SARS-CoV-2 infection rates of antibody-positive compared with antibody-negative health-care workers in England: a large, multicentre, prospective cohort study (SIREN)

SARS-CoV-2 Immunization Index in the Academic Community: A Retrospective Post-Vaccination Study

BACKGROUND/OBJECTIVES

The COVID-19 pandemic has revolutionized vaccine production and compelled a massive global vaccination campaign. This study aimed to estimate the positivity and levels of SARS-CoV-2 IgG antibodies acquired due to vaccination and infection in the academic population of a Portuguese university.

METHODS

Blood samples were collected and analyzed through the ELISA methodology, and statistical analysis was performed.

RESULTS

A total of 529 volunteers with at least one dose of the vaccine were enrolled in this study. Individuals without a prior COVID-19 diagnosis were divided into two groups: 350, who received a full vaccination, and 114, who received a full vaccination and a booster dose of the same vaccine (81) and mixed vaccines (33). Regarding the individuals who reported a prior SARS-CoV-2 infection, 31 received a full vaccination, and 34 received only one vaccination dose. Data analysis showed a higher level of IgG against SARS-CoV-2 in individuals who were younger, female, who received the Moderna vaccine, with recent post-vaccine administration, a mixed booster dose, and prior SARS-CoV-2 infection.

CONCLUSIONS

Assessing vaccination's effectiveness and group immunity is crucial for pandemic management, particularly in academic environments with high individual mobility, in order to define groups at risk and redirect infection control strategies.

High Post-Infection Protection after COVID-19 among Healthcare Workers: A Population-Level Observational Study

Background

Even though a few years have passed since the coronavirus disease 2019 (COVID-19) outbreak, information regarding certain aspects of the disease, such as post-infection immunity, is still quite limited. This study aimed to evaluate post-infection protection and COVID-19 features among healthcare workers (HCWs), during three successive surges, as well as the rate of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection, reactivation, re-positivity, and severity.

Methods

This cross-sectional population-level observational study was conducted from 20 April 2020 to 18 February 2021. The study population included all HCWs in public or private hospitals in Fars Province, Southern Iran. The infection rate was computed as the number of individuals with positive polymerase chain reaction (PCR) tests divided by the total number of person-days at risk. The re-infection was evaluated after 90 days.

Results

A total of 30,546 PCR tests were performed among HCWs, of which 13,749 (61.94% of total HCWs) were positive. Considering the applied 90-day threshold, there were 44 (31.2%) cases of reactivation and relapse, and 97 (68.8% of infected and 1.81% of total HCWs) cases of reinfection among 141 (2.64%) diagnosed cases who experienced a second episode of COVID-19. There was no significant difference in symptoms (P=0.65) or the necessity for ICU admission (P=0.25). The estimated protection against repeated infection after a previous SARS-CoV-2 infection was 94.8% (95% CI=93.6-95.7).

Conclusion

SARS-CoV-2 re-positivity, relapse, and reinfection were rare in the HCW population. After the first episode of infection, an estimated 94.8% protection against recurring infections was achieved. A preprint version of this manuscript is available at DOI:10.21203/rs.3.rs-772662/v1 (https://www.researchsquare.com/article/rs-772662/v1).

Genetic determinants of SARS-CoV-2 and the clinical outcome of COVID-19 in Southern Bangladesh

BACKGROUND

The coronavirus disease 2019 (COVID-19) pandemic has had a severe impact on population health. The genetic determinants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in southern Bangladesh are not well understood.

METHODS

This study aimed to determine the genomic variation in SARS-CoV-2 genomes that have evolved over 2 years of the pandemic in southern Bangladesh and their association with disease outcomes and virulence of this virus. We investigated demographic variables, disease outcomes of COVID-19 patients and genomic features of SARS-CoV-2.

RESULTS

We observed that the disease severity was significantly higher in adults (85.3%) than in children (14.7%), because the expression of angiotensin-converting enzyme-2 (ACE-2) diminishes with ageing that causes differences in innate and adaptive immunity. The clade GK (n = 66) was remarkable between June 2021 and January 2022. Because of the mutation burden, another clade, GRA started a newly separated clustering in December 2021. The burden was significantly higher in GRA (1.5-fold) highlighted in mild symptoms of COVID-19 patients than in other clades (GH, GK, and GR). Mutations were accumulated mainly in S (22.15 mutations per segment) and ORF1ab segments. Missense (67.5%) and synonymous (18.31%) mutations were highly noticed in adult patients with mild cases rather than severe cases, especially in ORF1ab segments. Moreover, we observed many unique mutations in S protein in mild cases compared to severe, and homology modeling revealed that those might cause more folding in the protein's alpha helix and beta sheets.

CONCLUSION

Our study identifies some risk factors such as age comorbidities (diabetes, hypertension, and renal disease) that are associated with severe COVID-19, providing valuable insight regarding prioritizing vaccination for high-risk individuals and allocating health care and resources. The findings of this work outlined the knowledge and mutational basis of SARS-CoV-2 for the next treatment steps. Further studies are needed to confirm the effects of structural and functional proteins of SARS-CoV-2 in detail for monitoring the emergence of new variants in future.

Prescriptive Analytics-Based SIRM Model for Predicting Covid-19 Outbreak

Predicting the outbreak of a pandemic is an important measure in order to help saving people lives threatened by Covid-19. Having information about the possible spread of the pandemic, authorities and people can make better decisions. For example, such analyses help developing better strategies for distributing vaccines and medicines. This paper has modified the original Susceptible-Infectious-Recovered (SIR) model to Susceptible-Immune-Infected-Recovered (SIRM) which includes the Immunity ratio as a parameter to enhance the prediction of the pandemic. SIR is a widely used model to predict the spread of a pandemic. Many types of pandemics imply many variants of the SIR models which make it very difficult to find out the best model that matches the running pandemic. The simulation of this paper used the published data about the spread of the pandemic in order to examine our new SIRM. The results showed clearly that our new SIRM covering the aspects of vaccine and medicine is an appropriate model to predict the behavior of the pandemic.

Correlation between chest CT scores and clinical impact in patients re-infected with COVID-19 during the two attacks: an observational study

Background

Worldwide, millions of people got COVID-19 infection since the start of the pandemic with a large number of deaths. Re-infection with SARS-CoV-2 is possible, because it can mutate into new strains as it is an RNA virus. The main objective of our study is to correlate between CT severity score of the patients re-infected with COVID-19 during the first and second attack and its clinical impact.

Results

We performed a retrospective cohort study. It was carried out on fifty symptomatic patients (11 females and 39 males). Their ages ranged from 38 to 71 years. We included only patients who were re-infected after more than 6 months of the first infection and showed clinical symptoms with SARS-CoV-2 PCR-positive test. We found that CT severity score was decreased in the second infection in 47 (94%) of our patients associated with decreased respiratory distress as well as oxygen requirements, while the CT severity score was increased in two patients and only one patient showed no change in CT score severity between two infections.

Conclusion

The reduction in CT severity score in the majority of re-infected patients suggested the role of the immunity developed from first infection in protection against severe lung affection in case of repeated infection even after 6 months despite poor immunity against re-infection.

PARIS and SPARTA: Finding the Achilles' Heel of SARS-CoV-2

To understand reinfection rates and correlates of protection for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we established eight different longitudinal cohorts in 2020 under the umbrella of the PARIS (Protection Associated with Rapid Immunity to SARS-CoV-2)/SPARTA (SARS SeroPrevalence And Respiratory Tract Assessment) studies. Here, we describe the PARIS/SPARTA cohorts, the harmonized assays and analysis that are performed across the cohorts, as well as case definitions for SARS-CoV-2 infection and reinfection that have been established by the team of PARIS/SPARTA investigators. IMPORTANCE Determining reinfection rates and correlates of protection against SARS-CoV-2 infection induced by both natural infection and vaccination is of high significance for the prevention and control of coronavirus disease 2019 (COVID-19). Furthermore, understanding reinfections or infection after vaccination and the role immune escape plays in these scenarios will inform the need for updates of the current SARS-CoV-2 vaccines and help update guidelines suitable for the postpandemic world.

Incidence of SARS-CoV-2 reinfection in a paediatric cohort in Kuwait

OBJECTIVE

Subsequent protection from SARS-CoV-2 infection in paediatrics is not well reported in the literature. We aimed to describe the clinical characteristics and dynamics of SARS-CoV-2 PCR repositivity in children.

DESIGN

This is a population-level retrospective cohort study.

SETTING

Patients were identified through multiple national-level electronic COVID-19 databases that cover all primary, secondary and tertiary centres in Kuwait.

PARTICIPANTS

The study included children 12 years and younger between 28 February 2020 and 6 March 2021. SARS-CoV-2 reinfection was defined as having two or more positive SARS-CoV-2 PCR tests done on a respiratory sample, at least 45 days apart. Clinical data were obtained from the Pediatric COVID-19 Registry in Kuwait.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary measure is to estimate SARS-CoV-2 PCR repositivity rate. The secondary objective was to establish average duration between first and subsequent SARS-CoV-2 infection. Descriptive statistics were used to present clinical data for each infection episode. Also, incidence-sensitivity analysis was performed to evaluate 60-day and 90-day PCR repositivity intervals.

RESULTS

Thirty paediatric patients with COVID-19 had SARS-CoV-2 reinfection at an incidence of 1.02 (95% CI 0.71 to 1.45) infection per 100 000 person-days and a median time to reinfection of 83 (IQR 62-128.75) days. The incidence of reinfection decreased to 0.78 (95% CI 0.52 to 1.17) and 0.47 (95% CI 0.28 to 0.79) per person-day when the minimum interval between PCR repositivity was increased to 60 and 90 days, respectively. The mean age of reinfected subjects was 8.5 (IQR 3.7-10.3) years and the majority (70%) were girls. Most children (55.2%) had asymptomatic reinfection. Fever was the most common presentation in symptomatic patients. One immunocompromised experienced two reinfection episodes.

