BNT162b2 mRNA vaccination did not prevent an outbreak of SARS COV-2 variant 501Y.V2 in an elderly nursing home but reduced transmission and disease severity

Epidemiology of COVID-19 outbreaks in aged care facilities during postvaccine period: a systematic review and meta-analysis

OBJECTIVE

We aimed to define the epidemiology of COVID-19 outbreaks in aged care facilities (ACFs) during the postvaccine period, including vaccine effectiveness (VE) for this high-risk group.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Ovid Medline, Ovid Embase, Scopus, Web of Science and Cochrane databases were searched through 1 September 2023.

ELIGIBILITY CRITERIA

Any original observational studies and trials reporting data on COVID-19 outbreaks among the partially/fully vaccinated residents from ACFs during or after the worldwide implementation of vaccine roll-out.

DATA EXTRACTION AND SYNTHESIS

We estimated the attack rate, case fatality rate, mortality rate and VE during postvaccine period. Random effect model was adopted for meta-analysis. Quality assessment on all included studies was performed using the Meta Quality Appraisal Tool.

RESULTS

38 articles were included from 12 countries reporting 79 outbreaks with 1708 confirmed cases of COVID-19 from 78 ACFs. The pooled attack rate was 28% (95% CI 20% to 37%) among the fully vaccinated residents. Two-thirds (62.5%) of the index cases were unvaccinated healthcare professionals (eg, physicians, nurses) and caregivers. Unvaccinated residents had a significantly higher rates (12%) (95% CI 7% to 19%) of mortality compared with the vaccinated residents (2%) (95% CI% 1 to 4%) and the post-COVID-19 vaccine estimates for case fatality rate (13% vs 23%) and hospitalisation rate (17% vs 37%) were substantially lower. VE in preventing disease among residents in ACFs was 73% (95% CI 49% to 86). Overall, the included studies were heterogeneous in nature, however, the risk of bias was low to moderate.

CONCLUSIONS

Our study reaffirmed the impact of vaccination as a key public health measure to minimise the burden of COVID-19 in ACFs. Facilities with higher crowding indexes should be prioritised for vaccination and should advocate for higher vaccination targets among staff and residents as a critical intervention strategy to minimise disease burden in this vulnerable population.

The gut microbe pair of Oribacterium sp. GMB0313 and Ruminococcus sp. GMB0270 confers complete protection against SARS-CoV-2 infection by activating CD8+ T cell-mediated immunity

Despite the potential protective role of the gut microbiome against COVID-19, specific microbes conferring resistance to COVID-19 have not yet been identified. In this work, we aimed to identify and validate gut microbes at the species level that provide protection against SARS-CoV-2 infection. To identify gut microbes conferring protection against COVID-19, we conducted a fecal microbiota transplantation (FMT) from an individual with no history of COVID-19 infection or immunization into a lethal COVID-19 hamster model. FMT from this COVID-19-resistant donor resulted in significant phenotypic changes related to COVID-19 sensitivity in the hamsters. Metagenomic analysis revealed distinct differences in the gut microbiome composition among the hamster groups, leading to the identification of two previously unknown bacterial species: Oribacterium sp. GMB0313 and Ruminococcus sp. GMB0270, both associated with COVID-19 resistance. Subsequently, we conducted a proof-of-concept confirmation animal experiment adhering to Koch's postulates. Oral administration of this gut microbe pair, Oribacterium sp. GMB0313 and Ruminococcus sp. GMB0270, to the hamsters provided complete protection against SARS-CoV-2 infection through the activation of CD8+ T cell mediated immunity. The prophylactic efficacy of the gut microbe pair against SARS-CoV-2 infection was comparable to, or even superior to, current mRNA vaccines. This strong prophylactic efficacy suggests that the gut microbe pair could be developed as a host-directed universal vaccine for all betacoronaviruses, including potential future emerging viruses.

