Binding and Neutralization Antibody Titers After a Single Vaccine Dose in Health Care Workers Previously Infected With SARS-CoV-2

The temporal course of T- and B-cell responses to vaccination with BNT162b2 and mRNA-1273

OBJECTIVES

To investigate the response of the immune system (and its influencing factors) to vaccination with BNT162b2 or mRNA-1273.

METHODS

531 vaccinees, recruited from healthcare professionals, donated samples before, in between, and after the administration of the two doses of the vaccine. T- and B-cell responses were examined via interferon-γ (IFN-γ) release assay, and antibodies against different epitopes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (S1 and NCP) were detected via ELISA and surrogate neutralization assay. Results were correlated with influencing factors such as age, sex, prior infection, vaccine received (BNT162b2 or mRNA-1273), and immunosuppression. Furthermore, antinuclear antibodies (ANAs) were measured to screen for autoimmune responses following vaccination with an mRNA vaccine.

RESULTS

No markers of immunity against SARS-CoV-2 were found before the first vaccination. Two weeks after it, specific responses against SARS-CoV-2 were already measurable (median ± median absolute deviation (MAD): anti-S1 IgG 195.5 ± 172.7 BAU/mL; IgA 6.7 ± 4.9 OD; surrogate neutralization 39 ± 23.7%), and were significantly increased two weeks after the second dose (anti-S1 IgG 3744 ± 2571.4 BAU/mL; IgA 12 ± 0 OD; surrogate neutralization 100 ± 0%, IFN-γ 1897.2 ± 886.7 mIU/mL). Responses were stronger for younger participants (this difference decreasing after the second dose). Further influences were previous infection with SARS-CoV-2 (causing significantly stronger responses after the first dose compared to unexposed individuals (p ≤ 0.0001)) and the vaccine received (significantly stronger reactions for recipients of mRNA-1273 after both doses, p < 0.05-0.0001). Some forms of immunosuppression significantly impeded the immune response to the vaccination (with no observable immune response in three immunosuppressed participants). There was no significant induction of ANAs by the vaccination (no change in qualitative ANA results (p 0.2592) nor ANA titres (p 0.08) from pre-to post-vaccination.

CONCLUSIONS

Both vaccines elicit strong and specific immune responses against SARS-CoV-2 which become detectable one week (T-cell response) or two weeks (B-cell response) after the first dose.

Safety and immunogenicity of an AS03-adjuvanted SARS-CoV-2 recombinant protein vaccine (CoV2 preS dTM) in healthy adults: interim findings from a phase 2, randomised, dose-finding, multicentre study

BACKGROUND

We evaluated our SARS-CoV-2 prefusion spike recombinant protein vaccine (CoV2 preS dTM) with different adjuvants, unadjuvanted, and in a one-injection and two-injection dosing schedule in a previous phase 1-2 study. Based on interim results from that study, we selected a two-injection schedule and the AS03 adjuvant for further clinical development. However, lower than expected antibody responses, particularly in older adults, and higher than expected reactogenicity after the second vaccination were observed. In the current study, we evaluated the safety and immunogenicity of an optimised formulation of CoV2 preS dTM adjuvanted with AS03 to inform progression to phase 3 clinical trial.