CONCLUSION

SARS-CoV-2 reinfection is uncommon in children. Previous confirmed COVID-19 in children seems to result in a milder reinfection.

The unnaturalistic fallacy: COVID-19 vaccine mandates should not discriminate against natural immunity

COVID-19 vaccine requirements have generated significant debate. Here, we argue that, on the evidence available, such policies should have recognised proof of natural immunity as a sufficient basis for exemption to vaccination requirements. We begin by distinguishing our argument from two implausible claims about natural immunity: (1) natural immunity is superior to 'artificial' vaccine-induced immunity simply because it is 'natural' and (2) it is better to acquire immunity through natural infection than via vaccination. We then briefly survey the evidence base for the comparison between naturally acquired immunity and vaccine-induced immunity. While we clearly cannot settle the scientific debates on this point, we suggest that we lack clear and convincing scientific evidence that vaccine-induced immunity has a significantly higher protective effect than natural immunity. Since vaccine requirements represent a substantial infringement of individual liberty, as well as imposing other significant costs, they can only be justified if they are necessary for achieving a proportionate public health benefit. Without compelling evidence for the superiority of vaccine-induced immunity, it cannot be deemed necessary to require vaccination for those with natural immunity. Subjecting them to vaccine mandates is therefore not justified. We conclude by defending the standard of proof that this argument from necessity invokes, and address other pragmatic and practical considerations that may speak against natural immunity exemptions.

COVID-19 vaccinations: The unknowns, challenges, and hopes

The entire world has been suffering from the coronavirus disease 2019 (COVID-19) pandemic since March 11, 2020. More than a year later, the COVID-19 vaccination brought hope to control this viral pandemic. Here, we review the unknowns of the COVID-19 vaccination, such as its longevity, asymptomatic spread, long-term side effects, and its efficacy on immunocompromised patients. In addition, we discuss challenges associated with the COVID-19 vaccination, such as the global access and distribution of vaccine doses, adherence to hygiene guidelines after vaccination, the emergence of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, and vaccine resistance. Despite all these challenges and the fact that the end of the COVID-19 pandemic is still unclear, vaccines have brought great hope for the world, with several reports indicating a significant decline in the risk of COVID19-related infection and hospitalizations.

Duration of Protection Against SARS-CoV-2 Reinfection and Associated Risk of Reinfection Assessed with Real-World Data

IMPORTANCE

Better understanding of the protective duration of prior SARS-CoV-2 infection against reinfection is needed.

OBJECTIVE

Primary: To assess the durability of immunity to SARS-CoV-2 reinfection among initially unvaccinated individuals with previous SARS-CoV-2 infection. Secondary: Evaluate the crude SARS-CoV-2 reinfection rate and associated characteristics.

DESIGN AND SETTING

Retrospective observational study of HealthVerity data among 144,678,382 individuals, during the pandemic era through April 2021.

PARTICIPANTS

Individuals studied had SARS-CoV-2 molecular diagnostic or antibody index test results from February 29 through December 9, 2020, with ≥365 days of pre-index continuous closed medical enrollment, claims, or electronic health record activity.

MAIN OUTCOMES AND MEASURES

Rates of reinfection among index-positive individuals were compared to rates of infection among index-negative individuals. Factors associated with reinfection were evaluated using multivariable logistic regression. For both objectives, the outcome was a subsequent positive molecular diagnostic test result.

RESULTS

Among 22,786,982 individuals with index SARS-CoV-2 laboratory test data (2,023,341 index positive), the crude rate of reinfection during follow-up was significantly lower (9.89/1,000-person years) than that of primary infection (78.39/1,000 person years). Consistent with prior findings, the risk of reinfection among index-positive individuals was 87% lower than the risk of infection among index-negative individuals (hazard ratio, 0.13; 95% CI, 0.13, 0.13). The cumulative incidence of reinfection among index-positive individuals and infection among index-negative individuals was 0.85% (95% CI: 0.82%, 0.88%) and 6.2% (95% CI: 6.1%, 6.3%), respectively, over follow-up of 375 days. The duration of protection against reinfection was stable over the median 5 months and up to 1-year follow-up interval. Factors associated with an increased reinfection risk included older age, comorbid immunologic conditions, and living in congregate care settings; healthcare workers had a decreased reinfection risk.

CONCLUSIONS AND RELEVANCE

This large US population-based study demonstrates that SARS-CoV-2 reinfection is uncommon among individuals with laboratory evidence of a previous infection. Protection from SARS-CoV-2 reinfection is stable up to one year. Reinfection risk was primarily associated with age 85+ years, comorbid immunologic conditions and living in congregate care settings; healthcare workers demonstrated a decreased reinfection risk. These findings suggest that infection induced immunity is durable for variants circulating prior to Delta.

KEY POINTS

Question: How long does prior SARS-CoV-2 infection provide protection against SARS-CoV-2 reinfection?Finding: Among >22 million individuals tested February 2020 through April 2021, the relative risk of reinfection among those with prior infection was 87% lower than the risk of infection among individuals without prior infection. This protection was durable for up to a year. Factors associated with increased likelihood of reinfection included older age (85+ years), comorbid immunologic conditions, and living in congregate care settings; healthcare workers had lower risk.Meaning: Prior SARS-CoV-2 infection provides a durable, high relative degree of protection against reinfection.

Model based estimation of the SARS-CoV-2 immunization level in austria and consequences for herd immunity effects

Several systemic factors indicate that worldwide herd immunity against COVID-19 will probably not be achieved in 2021. On the one hand, vaccination programs are limited by availability of doses and on the other hand, the number of people already infected is still too low to have a disease preventing impact and new emerging variants of the virus seem to partially neglect developed antibodies from previous infections. Nevertheless, by February 2021 after one year of observing high numbers of reported COVID-19 cases in most European countries, we might expect that the immunization level should have an impact on the spread of SARS-CoV-2. Here we present an approach for estimating the immunization of the Austrian population and discuss potential consequences on herd immunity effects. To estimate immunization we use a calibrated agent-based simulation model that reproduces the actual COVID-19 pandemic in Austria. From the resulting synthetic individual-based data we can extract the number of immunized persons. We then extrapolate the progression of the epidemic by varying the obtained level of immunization in simulations of an hypothetical uncontrolled epidemic wave indicating potential effects on the effective reproduction number. We compared our theoretical findings with results derived from a classic differential equation SIR-model. As of February 2021, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$14.7\%$$\end{document}14.7% of the Austrian population has been affected by a SARS-CoV-2 infection which causes a \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$9\%$$\end{document}9% reduction of the effective reproduction number and a \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$24.7\%$$\end{document}24.7% reduction of the prevalence peak compared to a fully susceptible population. This estimation is now recomputed on a regular basis to publish model based analysis of immunization level in Austria also including the fast growing effects of vaccination programs. This provides substantial information for decision makers to evaluate the necessity of non pharmaceutical intervention measures based on the estimated impact of natural and vaccinated immunization.

Hesitancy towards a COVID-19 vaccine among midwives in Turkey during the COVID-19 pandemic: A cross-sectional web-based survey

INTRODUCTION

One of the most significant barriers to social immunization, which is critical in combating the COVID-19 pandemic, is vaccine hesitancy or rejection. The purpose of this study was to determine the acceptance, hesitancy and barriers to COVID-19 vaccines among midwives in Turkey.

METHODS

A total of 806 midwives participated in the cross-sectional study, which was conducted online from November 2020 to January 2021. The data were collected by using an Introductory Information Form, Anti-Vaccination Scale - Short Form, and Attitudes to the COVID-19 Vaccine Scale.

RESULTS

In all, 17.2% of the midwives in the study had a history of COVID-19 infection, which was confirmed by a PCR test; 69% were exposed to COVID-19 patients; 36.8% had a person diagnosed with COVID-19 with PCR in their family; and 18.1% had a relative die due to COVID-19. In the study, 16.8% of midwives considered getting the COVID-19 vaccine, while the majority (48.8%) stated they would get the vaccine once vaccine safety was established, while 10.5% stated that they did not wish to receive the vaccine. Insufficient phase studies of COVID-19 vaccine studies (75.6%) and insufficient control due to imported COVID-19 vaccines developed (48.1%) were among the most important determinants of COVID-19 vaccine reluctance.

CONCLUSIONS

The potential acceptance rate of COVID-19 vaccines by the study midwives was found to be low. The knowledge, confidence and attitude of midwives toward vaccines are important determinants of patients' vaccine acceptance and recommendation.

Virological and Serological Characterisation of SARS-CoV-2 Infections Diagnosed After mRNA BNT162b2 Vaccination Between December 2020 and March 2021

BACKGROUND

Vaccines for coronavirus disease 2019 (COVID-19) are proving to be very effective in preventing severe illness; however, although rare, post-vaccine infections have been reported. The present study focuses on virological and serological features of 94 infections that occurred in Lazio Region (Central Italy) between 27 December 2020, and 30 March 2021, after one or two doses of mRNA BNT162b2 vaccine.

METHODS

We evaluated clinical features, virological (viral load; viral infectiousness; genomic characterisation), and serological (anti-nucleoprotein Ig; anti-Spike RBD IgG; neutralising antibodies, nAb) characteristics of 94 post-vaccine infections at the time of diagnosis. Nasopharyngeal swabs (NPSs) and serum samples were collected in the framework of the surveillance activities on SARS-CoV-2 variants established in Lazio Region (Central Italy) and analysed at the National Institute for Infectious Diseases "L. Spallanzani" in Rome.