Universal masking during COVID-19 outbreaks in aged care settings: A systematic review and meta-analysis

Aged care facilities (ACF) are a high-risk COVID-19 transmission setting, and older residents are at greater risk of severe outcomes. This systematic review and meta-analysis assessed whether universal masking and COVID-19 vaccination reduce SARS-CoV-2 attack rates (ARs) in ACF. Articles published between 1 December 2019 and 28 February 2022 were screened across five databases (Medline, Embase, PubMed, Scopus, Web of Science and Cumulative Index to Nursing and Allied Health Literature (CINAHL)). Risk of bias was assessed using relevant Joanna Briggs Institute critical appraisal tools. Meta-analysis of single proportions, subgroup analysis, and meta-regression were performed to compare the effects of universal masking and vaccine doses on pooled SARS-CoV-2 ARs. Of 99 included articles, SARS-CoV-2 ARs for residents were available in 86 studies (representing 139 outbreaks), and for staff in 49 studies (78 outbreaks). Universal masking was associated with lower SARS-CoV-2 ARs in ACF outbreaks (AR = 34.9% [95% CI: 27.2-42.6%]) compared to facilities without universal masking (67.3% [54.2-80.4%], p < .0001). In ACF with universal masking prior to outbreak onset, facility-wide testing, and documentation of asymptomatic infection, the asymptomatic AR at time of testing was 11.4% (6.5-17.4%) in residents. Receipt of zero, one and two vaccination doses were associated with ARs of 64.9% (49.6-80.2%), 54.9% (33.7-76.1%) and 45.2% (29.2-61.3%), respectively. To protect residents from COVID-19, ACF should provide vaccination of residents and staff, universal masking for staff, and facility-wide testing during times of heightened community transmission.

Determining the Time of Booster Dose Based on the Half-Life and Neutralization Titers against SARS-CoV-2 Variants of Concern in Fully Vaccinated Individuals

Although mRNA-based COVID-19 vaccines reduce the risk of severe disease, hospitalization and death, vaccine effectiveness (VE) against infection and disease from variants of concern (VOC) wanes over time. Neutralizing antibodies (NAb) are surrogates of protection and are enhanced by a booster dose, but their kinetics and durability remain understudied. Current recommendation of a booster dose does not consider the existing NAb in each individual. Here, we investigated 50% neutralization (NT50) titers against VOC among COVID-19-naive participants receiving the Moderna (n = 26) or Pfizer (n = 25) vaccine for up to 7 months following the second dose, and determined their half-lives. We found that the time it took for NT50 titers to decline to 24, equivalent to 50% inhibitory dilution of 10 international units/mL, was longer in the Moderna (325/324/235/274 days for the D614G/alpha/beta/delta variants) group than in the Pfizer (253/252/174/226 days) group, which may account for the slower decline in VE of the Moderna vaccine observed in real-world settings and supports our hypothesis that measuring the NT50 titers against VOC, together with information on NAb half-lives, can be used to dictate the time of booster vaccination. Our study provides a framework to determine the optimal time of a booster dose against VOC at the individual level. In response to future VOC with high morbidity and mortality, a quick evaluation of NAb half-lives using longitudinal serum samples from clinical trials or research programs of different primary-series vaccinations and/or one or two boosters could provide references for determining the time of booster in different individuals. IMPORTANCE Despite improved understanding of the biology of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), the evolutionary trajectory of the virus is uncertain, and the concern of future antigenically distinct variants remains. Current recommendations for a COVID-19 vaccine booster dose are primarily based on neutralization capacity, effectiveness against circulating variants of concern (VOC), and other host factors. We hypothesized that measuring neutralizing antibody titers against SARS-CoV-2 VOC together with half-life information can be used to dictate the time of booster vaccination. Through detailed analysis of neutralizing antibodies against VOC among COVID-19-naive vaccinees receiving either of two mRNA vaccines, we found that the time it took for 50% neutralization titers to decline to a reference level of protection was longer in the Moderna than in the Pfizer group, which supports our hypothesis. In response to future VOC with potentially high morbidity and mortality, our proof-of-concept study provides a framework to determine the optimal time of a booster dose at the individual level.