METHODS

This phase 2, randomised, parallel-group, dose-ranging study was done in adults (≥18 years old), including those with pre-existing medical conditions, those who were immunocompromised (except those with recent organ transplant or chemotherapy) and those with a potentially increased risk for severe COVID-19, at 20 clinical research centres in the USA and Honduras. Women who were pregnant or lactating or, for those of childbearing potential, not using an effective method of contraception or abstinence, and those who had received a COVID-19 vaccine, were excluded. Participants were randomly assigned (1:1:1) using an interactive response technology system, with stratification by age (18-59 years and ≥60 years), rapid serodiagnostic test result (positive or negative), and high-risk medical conditions (yes or no), to receive two injections (day 1 and day 22) of 5 7mu;g (low dose), 10 7mu;g (medium dose), or 15 7mu;g (high dose) CoV2 preS dTM antigen with fixed AS03 content. All participants and outcome assessors were masked to group assignment; unmasked study staff involved in vaccine preparation were not involved in safety outcome assessments. All laboratory staff performing the assays were masked to treatment. The primary safety objective was to describe the safety profile in all participants, for each candidate vaccine formulation. Safety endpoints were evaluated for all randomised participants who received at least one dose of the study vaccine (safety analysis set), and are presented here for the interim study period (up to day 43). The primary immunogenicity objective was to describe the neutralising antibody titres to the D614G variant 14 days after the second vaccination (day 36) in participants who were SARS-CoV-2 naive who received both injections, provided samples at day 1 and day 36, did not have protocol deviations, and did not receive an authorised COVID-19 vaccine before day 36. Neutralising antibodies were measured using a pseudovirus neutralisation assay and are presented here up to 14 days after the second dose. As a secondary immunogenicity objective, we assessed neutralising antibodies in non-naive participants. This trial is registered with ClinicalTrials.gov (NCT04762680) and is closed to new participants for the cohort reported here.

FINDINGS

Of 722 participants enrolled and randomly assigned between Feb 24, 2021, and March 8, 2021, 721 received at least one injection (low dose=240, medium dose=239, and high dose=242). The proportion of participants reporting at least one solicited adverse reaction (injection site or systemic) in the first 7 days after any vaccination was similar between treatment groups (217 [91%] of 238 in the low-dose group, 213 [90%] of 237 in the medium-dose group, and 218 [91%] of 239 in the high-dose group); these adverse reactions were transient, were mostly mild to moderate in intensity, and occurred at a higher frequency and intensity after the second vaccination. Four participants reported immediate unsolicited adverse events; two (one each in the low-dose group and medium-dose group) were considered by the investigators to be vaccine related and two (one each in the low-dose and high-dose groups) were considered unrelated. Five participants reported seven vaccine-related medically attended adverse events (two in the low-dose group, one in the medium-dose group, and four in the high-dose group). No vaccine-related serious adverse events and no adverse events of special interest were reported. Among participants naive to SARS-CoV-2 at day 36, 158 (98%) of 162 in the low-dose group, 166 (99%) of 168 in the medium-dose group, and 163 (98%) of 166 in the high-dose group had at least a two-fold increase in neutralising antibody titres to the D614G variant from baseline. Neutralising antibody geometric mean titres (GMTs) at day 36 for participants who were naive were 2189 (95% CI 1744-2746) for the low-dose group, 2269 (1792-2873) for the medium-dose group, and 2895 (2294-3654) for the high-dose group. GMT ratios (day 36: day 1) were 107 (95% CI 85-135) in the low-dose group, 110 (87-140) in the medium-dose group, and 141 (111-179) in the high-dose group. Neutralising antibody titres in non-naive adults 21 days after one injection tended to be higher than titres after two injections in adults who were naive, with GMTs 21 days after one injection for participants who were non-naive being 3143 (95% CI 836-11 815) in the low-dose group, 2338 (593-9226) in the medium-dose group, and 7069 (1361-36 725) in the high-dose group.

INTERPRETATION

Two injections of CoV2 preS dTM-AS03 showed acceptable safety and reactogenicity, and robust immunogenicity in adults who were SARS-CoV-2 naive and non-naive. These results supported progression to phase 3 evaluation of the 10 7mu;g antigen dose for primary vaccination and a 5 7mu;g antigen dose for booster vaccination.

FUNDING

Sanofi Pasteur and Biomedical Advanced Research and Development Authority.

