new variant against severe disease for SARS-CoV-2 using robust datasets from several populations. We developed predictive models for VE against COVID-19 symptomatic disease and hospitalization across a 54-fold range of mean neutralizing antibody titers. For two mRNA vaccines (mRNA-1273, BNT162b2), models fit without Omicron data predicted that infection with the BA.1 Omicron variant increased the risk of hospitalization 2.8-4.4-fold and increased the risk of symptomatic disease 1.7-4.2-fold compared to the Delta variant. Out-of-sample validation showed that model predictions were accurate; all predictions were within 10% of observed VE estimates and fell within the model prediction intervals. Predictive models using neutralizing antibody titers can provide rapid VE estimates, which can inform vaccine booster timing, vaccine design, and vaccine selection for new virus variants.

COVID-19 Associated Cardiovascular Disease-Risks, Prevention and Management: Heart at Risk Due to COVID-19

The SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus-2) virus and the resulting COVID-19 pandemic have had devastating and lasting impact on the global population. Although the main target of the disease is the respiratory tract, clinical outcomes, and research have also shown significant effects of infection on other organ systems. Of interest in this review is the effect of the virus on the cardiovascular system. Complications, including hyperinflammatory syndrome, myocarditis, and cardiac failure, have been documented in the context of COVID-19 infection. These complications ultimately contribute to worse patient outcomes, especially in patients with pre-existing conditions such as hypertension, diabetes, or cardiovascular disease (CVD). Importantly and interestingly, reports have demonstrated that COVID-19 also causes myocardial injury in adults without pre-existing conditions and contributes to systemic complications in pediatric populations, such as the development of multisystem inflammatory syndrome in children (MIS-C). Although there is still a debate over the exact mechanisms by which such complications arise, understanding the potential paths by which the virus can influence the cardiovascular system to create an inflammatory environment may clarify how SARS-CoV-2 interacts with human physiology. In addition to describing the mechanisms of disease propagation and patient presentation, this review discusses the diagnostic findings and treatment strategies and the evolution of management for patients presenting with cardiovascular complications, focusing on disease treatment and prevention.

Mucosal boosting enhances vaccine protection against SARS-CoV-2 in macaques

A limitation of current SARS-CoV-2 vaccines is that they provide minimal protection against infection with current Omicron subvariants1,2, although they still provide protection against severe disease. Enhanced mucosal immunity may be required to block infection and onward transmission. Intranasal administration of current vaccines has proven inconsistent3-7, suggesting that alternative immunization strategies may be required. Here we show that intratracheal boosting with a bivalent Ad26-based SARS-CoV-2 vaccine results in substantial induction of mucosal humoral and cellular immunity and near-complete protection against SARS-CoV-2 BQ.1.1 challenge. A total of 40 previously immunized rhesus macaques were boosted with a bivalent Ad26 vaccine by the intramuscular, intranasal and intratracheal routes, or with a bivalent mRNA vaccine by the intranasal route. Ad26 boosting by the intratracheal route led to a substantial expansion of mucosal neutralizing antibodies, IgG and IgA binding antibodies, and CD8+ and CD4+ T cell responses, which exceeded those induced by Ad26 boosting by the intramuscular and intranasal routes. Intratracheal Ad26 boosting also led to robust upregulation of cytokine, natural killer, and T and B cell pathways in the lungs. After challenge with a high dose of SARS-CoV-2 BQ.1.1, intratracheal Ad26 boosting provided near-complete protection, whereas the other boosting strategies proved less effective. Protective efficacy correlated best with mucosal humoral and cellular immune responses. These data demonstrate that these immunization strategies induce robust mucosal immunity, suggesting the feasibility of developing vaccines that block respiratory viral infections.

COVID-19 Vaccines: Where Did We Stand at the End of 2023?

Vaccine development against SARS-CoV-2 has been highly successful in slowing down the COVID-19 pandemic. A wide spectrum of approaches including vaccines based on whole viruses, protein subunits and peptides, viral vectors, and nucleic acids has been developed in parallel. For all types of COVID-19 vaccines, good safety and efficacy have been obtained in both preclinical animal studies and in clinical trials in humans. Moreover, emergency use authorization has been granted for the major types of COVID-19 vaccines. Although high safety has been demonstrated, rare cases of severe adverse events have been detected after global mass vaccinations. Emerging SARS-CoV-2 variants possessing enhanced infectivity have affected vaccine protection efficacy requiring re-design and re-engineering of novel COVID-19 vaccine candidates. Furthermore, insight is given into preparedness against emerging SARS-CoV-2 variants.

Comparison of healthcare resource use and cost between influenza and COVID-19 vaccine coadministration and influenza vaccination only

OBJECTIVE

To compare healthcare resource utilization (HCRU) and all-cause medical costs among individuals aged ≥50 years who received influenza and COVID-19 vaccines on the same day and those who received influenza vaccine only.

METHODS

We conducted a retrospective cohort study leveraging Optum's de-identified Clinformatics DataMart from 8/31/2021 to 7/31/2023. Individuals aged ≥50 years continuously enrolled in health plans for 1 year prior and until 7/31/2023 were included. Two cohorts were formed based on vaccination status between 8/31/2022 and 1/31/2023: co-administered influenza and COVID-19 vaccines (co-admin cohort) and influenza vaccine only (influenza cohort). Associations between vaccination status and all-cause, influenza-related, COVID-related, pneumonia-related, and cardiorespiratory-related hospitalization, outpatient or emergency room visits and all-cause medical costs were estimated by weighted generalized linear models, adjusting for confounding by stabilized inverse probability of treatment weighting.

RESULTS

613,156 (mean age: 71) and 1,340,011 (mean age: 72) individuals were included in the co-admin and influenza cohorts, respectively. After weighting, the baseline characteristics were balanced between cohorts. The co-admin cohort was at statistically significant lower risk of all-cause (RR: 0.95, 95% CI: 0.93-0.96), COVID-19-related (RR: 0.59, 95% CI: 0.56-0.63), cardiorespiratory-related (RR: 0.94, 95% CI: 0.93-0.96) and pneumonia-related (RR: 0.86, 95% CI: 0.83-0.90) hospitalization but not influenza-related hospitalizations (RR: 0.91, 95% CI: 0.81, 1.04) compared with the influenza cohort. Co-administration was associated with 3% lower all-cause medical cost (cost ratio: 0.974, 95% CI: 0.968, 0.979) during the follow-up period compared to receiving influenza vaccine only.

LIMITATIONS

Limitations include the potential residual confounding bias in observational data, measurement errors from claims data, and that the cohort was followed for a single season.

CONCLUSION

Receiving co-administered COVID-19 and influenza vaccines versus only receiving influenza vaccination reduced the risk of HCRU, especially COVID-19-related hospitalization and all-cause medical costs. Increasing vaccine coverage, particularly for COVID-19, might have public health and economic benefits.