The dynamics of SARS-CoV-2 infection in unvaccinated and vaccinated populations in Mumbai, India, between 28 December 2020 and 30 August 2021

The emergence and evolution of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants that could compromise vaccine efficacy (VE) with re-infections in immunized individuals have necessitated continuous surveillance of VE. Here, the occurrence and dynamics of SARS-CoV-2 infections in the context of vaccination during the second wave of infection in Mumbai were evaluated. RT-PCR cycle threshold (Ct) values of the open reading frame (ORF)/envelope (E)/nucleocapsid (N) genes obtained from a total of 42415 samples, comprising unvaccinated (96.88%) and vaccinated cases (3.12%) were analyzed between December 28, 2020, and August 30, 2021. A lower incidence of SARS-CoV-2 infection in fully vaccinated cases (5.07%) compared to partially vaccinated cases (6.5%) and unvaccinated cases (13.453%) was recorded. VE was significant after the first dose of vaccination (ORF gene p-value = 0.003429, and E/N gene p-value = 0.000866). Furthermore, VE was observed to be significant when the post-immunization (first dose) period was stratified to within 30 days (ORF gene p-value = 0.0094 and E/N gene p-value = 0.0023) and to 60 days following the second dose of vaccination (ORF gene p-value = 0.0238). Also, significantly higher efficacy was observed within individuals receiving two doses compared to a single dose (ORF gene p-value = 0.0132 and E/N gene p-value = 0.0387). The emergence of breakthrough infections was also evident (odds ratio= 0.34; 95% confidence interval= 0.27-0.43). Interestingly, viral loads trended towards being higher in some groups of partially vaccinated individuals compared to completely vaccinated and unvaccinated populations. Finally, our results delineated a significantly higher incidence of SARS-CoV-2 acquisition in males, asymptomatic individuals, individuals with comorbidities, and those who were unvaccinated.

After COVID-19 vaccinations: what does living and working in nursing homes look like?

BACKGROUND

Nursing homes were disproportionally affected by the COVID-19 pandemic. Vaccination was considered critical for the normalization of daily live of nursing home residents. The present study investigates the impact of the prolonged COVID-19 pandemic and the effect of vaccinations on the daily lives of residents and staff in Dutch nursing homes.

SETTING AND PARTICIPANTS

The sample consisted of 78 nursing homes that participated in the Dutch national pilot on nursing home visits after the COVID-19 pandemic. One contact person per nursing home was approached for participation in this mixed-methods cross-sectional study.

METHODS

Data was collected twice through questionnaires in April and December 2021. Quantitative questions focused on recent COVID-19 outbreaks, progress of vaccination, effects of vaccination on daily living in the nursing home and burden experienced by staff. Open-ended questions addressed the prolonged effect of the pandemic on residents, family members and staff.

RESULTS

The overall vaccination rate of residents across nursing homes appeared to be high among both residents and staff. However, daily living in the nursing home had not returned to normal concerning personal interactions, visits, the use of facilities and work pressure. Nursing homes continued to report a negative impact of the pandemic on residents, family members and staff.

CONCLUSIONS

Restrictions to the daily lives of residents in nursing homes were stricter than restrictions imposed on society as a whole. Returning to a normal daily living and working was found to be complex for nursing homes. With the emergence of new variants of the virus, policies strongly focusing on risk aversion were predominantly present in nursing homes.

Does potential antibody-dependent enhancement occur during SARS-CoV-2 infection after natural infection or vaccination? A meta-analysis

Coronavirus disease 2019 (COVID-19) continues to constitute an international public health emergency. Vaccination is a prospective approach to control this pandemic. However, apprehension about the safety of vaccines is a major obstacle to vaccination. Amongst health professionals, one evident concern is the risk of antibody-dependent enhancement (ADE), which may increase the severity of COVID-19. To explore whether ADE occurs in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and increase confidence in the safety of vaccination, we conducted a meta-analysis to investigate the relationship between post-immune infection and disease severity from a population perspective. Databases, including PubMed, EMBASE, Chinese National Knowledge Infrastructure, SinoMed, Scopus, Science Direct, and Cochrane Library, were searched for articles on SARS-CoV-2 reinfection published until 25 October 2021. The papers were reviewed for methodological quality, and a random effects model was used to analyse the results. Heterogeneity was assessed using the I2 statistic. Publication bias was evaluated using a funnel plot and Egger's test. Eleven studies were included in the final meta-analysis. The pooled results indicated that initial infection and vaccination were protective factors against severe COVID-19 during post-immune infection (OR = 0.55, 95%CI = 0.31-0.98). A subgroup (post-immune infection after natural infection or vaccination) analysis showed similar results. Primary SARS-CoV-2 infection and vaccination provide adequate protection against severe clinical symptoms after post-immune infection. This finding demonstrates that SARS-CoV-2 may not trigger ADE at the population level.