RESULTS

The majority (92.6%) of the post-vaccine infections showed pauci/asymptomatic or mild clinical course, with symptoms and hospitalisation rate significantly less frequent in patients infected after full vaccination course as compared to patients who received a single dose vaccine. Although differences were not statistically significant, viral loads and isolation rates were lower in NPSs from patients infected after receiving two vaccine doses as compared to patients with one dose. Most cases (84%) had nAb in serum at the time of infection diagnosis, which is a sub-group of vaccinees, were found similarly able to neutralise Alpha and Gamma variants. Asymptomatic individuals showed higher nAb titres as compared to symptomatic cases (median titre: 1:120 vs. 1:40, respectively). Finally, the proportion of post-vaccine infections attributed either to Alpha and Gamma variants was similar to the proportion observed in the contemporary unvaccinated population in the Lazio region, and mutational analysis did not reveal enrichment of a defined set of Spike protein substitutions depending on the vaccination status.

CONCLUSION

Our study conducted using real-life data, emphasised the importance of monitoring vaccine breakthrough infections, through the characterisation of virological, immunological, and clinical features associated with these events, in order to tune prevention measures in the next phase of the COVID-19 pandemic.

SARS-CoV-2-specific memory B cells can persist in the elderly who have lost detectable neutralizing antibodies

Memory B cells (MBCs) can provide a recall response able to supplement waning antibodies (Abs) with an affinity-matured response better able to neutralize variant viruses. We studied a cohort of elderly care home residents and younger staff (median age of 87 years and 56 years, respectively), who had survived COVID-19 outbreaks with only mild or asymptomatic infection. The cohort was selected because of its high proportion of individuals who had lost neutralizing antibodies (nAbs), thus allowing us to specifically investigate the reserve immunity from SARS-CoV-2-specific MBCs in this setting. Class-switched spike and receptor-binding domain (RBD) tetramer-binding MBCs persisted 5 months after mild or asymptomatic SARS-CoV-2 infection, irrespective of age. The majority of spike- and RBD-specific MBCs had a classical phenotype, but we found that activated MBCs, indicating possible ongoing antigenic stimulation or inflammation, were expanded in the elderly group. Spike- and RBD-specific MBCs remained detectable in the majority of individuals who had lost nAbs, although at lower frequencies and with a reduced IgG/IgA isotype ratio. Functional spike-, S1 subunit of the spike protein- (S1-), and RBD-specific recall was also detectable by enzyme-linked immune absorbent spot (ELISPOT) assay in some individuals who had lost nAbs, but was significantly impaired in the elderly. Our findings demonstrate that a reserve of SARS-CoV-2-specific MBCs persists beyond the loss of nAbs but highlight the need for careful monitoring of functional defects in spike- and RBD-specific B cell immunity in the elderly.

Modelling the impact of vaccine hesitancy in prolonging the need for Non-Pharmaceutical Interventions to control the COVID-19 pandemic

Background

Vaccine hesitancy - a delay in acceptance or refusal of vaccines despite availability - has the potential to threaten the successful roll-out of SARS-CoV-2 vaccines globally. In this study, we aim to understand the likely impact of vaccine hesitancy on the control of the COVID-19 pandemic.

Methods

We modelled the potential impact of vaccine hesitancy on the control of the pandemic and the relaxation of non-pharmaceutical interventions (NPIs) by combining an epidemiological model of SARS-CoV-2 transmission with data on vaccine hesitancy from population surveys.

Results

Our simulations suggest that the mortality over a 2-year period could be up to 7.6 times higher in countries with high vaccine hesitancy compared to an ideal vaccination uptake if NPIs are relaxed. Alternatively, high vaccine hesitancy could prolong the need for NPIs to remain in place.

Conclusions

While vaccination is an individual choice, vaccine-hesitant individuals have a substantial impact on the pandemic trajectory, which may challenge current efforts to control COVID-19. In order to prevent such outcomes, addressing vaccine hesitancy with behavioural interventions is an important priority in the control of the COVID-19 pandemic.

Quantifying the risk of SARS-CoV-2 reinfection over time

Despite over 140 million SARS-CoV-2 infections worldwide since the beginning of the pandemic, relatively few confirmed cases of SARS-CoV-2 reinfection have been reported. While immunity from SARS-CoV-2 infection is probable, at least in the short term, few studies have quantified the reinfection risk. To our knowledge, this is the first systematic review to synthesise the evidence on the risk of SARS-CoV-2 reinfection over time. A standardised protocol was employed, based on Cochrane methodology. Electronic databases and preprint servers were searched from 1 January 2020 to 19 February 2021. Eleven large cohort studies were identified that estimated the risk of SARS-CoV-2 reinfection over time, including three that enrolled healthcare workers and two that enrolled residents and staff of elderly care homes. Across studies, the total number of PCR-positive or antibody-positive participants at baseline was 615,777, and the maximum duration of follow-up was more than 10 months in three studies. Reinfection was an uncommon event (absolute rate 0%-1.1%), with no study reporting an increase in the risk of reinfection over time. Only one study estimated the population-level risk of reinfection based on whole genome sequencing in a subset of patients; the estimated risk was low (0.1% [95% CI: 0.08-0.11%]) with no evidence of waning immunity for up to 7 months following primary infection. These data suggest that naturally acquired SARS-CoV-2 immunity does not wane for at least 10 months post-infection. However, the applicability of these studies to new variants or to vaccine-induced immunity remains uncertain.

Reinfection with SARS-CoV-2: An inconvenient truth?

Data show that antibody-related immunity against SARS-CoV-2 may not be long-lasting. We report two cases regarded as cured from COVID-19, which presented again with symptoms and a positive SARS-CoV-2 RT-PCR test. Case one, a 60-year-old male, had a biphasic presentation of symptoms compatible with COVID-19 infection, associated with a positive RT-PCR test. Case two, a 25-year-old female, had a first positive RT-PCR test during hospital screening, and months later a symptomatic presentation of COVID-19, associated with a positive RT-PCR test. All cases were immunocompetent. Anti-IgG-SARS-CoV-2 blood samples were negative in both. Elevation of analytical inflammatory markers suggested new infection in both cases. COVID-19 reinfection may be a differential diagnosis and primary care physicians should acknowledge it. Previously cured patients should be encouraged to comply with health public preventive measures.

Estimating the duration of seropositivity of human seasonal coronaviruses using seroprevalence studies

Background: The duration of immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still uncertain, but it is of key clinical and epidemiological importance. Seasonal human coronaviruses (HCoV) have been circulating for longer and, therefore, may offer insights into the long-term dynamics of reinfection for such viruses. Methods: Combining historical seroprevalence data from five studies covering the four circulating HCoVs with an age-structured reverse catalytic model, we estimated the likely duration of seropositivity following seroconversion. Results: We estimated that antibody persistence lasted between 0.9 (95% Credible interval: 0.6 - 1.6) and 3.8 (95% CrI: 2.0 - 7.4) years. Furthermore, we found the force of infection in older children and adults (those over 8.5 [95% CrI: 7.5 - 9.9] years) to be higher compared with young children in the majority of studies. Conclusions: These estimates of endemic HCoV dynamics could provide an indication of the future long-term infection and reinfection patterns of SARS-CoV-2.

Formal and informal science advice in emergencies: COVID-19 in the UK

The importance of scientific advice to government gains greater recognition in emergencies but inevitably has to be done in an environment of uncertainty, with limited data and at high speed. Adapting existing structures is more effective than creating new ones in an emergency. Between emergencies, the UK has a structured scientific advice system, including Chief Scientific Advisers, scientists in government, regulatory bodies and independent expert committees, which were adapted to COVID-19 under the umbrella of the Scientific Advisory Group for Emergencies. These worked alongside networks of informal scientific advice, including internationally. Multiple sciences were needed, including from the social sciences and engineering in addition to clinical science and epidemiology, and these had to be integrated. A centrally directed clinical research programme helped provide practitioners robust evidence, with observational and interventional trials providing data for policy and testing treatments and vaccines. The scale of the emergency meant unavoidable tension between detailed work and speed, and between an integrated scientific view usable in decision-making and constructive challenge. While a final judgement of the UK scientific response will take time, everyone should be grateful to the thousands of scientists involved for the research, synthesis and advice, which improved outcomes for the public.

COVID-19 reinfection: the role of natural immunity, vaccines, and variants

The COVID-19 pandemic has altered innumerable lives. Although recent mass vaccinations offer a glimmer of hope, the rising death toll and new variants continue to dominate the current scenario. As we begin to understand more about SARS-CoV-2 infections, the territory of reinfections with COVID-19 remains unexplored. In this review, we will discuss several aspects of reinfection: (a) How is COVID-19 reinfection characterized? (b) Does prior literature differentiate between reinfection and reactivation? (c) What SARS-CoV-2 strains do the vaccines target and can they protect against new strains? Larger and longer timeline studies are needed to understand reinfection risks. With the ongoing distribution of the SARS-CoV-2 vaccines to provide protection, the understanding of the possibility for SARS-CoV-2 reinfection remains critical.

Abbreviations CDC: Centers for Disease ControlSARS-CoV-2: Severe acute respiratory syndrome coronavirus 2COVID-19: Coronavirus disease 2019RT-PCR: Reverse Transcription Polymerase Chain ReactionPASC: Post-Acute Sequelae of SARS-CoV-2 infection

Estimating the duration of seropositivity of human seasonal coronaviruses using seroprevalence studies

Background: The duration of immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still uncertain, but it is of key clinical and epidemiological importance. Seasonal human coronaviruses (HCoV) have been circulating for longer and, therefore, may offer insights into the long-term dynamics of reinfection for such viruses. Methods: Combining historical seroprevalence data from five studies covering the four circulating HCoVs with an age-structured reverse catalytic model, we estimated the likely duration of seropositivity following seroconversion. Results: We estimated that antibody persistence lasted between 0.9 (95% Credible interval: 0.6 - 1.6) and 3.8 (95% CrI: 2.0 - 7.4) years. Furthermore, we found the force of infection in older children and adults (those over 8.5 [95% CrI: 7.5 - 9.9] years) to be higher compared with young children in the majority of studies. Conclusions: These estimates of endemic HCoV dynamics could provide an indication of the future long-term infection and reinfection patterns of SARS-CoV-2.