Low neutralizing antibody responses in WM, CLL and NHL patients after the first dose of the BNT162b2 and AZD1222 vaccine

Vaccination against SARS-CoV-2 is considered as the most important preventive strategy against COVID-19, but its efficacy in patients with hematological malignancies is largely unknown. We investigated the development of neutralizing antibodies (NAbs) against SARS-CoV-2 in patients with Waldenstrom Macroglobulinemia (WM), Chronic Lymphocytic Leukemia (CLL) and Non-Hodgkin Lymphoma (NHL). After the first dose of the vaccine, on D22, WM/CLL/NHL patients had lower NAb titers compared to controls: the median NAb inhibition titer was 17% (range 0-91%, IQR 8-27%) for WM/CLL/NHL patients versus 32% (range 2-98%, IQR 19-48%) for controls (P < 0.001). Only 8 (14%) patients versus 114 (54%) controls developed NAb titers ≥ 30% on D22 (p < 0.001). Our data indicate that the first dose of both BNT162b2 and AZD1222 leads to lower production of NAbs against SARS-CoV-2 in patients with WM/CLL/NHL compared to controls of similar age and gender and without malignant disease. Even though the response rates were not optimal, vaccination is still considered essential and if possible should be performed before treatment initiation. These patients with suboptimal responses should be considered to be prioritized for booster doses.

Antibody profile in post-vaccinated & SARS-CoV-2 infected individuals

Background & objectives

During the COVID-19 pandemic it was important to assess the antibody profile in individuals vaccinated with Covaxin (BBV152) and Covishield (ChAdOx1 nCoV-19) with both 28 and 84 days gaps between two doses, those infected with SARS-CoV-2 and post-COVID-19-infected individuals vaccinated with only one dose of either of the vaccines. The present study was aimed to assess these objectives.

Methods

Fifty real time reverse transcription-polymerase chain reaction (qRT-PCR)-confirmed COVID-19-infected individuals, along with 90 COVID-19-naïve (BBV152 and ChAdOx1 nCov-19)-vaccinated individuals, were included in the study. Individuals who received a single dose of either vaccine with a confirmed past diagnosis of SARS-CoV-2 infection (n=15) were also included. Blood samples were collected strictly between the 4th and 5th wk after development of symptoms for SARS-CoV-2 infected individuals and after the first/second vaccination dose. Antibody profile assessment was done using whole-virus, spike-receptor binding domain (RBD) and nucleocapsid-specific ELISA kits along with neutralizing antibody kit.

Results

There was an overall 97.7 per cent seropositivity rate in vaccinated individuals, and a strong correlation (R2=0.8, P<0.001) between neutralizing and spike-RBD antibodies. Among individuals who received two standard doses of ChAdOx1 nCoV-19 vaccine, the spike antibody levels developed were of higher titre with a longer prime boost interval than in those with shorter intervals (P<0.01). Individuals vaccinated with two doses as well as only one dose post-SARS-CoV-2 infection had high neutralizing and spike-specific antibodies.

Interpretation & conclusions

High neutralizing and spike-specific antibodies were developed in individuals vaccinated only with one dose of either vaccine post-SARS-CoV-2 infection. With the main priority being vaccinating majority of the population in our country, single-dose administration to such individuals would be a sensible way to make the most of the limited supplies. Furthermore, neutralizing antibody levels observed in COVID-19-naïve vaccinees imply the need for booster vaccination.

Defining the risk of SARS-CoV-2 variants on immune protection

The global emergence of many severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants jeopardizes the protective antiviral immunity induced after infection or vaccination. To address the public health threat caused by the increasing SARS-CoV-2 genomic diversity, the National Institute of Allergy and Infectious Diseases within the National Institutes of Health established the SARS-CoV-2 Assessment of Viral Evolution (SAVE) programme. This effort was designed to provide a real-time risk assessment of SARS-CoV-2 variants that could potentially affect the transmission, virulence, and resistance to infection- and vaccine-induced immunity. The SAVE programme is a critical data-generating component of the US Government SARS-CoV-2 Interagency Group to assess implications of SARS-CoV-2 variants on diagnostics, vaccines and therapeutics, and for communicating public health risk. Here we describe the coordinated approach used to identify and curate data about emerging variants, their impact on immunity and effects on vaccine protection using animal models. We report the development of reagents, methodologies, models and notable findings facilitated by this collaborative approach and identify future challenges. This programme is a template for the response to rapidly evolving pathogens with pandemic potential by monitoring viral evolution in the human population to identify variants that could reduce the effectiveness of countermeasures.