Impaired immunity and high attack rates caused by SARS‐CoV‐2 variants among vaccinated long‐term care facility residents

Introduction

Long‐term care facilities (LTCF) residents are at high risk for severe coronavirus disease 2019 (COVID‐19), and therefore, COVID‐19 vaccinations were prioritized for residents and personnel in Finland at the beginning of 2021.

Methods

We investigated COVID‐19 outbreaks in two LTCFs, where residents were once or twice vaccinated. After the outbreaks we measured immunoglobulin G (IgG) antibodies to severe acute respiratory syndrome coronavirus 2 spike glycoprotein, neutralizing antibody (NAb) titers, and cell‐mediated immunity markers from residents and healthcare workers (HCWs).

Results

In LTFC‐1, the outbreak was caused by an Alpha variant (B.1.1.7) and the attack rate (AR) among once vaccinated residents was 23%. In LTCF‐2 the outbreak was caused by a Beta variant (B.1.351). Its AR was 47% although all residents had received their second dose 1 month before the outbreak. We observed that vaccination had induced lower IgG concentrations, NAb titers and cell‐mediated immune responses in residents compared to HCWs. Only 1/8 residents had NAb to the Beta variant after two vaccine doses.

Conclusions

The vaccinated elderly remain susceptible to breakthrough infections caused by Alpha and Beta variants. The weaker vaccine response in the elderly needs to be addressed in vaccination protocols, while new variants capable of evading vaccine‐induced immunity continue to emerge.

Antibody response after first and second BNT162b2 vaccination to predict the need for subsequent injections in nursing home residents

We explored antibody response after first and second BNT162b2 vaccinations, to predict the need for subsequent injections in nursing home (NH) residents. 369 NH residents were tested for IgG against SARS-CoV-2 Receptor-Binding Domain (RBD-IgG) and nucleoprotein-IgG (SARS-CoV-2 IgG II Quant and SARS-CoV-2 IgG Alinity assays, Abbott Diagnostics). In NH residents with prior SARS-CoV-2 infection, the first dose elicited high RBD-IgG levels (≥ 4160 AU/mL) in 99/129 cases (76.9%), with no additional antibody gain after the second dose in 74 cases (74.7%). However, a low RBD-IgG level (< 1050 AU/mL) was observed in 28 (21.7%) residents. The persistence of nucleoprotein-IgG and a longer interval between infection and the first dose were associated with a higher RBD-IgG response (p < 0.0001 and p = 0.0013, respectively). RBD-IgG below 50 AU/mL after the first dose predicted failure to reach the antibody concentration associated with a neutralizing effect after the second dose (≥ 1050 AU/mL). The BNT162b2 vaccine elicited a strong humoral response after the first dose in a majority of NH residents with prior SARS-CoV-2 infection. However, about one quarter of these residents require a second injection. Consideration should be given to immunological monitoring in NH residents to optimize the vaccine response in this vulnerable population.

A SARS-CoV-2 Negative Antigen Rapid Diagnostic in RT-qPCR Positive Samples Correlates With a Low Likelihood of Infectious Viruses in the Nasopharynx