Model-based estimation of transmissibility and reinfection of SARS-CoV-2 P.1 variant

Background

The SARS-CoV-2 variant of concern (VOC) P.1 (Gamma variant) emerged in the Amazonas State, Brazil, in November 2020. The epidemiological consequences of its mutations have not been widely studied, despite detection of P.1 in 36 countries, with local transmission in at least 5 countries. A range of mutations are seen in P.1, ten of them in the spike protein. It shares mutations with VOCs previously detected in the United Kingdom (B.1.1.7, Alpha variant) and South Africa (B.1.351, Beta variant).

Methods

We estimated the transmissibility and reinfection of P.1 using a model-based approach, fitting data from the national health surveillance of hospitalized individuals and frequency of the P.1 variant in Manaus from December-2020 to February-2021.

Results

Here we estimate that the new variant is about 2.6 times more transmissible (95% Confidence Interval: 2.4-2.8) than previous circulating variant(s). Manaus already had a high prevalence of individuals previously affected by the SARS-CoV-2 virus and our fitted model attributed 28% of Manaus cases in the period to reinfections by P.1, confirming the importance of reinfection by this variant. This value is in line with estimates from blood donors samples in Manaus city.

Conclusions

Our estimates rank P.1 as one of the most transmissible among the SARS-CoV-2 VOCs currently identified, and potentially as transmissible as the posteriorly detected VOC B.1.617.2 (Delta variant), posing a serious threat and requiring measures to control its global spread.

Longitudinal humoral antibody response to SARS-CoV-2 infection among healthcare workers in a New York City hospital

OBJECTIVE

Dynamics of humoral immune responses to SARS-CoV-2 antigens following infection suggest an initial decay of antibody followed by subsequent stabilisation. We aim to understand the longitudinal humoral responses to SARS-CoV-2 nucleocapsid (N) protein and spike (S) protein and to evaluate their correlation to clinical symptoms among healthcare workers (HCWs).

DESIGN

A prospective longitudinal study.

SETTING

This study was conducted in a New York City public hospital in the South Bronx, New York.

PARTICIPANTS

HCWs participated in phase 1 (N=500) and were followed up 4 months later in phase 2 (N=178) of the study. They underwent SARS-CoV-2 PCR and serology testing for N and S protein antibodies, in addition to completion of an online survey in both phases. Analysis was performed on the 178 participants who participated in both phases of the study.

PRIMARY OUTCOME MEASURE

Evaluate longitudinal humoral responses to viral N (qualitative serology testing) and S protein (quantitative Mount Sinai Health System ELISA to detect receptor-binding domain and full-length S reactive antibodies) by measuring rate of decay.

RESULTS

Anti-N antibody positivity was 27% and anti-S positivity was 28% in phase 1. In phase 1, anti-S titres were higher in symptomatic (6754 (5177-8812)) than in asymptomatic positive subjects (5803 (2825-11 920)). Marginally higher titres (2382 (1494-3797)) were seen in asymptomatic compared with the symptomatic positive subgroup (2198 (1753-2755)) in phase 2. A positive correlation was noted between age (R=0.269, p<0.01), number (R=0.310, p<0.01) and duration of symptoms (R=0.434, p<0.01), and phase 1 anti-S antibody titre. A strong correlation (R=0.898, p<0.001) was observed between phase 1 titres and decay of anti-S antibody titres between the two phases. Significant correlation with rate of decay was also noted with fever (R=0.428, p<0.001), gastrointestinal symptoms (R=0.340, p<0.05), and total number (R=0.357, p<0.01) and duration of COVID-19 symptoms (R=0.469, p<0.001).

CONCLUSIONS

Higher initial anti-S antibody titres were associated with larger number and longer duration of symptoms as well as a faster decay between the two time points.

Uncertainty around the Long-Term Implications of COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has infected more than 231 million people globally, with more than 4.7 million deaths recorded by the World Health Organization as of 26 September 2021. In response to the pandemic, some countries (New Zealand, Vietnam, Taiwan, South Korea and others) have pursued suppression strategies, so-called Zero COVID policies, to drive and maintain infection rates as close to zero as possible and respond aggressively to new cases. In comparison, European countries and North America have adopted mitigation strategies (of varying intensity and effectiveness) that aim primarily to prevent health systems from being overwhelmed. With recent advances in our understanding of SARS-CoV-2 and its biology, and the increasing recognition there is more to COVID-19 beyond the acute infection, we offer a perspective on some of the long-term risks of mutational escape, viral persistence, reinfection, immune dysregulation and neurological and multi-system complications (Long COVID).

High level of protection against COVID-19 after two doses of BNT162b2 vaccine in the working age population - first results from a cohort study in Southern Sweden

BACKGROUND

Vaccine effectiveness against COVID-19 needs to be assessed in diverse real-world population settings.

METHODS

A cohort study of 805,741 residents in Skåne county, Southern Sweden, aged 18-64 years, of whom 26,587 received at least one dose of the BNT162b2 vaccine. Incidence rates of COVID-19 were estimated in sex- and age-adjusted analysis and stratified in two-week periods with substantial community spread of the disease.

RESULTS

The estimated vaccine effectiveness in preventing infection ≥7 days after second dose was 86% (95% CI 72-94%) but only 42% (95% CI 14-63%) ≥14 days after a single dose. No difference in vaccine effectiveness was observed between females and males. Having a prior positive test was associated with 91% (95% CI 85-94%) effectiveness against new infection among the unvaccinated.

CONCLUSION

A satisfactory effectiveness of BNT162b2 after the second dose was suggested, but with possibly substantially lower effect before the second dose.

Complexities in Case Definition of SARS-CoV-2 Reinfection: Clinical Evidence and Implications in COVID-19 Surveillance and Diagnosis

Reinfection cases have been reported in some countries with clinical symptoms ranging from mild to severe. In addition to clinical diagnosis, virus genome sequence from the first and second infection has to be confirmed to either belong to separate clades or had significant mutations for the confirmation of SARS-CoV-2 reinfection. While phylogenetic analysis with paired specimens offers the strongest evidence for reinfection, there remains concerns on the definition of SARS-CoV-2 reinfection, for reasons including accessibility to paired-samples and technical challenges in phylogenetic analysis. In light of the emergence of new SARS-CoV-2 variants that are associated with increased transmissibility and immune-escape further understanding of COVID-19 protective immunity, real-time surveillance directed at identifying COVID-19 transmission patterns, transmissibility of emerging variants and clinical implications of reinfection would be important in addressing the challenges in definition of COVID-19 reinfection and understanding the true disease burden.

Understanding the Patterns of Serological Testing for COVID-19 Pre- and Post-Vaccination Rollout in Michigan

Testing for SARS-CoV-2 antibodies is commonly used to determine prior COVID-19 infections and to gauge levels of infection- or vaccine-induced immunity. Michigan Medicine, a primary regional health center, provided an ideal setting to understand serologic testing patterns over time. Between 27 April 2020 and 3 May 2021, characteristics for 10,416 individuals presenting for SARS-CoV-2 antibody tests (10,932 tests in total) were collected. Relative to the COVID-19 vaccine roll-out date, 14 December 2020, the data were split into a pre- (8026 individuals) and post-vaccine launch (2587 individuals) period and contrasted with untested individuals to identify factors associated with tested individuals and seropositivity. Exploratory analysis of vaccine-mediated seropositivity was performed in 347 fully vaccinated individuals. Predictors of tested individuals included age, sex, smoking, neighborhood variables, and pre-existing conditions. Seropositivity in the pre-vaccine launch period was 9.2% and increased to 46.7% in the post-vaccine launch period. In the pre-vaccine launch period, seropositivity was significantly associated with age (10 year; OR = 0.80 (0.73, 0.89)), ever-smoker status (0.49 (0.35, 0.67)), respiratory disease (4.38 (3.13, 6.12)), circulatory disease (2.09 (1.48, 2.96)), liver disease (2.06 (1.11, 3.84)), non-Hispanic Black race/ethnicity (2.18 (1.33, 3.58)), and population density (1.10 (1.03, 1.18)). Except for the latter two, these associations remained statistically significant in the post-vaccine launch period. The positivity rate of fully vaccinated individual was 296/347(85.3% (81.0%, 88.8%)).

Robust immune responses after one dose of BNT162b2 mRNA vaccine dose in SARS-CoV-2 experienced individuals

The use of COVID-19 vaccines will play the major role in helping to end the pandemic that has killed millions worldwide. COVID-19 vaccines have resulted in robust humoral responses and protective efficacy in human trials, but efficacy trials excluded individuals with a prior diagnosis of COVID-19. As a result, little is known about how immune responses induced by mRNA vaccines differ in individuals who recovered from COVID-19. Here, we evaluated longitudinal immune responses to two-dose BNT162b2 mRNA vaccination in 15 adults who recovered from COVID-19, compared to 21 adults who did not have prior COVID-19 diagnosis. Consistent with prior studies of mRNA vaccines, we observed robust cytotoxic CD8+ T cell responses in both cohorts following the second dose. Furthermore, SARS-CoV-2-naive individuals had progressive increases in humoral and antigen-specific antibody-secreting cell (ASC) responses following each dose of vaccine, whereas SARS-CoV-2-experienced individuals demonstrated strong humoral and antigen-specific ASC responses to the first dose but muted responses to the second dose of the vaccine at the time points studied. Together, these data highlight the relevance of immunological history for understanding vaccine immune responses and may have significant implications for personalizing mRNA vaccination regimens used to prevent COVID-19, including booster shots.