Broad Neutralization of SARS-CoV-2 Variants, Including Omicron, following Breakthrough Infection with Delta in COVID-19-Vaccinated Individuals

Numerous studies have shown that a prior SARS-CoV-2 infection can greatly enhance the antibody response to COVID-19 vaccination, with this so called "hybrid immunity" leading to greater neutralization breadth against SARS-CoV-2 variants of concern. However, little is known about how breakthrough infection (BTI) in COVID-19-vaccinated individuals will impact the magnitude and breadth of the neutralizing antibody response. Here, we compared neutralizing antibody responses between unvaccinated and COVID-19-double-vaccinated individuals (including both AZD1222 and BNT162b2 vaccinees) who have been infected with the Delta (B.1.617.2) variant. Rapid production of spike-reactive IgG was observed in the vaccinated group, providing evidence of effective vaccine priming. Overall, potent cross-neutralizing activity against current SARS-CoV-2 variants of concern was observed in the BTI group compared to the infection group, including neutralization of the Omicron (B.1.1.529) variant. This study provides important insights into population immunity where transmission levels remain high and in the context of new or emerging variants of concern. IMPORTANCE COVID-19 vaccines have been vital in controlling SARS-CoV-2 infections and reducing hospitalizations. However, breakthrough SARS-CoV-2 infections (BTI) occur in some vaccinated individuals. Here, we study how BTI impacts on the potency and the breadth of the neutralizing antibody response. We show that a Delta infection in COVID-19-vaccinated individuals provides potent neutralization against the current SARS-CoV-2 variants of concern, including the Omicron variant.

Differences in Immunogenicity of Three Different Homo- and Heterologous Vaccination Regimens against SARS-CoV-2

Background: Due to findings on adverse reactions and clinical efficacy of different vaccinations against SARS-CoV-2, the administration of vaccination regimens containing both adenoviral vector vaccines and mRNA-based vaccines has become common. Data are still needed on the direct comparison of immunogenicity for these different regimens. Methods: We compared markers for immunogenicity (anti-S1 IgG/IgA, neutralizing antibodies, and T-cell response) with three different vaccination regimens (homologous ChAdOx1 nCoV-19 (n = 103), or mixture of ChAdOx1 nCoV-19 with mRNA-1273 (n = 116) or BNT162b2 (n = 105)) at two time points: the day of the second vaccination as a baseline and 14 days later. Results: All examined vaccination regimens elicited measurable immune responses that were significantly enhanced after the second dose. Homologous ChAdOx1 nCoV-19 was markedly inferior in immunogenicity to all other examined regimens after administration of the second dose. Between the heterologous regimens, mRNA-1273 as second dose induced greater antibody responses than BNT162b2, with no difference found for neutralizing antibodies and T-cell response. Discussion: While these findings allow no prediction about clinical protection, from an immunological point of view, vaccination against SARS-CoV-2 with an mRNA-based vaccine at one or both time points appears preferable to homologous vaccination with ChAdOx1 nCoV-19. Whether or not the demonstrated differences between the heterologous regimens are of clinical significance will be subject to further research.

SARS-CoV-2 Spike S1-specific IgG kinetic profiles following mRNA or vector-based vaccination in the general Dutch population show distinct kinetics