Severe acute respiratory syndrome-related coronavirus (SARS-CoV-2) transmission occurs even among fully vaccinated individuals; thus, prompt identification of infected patients is central to control viral circulation. Antigen rapid diagnostic tests (Ag-RDTs) are highly specific, but sensitivity is variable. Discordant RT-qPCR vs. Ag-RDT results are reported, raising the question of whether negative Ag-RDT in positive RT-qPCR samples could imply the absence of infectious viruses. To study the relationship between negative Ag-RDT results with virological, molecular, and serological parameters, we selected a cross-sectional and a follow-up dataset and analyzed virus culture, subgenomic RNA quantification, and sequencing to determine infectious viruses and mutations. We demonstrated that RT-qPCR positive while SARS-CoV-2 Ag-RDT negative discordant results correlate with the absence of infectious virus in nasopharyngeal samples. A decrease in sgRNA detection together with an expected increase in detectable anti-S and anti-N IgGs was also verified in these samples. The data clearly demonstrate that a negative Ag-RDT sample is less likely to harbor infectious SARS-CoV-2 and, consequently, has a lower transmissible potential.

Receptor binding domain-IgG levels correlate with protection in residents facing SARS-CoV-2 B.1.1.7 outbreaks

Background

Limited information exists on nursing home (NH) residents regarding BNT162b2 vaccine efficacy in preventing SARS‐CoV‐2 and severe COVID‐19, and its association with post‐vaccine humoral response.

Methods

396 residents from seven NHs suffering a SARS‐CoV‐2 B.1.1.7 (VOC‐α) outbreak at least 14 days after a vaccine campaign were repeatedly tested using SARS‐CoV‐2 real‐time reverse‐transcriptase polymerase chain reaction on nasopharyngeal swab test (RT‐qPCR). SARS‐CoV‐2 receptor‐binding domain (RBD) of the S1 subunit (RBD‐IgG) was measured in all residents. Nucleocapsid antigenemia (N‐Ag) was measured in RT‐qPCR‐positive residents and serum neutralizing antibodies in vaccinated residents from one NH.

Results

The incidence of positive RT‐qPCR was lower in residents vaccinated by two doses (72/317; 22.7%) vs one dose (10/31; 32.3%) or non‐vaccinated residents (21/48; 43.7%; p < .01). COVID‐19–induced deaths were observed in 5 of the 48 non‐vaccinated residents (10.4%), in 2 of the 31 who had received one dose (6.4%), and in 3 of the 317 (0.9%) who had received two doses (p = .0007). Severe symptoms were more common in infected non‐vaccinated residents (10/21; 47.6%) than in infected vaccinated residents (15/72; 21.0%; p = .002). Higher levels of RBD‐IgG (n = 325) were associated with a lower SARS‐CoV‐2 incidence. No in vitro serum neutralization activity was found for RBD‐IgG levels below 1050 AU/ml. RBD‐IgG levels were inversely associated with N‐Ag levels, found as a risk factor of severe COVID‐19.

Conclusions

Two BNT162b2 doses are associated with a 48% reduction of SARS‐CoV‐2 incidence and a 91.3% reduction of death risk in residents from NHs facing a VOC‐α outbreak. Post‐vaccine RBD‐IgG levels correlate with BNT162b2 protection against SARS‐CoV‐2 B.1.1.7.

Real-Word Effectiveness of Global COVID-19 Vaccines Against SARS-CoV-2 Variants: A Systematic Review and Meta-Analysis

Background

Currently, promoted vaccinations against SARS-CoV-2 are being given out globally. However, the occurrence of numerous COVID-19 variants has hindered the goal of rapid mitigation of the COVID-19 pandemic by effective mass vaccinations. The real-word effectiveness of the current vaccines against COVID-19 variants has not been assessed by published reviews. Therefore, our study evaluated the overall effectiveness of current vaccines and the differences between the various vaccines and variants.

Methods

PubMed, Embase, Cochrane Library, medRxiv, bioRxiv, and arXiv were searched to screen the eligible studies. The Newcastle-Ottawa scale and the Egger test were applied to estimate the quality of the literature and any publication bias, respectively. The pooled incident rates of different variants after vaccination were estimated by single-arm analysis. Meanwhile, the pooled efficacies of various vaccines against variants were evaluated by two-arm analysis using odds ratios (ORs) and vaccine effectiveness (VE).