SARS-CoV-2 infection in general practice in Ireland: a seroprevalence study

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody testing in community settings may help us better understand the immune response to this virus and, therefore, help guide public health efforts.

Aim

To conduct a seroprevalence study of immunoglobulin G (IgG) antibodies in Irish GP clinics.

Design & setting

Participants were 172 staff and 799 patients from 15 general practices in the Midwest region of Ireland.

Method

This seroprevalence study utilised two manufacturers’ point-of-care (POC) SARS-CoV-2 immunoglobulin M (IgM)—IgG combined antibody tests, which were offered to patients and staff in general practice from 15 June to 10 July 2020.

Results

IgG seroprevalence was 12.6% in patients attending general practice and 11.1% in staff working in general practice, with administrative staff having the lowest seroprevalence at 2.5% and nursing staff having the highest at 17.6%. Previous symptoms suggestive of COVID-19 and history of a polymerase chain reaction (PCR) test were associated with higher seroprevalence. IgG antibodies were detected in approximately 80% of participants who had a previous PCR-confirmed infection. Average length of time between participants’ positive PCR test and positive IgG antibody test was 83 days.

Conclusion

Patients and healthcare staff in general practice in Ireland had relatively high rates of IgG to SARS-CoV-2 compared with the national average between 15 June and 10 July 2020 (1.7%). Four-fifths of participants with a history of confirmed COVID-19 disease still had detectable antibodies an average of 12 weeks post-infection. While not proof of immunity, SARS-CoV-2 POC testing can be used to estimate IgG seroprevalence in general practice settings.

The fall in antibody response to SARS-CoV-2: a longitudinal study of asymptomatic to critically ill patients up to 10 months after recovery

The aim of this study was to assess the long-term dynamics and factors associated with the serological response against the severe acute respiratory syndrome coronavirus 2 after primary infection. A prospective longitudinal study was conducted with monthly serological follow-up during the first 4 months, and then at 6, 8, and 10 months after the disease onset of all recovered adult in- and outpatients with coronavirus disease 2019 (COVID-19) attending Udine Hospital (Italy) during the first wave (from March to May 2020). A total of 546 individuals were included (289 female, mean age 53.1 years), mostly with mild COVID-19 (370, 68.3%). Patients were followed for a median of 302 days (interquartile range, 186 to 311). The overall seroconversion rate within 2 months was 32% for IgM and 90% for IgG. Seroreversion was observed in 90% of patients for IgM at 4 months and in 47% for IgG at 10 months. Older age, number of symptoms at acute onset, and severity of acute COVID-19 were all independent predictors of long-term immunity both for IgM (β, linear regression coefficient, 1.10, P = 0.001; β 5.15 P = 0.014; β 43.84 P = 0.021, respectively) and for IgG (β 1.43 P < 0.001; β 10.46 P < 0.001; β 46.79 P < 0.001, respectively), whereas the initial IgG peak was associated only with IgG duration (β 1.12, P < 0.001). IgM antibodies disappeared at 4 months, and IgG antibodies declined in about half of patients 10 months after acute COVID-19. These effects varied depending on the intensity of the initial antibody response, age, and burden of acute COVID-19.

Serologic Status and SARS CoV-2 Infection over 6-Months of Follow-Up in Healthcare Workers in Chicago: A Cohort Study

OBJECTIVE

To determine the changes in SARS-CoV-2 serologic status and SARS-CoV-2 infection rates in healthcare workers (HCW) over 6-months of follow-up.

DESIGN

Prospective cohort study.

SETTING AND PARTICIPANTS

HCW in the Chicago area, USA.

METHODS

Cohort participants were recruited in May/June 2020 for baseline serology testing (Abbott anti-Nucleocapsid IgG) and were then invited for follow-up serology testing 6 months later. Participants completed monthly online surveys which assessed demographics, medical history, COVID-19 illness, and exposures to SARS-CoV-2. The electronic medical record was used to identify SARS-CoV-2 PCR positivity during follow-up. Serologic conversion and SARS-CoV-2 infection or possible reinfection rates (cases per 10,000 person*days) by antibody status at baseline and follow-up were assessed.

RESULTS

6510 HCW were followed for a total of 1,285,395 person*days (median follow-up, 216 days). For participants who had baseline and follow-up serology checked, 285 (6.1%) of the 4681 seronegative participants at baseline seroconverted to positive at follow-up; 138 (48%) of the 263 who were seropositive at baseline were seronegative at follow-up. When analyzed by baseline serostatus alone, 519 (8.4%) of 6194 baseline seronegative cohort participants had a positive PCR after baseline serology testing (rate = 4.25/10,000 person days). Of 316 participants who were seropositive at baseline, 8 (2.5%) met criteria for possible SARS-CoV-2 reinfection (PCR+ more than 90 days after baseline serology) during follow-up representing a rate of 1.27/10,000 days at risk. The adjusted rate ratio for possible reinfection in baseline seropositive compared to infection in baseline seronegative participants was 0.26, (95%CI: 0.13 - 0.53).

CONCLUSIONS

Seropositivity in HCWs is associated with moderate protection from future SARS-CoV-2 infection.

Modelling, prediction and design of COVID-19 lockdowns by stringency and duration

The implementation of lockdowns has been a key policy to curb the spread of COVID-19 and to keep under control the number of infections. However, quantitatively predicting in advance the effects of lockdowns based on their stringency and duration is a complex task, in turn making it difficult for governments to design effective strategies to stop the disease. Leveraging a novel mathematical "hybrid" approach, we propose a new epidemic model that is able to predict the future number of active cases and deaths when lockdowns with different stringency levels or durations are enforced. The key observation is that lockdown-induced modifications of social habits may not be captured by traditional mean-field compartmental models because these models assume uniformity of social interactions among the population, which fails during lockdown. Our model is able to capture the abrupt social habit changes caused by lockdowns. The results are validated on the data of Israel and Germany by predicting past lockdowns and providing predictions in alternative lockdown scenarios (different stringency and duration). The findings show that our model can effectively support the design of lockdown strategies by stringency and duration, and quantitatively forecast the course of the epidemic during lockdown.

Key Considerations for the Development of Safe and Effective SARS-CoV-2 Subunit Vaccine: A Peptide-Based Vaccine Alternative

COVID-19 is disastrous to global health and the economy. SARS-CoV-2 infection exhibits similar clinical symptoms and immunopathological sequelae to SARS-CoV infection. Therefore, much of the developmental progress on SARS-CoV vaccines can be utilized for the development of SARS-CoV-2 vaccines. Careful antigen selection during development is always of utmost importance for the production of effective vaccines that do not compromise recipient safety. This holds especially true for SARS-CoV vaccines, as several immunopathological disorders are associated with the activity of structural and nonstructural proteins encoded in the virus's genetic material. Whole viral protein and RNA-encoding full-length proteins contain both protective and "dangerous" sequences, unless pathological fragments are deleted. In light of recent advances, peptide vaccines may present a very safe and effective alternative. Peptide vaccines can avoid immunopathological pro-inflammatory sequences, focus immune responses on neutralizing immunogenic epitopes, avoid off-target antigen loss, combine antigens with different protective roles or mechanisms, even from different viral proteins, and avoid mutant escape by employing highly conserved cryptic epitopes. In this review, an attempt is made to exploit the similarities between SARS-CoV and SARS-CoV-2 in vaccine antigen screening, with particular attention to the pathological and immunogenic properties of SARS proteins.

Optimising health and economic impacts of COVID-19 vaccine prioritisation strategies in the WHO European Region

BACKGROUND

Countries in the World Health Organization (WHO) European Region differ in terms of the COVID-19 vaccine roll-out speed. We evaluated the health and economic impact of different age-based vaccine prioritisation strategies across this demographically and socio-economically diverse region.

METHODS

We fitted country-specific age-stratified compartmental transmission models to reported COVID-19 mortality in the WHO European Region to inform the immunity level before vaccine roll-out. Building upon broad recommendations from the WHO Strategic Advisory Group of Experts on Immunisation (SAGE), we examined four strategies that prioritise: all adults (V+), younger (20-59 year-olds) followed by older adults (60+) (V20), older followed by younger adults (V60), and the oldest adults (75+) (V75) followed by incremental expansion to successively younger five-year age groups. We explored four roll-out scenarios based on projections or recent observations (R1-4) - the slowest scenario (R1) covers 30% of the total population by December 2022 and the fastest (R4) 80% by December 2021. Five decision-making metrics were summarised over 2021-22: mortality, morbidity, and losses in comorbidity-adjusted life expectancy (cLE), comorbidity- and quality-adjusted life years (cQALY), and the value of human capital (HC). Six sets of infection-blocking and disease-reducing vaccine efficacies were considered.

FINDINGS

The optimal age-based vaccine prioritisation strategies were sensitive to country characteristics, decision-making metrics and roll-out speeds. Overall, V60 consistently performed better than or comparably to V75. There were greater benefits in prioritising older adults when roll-out is slow and when VE is low. Under faster roll-out, V+ was the most desirable option.

INTERPRETATION

A prioritisation strategy involving more age-based stages (V75) does not necessarily lead to better health and economic outcomes than targeting broad age groups (V60). Countries expecting a slow vaccine roll-out may particularly benefit from prioritising older adults.

FUNDING

World Health Organization, Bill and Melinda Gates Foundation, the Medical Research Council (United Kingdom), the National Institute of Health Research (United Kingdom), the European Commission, the Foreign, Commonwealth and Development Office (United Kingdom), Wellcome Trust.