mRNA- and vector-based vaccines are used at a large scale to prevent COVID-19. We compared Spike S1-specific (S1) IgG antibodies after vaccination with mRNA-based (Comirnaty, Spikevax) or vector-based (Janssen, Vaxzevria) vaccines, using samples from a Dutch nationwide cohort. In adults 18-64 years old (n = 2412), the median vaccination interval between the two doses was 77 days for Vaxzevria (interquartile range, IQR: 69-77), 35 days (28-35) for Comirnaty and 33 days (28-35) for Spikevax. mRNA vaccines induced faster inclines and higher S1 antibodies compared to vector-based vaccines. For all vaccines, one dose resulted in boosting of S1 antibodies in adults with a history of SARS-CoV-2 infection. For Comirnaty, two to four months following the second dose (n = 196), S1 antibodies in adults aged 18-64 years old (436 BAU/mL, IQR: 328-891) were less variable and median concentrations higher compared to those in persons ≥ 80 years old (366, 177-743), but differences were not statistically significant (p > 0.100). Nearly all participants seroconverted following COVID-19 vaccination, including the aging population. These data confirm results from controlled vaccine trials in a general population, including vulnerable groups.

Determinants of Immune Response to Anti-SARS-CoV-2 mRNA Vaccines in Kidney Transplant Recipients: A Prospective Cohort Study

BACKGROUND

Immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination has been recently shown to be impaired in kidney transplant recipients (KTRs), but the underlying factors affecting vaccine effectiveness need to be further elucidated.

METHODS

In this prospective cohort study, antibodies against S1 and S2 subunits of SARS-CoV-2 were evaluated using an immunochemiluminescent assay (cutoff 9.5 AU/mL, sensitivity 91.2%, and specificity 90.2%) in 736 KTRs, who were previously either naive or infected with SARS-CoV-2 and vaccinated before or after transplantation. Cellular response was analyzed in a subset of patients using an interferon gamma release assay (cutoff 0.15 IU/mL, sensitivity 92%, and specificity 100%).

RESULTS

Seroconversion was significantly more impaired in SARS-CoV-2-naive KTRs than in those previously infected (40.1% versus 97.1%; P < 0.001). Mycophenolate use (odds ratio, 0.15; 95% confidence interval, 0.09-0.24; P < 0.001) and depleting therapy in the past year (odds ratio, 0.19; 95% confidence interval, 0.05-0.8; P = 0.023) were found to be among independent factors associated with impaired humoral response. Similarly, the interferon gamma release assay tested in 50 KTRs (cutoff 0.15 IU/mL, sensitivity 92%, specificity 100%) showed that specific T-cell responses against spike protein epitopes are impaired in SARS-CoV-2-naive KTRs, as compared to previously infected KTRs (9.4% versus 90%, P < 0.001). All 35 KTRs vaccinated on the waiting list before transplantation exhibited sustained seroconversion persisting after transplantation.

CONCLUSIONS

Survivors of coronavirus disease 2019 and those vaccinated while on the waiting list exhibited a marked immune response to mRNA vaccines, contrary to poor response in naive KTRs vaccinated after transplantation (NCT04832841).

SARS COV-2 anti-nucleocapsid and anti-spike antibodies in an emergency department healthcare worker cohort: September 2020 – April 2021

Background

Emergency department (ED) workers have an increased seroprevalence of SARS-CoV-2 antibodies. However, breakthrough infections in ED workers have led to a reduced workforce within a strained healthcare system. By measuring levels of IgG antibodies to the SARS-CoV-2 nucleocapsid and spike antigens in ED workers, we determined the incidence of infection and described the course of antibody levels. We also measured the antibody response to vaccination and examined factors associated with immunogenicity.

Methods

We conducted a prospective cohort study of ED workers conducted at a single ED from September 2020–April 2021. IgG antibodies to the SARS-CoV-2 nucleocapsid antigen were measured at baseline, 3, and 6 months, and IgG antibodies to the SARS-CoV-2 spike antigen were measured at 6 months.

Results

At baseline, we found 5 out of 139 (3.6%) participants with prior infection. At 6 months, 4 of the 5 had antibody results below the test manufacturer's positivity threshold. We identified one incident case of SARS-COV-2 infection out of 130 seronegative participants (0.8%, 95% CI 0.02–4.2%). In 131 vaccinated participants (125 BNT162b2, 6 mRNA-1273), 131 tested positive for anti-spike antibodies. We identified predictors of anti-spike antibody levels: time since vaccination, prior COVID-19 infection, age, and vaccine type. Each additional week since vaccination was associated with an 11.1% decrease in anti-spike antibody levels. (95% CI 6.2–15.8%).