Results

A total of 6,118 studies were identified initially and 44 articles were included. We found that the overall incidence of variants post first/second vaccine were 0.07 and 0.03, respectively. The VE of the incidence of variants post first vaccine between the vaccine and the placebo or unvaccinated population was 40% and post second vaccine was 96%, respectively. The sub-single-arm analysis showed a low prevalence rate of COVID-19 variants after specific vaccination with the pooled incidence below 0.10 in most subgroups. Meanwhile, the sub-two-arm analysis indicated that most current vaccines had a good or moderate preventive effect on certain variants considering that the VE in these subgroups was between 66 and 95%, which was broadly in line with the results of the sub-single-arm analysis.

Conclusion

Our meta-analysis shows that the current vaccines that are used globally could prevent COVID-19 infection and restrict the spread of variants to a great extent. We would also support maximizing vaccine uptake with two doses, as the effectiveness of which was more marked compared with one dose. Although the mRNA vaccine was the most effective against variants according to our study, specific vaccines should be taken into account based on the local dominant prevalence of variants.

Best practice approaches to outpatient management of people living with Parkinson's disease during the COVID-19 pandemic

The prevalence of Parkinson’s disease (PD) is rising, rendering it one of the most common neurodegenerative diseases. Treatment and monitoring of patients require regular specialized in- and outpatient care. Patients with PD are more likely to have a complicated disease course if they become infected with severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). Regular in-hospital appointments place these patients at risk of exposure to SARS-CoV-2 due to travel and contact with other patients and staff. However, guidelines for the management of outpatients with PD during times of increased risk of infection are currently lacking. These are urgently needed to conduct risk–benefit evaluations to recommend the best medical treatment. This article discusses best practice approaches based on the current literature, as suggested by the multidisciplinary Network of University Medicine (NUM) in Germany. These include measures such as mask-wearing, hand hygiene, social distancing measures, and appropriate testing strategies in outpatient settings, which can minimize the risk of exposure. Furthermore, the urgency of appointments should be considered. Visits of low urgency may be conducted by general practitioners or via telemedicine consultations, whereas in-person presentation is required in case of moderate and high urgency visits. Classification of urgency should be carried out by skilled medical staff, and telemedicine (telephone or video consultations) may be a useful tool in this situation. The currently approved vaccines against SARS-CoV-2 are safe and effective for patients with PD and play a key role in minimizing infection risk for patients with PD.

Rapid antigen testing as a reactive response to surges in nosocomial SARS-CoV-2 outbreak risk

Healthcare facilities are vulnerable to SARS-CoV-2 introductions and subsequent nosocomial outbreaks. Antigen rapid diagnostic testing (Ag-RDT) is widely used for population screening, but its health and economic benefits as a reactive response to local surges in outbreak risk are unclear. We simulate SARS-CoV-2 transmission in a long-term care hospital with varying COVID-19 containment measures in place (social distancing, face masks, vaccination). Across scenarios, nosocomial incidence is reduced by up to 40-47% (range of means) with routine symptomatic RT-PCR testing, 59-63% with the addition of a timely round of Ag-RDT screening, and 69-75% with well-timed two-round screening. For the latter, a delay of 4-5 days between the two screening rounds is optimal for transmission prevention. Screening efficacy varies depending on test sensitivity, test type, subpopulations targeted, and community incidence. Efficiency, however, varies primarily depending on underlying outbreak risk, with health-economic benefits scaling by orders of magnitude depending on the COVID-19 containment measures in place.

Identification of severe acute respiratory syndrome coronavirus 2 breakthrough infections by anti-nucleocapsid antibody among fully vaccinated non-healthcare workers during the transition from the delta to omicron wave