RESEARCH IN CONTEXT

Evidence before this study: We searched PubMed and medRxiv for articles published in English from inception to 9 Jun 2021, with the search terms: ("COVID-19" OR "SARS-CoV-2") AND ("priorit*) AND ("model*") AND ("vaccin*") and identified 66 studies on vaccine prioritization strategies. Of the 25 studies that compared two or more age-based prioritisation strategies, 12 found that targeting younger adults minimised infections while targeting older adults minimised mortality; an additional handful of studies found similar outcomes between different age-based prioritisation strategies where large outbreaks had already occurred. However, only two studies have explored age-based vaccine prioritisation using models calibrated to observed outbreaks in more than one country, and no study has explored the effectiveness of vaccine prioritisation strategies across settings with different population structures, contact patterns, and outbreak history.Added-value of this study: We evaluated various age-based vaccine prioritisation strategies for 38 countries in the WHO European Region using various health and economic outcomes for decision-making, by parameterising models using observed outbreak history, known epidemiologic and vaccine characteristics, and a range of realistic vaccine roll-out scenarios. We showed that while targeting older adults was generally advantageous, broadly targeting everyone above 60 years might perform better than or comparably to a more detailed strategy that targeted the oldest age group above 75 years followed by those in the next younger five-year age band. Rapid vaccine roll-out has only been observed in a small number of countries. If vaccine coverage can reach 80% by the end of 2021, prioritising older adults may not be optimal in terms of health and economic impact. Lower vaccine efficacy was associated with greater relative benefits only under relatively slow roll-out scenarios considered.Implication of all the available evidence: COVID-19 vaccine prioritization strategies that require more precise targeting of individuals of a specific and narrow age range may not necessarily lead to better outcomes compared to strategies that prioritise populations across broader age ranges. In the WHO European Region, prioritising all adults equally or younger adults first will only optimise health and economic impact when roll-out is rapid, which may raise between-country equity issues given the global demand for COVID-19 vaccines.

SARS-CoV-2 Antigenemia as a Confounding Factor in Immunodiagnostic Assays: A Case Study

Humoral immunity has emerged as a vital immune component against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Nevertheless, a subset of recovered Coronavirus Disease-2019 (COVID-19) paucisymptomatic/asymptomatic individuals do not generate an antibody response, constituting a paradox. We assumed that immunodiagnostic assays may operate under a competitive format within the context of antigenemia, potentially explaining this phenomenon. We present a case where persistent antigenemia/viremia was documented for at least 73 days post-symptom onset using ‘in-house’ methodology, and as it progressively declined, seroconversion took place late, around day 55, supporting our hypothesis. Thus, prolonged SARS-CoV-2 antigenemia/viremia could mask humoral responses, rendering, in certain cases, the phenomenon of ‘non-responders’ a misnomer.

Estimating the duration of seropositivity of human seasonal coronaviruses using seroprevalence studies

Background: The duration of immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still uncertain, but it is of key clinical and epidemiological importance. Seasonal human coronaviruses (HCoV) have been circulating for longer and, therefore, may offer insights into the long-term dynamics of reinfection for such viruses. Methods: Combining historical seroprevalence data from five studies covering the four circulating HCoVs with an age-structured reverse catalytic model, we estimated the likely duration of seropositivity following seroconversion. Results: We estimated that antibody persistence lasted between 0.9 (95% Credible interval: 0.6 - 1.6) and 3.8 (95% CrI: 2.0 - 7.4) years. Furthermore, we found the force of infection in older children and adults (those over 8.5 [95% CrI: 7.5 - 9.9] years) to be higher compared with young children in the majority of studies. Conclusions: These estimates of endemic HCoV dynamics could provide an indication of the future long-term infection and reinfection patterns of SARS-CoV-2.

Longevity of SARS-CoV-2 immune responses in hemodialysis patients and protection against reinfection

Patients with end stage kidney disease receiving in-center hemodialysis (ICHD) have had high rates of SARS-CoV-2 infection. Following infection, patients receiving ICHD frequently develop circulating antibodies to SARS-CoV-2, even with asymptomatic infection. Here, we investigated the durability and functionality of the immune responses to SARS-CoV-2 infection in patients receiving ICHD. Three hundred and fifty-six such patients were longitudinally screened for SARS-CoV-2 antibodies and underwent routine PCR-testing for symptomatic and asymptomatic infection. Patients were regularly screened for nucleocapsid protein (anti-NP) and receptor binding domain (anti-RBD) antibodies, and those who became seronegative at six months were screened for SARS-CoV-2 specific T-cell responses. One hundred and twenty-nine (36.2%) patients had detectable antibody to anti-NP at time zero, of whom 127 also had detectable anti-RBD. Significantly, at six months, 71/111 (64.0%) and 99/116 (85.3%) remained anti-NP and anti-RBD seropositive, respectively. For patients who retained antibody, both anti-NP and anti-RBD levels were reduced significantly after six months. Eleven patients who were anti-NP seropositive at time zero, had no detectable antibody at six months; of whom eight were found to have SARS-CoV-2 antigen specific T cell responses. Independent of antibody status at six months, patients with baseline positive SARS-CoV-2 serology were significantly less likely to have PCR confirmed infection over the following six months. Thus, patients receiving ICHD mount durable immune responses six months post SARS-CoV-2 infection, with fewer than 3% of patients showing no evidence of humoral or cellular immunity.

Incidence of SARS-CoV-2 infection according to baseline antibody status in staff and residents of 100 long-term care facilities (VIVALDI): a prospective cohort study

BACKGROUND

SARS-CoV-2 infection represents a major challenge for long-term care facilities (LTCFs) and many residents and staff are seropositive following persistent outbreaks. We aimed to investigate the association between the SARS-CoV-2 antibody status at baseline and subsequent infection in this population.

METHODS

We did a prospective cohort study of SARS-CoV-2 infection in staff (aged <65 years) and residents (aged >65 years) at 100 LTCFs in England between Oct 1, 2020, and Feb 1, 2021. Blood samples were collected between June and November, 2020, at baseline, and 2 and 4 months thereafter and tested for IgG antibodies to SARS-CoV-2 nucleocapsid and spike proteins. PCR testing for SARS-CoV-2 was done weekly in staff and monthly in residents. Cox regression was used to estimate hazard ratios (HRs) of a PCR-positive test by baseline antibody status, adjusted for age and sex, and stratified by LTCF.

FINDINGS

682 residents from 86 LCTFs and 1429 staff members from 97 LTCFs met study inclusion criteria. At baseline, IgG antibodies to nucleocapsid were detected in 226 (33%) of 682 residents and 408 (29%) of 1429 staff members. 93 (20%) of 456 residents who were antibody-negative at baseline had a PCR-positive test (infection rate 0·054 per month at risk) compared with four (2%) of 226 residents who were antibody-positive at baseline (0·007 per month at risk). 111 (11%) of 1021 staff members who were antibody-negative at baseline had PCR-positive tests (0·042 per month at risk) compared with ten (2%) of 408 staff members who were antibody-positive staff at baseline (0·009 per month at risk). The risk of PCR-positive infection was higher for residents who were antibody-negative at baseline than residents who were antibody-positive at baseline (adjusted HR [aHR] 0·15, 95% CI 0·05-0·44, p=0·0006), and the risk of a PCR-positive infection was also higher for staff who were antibody-negative at baseline compared with staff who were antibody-positive at baseline (aHR 0·39, 0·19-0·82; p=0·012). 12 of 14 reinfected participants had available data on symptoms, and 11 of these participants were symptomatic. Antibody titres to spike and nucleocapsid proteins were comparable in PCR-positive and PCR-negative cases.

INTERPRETATION

The presence of IgG antibodies to nucleocapsid protein was associated with substantially reduced risk of reinfection in staff and residents for up to 10 months after primary infection.

FUNDING

UK Government Department of Health and Social Care.

Genomics and epidemiology of the P.1 SARS-CoV-2 lineage in Manaus, Brazil

Cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in Manaus, Brazil, resurged in late 2020 despite previously high levels of infection. Genome sequencing of viruses sampled in Manaus between November 2020 and January 2021 revealed the emergence and circulation of a novel SARS-CoV-2 variant of concern. Lineage P.1 acquired 17 mutations, including a trio in the spike protein (K417T, E484K, and N501Y) associated with increased binding to the human ACE2 (angiotensin-converting enzyme 2) receptor. Molecular clock analysis shows that P.1 emergence occurred around mid-November 2020 and was preceded by a period of faster molecular evolution. Using a two-category dynamical model that integrates genomic and mortality data, we estimate that P.1 may be 1.7- to 2.4-fold more transmissible and that previous (non-P.1) infection provides 54 to 79% of the protection against infection with P.1 that it provides against non-P.1 lineages. Enhanced global genomic surveillance of variants of concern, which may exhibit increased transmissibility and/or immune evasion, is critical to accelerate pandemic responsiveness.

COVID-19 reinfection: a rapid systematic review of case reports and case series

The COVID-19 pandemic has infected millions of people worldwide and many countries have been suffering from a large number of deaths. Acknowledging the ability of SARS-CoV-2 to mutate into distinct strains as an RNA virus and investigating its potential to cause reinfection is important for future health policy guidelines. It was thought that individuals who recovered from COVID-19 generate a robust immune response and develop protective immunity; however, since the first case of documented reinfection of COVID-19 in August 2020, there have been a number of cases with reinfection. Many cases are lacking genomic data of the two infections, and it remains unclear whether they were caused by different strains. In the present study, we undertook a rapid systematic review to identify cases infected with different genetic strains of SARS-CoV-2 confirmed by PCR and viral genome sequencing. A total of 17 cases of genetically confirmed COVID-19 reinfection were found. One immunocompromised patient had mild symptoms with the first infection but developed severe symptoms resulting in death with the second infection. Overall, 68.8% (11/16) had similar severity; 18.8% (3/16) had worse symptoms; and 12.5% (2/16) had milder symptoms with the second episode. Our case series shows that reinfection with different strains is possible, and some cases may experience more severe infections with the second episode. The findings also suggest that COVID-19 may continue to circulate even after achieving herd immunity through natural infection or vaccination, suggesting the need for longer-term transmission mitigation efforts.