Conclusion

ED workers experienced a low incidence of SARS-CoV-2 infection and developed antibodies in response to vaccines and prior infection. Antibody levels decreased markedly with time since infection or vaccination.

Early post-infection treatment of SARS-CoV-2 infected macaques with human convalescent plasma with high neutralizing activity had no antiviral effects but moderately reduced lung inflammation

Early in the SARS-CoV-2 pandemic, there was a high level of optimism based on observational studies and small controlled trials that treating hospitalized patients with convalescent plasma from COVID-19 survivors (CCP) would be an important immunotherapy. However, as more data from controlled trials became available, the results became disappointing, with at best moderate evidence of efficacy when CCP with high titers of neutralizing antibodies was used early in infection. To better understand the potential therapeutic efficacy of CCP, and to further validate SARS-CoV-2 infection of macaques as a reliable animal model for testing such strategies, we inoculated 12 adult rhesus macaques with SARS-CoV-2 by intratracheal and intranasal routes. One day later, 8 animals were infused with pooled human CCP with a high titer of neutralizing antibodies (RVPN NT50 value of 3,003), while 4 control animals received normal human plasma. Animals were monitored for 7 days. Animals treated with CCP had detectable but low levels of antiviral antibodies after infusion. In comparison to the control animals, CCP-treated animals had similar levels of viral RNA in upper and lower respiratory tract secretions, similar detection of viral RNA in lung tissues by in situ hybridization, but lower amounts of infectious virus in the lungs. CCP-treated animals had a moderate, but statistically significant reduction in interstitial pneumonia, as measured by comprehensive lung histology. Thus overall, therapeutic benefits of CCP were marginal and inferior to results obtained earlier with monoclonal antibodies in this animal model. By highlighting strengths and weaknesses, data of this study can help to further optimize nonhuman primate models to provide proof-of-concept of intervention strategies, and guide the future use of convalescent plasma against SARS-CoV-2 and potentially other newly emerging respiratory viruses.

Modeling of waning immunity after SARS-CoV-2 vaccination and influencing factors

SARS-CoV-2 vaccines are crucial in controlling COVID-19, but knowledge of which factors determine waning immunity is limited. We examined antibody levels and T-cell gamma-interferon release after two doses of BNT162b2 vaccine or a combination of ChAdOx1-nCoV19 and BNT162b2 vaccines for up to 230 days after the first dose. Generalized mixed models with and without natural cubic splines were used to determine immunity over time. Antibody responses were influenced by natural infection, sex, and age. IgA only became significant in naturally infected. A one-year IgG projection suggested an initial two-phase response in those given the second dose delayed (ChAdOx1/BNT162b2) followed by a more rapid decrease of antibody levels. T-cell responses correlated significantly with IgG antibody responses. Our results indicate that IgG levels will drop at different rates depending on prior infection, age, sex, T-cell response, and the interval between vaccine injections. Only natural infection mounted a significant and lasting IgA response.

This study investigates the dynamics of immunological markers after first SARS-CoV-2 vaccination dose in cohort of healthcare professionals in Denmark. Natural infection was associated with higher antibody responses, and IgG decline varied by age, sex, T-cell response, previous infection, and interval between vaccine doses.

SARS-CoV-2 Vaccination and the Bridge between First and Fourth Dose: Where Are We?