Ethical and Legal Debates on Vaccine Infodemics

Over the course of three and a half years, the global toll of coronavirus disease 2019 (COVID-19) has claimed the lives of millions of individuals. Scientific breakthroughs, exemplified by mRNA vaccines, have emerged as crucial tools in saving numerous lives and fortifying our defenses against future pandemics. However, the battle against the virus has been complicated by the dissemination of misleading political and ethical information, resulting in avoidable fatalities. Recognizing this phenomenon, the term 'infodemics' has been coined to denote the proliferation of false or misleading information that hinders effective social responses. Given the historical prevalence of infodemics surrounding vaccinations, this discussion delves into the ongoing ethical and legal deliberations concerning vaccination mandates, an indispensable health intervention in the face of pandemics. Governments bear the responsibility of safeguarding their citizens, acknowledging the social requirements imposed by the collective well-being. The protection of both citizens and healthcare workers becomes paramount, considering the potential risks of infection and mortality associated with individuals refusing vaccination. Historically, governments have played a pivotal role in eradicating pandemics through the implementation of vaccine mandates. However, the contemporary landscape is marked by the infusion of political and misleading misinformation, presenting new challenges. Governments are now confronted with an ethical duty to ensure that citizens possess the necessary information to make informed decisions and safeguard their well-being. While grappling with the realization that extraordinary circumstances demand extraordinary responses, the lessons from past pandemics underscore the imperative of prioritizing public health, especially in the context of the high numbers of casualties worldwide. This discourse explores the ethical and legal dimensions surrounding vaccine mandates, with particular emphasis on their relevance to healthcare workers.

Evaluation of the Abdala Vaccine: Antibody and Cellular Response to the RBD Domain of SARS-CoV-2

Abdala is a recently released RBD protein subunit vaccine against SARS-CoV-2. A few countries, including Mexico, have adopted Abdala as a booster dose in their COVID-19 vaccination schemes. Despite that, most of the Mexican population has received full-scheme vaccination with platforms other than Abdala; little is known regarding Abdala's immunological features, such as its antibody production and T- and B-cell-specific response induction. This work aimed to study antibody production and the adaptive cellular response in the Mexican population that received the Abdala vaccine as a booster. We recruited 25 volunteers and evaluated their RBD-specific antibody production, T- and B-cell-activating profiles, and cytokine production. Our results showed that the Abdala vaccine increases the concentration of RBD IgG-specific antibodies. Regarding the cellular response, after challenging peripheral blood cultures with RBD, the plasmablast (CD19+CD27+CD38High) and transitional B-cell (CD19+CD21+CD38High) percentages increased significantly, while T cells showed an increased activated phenotype (CD3+CD4+CD25+CD69+ and CD3+CD4+CD25+HLA-DR+). Also, IL-2 and IFN-γ increased significantly in the supernatant of the RBD-stimulated cells. Our results suggest that Abdala vaccination, used as a booster, evokes antibody production and the activation of previously generated memory against the SARS-CoV-2 RBD domain.

Testing for Cytomegalovirus Among Individuals Who Were Immunocompromised, 2018-2022

This cohort study investigates rates of cytomegalovirus testing before and during the COVID-19 pandemic among individuals who were immunocompromised.

In vitro generated antibodies guide thermostable ADDomer nanoparticle design for nasal vaccination and passive immunization against SARS-CoV-2

Background

Due to COVID-19, pandemic preparedness emerges as a key imperative, necessitating new approaches to accelerate development of reagents against infectious pathogens.

Methods

Here, we developed an integrated approach combining synthetic, computational and structural methods with in vitro antibody selection and in vivo immunization to design, produce and validate nature-inspired nanoparticle-based reagents against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Results

Our approach resulted in two innovations: (i) a thermostable nasal vaccine called ADDoCoV, displaying multiple copies of a SARS-CoV-2 receptor binding motif derived epitope and (ii) a multivalent nanoparticle superbinder, called Gigabody, against SARS-CoV-2 including immune-evasive variants of concern (VOCs). In vitro generated neutralizing nanobodies and electron cryo-microscopy established authenticity and accessibility of epitopes displayed by ADDoCoV. Gigabody comprising multimerized nanobodies prevented SARS-CoV-2 virion attachment with picomolar EC50. Vaccinating mice resulted in antibodies cross-reacting with VOCs including Delta and Omicron.

Conclusion

Our study elucidates Adenovirus-derived dodecamer (ADDomer)-based nanoparticles for use in active and passive immunization and provides a blueprint for crafting reagents to combat respiratory viral infections.

Hospitalization Among Patients Treated With Molnupiravir: A Retrospective Study of Administrative Data

PURPOSE

Molnupiravir is an oral antiviral agent authorized for emergency use to treat mild to moderate cases of coronavirus disease 2019 (COVID-19) in adults at high risk for progression to severe clinical outcomes. This study aimed to describe patient characteristics and health outcomes in a cohort of adult patients treated with molnupiravir in an outpatient setting in the United States.

METHODS

This was a retrospective cohort study of adults identified in the HealthVerity database with a pharmacy claim for molnupiravir between December 24, 2021, and April 14, 2022. Hospitalization and health care use were assessed over the 28 days after the molnupiravir pharmacy claim.

FINDINGS

Among 26,554 patients identified, 71.1% were aged ≥50 years and 58.9% were female. A total of 8794 patients (33.1%) had received at least 1 dose of the COVID-19 vaccine. The most prevalent risk factors for severe COVID-19 identified were hypertension (45.1%), steroid and/or immunosuppressant use (39.6%), and being obese or overweight (24.6%), with 79.1% of patients having ≥1 risk factor. The majority (61.0%) of patients were prescribed comedications contraindicated with or had the potential for major drug-drug interactions with ritonavir-containing regimens. Within 28 days after initiating molnupiravir, 3.3% of patients were hospitalized for any cause and 1.7% for COVID-19-related reasons. Among all hospitalized patients, 9.2% were admitted to an intensive care unit, 3.9% received oxygen, and 3.8% required mechanical ventilation.

IMPLICATIONS

The majority of patients treated with molnupiravir in early 2022 had at least one risk factor for severe COVID-19 and had comedications that could require treatment modification or monitoring if given a ritonavir-containing regimen. Hospitalization was uncommon after treatment with molnupiravir, with COVID-19-related inpatient admission in <2% of patients. Among those hospitalized, patient use of intensive care and oxygen-based resources was infrequent. The study design, however, does not permit any conclusions regarding the effectiveness of molnupiravir.

SARS-CoV-2 vaccine breakthrough infection in the older adults: a meta-analysis and systematic review

BACKGROUND

Corona Virus Disease 2019 (COVID-19) mRNA vaccine effectiveness (VE) has recently declined, and reports about COVID-19 breakthrough infection have increased. We aimed to conduct a meta-analysis on population-based studies of the prevalence and incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) breakthrough infection amongst older adults worldwide.