Knowledge and Attitudes Toward Covid-19 and Vaccines Among a New York Haredi-Orthodox Jewish Community

The Covid-19 pandemic has exposed the difficulty of the US public health system to respond effectively to vulnerable subpopulations, causing disproportionate rates of morbidity and mortality. New York Haredi-Orthodox Jewish communities represent a group that have been heavily impacted by Covid-19. Little research has examined their experience or perceptions toward Covid-19 and vaccines. We conducted a cross-sectional, observational study to explore the experience of Covid-19 among Haredim. Paper surveys were self-administered between December 2020 and January 2021 in Haredi neighborhood pediatricians' offices in Brooklyn, New York. Of 102 respondents, 43% reported either a positive SARS-CoV-2 viral or antibody test. Participants trusted their physicians, Orthodox medical organizations, and rabbinic leaders for medical information. Knowledge of Covid-19 transmission and risk was good (69% answered ≥ 4/6 questions correctly). Only 12% of respondents would accept a Covid-19 vaccine, 41% were undecided and 47% were strongly hesitant. Independent predictors of strong vaccine hesitancy included believing natural infection to be better than vaccination for developing immunity (adjusted odds ratio [aOR] 4.28; 95% confidence interval [CI] 1.23-14.86), agreement that prior infection provides a path toward resuming communal life (aOR 4.10; 95% CI 1.22-13.77), and pandemic-related loss of trust in physicians (aOR 5.01; 95% CI 1.05-23.96). The primary disseminators of health information for self-protective religious communities should be stakeholders who understand these groups' unique health needs. In communities with significant Covid-19 experience, vaccination messaging may need to be tailored toward protecting infection-naïve individuals and boosting natural immunity against emerging variants.

COVID-19 vaccine coverage in health-care workers in England and effectiveness of BNT162b2 mRNA vaccine against infection (SIREN): a prospective, multicentre, cohort study

BACKGROUND

BNT162b2 mRNA and ChAdOx1 nCOV-19 adenoviral vector vaccines have been rapidly rolled out in the UK from December, 2020. We aimed to determine the factors associated with vaccine coverage for both vaccines and documented the vaccine effectiveness of the BNT162b2 mRNA vaccine in a cohort of health-care workers undergoing regular asymptomatic testing.

METHODS

The SIREN study is a prospective cohort study among staff (aged ≥18 years) working in publicly-funded hospitals in the UK. Participants were assigned into either the positive cohort (antibody positive or history of infection [indicated by previous positivity of antibody or PCR tests]) or the negative cohort (antibody negative with no previous positive test) at the beginning of the follow-up period. Baseline risk factors were collected at enrolment, symptom status was collected every 2 weeks, and vaccination status was collected through linkage to the National Immunisations Management System and questionnaires. Participants had fortnightly asymptomatic SARS-CoV-2 PCR testing and monthly antibody testing, and all tests (including symptomatic testing) outside SIREN were captured. Data cutoff for this analysis was Feb 5, 2021. The follow-up period was Dec 7, 2020, to Feb 5, 2021. The primary outcomes were vaccinated participants (binary ever vacinated variable; indicated by at least one vaccine dose recorded by at least one of the two vaccination data sources) for the vaccine coverage analysis and SARS-CoV-2 infection confirmed by a PCR test for the vaccine effectiveness analysis. We did a mixed-effect logistic regression analysis to identify factors associated with vaccine coverage. We used a piecewise exponential hazard mixed-effects model (shared frailty-type model) using a Poisson distribution to calculate hazard ratios to compare time-to-infection in unvaccinated and vaccinated participants and estimate the impact of the BNT162b2 vaccine on all PCR-positive infections (asymptomatic and symptomatic). This study is registered with ISRCTN, number ISRCTN11041050, and is ongoing.

FINDINGS

23 324 participants from 104 sites (all in England) met the inclusion criteria for this analysis and were enrolled. Included participants had a median age of 46·1 years (IQR 36·0-54·1) and 19 692 (84%) were female; 8203 (35%) were assigned to the positive cohort at the start of the analysis period, and 15 121 (65%) assigned to the negative cohort. Total follow-up time was 2 calendar months and 1 106 905 person-days (396 318 vaccinated and 710 587 unvaccinated). Vaccine coverage was 89% on Feb 5, 2021, 94% of whom had BNT162b2 vaccine. Significantly lower coverage was associated with previous infection, gender, age, ethnicity, job role, and Index of Multiple Deprivation score. During follow-up, there were 977 new infections in the unvaccinated cohort, an incidence density of 14 infections per 10 000 person-days; the vaccinated cohort had 71 new infections 21 days or more after their first dose (incidence density of eight infections per 10 000 person-days) and nine infections 7 days after the second dose (incidence density four infections per 10 000 person-days). In the unvaccinated cohort, 543 (56%) participants had typical COVID-19 symptoms and 140 (14%) were asymptomatic on or 14 days before their PCR positive test date, compared with 29 (36%) with typical COVID-19 symptoms and 15 (19%) asymptomatic in the vaccinated cohort. A single dose of BNT162b2 vaccine showed vaccine effectiveness of 70% (95% CI 55-85) 21 days after first dose and 85% (74-96) 7 days after two doses in the study population.

INTERPRETATION

Our findings show that the BNT162b2 vaccine can prevent both symptomatic and asymptomatic infection in working-age adults. This cohort was vaccinated when the dominant variant in circulation was B1.1.7 and shows effectiveness against this variant.

FUNDING

Public Health England, UK Department of Health and Social Care, and the National Institute for Health Research.

Changes in symptomatology, reinfection, and transmissibility associated with the SARS-CoV-2 variant B.1.1.7: an ecological study

BACKGROUND

The SARS-CoV-2 variant B.1.1.7 was first identified in December, 2020, in England. We aimed to investigate whether increases in the proportion of infections with this variant are associated with differences in symptoms or disease course, reinfection rates, or transmissibility.

METHODS

We did an ecological study to examine the association between the regional proportion of infections with the SARS-CoV-2 B.1.1.7 variant and reported symptoms, disease course, rates of reinfection, and transmissibility. Data on types and duration of symptoms were obtained from longitudinal reports from users of the COVID Symptom Study app who reported a positive test for COVID-19 between Sept 28 and Dec 27, 2020 (during which the prevalence of B.1.1.7 increased most notably in parts of the UK). From this dataset, we also estimated the frequency of possible reinfection, defined as the presence of two reported positive tests separated by more than 90 days with a period of reporting no symptoms for more than 7 days before the second positive test. The proportion of SARS-CoV-2 infections with the B.1.1.7 variant across the UK was estimated with use of genomic data from the COVID-19 Genomics UK Consortium and data from Public Health England on spike-gene target failure (a non-specific indicator of the B.1.1.7 variant) in community cases in England. We used linear regression to examine the association between reported symptoms and proportion of B.1.1.7. We assessed the Spearman correlation between the proportion of B.1.1.7 cases and number of reinfections over time, and between the number of positive tests and reinfections. We estimated incidence for B.1.1.7 and previous variants, and compared the effective reproduction number, Rt, for the two incidence estimates.

FINDINGS

From Sept 28 to Dec 27, 2020, positive COVID-19 tests were reported by 36 920 COVID Symptom Study app users whose region was known and who reported as healthy on app sign-up. We found no changes in reported symptoms or disease duration associated with B.1.1.7. For the same period, possible reinfections were identified in 249 (0·7% [95% CI 0·6-0·8]) of 36 509 app users who reported a positive swab test before Oct 1, 2020, but there was no evidence that the frequency of reinfections was higher for the B.1.1.7 variant than for pre-existing variants. Reinfection occurrences were more positively correlated with the overall regional rise in cases (Spearman correlation 0·56-0·69 for South East, London, and East of England) than with the regional increase in the proportion of infections with the B.1.1.7 variant (Spearman correlation 0·38-0·56 in the same regions), suggesting B.1.1.7 does not substantially alter the risk of reinfection. We found a multiplicative increase in the Rt of B.1.1.7 by a factor of 1·35 (95% CI 1·02-1·69) relative to pre-existing variants. However, Rt fell below 1 during regional and national lockdowns, even in regions with high proportions of infections with the B.1.1.7 variant.

INTERPRETATION

The lack of change in symptoms identified in this study indicates that existing testing and surveillance infrastructure do not need to change specifically for the B.1.1.7 variant. In addition, given that there was no apparent increase in the reinfection rate, vaccines are likely to remain effective against the B.1.1.7 variant.

FUNDING

Zoe Global, Department of Health (UK), Wellcome Trust, Engineering and Physical Sciences Research Council (UK), National Institute for Health Research (UK), Medical Research Council (UK), Alzheimer's Society.

Changes in symptomatology, reinfection, and transmissibility associated with the SARS-CoV-2 variant B.1.1.7: an ecological study

BACKGROUND

The SARS-CoV-2 variant B.1.1.7 was first identified in December, 2020, in England. We aimed to investigate whether increases in the proportion of infections with this variant are associated with differences in symptoms or disease course, reinfection rates, or transmissibility.