Uncontrolled transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to the emergence of several variants of concern (VOC). As vaccine-induced neutralizing antibodies against VOC waned over time, breakthrough infections (BTIs) have been reported primarily among healthcare workers or in long-term care facilities. Most BTIs were identified by reverse transcription-polymerase chain reaction (RT-PCR) or antigen test for individuals experiencing symptoms, known as symptomatic BTIs. In this study, we detected seroconversion of anti-nucleocapsid (N) antibody to identify both symptomatic and asymptomatic BTIs in a cohort of COVID-19-naive university employees and students following two or three doses of mRNA vaccines. We reported 4 BTIs among 85 (4.7%) participants caused by the Omicron and Delta VOC during the transition from the Delta to Omicron wave of the pandemic; three were symptomatic and confirmed by RT-PCR test and one asymptomatic. A symptomatic reinfection two and half months after a BTI was found in one participant. Two of three symptomatic BTIs and the reinfection were confirmed by whole genome sequencing. All were supported by a >4-fold increase in neutralizing antibodies against the Delta or Omicron variant. Moreover, we found both symptomatic and asymptomatic BTIs can boost neutralizing antibodies against VOC with variable degrees ranging from 2.5- to 77.4-fold increase in neutralizing antibody titers. As BTIs continue, our findings highlight the application of anti-N antibody test to ongoing studies of immunity induced by spike-based vaccine, and provide new insights into the establishment of herd immunity in the community during the post-vaccination era.

Disentangling post-vaccination symptoms from early COVID-19

BACKGROUND

Identifying and testing individuals likely to have SARS-CoV-2 is critical for infection control, including post-vaccination. Vaccination is a major public health strategy to reduce SARS-CoV-2 infection globally. Some individuals experience systemic symptoms post-vaccination, which overlap with COVID-19 symptoms. This study compared early post-vaccination symptoms in individuals who subsequently tested positive or negative for SARS-CoV-2, using data from the COVID Symptom Study (CSS) app.

METHODS

We conducted a prospective observational study in 1,072,313 UK CSS participants who were asymptomatic when vaccinated with Pfizer-BioNTech mRNA vaccine (BNT162b2) or Oxford-AstraZeneca adenovirus-vectored vaccine (ChAdOx1 nCoV-19) between 8 December 2020 and 17 May 2021, who subsequently reported symptoms within seven days (N=362,770) (other than local symptoms at injection site) and were tested for SARS-CoV-2 (N=14,842), aiming to differentiate vaccination side-effects per se from superimposed SARS-CoV-2 infection. The post-vaccination symptoms and SARS-CoV-2 test results were contemporaneously logged by participants. Demographic and clinical information (including comorbidities) were recorded. Symptom profiles in individuals testing positive were compared with a 1:1 matched population testing negative, including using machine learning and multiple models considering UK testing criteria.

FINDINGS

Differentiating post-vaccination side-effects alone from early COVID-19 was challenging, with a sensitivity in identification of individuals testing positive of 0.6 at best. Most of these individuals did not have fever, persistent cough, or anosmia/dysosmia, requisite symptoms for accessing UK testing; and many only had systemic symptoms commonly seen post-vaccination in individuals negative for SARS-CoV-2 (headache, myalgia, and fatigue).

INTERPRETATION

Post-vaccination symptoms per se cannot be differentiated from COVID-19 with clinical robustness, either using symptom profiles or machine-derived models. Individuals presenting with systemic symptoms post-vaccination should be tested for SARS-CoV-2 or quarantining, to prevent community spread.

FUNDING

UK Government Department of Health and Social Care, Wellcome Trust, UK Engineering and Physical Sciences Research Council, UK National Institute for Health Research, UK Medical Research Council and British Heart Foundation, Chronic Disease Research Foundation, Zoe Limited.

Nature of Acquired Immune Responses, Epitope Specificity and Resultant Protection from SARS-CoV-2

The primary global response to the SARS-CoV-2 pandemic has been to bring to the clinic as rapidly as possible a number of vaccines that are predicted to enhance immunity to this viral infection. While the rapidity with which these vaccines have been developed and tested (at least for short-term efficacy and safety) is commendable, it should be acknowledged that this has occurred despite the lack of research into, and understanding of, the immune elements important for natural host protection against the virus, making this endeavor a somewhat unique one in medical history. In contrast, as pointed out in the review below, there were already important past observations that suggested that respiratory infections at mucosal surfaces were susceptible to immune clearance by mechanisms not typical of infections caused by systemic (blood-borne) pathogens. Accordingly, it was likely to be important to understand the role for both innate and acquired immunity in response to viral infection, as well as the optimum acquired immune resistance mechanisms for viral clearance (B cell or antibody-mediated, versus T cell mediated). This information was needed both to guide vaccine development and to monitor its success. We have known that many pathogens enter into a quasi-symbiotic relationship with the host, with each undergoing sequential change in response to alterations the other makes to its presence. The subsequent evolution of viral variants which has caused such widespread concern over the last 3-6 months as host immunity develops was an entirely predictable response. What is still not known is whether there will be other unexpected side-effects of the deployment of novel vaccines in humans which have yet to be characterized, and, if so, how and if these can be avoided. We conclude by remarking that to ignore a substantial body of well-attested immunological research in favour of expediency is a poor way to proceed.