METHODS

Studies from PubMed, Embase, Cochrane Library, and Web of Science were systematically screened to determine the prevalence and incidence of SARS-CoV-2 breakthrough infection in older adults from inception to November 2, 2022. Our meta-analysis included 30 studies, all published in English. Pooled estimates were calculated using a random-effect model through the inverse variance method. Publication bias was tested through funnel plots and Egger's regression test, and sensitivity analyses were performed to confirm the robustness of the results. This research was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Thirty publications were included in this meta-analysis (17 on prevalence, 17 on incidence, and 4 on both). The pooled prevalence of COVID-19 breakthrough infection among older adults was 7.7 per 1,000 persons (95% confidence interval [95%CI] 4.0-15.0). At the same time, the pooled incidence was 29.1 per 1000 person-years (95%CI 15.2-55.7).

CONCLUSIONS

This meta-analysis provides estimates of prevalence and incidence in older adults. We concluded that the prevalence and incidence of SARS-CoV-19 breakthrough infection in older people was low. The prevalence and incidence of breakthrough infection admitted to hospital, severe-critical, and deathly was significantly lower. Otherwise, there was considerable heterogeneity among estimates in this study, which should be considered when interpreting the results.

Comparison of antibody persistency through one year between one-dose and two-dose regimens of Ad5-nCoV vaccine for COVID-19

This post-hoc analysis compared the receptor-binding domain (RBD)-specific and pseudovirus neutralizing antibodies against the wild-type SARS-CoV-2 strain elicited by one or two doses (56-d interval) of Ad5-nCoV vaccine regimen (NCT04341389 and NCT04566770). Both trials had low-dose and high-dose groups. Propensity score matching was used to adjust the baseline between one- and two-dose regimens. To predict the decrease in antibody titers 1 y after vaccination, half-lives of RBD-binding antibodies and pseudovirus neutralizing antibodies were computed. We obtained 34 and 29 pairs of participants in the low- and high-dose groups based on the propensity score matching. The two-dose regimen of Ad5-nCoV increased the peaking level of neutralizing antibodies compared to the one-dose regimen at day 28, but the responses of the neutralizing antibodies were not consistent with those of the RBD antibodies. Half-lives of the RBD-binding antibodies in the two-dose Ad5-nCoV regimen (202-209 days) were longer than those in the one-dose regimen (136-137 d); half-lives of the pseudovirus neutralizing antibody in the one-dose Ad5-nCoV regimen (177 d) were longer than those in the two-dose regimen (116-131 d). The predicted positive rates of RBD-binding antibodies in the one-dose regimen (34.1%-38.3%) would be lower than those in the two-dose Ad5-nCoV regimen (67.0%-84.0%), while the positive rates of pseudovirus neutralizing antibodies in the one-dose regimen (65.4%-66.7%) would be higher than those in the two-dose regimen (48.3%-58.0%). The two-dose Ad5-nCoV regimen with a 56-d interval had no effect on the persistence of neutralizing antibodies but slowed decay trend of RBD-binding antibodies.

The End or a New Era of Development of SARS-CoV-2 Virus: Genetic Variants Responsible for Severe COVID-19 and Clinical Efficacy of the Most Commonly Used Vaccines in Clinical Practice

Although the chief of the World Health Organization (WHO) has declared the end of the coronavirus disease 2019 (COVID-19) as a global health emergency, the disease is still a global threat. To be able to manage such pandemics in the future, it is necessary to develop proper strategies and opportunities to protect human life. The data on the SARS-CoV-2 virus must be continuously analyzed, and the possibilities of mutation and the emergence of new, more infectious variants must be anticipated, as well as the options of using different preventive and therapeutic techniques. This is because the fast development of severe acute coronavirus 2 syndrome (SARS-CoV-2) variants of concern have posed a significant problem for COVID-19 pandemic control using the presently available vaccinations. This review summarizes data on the SARS-CoV-2 variants that are responsible for severe COVID-19 and the clinical efficacy of the most commonly used vaccines in clinical practice. The consequences after the disease (long COVID or post-COVID conditions) continue to be the subject of studies and research, and affect social and economic life worldwide.

A Meta-Analysis To Ascertain the Effectiveness of COVID-19 Vaccines on Clinical Outcomes in Patients With COVID-19 Infection in North America

The challenges in controlling the pandemic have been exacerbated by the disease's morbidity and the emergence of additional COVID-19 variants. The use of emergency vaccines to circumvent these challenges has sparked mixed opinions on their effectiveness. Therefore, we conducted a meta-analysis to assess the efficacy of COVID-19 vaccines on clinical outcomes such as incidence, hospitalization, and ventilation rates in both vaccinated and unvaccinated patients. PubMed, Google Scholar, and Cochrane Central Register of Clinical Trials were searched on April 21, 2022, to extract published articles comparing vaccinated COVID-19 patients versus unvaccinated COVID-19 patients and their clinical outcomes. The clinical outcomes studied were incidence rate, intensive care unit (ICU) admission, mechanical ventilation, and hospitalization rates. The analysis was performed with Review Manager (RevMan) software. Random-effect models were used to calculate pooled odds ratio and corresponding 95% confidence interval (CI). In our meta-analysis, we have identified a total of 250 published findings, encompassing 15 studies that involved a cumulative count of 24,164,227 individuals diagnosed with COVID-19. Being unvaccinated had a significant association with severe clinical outcomes in patients infected with COVID-19. Unvaccinated individuals were 2.36 times more likely to be infected, with a 95% CI ranging from 1.13 to 4.94 (p = 0.02). Unvaccinated subjects with COVID-19 infection were 6.93 times more likely to be admitted to the ICU than their vaccinated counterparts, with a 95% CI ranging from 3.57 to 13.46 (p < 0.0001). The hospitalization rate was 3.37 higher among the unvaccinated compared to those vaccinated, with a 95% CI ranging from 1.92 to 5.93 (p < 0.0001). In addition, patients with COVID-19 infection who are unvaccinated were 6.44 times more likely to be mechanically ventilated than those vaccinated, with a 95% CI ranging from 3.13 to 13.23 (p < 0.0001). Overall, our study revealed that vaccination against COVID-19 disease is beneficial and effective in mitigating the spread of the infection and associated clinical outcomes. However, more awareness and proper education must be made to increase vaccine acceptance. We, therefore, recommend and urge all stakeholders involved in COVID-19 prevention, management, and control to strengthen awareness and educate the people on the effectiveness of COVID-19 vaccination.