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has induced the explosion of vaccine research. Currently, according to the data of the World Health Organization, there are several vaccines in clinical (145) and preclinical (195) stages, while at least 10 are already in clinical phase 4 (post-marketing). Vaccines have proven to be safe, effective, and able to reduce the spread of SARS-CoV-2 infection and its variants, as well as the clinical consequences of the development of coronavirus disease-19 (COVID-19). In the two-dose primary vaccination, different time intervals between the two doses have been used. Recently, special attention has been paid to assessing the immunogenicity following booster administration. The third dose of the vaccine against COVID-19 may be administered at least 8 weeks after the second dose. In Israel, a fourth dose has already been approved in immunocompromised groups. The main objective of this review is to describe the principal results of studies on the effectiveness of first-to-fourth dose vaccination to reduce reinfection by variants and the incidence of severe disease/death caused by COVID-19. Vaccines have shown a high level of protection from symptomatic infection and reinfection by variants after a third dose. Accelerating mass third-dose vaccination could potentially induce immunogenicity against variants.

COVID-19 Vaccination within the Context of Reactogenicity and Immunogenicity of ChAdOx1 Vaccine Administered to Teachers in Poland

In February 2021, Polish teachers were offered the ChAdOx1-S vaccine as a priority group. However, there have been concerns among educators regarding the efficacy of this vaccine, as compared to the other types of vaccines (e.g., mRNA). The objective of this study was to investigate the reactogenicity and the immunogenicity of this vaccine. Participants, specifically teachers, were invited for serological testing ≥ 4 weeks post-vaccination. Antibodies against the receptor-binding domain (RBD) were measured. Of the 192 participants, the mean age was 50.5 ± 8.3 years and the mean (range) dosing interval was 69.6 ± (25−111) days. Adverse reactions included feeling feverish (44.8%), headache (41.7%), malaise/chills (38.0%), and injection-site tenderness (37.5%); these were reported more frequently after the first dose (84.9%). Fewer males than females (54.8% vs. 80.1%) and fewer older participants (65.7% vs. 90.4%) reported side effects (p < 0.002; p < 0.0001, respectively). All participants presented detectable anti-RBD IgG; the median (range) reading was 525.0 BAU/mL (20.6−5680.0); 1008.02 BAU/mL (115.3−5680.0) in those with prior SARS-CoV-2 infection; and 381.42 BAU/mL (20.6−3108.8) in those without (p = 0.001). In 27.6%, the anti-RBD IgG level was >500 BAU/mL. A multivariate logistic regression revealed that previous infection and longer dose intervals were predictors of higher immunologic responses (p < 0.0001; p = 0.01, respectively). The results demonstrated good tolerability and immunogenicity of the ChAdOx1-S vaccine. Our study justified the longer dose interval to enhance a higher antibody response. Our findings may also support the prioritization of uninfected individuals in regions where COVID-19 vaccine-sparing strategies are required.

SARS-CoV-2 breakthrough infections elicit potent, broad, and durable neutralizing antibody responses

Although infections among vaccinated individuals lead to milder COVID-19 symptoms relative to those in unvaccinated subjects, the specificity and durability of antibody responses elicited by breakthrough cases remain unknown. Here, we demonstrate that breakthrough infections induce serum-binding and -neutralizing antibody responses that are markedly more potent, durable, and resilient to spike mutations observed in variants than those in subjects who received only 2 doses of vaccine. However, we show that breakthrough cases, subjects who were vaccinated after infection, and individuals vaccinated three times have serum-neutralizing activity of comparable magnitude and breadth, indicating that an increased number of exposures to SARS-CoV-2 antigen(s) enhance the quality of antibody responses. Neutralization of SARS-CoV was moderate, however, underscoring the importance of developing vaccines eliciting broad sarbecovirus immunity for pandemic preparedness.

Low Levels of Neutralizing Antibodies After Natural Infection With Severe Acute Respiratory Syndrome Coronavirus 2 in a Community-Based Serological Study

BACKGROUND

Confidence in natural immunity after infection with severe acute respiratory syndrome coronavirus 2 is one reason for vaccine hesitancy.

METHODS

We measured antibody-mediated neutralization of spike protein-ACE2 receptor binding in a large community-based sample of seropositive individuals who differed in severity of infection (N = 790).

RESULTS

A total of 39.8% of infections were asymptomatic, 46.5% were symptomatic with no clinical care, 13.8% were symptomatic with clinical care, and 3.7% required hospitalization. Moderate/high neutralizing activity was present after 41.3% of clinically managed infections, in comparison with 7.9% of symptomatic and 1.9% of asymptomatic infections.