Quantifying the relationship between SARS-CoV-2 viral load and infectiousness

The relationship between SARS-CoV-2 viral load and infectiousness is poorly known. Using data from a cohort of cases and high-risk contacts, we reconstructed viral load at the time of contact and inferred the probability of infection. The effect of viral load was larger in household contacts than in non-household contacts, with a transmission probability as large as 48% when the viral load was greater than 1010 copies per mL. The transmission probability peaked at symptom onset, with a mean probability of transmission of 29%, with large individual variations. The model also projects the effects of variants on disease transmission. Based on the current knowledge that viral load is increased by two- to eightfold with variants of concern and assuming no changes in the pattern of contacts across variants, the model predicts that larger viral load levels could lead to a relative increase in the probability of transmission of 24% to 58% in household contacts, and of 15% to 39% in non-household contacts.

Dynamics of the cellular and humoral immune response after BNT162b2 mRNA Covid-19 vaccination in Covid-19 naive nursing home residents

Short-term humoral and cellular immune responses are diminished after BNT162b2 mRNA Covid-19 vaccination in Covid-19 naive nursing home residents, a population particularly vulnerable to the disease. We found both responses to decline after four weeks and remain lower than those of healthcare workers after twenty-four weeks, with an estimated half-life of the antibody response of 47 days. At four weeks, older age was significantly associated with a decreased humoral response, and diabetes mellitus and active malignancy with a decreased cellular response. Our results imply that Covid-19 naive nursing home residents are a target group for booster vaccination trials.

An Overview of Vaccines against SARS-CoV-2 in the COVID-19 Pandemic Era

The emergence of SARS-CoV-2 in late 2019 led to the COVID-19 pandemic all over the world. When the virus was first isolated and its genome was sequenced in the early months of 2020, the efforts to develop a vaccine began. Based on prior well-known knowledge about coronavirus, the SARS-CoV-2 spike (S) protein was selected as the main target. Currently, more than one hundred vaccines are being investigated and several of them are already authorized by medical agencies. This review summarizes and compares the current knowledge about main approaches for vaccine development, focusing on those authorized and specifically their immunogenicity, efficacy preventing severe disease, adverse side effects, protection, and ability to cope with emergent SARS-CoV-2 variants.

COVID-19 Outbreak Associated with a SARS-CoV-2 P.1 Lineage in a Long-Term Care Home after Implementation of a Vaccination Program - Ontario, April-May 2021

In a P.1 COVID-19 outbreak in long-term-care, vaccine effectiveness against SARS-CoV-2 infection was 52.5% (95%CI 26.9-69.8%) in residents and 62.2% (95%CI, 2.3-88.3%) in staff. VE against severe illness was 78.6% (95%CI 47.9-91.2) in residents. Two of 19 vaccinated resident cases died. Outbreak management required both vaccination and infection control measures.

SARS-CoV-2 Portrayed against HIV: Contrary Viral Strategies in Similar Disguise

SARS-CoV-2 and HIV are zoonotic viruses that rapidly reached pandemic scale, causing global losses and fear. The COVID-19 and AIDS pandemics ignited massive efforts worldwide to develop antiviral strategies and characterize viral architectures, biological and immunological properties, and clinical outcomes. Although both viruses have a comparable appearance as enveloped viruses with positive-stranded RNA and envelope spikes mediating cellular entry, the entry process, downstream biological and immunological pathways, clinical outcomes, and disease courses are strikingly different. This review provides a systemic comparison of both viruses' structural and functional characteristics, delineating their distinct strategies for efficient spread.