Prevalence of potential drug-drug interactions with ritonavir-containing COVID-19 therapy

BACKGROUND: Patients with COVID-19 receiving ritonavir-containing therapies are at risk of potential drug-drug interactions (pDDIs) because of ritonavir's effects on cytochrome P450 3A4. OBJECTIVE: To assess the prevalence of pDDIs with ritonavir-containing COVID-19 therapy in adults with COVID-19 using the Optum Clinformatics Data Mart database. METHODS: In this retrospective, observational cohort study, patients with COVID-19 aged 18 years or older prescribed cytochrome P450 3A4-mediated medications with supply days overlapping the date of COVID-19 diagnosis between January 1, 2020, and June 30, 2021, were classified as having pDDIs. pDDI was classified as contraindicated, major, moderate, or mild using established drug interaction resources. Prevalence of pDDIs with ritonavir-containing COVID-19 therapy was estimated for the entire cohort and in patient groups with high risk of severe COVID-19 progression or pDDIs. Actual COVID-19 treatments received by the patients, if any, were not considered. Outcomes were presented descriptively without adjusted comparisons. RESULTS: A total of 718,387 patients with COVID-19 were identified. The age-sex standardized national prevalence of pDDIs of any severity was estimated at 52.2%. Approximately 34.5% were at risk of contraindicated or major pDDIs. Compared with patients without pDDI, patients exposed to pDDIs were older and more likely to be female, reside in long-term care facilities, and have risk factors for progression to severe COVID-19. Higher prevalence of major/contraindicated pDDIs was observed in older patients (76.1%), female patients (65.0%), and patients with multiple morbidities (84.6%). CONCLUSIONS: Study findings demonstrate that more than one-third of patients with COVID-19 were at risk of significant pDDIs if treated with ritonavir-containing COVID-19 therapy and highlight the need to assess all patients with COVID-19 for pDDIs. Ritonavir-based therapies may not be appropriate for certain patient groups, and alternative therapies should be considered. DISCLOSURES: Drs Igho-Osagie, Puenpatom, and Grifasi Williams are employees of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc. Dr Song and Ms He are employees of Analysis Group, Inc., and served as paid consultants for Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc. Drs Yi and Wang, and Mr Berman, and Ms Gu were employees of Analysis Group, Inc., at the time of study conduct. Financial support for this study was provided by Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc. The study sponsor was involved in the design and conduct of the study; collection, management, analysis, interpretation of data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Booster vaccination with Ad26.COV2.S or an Omicron-adapted vaccine in pre-immune hamsters protects against Omicron BA.2

Since the original outbreak of the SARS-CoV-2 virus, several rapidly spreading SARS-CoV-2 variants of concern (VOC) have emerged. Here, we show that a single dose of Ad26.COV2.S (based on the Wuhan-Hu-1 spike variant) protects against the Gamma and Delta variants in naive hamsters, supporting the observed maintained vaccine efficacy in humans against these VOC. Adapted spike-based booster vaccines targeting Omicron variants have now been authorized in the absence of human efficacy data. We evaluated the immunogenicity and efficacy of Ad26.COV2.S.529 (encoding a stabilized Omicron BA.1 spike) in naive mice and in hamsters with pre-existing immunity to the Wuhan-Hu-1 spike. In naive mice, Ad26.COV2.S.529 elicited higher neutralizing antibody titers against SARS-CoV-2 Omicron BA.1 and BA.2, compared with Ad26.COV2.S. However, neutralizing titers against the SARS-CoV-2 B.1 (D614G) and Delta variants were lower after primary vaccination with Ad26.COV2.S.529 compared with Ad26.COV2.S. In contrast, we found comparable Omicron BA.1 and BA.2 neutralizing titers in hamsters with pre-existing Wuhan-Hu-1 spike immunity after vaccination with Ad26.COV2.S, Ad26.COV2.S.529 or a combination of the two vaccines. Moreover, all three vaccine modalities induced equivalent protection against Omicron BA.2 challenge in these animals. Overall, our data suggest that an Omicron BA.1-based booster in rodents does not improve immunogenicity and efficacy against Omicron BA.2 over an Ad26.COV2.S booster in a setting of pre-existing immunity to SARS-CoV-2.

COVID-19 Health Passes: Practical and Ethical Issues

Several countries have implemented COVID-19 health passes or certificates to promote a safer return to in-person social activities. These passes have been proposed as a way to prove that someone has been vaccinated, has recovered from the disease, or has negative results on a diagnostic test. However, many people have questioned their ethical justification. This article presents some practical and ethical problems to consider in the event of wishing to implement these passes. Among the former, it is questioned how accurate diagnostic tests are as a means of ensuring that a person is not contagious, whether vaccination guarantees immunity, the fact that health passes can be forged, whether they encourage vaccination, and the problem that there is no universally recognized health pass. Among the ethical issues, it is discussed whether health passes promote discrimination and inequality and whether they violate rights to privacy and freedom. It is concluded that health passes have enough ethical justification to be implemented.

Quantifying Antibody Persistence After a Single Dose of COVID-19 Vaccine Ad26.COV2.S in Humans Using a Mechanistic Modeling and Simulation Approach

Understanding persistence of humoral immune responses elicited by vaccination against coronavirus disease 2019 (COVID-19) is critical for informing the duration of protection and appropriate booster timing. We developed a mechanistic model to characterize the time course of humoral immune responses in severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-seronegative adults after primary vaccination with the Janssen COVID-19 vaccine, Ad26.COV2.S. The persistence of antibody responses was quantified through mechanistic modeling-based simulations. Two biomarkers of humoral immune responses were examined: SARS-CoV-2 neutralizing antibodies determined by wild-type virus neutralization assay (wtVNA) and spike protein-binding antibodies determined by indirect spike protein enzyme-linked immunosorbent assay (S-ELISA). The persistence of antibody responses was defined as the period of time during which wtVNA and S-ELISA titers remained above the lower limit of quantification. A total of 442 wtVNA and 1,185 S-ELISA titers from 82 and 220 participants, respectively, were analyzed following administration of a single dose of Ad26.COV2.S (5 × 10¹⁰ viral particles). The mechanistic model adequately described the time course of observed wtVNA and S-ELISA serum titers and its associated variability up to 8 months following vaccination. Mechanistic model-based simulations show that single-dose Ad26.COV2.S elicits durable but waning antibody responses up to 24 months following immunization. Of the estimated model parameters, the production rate of memory B cells was decreased in older adults relative to younger adults, and the antibody production rate mediated by long-lived plasma cells was increased in women relative to men. A steeper waning of antibody responses was predicted in men and in older adults.

Evaluating Johnson and Johnson COVID-19 Vaccination Outcomes in a Low-Income Hispanic Population

BACKGROUND

A pilot study was performed at a low-income emergency care clinic to assess the humoral immune response to the Johnson & Johnson (J&J) COVID-19 vaccine (Ad26.COV2.S) to better understand how to evaluate the COVID-19 health status of its Hispanic patient population following vaccination.