METHODS

We did an ecological study to examine the association between the regional proportion of infections with the SARS-CoV-2 B.1.1.7 variant and reported symptoms, disease course, rates of reinfection, and transmissibility. Data on types and duration of symptoms were obtained from longitudinal reports from users of the COVID Symptom Study app who reported a positive test for COVID-19 between Sept 28 and Dec 27, 2020 (during which the prevalence of B.1.1.7 increased most notably in parts of the UK). From this dataset, we also estimated the frequency of possible reinfection, defined as the presence of two reported positive tests separated by more than 90 days with a period of reporting no symptoms for more than 7 days before the second positive test. The proportion of SARS-CoV-2 infections with the B.1.1.7 variant across the UK was estimated with use of genomic data from the COVID-19 Genomics UK Consortium and data from Public Health England on spike-gene target failure (a non-specific indicator of the B.1.1.7 variant) in community cases in England. We used linear regression to examine the association between reported symptoms and proportion of B.1.1.7. We assessed the Spearman correlation between the proportion of B.1.1.7 cases and number of reinfections over time, and between the number of positive tests and reinfections. We estimated incidence for B.1.1.7 and previous variants, and compared the effective reproduction number, R_t, for the two incidence estimates.

FINDINGS

From Sept 28 to Dec 27, 2020, positive COVID-19 tests were reported by 36 920 COVID Symptom Study app users whose region was known and who reported as healthy on app sign-up. We found no changes in reported symptoms or disease duration associated with B.1.1.7. For the same period, possible reinfections were identified in 249 (0·7% [95% CI 0·6-0·8]) of 36 509 app users who reported a positive swab test before Oct 1, 2020, but there was no evidence that the frequency of reinfections was higher for the B.1.1.7 variant than for pre-existing variants. Reinfection occurrences were more positively correlated with the overall regional rise in cases (Spearman correlation 0·56-0·69 for South East, London, and East of England) than with the regional increase in the proportion of infections with the B.1.1.7 variant (Spearman correlation 0·38-0·56 in the same regions), suggesting B.1.1.7 does not substantially alter the risk of reinfection. We found a multiplicative increase in the R_t of B.1.1.7 by a factor of 1·35 (95% CI 1·02-1·69) relative to pre-existing variants. However, R_t fell below 1 during regional and national lockdowns, even in regions with high proportions of infections with the B.1.1.7 variant.

INTERPRETATION

The lack of change in symptoms identified in this study indicates that existing testing and surveillance infrastructure do not need to change specifically for the B.1.1.7 variant. In addition, given that there was no apparent increase in the reinfection rate, vaccines are likely to remain effective against the B.1.1.7 variant.

FUNDING

Zoe Global, Department of Health (UK), Wellcome Trust, Engineering and Physical Sciences Research Council (UK), National Institute for Health Research (UK), Medical Research Council (UK), Alzheimer's Society.

Disparities of SARS-CoV-2 Nucleoprotein-Specific IgG in Healthcare Workers in East London, UK

Introduction: SARS-CoV-2 antibody detection serves as an important diagnostic marker for past SARS-CoV-2 infection and is essential to determine the spread of COVID-19, monitor potential COVID-19 long-term effects, and to evaluate possible protection from reinfection. A study was conducted across three hospital sites in a large central London NHS Trust in the UK, to evaluate the prevalence and duration of SARS-CoV-2 IgG antibody positivity in healthcare workers. Methods: A matrix equivalence study consisting of 228 participants was undertaken to evaluate the Abbott Panbio™ COVID-19 IgG/IgM rapid test device. Subsequently, 2001 evaluable healthcare workers (HCW), representing a diverse population, were enrolled in a HCW study between June and August 2020. A plasma sample from each HCW was evaluated using the Abbott Panbio™ COVID-19 IgG/IgM rapid test device, with confirmation of IgG-positive results by the Abbott ArchitectTM SARS-CoV-2 IgG assay. 545 participants, of whom 399 were antibody positive at enrolment, were followed up at 3 months. Results: The Panbio™ COVID-19 IgG/IgM rapid test device demonstrated a high concordance with laboratory tests. SARS-CoV-2 antibodies were detected in 506 participants (25.3%) at enrolment, with a higher prevalence in COVID-19 frontline (28.3%) than non-frontline (19.9%) staff. At follow-up, 274/399 antibody positive participants (68.7%) retained antibodies; 4/146 participants negative at enrolment (2.7%) had seroconverted. Non-white ethnicity, older age, hypertension and COVID-19 symptoms were independent predictors of higher antibody levels (OR 1.881, 2.422-3.034, 2.128, and 1.869 respectively), based on Architect™ index quartiles; participants in the first three categories also showed a greater antibody persistence at 3 months. Conclusion: The SARS-CoV-2 anti-nucleocapsid IgG positivity rate among healthcare staff was high, declining by 31.3% during the 3-month follow-up interval. Interestingly, the IgG-positive participants with certain risk factors for severe COVID-19 illness (older age, Black or Asian Ethnicity hypertension) demonstrated greater persistence over time when compared to the IgG-positive participants without these risk factors.

Immune Correlates of Protection by mRNA-1273 Immunization against SARS-CoV-2 Infection in Nonhuman Primates

Immune correlates of protection can be used as surrogate endpoints for vaccine efficacy. The nonhuman primate (NHP) model of SARS-CoV-2 infection replicates key features of human infection and may be used to define immune correlates of protection following vaccination. Here, NHP received either no vaccine or doses ranging from 0.3 - 100 μg of mRNA-1273, a mRNA vaccine encoding the prefusion-stabilized SARS-CoV-2 spike (S-2P) protein encapsulated in a lipid nanoparticle. mRNA-1273 vaccination elicited robust circulating and mucosal antibody responses in a dose-dependent manner. Viral replication was significantly reduced in bronchoalveolar lavages and nasal swabs following SARS-CoV-2 challenge in vaccinated animals and was most strongly correlated with levels of anti-S antibody binding and neutralizing activity. Consistent with antibodies being a correlate of protection, passive transfer of vaccine-induced IgG to naïve hamsters was sufficient to mediate protection. Taken together, these data show that mRNA-1273 vaccine-induced humoral immune responses are a mechanistic correlate of protection against SARS-CoV-2 infection in NHP.

One-Sentence Summary

mRNA-1273 vaccine-induced antibody responses are a mechanistic correlate of protection against SARS-CoV-2 infection in NHP.

A Delayed Case of Pericarditis Following Recovery From COVID-19 Infection

Pericarditis is a rare cardiac complication of coronavirus 19 (COVID-19) infection. Recent case reports describe severe sequelae of pericarditis, including cardiac tamponade, developing within days of initial COVID-19 symptoms. We present a case of pericarditis with slower onset and milder symptoms, developing over a period of a few weeks in an immunocompetent male who recovered from COVID-19 several months earlier. A 65-year-old male presented to an emergency department several times for one week of worsening chest and neck symptoms, along with fever. He had been symptom-free after a three-day course of cough, myalgias, and fever with positive COVID-19 testing, approximately 70 days earlier. He was ultimately admitted for fever and pericarditis with an associated pericardial effusion and positive PCR testing for COVID-19. Pericarditis should be considered in the differential diagnosis for patients with COVID-19 and unexplained persistent chest symptoms. The possibility of recurrent or atypical latent infection should additionally be considered in the months following the initial COVID-19 infection. Bedside ultrasound may facilitate early diagnosis and management of COVID-19 associated pericarditis.

Antibody Response to the BNT162b2 mRNA COVID-19 Vaccine in Subjects with Prior SARS-CoV-2 Infection

Although antibody levels progressively decrease following SARS-CoV-2 infection, the immune memory persists for months. Thus, individuals who naturally contracted SARS-CoV-2 are expected to develop a more rapid and sustained response to COVID-19 vaccines than naïve individuals. In this study, we analyzed the dynamics of the antibody response to the BNT162b2 mRNA COVID-19 vaccine in six healthcare workers who contracted SARS-CoV-2 in March 2020, in comparison to nine control subjects without a previous infection. The vaccine was well tolerated by both groups, with no significant difference in the frequency of vaccine-associated side effects, with the exception of local pain, which was more common in previously infected subjects. Overall, the titers of neutralizing antibodies were markedly higher in response to the vaccine than after natural infection. In all subjects with pre-existing immunity, a rapid increase in anti-spike receptor-binding domain (RBD) IgG antibodies and neutralizing antibody titers was observed one week after the first dose, which seemed to act as a booster. Notably, in previously infected individuals, neutralizing antibody titers 7 days after the first vaccine dose were not significantly different from those observed in naïve subjects 7 days after the second vaccine dose. These results suggest that, in previously infected people, a single dose of the vaccine might be sufficient to induce an effective response.

Ferreira AC, Schnekenberg RP, Laydon DJ, Walker PGT, Schlüter HM, dos Santos ALP, Vidal MS, Del Caro VS, Filho RMF, dos Santos HM, Aguiar RS, Modena JLP, Nelson B, Hay JA, Monod M, Miscouridou X, Coupland H, Sonabend R, Vollmer M, Gandy A, Suchard MA, Bowden TA, Pond SLK, Wu CH, Ratmann O, Ferguson NM, Dye C, Loman NJ, Lemey P, Rambaut A, Fraiji NA, Carvalho MDPSS, Pybus OG, Flaxman S, Bhatt S, Sabino EC. Genomics and epidemiology of a novel SARS-CoV-2 lineage in Manaus, Brazil

Cases of SARS-CoV-2 infection in Manaus, Brazil, resurged in late 2020, despite high levels of previous infection there. Through genome sequencing of viruses sampled in Manaus between November 2020 and January 2021, we identified the emergence and circulation of a novel SARS-CoV-2 variant of concern, lineage P.1, that acquired 17 mutations, including a trio in the spike protein (K417T, E484K and N501Y) associated with increased binding to the human ACE2 receptor. Molecular clock analysis shows that P.1 emergence occurred around early November 2020 and was preceded by a period of faster molecular evolution. Using a two-category dynamical model that integrates genomic and mortality data, we estimate that P.1 may be 1.4-2.2 times more transmissible and 25-61% more likely to evade protective immunity elicited by previous infection with non-P.1 lineages. Enhanced global genomic surveillance of variants of concern, which may exhibit increased transmissibility and/or immune evasion, is critical to accelerate pandemic responsiveness.