METHODS

This study used the Clungene^® SARS-CoV-2 IgG/IgM Rapid Test Cassette to determine the presence of binding antibodies resulting from the J&J COVID-19 vaccine. The Clungene test principle is based on the receptor-binding domain (RBD) of the spike protein. Antibodies targeting the spike protein are considered an appropriate measure of humoral response from spike-based vaccines.

RESULTS

The study confirmed previous research that antibodies wane over time, and results are consistent with reported vaccine efficacy. There was a statistically significant relationship between the humoral immune response and demographic and health status variables.

CONCLUSIONS

COVID-19 negative patients can be easily and efficiently monitored to determine the success and durability of COVID-19 vaccines in low-income minority populations. The use of simple low-cost spike targeted COVID-19 antibody lateral flow devices may serve as a useful adjunct to assist community-based physicians on the COVID-19 health status of its patients. Further research is needed to confirm the utility of this approach.

The impact of vaccination and outpatient treatment on the economic burden of Covid-19 in the United States omicron era: a systematic literature review

AIMS

To identify and synthesize evidence regarding how coronavirus disease 2019 (COVID-19) interventions, including vaccines and outpatient treatments, have impacted healthcare resource use (HCRU) and costs in the United States (US) during the Omicron era.

MATERIALS AND METHODS

A systematic literature review (SLR) was performed to identify articles published between 1 January 2021 and 10 March 2023 that assessed the impact of vaccination and outpatient treatment on costs and HCRU outcomes associated with COVID-19. Screening was performed by two independent researchers using predefined inclusion/exclusion criteria.

RESULTS

Fifty-eight unique studies were included in the SLR, of which all reported HCRU outcomes, and one reported costs. Overall, there was a significant reduction in the risk of COVID-19-related hospitalization for patients who received an original monovalent primary series vaccine plus booster dose vs. no vaccination. Moreover, receipt of a booster vaccine was associated with a lower risk of hospitalization vs. primary series vaccination. Evidence also indicated a significantly reduced risk of hospitalizations among recipients of nirmatrelvir/ritonavir (NMV/r), remdesivir, sotrovimab, and molnupiravir compared to non-recipients. Treated and/or vaccinated patients also experienced reductions in intensive care unit (ICU) admissions, length of stay, and emergency department (ED)/urgent care clinic encounters.

LIMITATIONS

The identified studies may not represent unique patient populations as many utilized the same regional/national data sources. Synthesis of the evidence was also limited by differences in populations, outcome definitions, and varying duration of follow-up across studies. Additionally, significant gaps, including HCRU associated with long COVID and various high-risk populations and cost data, were observed.

CONCLUSIONS

Despite evidence gaps, findings from the SLR highlight the significant positive impact that vaccination and outpatient treatment have had on HCRU in the US, including periods of Omicron predominance. Continued research is needed to inform clinical and policy decision-making in the US as COVID-19 continues to evolve as an endemic disease.

Frequently Asked Questions on Coronavirus Disease 2019 Vaccination for Hematopoietic Cell Transplantation and Chimeric Antigen Receptor T-Cell Recipients From the American Society for Transplantation and Cellular Therapy and the American Society of Hematology

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), disproportionately affects immunocompromised and elderly patients. Not only are hematopoietic cell transplantation (HCT) and chimeric antigen receptor (CAR) T-cell recipients at greater risk for severe COVID-19 and COVID-19-related complications, but they also may experience suboptimal immune responses to currently available COVID-19 vaccines. Optimizing the use, timing, and number of doses of the COVID-19 vaccines in these patients may provide better protection against SARS-CoV-2 infection and better outcomes after infection. To this end, current guidelines for COVID-19 vaccination in HCT and CAR T-cell recipients from the American Society of Transplantation and Cellular Therapy Transplant Infectious Disease Special Interest Group and the American Society of Hematology are provided in a frequently asked questions format.

Efficacy, safety, and immunogenicity of a booster regimen of Ad26.COV2.S vaccine against COVID-19 (ENSEMBLE2): results of a randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Despite the availability of effective vaccines against COVID-19, booster vaccinations are needed to maintain vaccine-induced protection against variant strains and breakthrough infections. This study aimed to investigate the efficacy, safety, and immunogenicity of the Ad26.COV2.S vaccine (Janssen) as primary vaccination plus a booster dose.

METHODS

ENSEMBLE2 is a randomised, double-blind, placebo-controlled, phase 3 trial including crossover vaccination after emergency authorisation of COVID-19 vaccines. Adults aged at least 18 years without previous COVID-19 vaccination at public and private medical practices and hospitals in Belgium, Brazil, Colombia, France, Germany, the Philippines, South Africa, Spain, the UK, and the USA were randomly assigned 1:1 via a computer algorithm to receive intramuscularly administered Ad26.COV2.S as a primary dose plus a booster dose at 2 months or two placebo injections 2 months apart. The primary endpoint was vaccine efficacy against the first occurrence of molecularly confirmed moderate to severe-critical COVID-19 with onset at least 14 days after booster vaccination, which was assessed in participants who received two doses of vaccine or placebo, were negative for SARS-CoV-2 by PCR at baseline and on serology at baseline and day 71, had no major protocol deviations, and were at risk of COVID-19 (ie, had no PCR-positive result or discontinued the study before day 71). Safety was assessed in all participants; reactogenicity, in terms of solicited local and systemic adverse events, was assessed as a secondary endpoint in a safety subset (approximately 6000 randomly selected participants). The trial is registered with ClinicalTrials.gov, NCT04614948, and is ongoing.

FINDINGS

Enrolment began on Nov 16, 2020, and the primary analysis data cutoff was June 25, 2021. From 34 571 participants screened, the double-blind phase enrolled 31 300 participants, 14 492 of whom received two doses (7484 in the Ad26.COV2.S group and 7008 in the placebo group) and 11 639 of whom were eligible for inclusion in the assessment of the primary endpoint (6024 in the Ad26.COV2.S group and 5615 in the placebo group). The median (IQR) follow-up post-booster vaccination was 36·0 (15·0-62·0) days. Vaccine efficacy was 75·2% (adjusted 95% CI 54·6-87·3) against moderate to severe-critical COVID-19 (14 cases in the Ad26.COV2.S group and 52 cases in the placebo group). Most cases were due to the variants alpha (B.1.1.7) and mu (B.1.621); endpoints for the primary analysis accrued from Nov 16, 2020, to June 25, 2021, before the global dominance of delta (B.1.617.2) or omicron (B.1.1.529). The booster vaccine exhibited an acceptable safety profile. The overall frequencies of solicited local and systemic adverse events (evaluated in the safety subset, n=6067) were higher among vaccine recipients than placebo recipients after the primary and booster doses. The frequency of solicited adverse events in the Ad26.COV2.S group were similar following the primary and booster vaccinations (local adverse events, 1676 [55·6%] of 3015 vs 896 [57·5%] of 1559, respectively; systemic adverse events, 1764 [58·5%] of 3015 vs 821 [52·7%] of 1559, respectively). Solicited adverse events were transient and mostly grade 1-2 in severity.

INTERPRETATION

A homologous Ad26.COV2.S booster administered 2 months after primary single-dose vaccination in adults had an acceptable safety profile and was efficacious against moderate to severe-critical COVID-19. Studies assessing efficacy against newer variants and with longer follow-up are needed.

FUNDING

Janssen Research & Development.

Delta variant (B.1.617.2) of SARS-CoV-2: Mutations, impact, challenges and possible solutions

Since commencement of COVID-19 pandemic, several SARS-CoV-2 variants have emerged amid containment efforts via vaccination. The Delta variant (B.1.617.2), discovered in October 2020, was designated as a VOC by the WHO on May 11, 2021. The enhanced transmissibility of Delta variant has been associated with critical mutations such as D614G, L452R, P681R, and T478K in the S-protein. The increased affinity of the S-protein and ACE2 has been postulated as a key reason for decreased vaccine efficacy. As per evidence, the Delta variant possesses increased transmissibility and decreased vaccine efficacy compared to other VOCs like Alpha and Beta. This has led to concerns regarding the acquisition of novel mutations in the Delta variant and outbreaks in vulnerable communities, including vaccinated people. In this mini-review of Delta variant, we have explained its evolution and characteristics, the impact of spike mutations on infectivity and immune evasion, and measures to combat future outbreaks.

Identifying susceptibility of children and adolescents to the Omicron variant (B.1.1.529)

BACKGROUND

The Omicron variant (B.1.1.529) is estimated to be more transmissible than previous strains of SARS-CoV-2 especially among children, potentially resulting in croup which is a characteristic disease in children. Current coronavirus disease 2019 (COVID-19) cases among children might be higher because (i) school-aged children have higher contact rates and (ii) the COVID-19 vaccination strategy prioritizes the elderly in most countries. However, there have been no reports confirming the age-varying susceptibility to the Omicron variant to date.

METHODS

We developed an age-structured compartmental model, combining age-specific contact matrix in South Korea and observed distribution of periods between each stage of infection in the national epidemiological investigation. A Bayesian inference method was used to estimate the age-specific force of infection and, accordingly, age-specific susceptibility, given epidemic data during the third (pre-Delta), fourth (Delta driven), and fifth (Omicron driven) waves in South Korea. As vaccine uptake increased, individuals who were vaccinated were excluded from the susceptible population in accordance with vaccine effectiveness against the Delta and Omicron variants, respectively.

RESULTS

A significant difference between the age-specific susceptibility to the Omicron and that to the pre-Omicron variants was found in the younger age group. The rise in susceptibility to the Omicron/pre-Delta variant was highest in the 10-15 years age group (5.28 times [95% CI, 4.94-5.60]), and the rise in susceptibility to the Omicron/Delta variant was highest in the 15-19 years age group (3.21 times [95% CI, 3.12-3.31]), whereas in those aged 50 years or more, the susceptibility to the Omicron/pre-Omicron remained stable at approximately twofold.

CONCLUSIONS

Even after adjusting for contact pattern, vaccination status, and waning of vaccine effectiveness, the Omicron variant of SARS-CoV-2 tends to propagate more easily among children than the pre-Omicron strains.

Real-world comparative effectiveness of mRNA-1273 and BNT162b2 vaccines among immunocompromised adults identified in administrative claims data in the United States

INTRODUCTION

Head-to-head studies comparing COVID-19 mRNA vaccine effectiveness in immunocompromised individuals, who are vulnerable to severe disease are lacking, as large sample sizes are required to make meaningful inferences.

METHODS

This observational comparative effectiveness study was conducted in closed administrative claims data from the US HealthVerity database (December 11, 2020-January 10, 2022, before omicron). A 2-dose mRNA-1273 versus BNT162b2 regimen was assessed for preventing medically-attended breakthrough COVID-19 diagnosis and hospitalizations among immunocompromised adults. Inverse probability of treatment weighting was applied to balance baseline characteristics between vaccine groups. Incidence rates from patient-level data and hazard ratios (HRs) using weighted Cox proportional hazards models were calculated.

RESULTS

Overall, 57,898 and 66,981 individuals received a 2-dose regimen of mRNA-1273 or BNT161b2, respectively. Among the weighted population, mean age was 51 years, 53 % were female, and baseline immunodeficiencies included prior blood transplant (8%-9%), prior organ transplant (7%), active cancer (12%-13%), primary immunodeficiency (5-6%), HIV (20%-21%), and immunosuppressive therapy use (60%-61%). Rates per 1,000 person-years (PYs; 95% confidence intervals [CI]s) of breakthrough medically-attended COVID-19 were 25.82 (23.83-27.97) with mRNA-1273 and 30.98 (28.93, 33.18) with BNT162b2 (HR, 0.83; 95% CI, 0.75-0.93). When requiring evidence of an antigen or polymerase chain reaction test before COVID-19 diagnosis, the HR for medically-attended COVID-19 was 0.78 (0.67-0.92). Breakthrough COVID-19 hospitalization rates per 1,000 PYs (95% CI) were 3.66 (2.96-4.51) for mRNA-1273 and 4.68 (3.91-5.59) for BNT162b2 (HR, 0.78; 0.59-1.03). Utilizing open and closed claims for outcome capture only, or both cohort entry/outcome capture, produced HRs (95% CIs) for COVID-19 hospitalization of 0.72 (0.57-0.92) and 0.66 (0.58-0.76), respectively.

CONCLUSIONS

Among immunocompromised adults, a 2-dose mRNA-1273 regimen was more effective in preventing medically-attended COVID-19 in any setting (inpatient and outpatient) than 2-dose BNT162b2. Results were similar for COVID-19 hospitalization, although statistical power was limited when using closed claims only.

STUDY REGISTRATION

NCT05366322.

Fast-track development of vaccines for SARS-CoV-2: The shots that saved the world

In December 2019, an outbreak emerged of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which leads to coronavirus disease 2019 (COVID-19). The World Health Organisation announced the outbreak a global health emergency on 30 January 2020 and by 11 March 2020 it was declared a pandemic. The spread and severity of the outbreak took a heavy toll and overburdening of the global health system, particularly since there were no available drugs against SARS-CoV-2. With an immediate worldwide effort, communication, and sharing of data, large amounts of funding, researchers and pharmaceutical companies immediately fast-tracked vaccine development in order to prevent severe disease, hospitalizations and death. A number of vaccines were quickly approved for emergency use, and worldwide vaccination rollouts were immediately put in place. However, due to several individuals being hesitant to vaccinations and many poorer countries not having access to vaccines, multiple SARS-CoV-2 variants quickly emerged that were distinct from the original variant. Uncertainties related to the effectiveness of the various vaccines against the new variants as well as vaccine specific-side effects have remained a concern. Despite these uncertainties, fast-track vaccine approval, manufacturing at large scale, and the effective distribution of COVID-19 vaccines remain the topmost priorities around the world. Unprecedented efforts made by vaccine developers/researchers as well as healthcare staff, played a major role in distributing vaccine shots that provided protection and/or reduced disease severity, and deaths, even with the delta and omicron variants. Fortunately, even for those who become infected, vaccination appears to protect against major disease, hospitalisation, and fatality from COVID-19. Herein, we analyse ongoing vaccination studies and vaccine platforms that have saved many deaths from the pandemic.

Preliminary Analysis of the Effects of Ad26.COV2.S Vaccination on CT Findings and High Intensive Care Admission Rates of COVID-19 Patients

On 27 February 2021, the Food and Drug Administration(FDA) authorized the administration of the adenovirus-based Ad26.COV2-S vaccine (J&J-Janssen) for the prevention of COVID-19, a viral pandemic that, to date, has killed more than 5.5 million people. Performed during the early phase of the COVID-19 4th wave, this retrospective observational study aims to report the computerized tomography (CT) findings and intensive care unit admission rates of Ad26.COV2-S-vaccinated vs. unvaccinated COVID-19 patients. From the 1st to the 23rd of December 2021, all confirmed COVID-19 patients that had been subjected to chest non-contrast CT scan analysis were enrolled in the study. These were divided into Ad26.COV2.S-vaccinated (group 1) and unvaccinated patients (group 2). The RSNA severity score was calculated for each patient and correlated to CT findings and type of admission to a healthcare setting after CT-i.e., home care, ordinary hospitalization, sub-intensive care, and intensive care. Descriptive and inference statistical analyses were performed by comparing the data from the two groups. Data from a total of 71 patients were collected: 10 patients in group 1 (4M, 6F, mean age 63.5 years, SD ± 4.2) and 61 patients in group 2 (32M, 29F, mean age 64.7 years, SD ± 3.7). Statistical analysis showed lower values of RSNA severity in group 1 compared to group 2 (mean value 14.1 vs. 15.7, p = 0.009, respectively). Furthermore, vaccinated patients were less frequently admitted to both sub-intensive and high-intensive care units than group 2, with an odds ratio of 0.45 [95%CI (0.01; 3.92)]. Ad26.COV2.S vaccination protects from severe COVID-19 based on CT severity scores. As a result, Ad26.COV2.S-vaccinated COVID-19 patients are more frequently admitted to home in comparison with unvaccinated patients.

Durability of Protection Post-Primary COVID-19 Vaccination in the United States

The durability of immune responses after COVID-19 vaccination will drive long-term vaccine effectiveness across settings and may differ by vaccine type. To determine durability of protection of COVID-19 vaccines (BNT162b2, mRNA-1273, and Ad26.COV2.S) following primary vaccination in the United States, a matched case-control study was conducted in three cohorts between 1 January and 7 September 2021 using de-identified data from a database covering 168 million lives. Odds ratios (ORs) for developing outcomes of interest (breakthrough SARS-CoV-2 infection, hospitalization, or intensive care unit admission) were determined for each vaccine (no direct comparisons). In total, 17,017,435 individuals were identified. Relative to the baseline, stable protection was observed for Ad26.COV2.S against infections (OR [95% confidence interval (CI)], 1.31 [1.18–1.47]) and hospitalizations (OR [95% CI], 1.25 [0.86–1.80]). Relative to the baseline, protection waned over time against infections for BNT162b2 (OR [95% CI], 2.20 [2.01–2.40]) and mRNA-1273 (OR [95% CI], 2.07 [1.87–2.29]) and against hospitalizations for BNT162b2 (OR [95% CI], 2.38 [1.79–3.17]). Baseline protection remained stable for intensive care unit admissions for all three vaccines. Calculated baseline VE was consistent with published literature. This study suggests that the three vaccines in three separate populations may have different durability profiles.

COVID-19 Vaccine Effectiveness Against Progression to In-Hospital Mortality in Zambia, 2021-2022

Background

Coronavirus disease 2019 (COVID-19) vaccines are highly effective for reducing severe disease and mortality. However, vaccine effectiveness data are limited from Sub-Saharan Africa. We report COVID-19 vaccine effectiveness against progression to in-hospital mortality in Zambia.

Methods

We conducted a retrospective cohort study among admitted patients at 8 COVID-19 treatment centers across Zambia during April 2021 through March 2022, when the Delta and Omicron variants were circulating. Patient demographic and clinical information including vaccination status and hospitalization outcome (discharged or died) were collected. Multivariable logistic regression was used to assess the odds of in-hospital mortality by vaccination status, adjusted for age, sex, number of comorbid conditions, disease severity, hospitalization month, and COVID-19 treatment center. Vaccine effectiveness of ≥1 vaccine dose was calculated from the adjusted odds ratio.

Results

Among 1653 patients with data on their vaccination status and hospitalization outcome, 365 (22.1%) died. Overall, 236 (14.3%) patients had received ≥1 vaccine dose before hospital admission. Of the patients who had received ≥1 vaccine dose, 22 (9.3%) died compared with 343 (24.2%) among unvaccinated patients (P < .01). The median time since receipt of a first vaccine dose (interquartile range) was 52.5 (28-107) days. Vaccine effectiveness for progression to in-hospital mortality among hospitalized patients was 64.8% (95% CI, 42.3%-79.4%).

Conclusions

Among patients admitted to COVID-19 treatment centers in Zambia, COVID-19 vaccination was associated with lower progression to in-hospital mortality. These data are consistent with evidence from other countries demonstrating the benefit of COVID-19 vaccination against severe complications. Vaccination is a critical tool for reducing the consequences of COVID-19 in Zambia.

Immunogenicity and efficacy of Ad26.COV2.S: An adenoviral vector-based COVID-19 vaccine

Since its emergence in late 2019, the coronavirus disease 2019 (COVID-19) pandemic has caused substantial morbidity and mortality. Despite the availability of efficacious vaccines, new variants with reduced sensitivity to vaccine-induced protection are a troubling new reality. The Ad26.COV2.S vaccine is a recombinant, replication-incompetent human adenovirus type 26 vector encoding a full-length, membrane-bound severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein in a prefusion-stabilized conformation. This review discusses the immunogenicity and efficacy of Ad26.COV2.S as a single-dose primary vaccination and as a homologous or heterologous booster vaccination. Ad26.COV2.S elicits broad humoral and cellular immune responses, which are associated with protective efficacy/effectiveness against SARS-CoV-2 infection, moderate to severe/critical COVID-19, and COVID-19-related hospitalization and death, including against emerging SARS-CoV-2 variants. The humoral immune responses elicited by Ad26.COV2.S vaccination are durable, continue to increase for at least 2-3 months postvaccination, and involve a range of functional antibodies. Ad26.COV2.S given as a heterologous booster to mRNA vaccine-primed individuals markedly increases humoral and cellular immune responses. The use of Ad26.COV2.S as primary vaccination and as part of booster regimens is supporting the ongoing efforts to control and mitigate the COVID-19 pandemic.

Heterologous immunity induced by 1st generation COVID-19 vaccines and its role in developing a pan-coronavirus vaccine

Severe acute respiratory syndrome virus-2 (SARS-CoV-2), the causative infectious agent of the COVID-19 pandemic, has led to multiple (4-6) waves of infections worldwide during the past two years. The development of vaccines against SARS-CoV-2 has led to successful mass immunizations worldwide, mitigating the worldwide mortality due the pandemic to a great extent. Yet the evolution of new variants highlights a need to develop a universal vaccine which can prevent infections from all virulent SARS-CoV-2. Most of the current first generation COVID-19 vaccines are based on the Spike protein from the original Wuhan-hu-1 virus strain. It is encouraging that they still protect from serious illnesses, hospitalizations and mortality against a number of mutated viral strains, to varying degrees. Understanding the mechanisms by which these vaccines provide heterologous protection against multiple highly mutated variants can reveal strategies to develop a universal vaccine. In addition, many unexposed individuals have been found to harbor T cells that are cross-reactive against SARS-CoV-2 antigens, with a possible protective role. In this review, we will discuss various aspects of natural or vaccine-induced heterologous (cross-reactive) adaptive immunity against SARS-CoV-2 and other coronaviruses, and their role in achieving the concept of a pan-coronavirus vaccine.

Durability of Heterologous and Homologous COVID-19 Vaccine Boosts

IMPORTANCE

Antibody responses elicited by current messenger RNA (mRNA) COVID-19 vaccines decline rapidly and require repeated boosting.

OBJECTIVE

To evaluate the immunogenicity and durability of heterologous and homologous prime-boost regimens involving the adenovirus vector vaccine Ad26.COV2.S and the mRNA vaccine BNT162b2.

DESIGN, SETTING, AND PARTICIPANTS

In this cohort study at a single clinical site in Boston, Massachusetts, 68 individuals who were vaccinated at least 6 months previously with 2 immunizations of BNT162b2 were boosted with either Ad26.COV2.S or BNT162b2. Enrollment of participants occurred from August 12, 2021, to October 25, 2021, and this study involved 4 months of follow-up. Data analysis was performed from November 2021 to February 2022.

EXPOSURES

Participants who were previously vaccinated with BNT162b2 received a boost with either Ad26.COV2.S or BNT162b2.

MAIN OUTCOMES AND MEASURES

Humoral immune responses were assessed by neutralizing, binding, and functional antibody responses for 16 weeks following the boost. CD8+ and CD4+ T-cell responses were evaluated by intracellular cytokine staining assays.

RESULTS

Among 68 participants who were originally vaccinated with BNT162b2 and boosted with Ad26.COV2.S (41 participants; median [range] age, 36 [23-84] years) or BNT162b2 (27 participants; median [range] age, 35 [23-76] years), 56 participants (82%) were female, 7 (10%) were Asian, 4 (6%) were Black, 4 (6%) were Hispanic or Latino, 3 (4%) were more than 1 race, and 53 (78%) were White. Both vaccines were found to be associated with increased humoral and cellular immune responses, including against SARS-CoV-2 variants of concern. BNT162b2 boosting was associated with a rapid increase of Omicron neutralizing antibodies that peaked at a median (IQR) titer of 1018 (699-1646) at week 2 and declined by 6.9-fold to a median (IQR) titer of 148 (95-266) by week 16. Ad26.COV2.S boosting was associated with increased Omicron neutralizing antibodies titers that peaked at a median (IQR) of 859 (467-1838) week 4 and declined by 2.1-fold to a median (IQR) of 403 (208-1130) by week 16.

CONCLUSIONS AND RELEVANCE

Heterologous Ad26.COV2.S boosting was associated with durable humoral and cellular immune responses in individuals who originally received the BNT162b2 vaccine. These data suggest potential benefits of heterologous prime-boost vaccine regimens for SARS-CoV-2.

The Role of Cellular Immunity in the Protective Efficacy of the SARS-CoV-2 Vaccines

Multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines have been approved for clinical use. SARS-CoV-2 neutralizing antibody titers after immunization are widely used as an evaluation indicator, and the roles of cellular immune responses in the protective efficacy of vaccines are rarely mentioned. However, therapeutic monoclonal neutralizing antibodies have shown limited efficacy in improving the outcomes of hospitalized patients with coronavirus disease 2019 (COVID-19), suggesting a passive role of cellular immunity in SARS-CoV-2 vaccines. The synergistic effect of virus-specific humoral and cellular immune responses helps the host to fight against viral infection. In fact, it has been observed that the early appearance of specific T-cell responses is strongly correlated with mild symptoms of COVID-19 patients and that individuals with pre-existing SARS-CoV-2 nonstructural-protein-specific T cells are more resistant to SARS-CoV-2 infection. These findings suggest the important contribution of the cellular immune response to the fight against SARS-CoV-2 infection and severe COVID-19. Nowadays, new SARS-CoV-2 variants that can escape from the neutralization of antibodies are rapidly increasing. However, the epitopes of these variants recognized by T cells are largely preserved. Paying more attention to cellular immune responses may provide new instructions for designing effective vaccines for the prevention of severe disease induced by the break-through infection of new variants and the sequelae caused by virus latency. In this review, we deliberate on the role of cellular immunity against COVID-19 and summarize recent advances in the development of SARS-CoV-2 vaccines and the immune responses induced by vaccines to improve the design of new vaccines and immunization strategies.

Understanding COVID-19 Vaccines Today: Are T-cells Key Players?

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has heavily mutated since the beginning of the coronavirus-2019 (COVID-19) pandemic. In this regard, the so-called variants of concern (VOCs) feature mutations that confer increased transmissibility and evasion of antibody responses. The VOCs have caused significant spikes in COVID-19 cases, raising significant concerns about whether COVID-19 vaccines will protect against current and future variants. In this context, whereas the protection COVID-19 vaccines offer against the acquisition of infection appears compromised, the protection against severe COVID-19 is maintained. From an immunologic standpoint, this is likely underpinned by the maintenance of T-cell responses against VOCs. Therefore, the role of T-cells is essential to understanding the broader adaptive immune response to COVID-19, which has the potential to shape public policies on vaccine protocols and inform future vaccine design. In this review, we survey the literature on the immunology of T-cell responses upon SARS-CoV-2 vaccination with the current FDA-approved and Emergency Use Authorized COVID-19 vaccines.