CONCLUSIONS

Prior coronavirus disease 2019 infection does not guarantee a high level of antibody-mediated protection against reinfection in the general population.

Kinetics and persistence of anti-SARS-CoV-2 neutralisation and antibodies after BNT162b2 vaccination in a Swiss cohort

Introduction

Since the emergence of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2), substantial effort has been made to gain knowledge about the immunity elicited by infection or vaccination.

Methods

We studied the kinetics of antibodies and virus neutralisation induced by vaccination with BNT162b2 in a Swiss cohort of SARS‐CoV‐2 naïve (n = 40) and convalescent (n = 9) persons. Blood sera were analysed in a live virus neutralisation assay and specific IgG and IgA levels were measured by enzyme‐linked immunoassay and analysed by descriptive statistics.

Results

Virus neutralisation was detected in all individuals 2–4 weeks after the second vaccine. Both neutralisation and antibodies remained positive for >4 months. Neutralisation and antibodies showed positive correlation, but immunoglobulin G (IgG) and immunoglobulin A (IgA) seroconversion took place 2–4 weeks faster than neutralisation. Spike‐protein specific IgG levels rose significantly faster and were more stable over time than virus neutralisation titres or IgA responses. For naïve but not convalescent persons, a clear boosting effect was observed. Convalescent individuals showed faster, more robust and longer‐lasting immune responses after vaccination compared to noninfected persons. No threshold could be determined for spike protein‐specific IgG or IgA that would confer protection in the neutralisation assay, implicating the need for a better correlate of protection then antibody titres alone.

Conclusions

This study clearly shows the complex translation of antibody data and virus neutralisation, while supporting the evidence of a single dose being sufficient for effective antibody response in convalescent individuals.

Humoral and Cellular Responses to COVID-19 Vaccines in SARS-CoV-2 Infection-Naïve and -Recovered Korean Individuals

In the face of a global COVID-19 vaccine shortage, an efficient vaccination strategy is required. Therefore, the immunogenicity of single or double COVID-19 vaccination doses (ChAdOX1, BNT162b2, or mRNA-1273) of SARS-CoV-2-recovered individuals was compared to that of unvaccinated individuals with SARS-CoV-2 infection at least one year post-convalescence. Moreover, the immunogenicity of SARS-CoV-2-naïve individuals vaccinated with a complete schedule of Ad26.CoV2.S, ChAdOX1, BNT162b2, mRNA-1273, or ChAdOX1/BNT162b2 vaccines was evaluated. Anti-SARS-CoV-2 S1 IgG antibody (S1-IgG), pseudotyped virus-neutralizing antibody titer (pVNT₅₀), and IFN-γ ELISpot counts were measured. Humoral immune responses were significantly higher in vaccinated than in unvaccinated recovered individuals, with a 43-fold increase in the mean pVNT₅₀ values. However, there was no significant difference in the pVNT₅₀ and IFN-γ ELISpot values between the single- and double-dose regimens. In SARS-CoV-2-naïve individuals, antibody responses varied according to the vaccine type: BNT162b2 and mRNA-1273 induced similar levels of S1-IgG to those observed in vaccinated, convalescent individuals; in contrast, pVNT₅₀ was much lower in SARS-CoV-2-naïve vaccinees than in vaccinated recovered individuals. Therefore, a single dose of ChAdOX1, BNT162b2, or mRNA-1273 vaccines would be a good alternative for recovered individuals instead of a double-dose regimen.

mRNA COVID-19 vaccine booster fosters B- and T-cell responses in immunocompromised patients

Immunocompromised patients poorly respond to two doses of SARS-CoV-2 mRNA vaccines. However, an additional booster dose elicits a strong humoral and cellular immune response in these subjects.

SARS-CoV-2 vaccination has proven effective in inducing an immune response in healthy individuals and is progressively us allowing to overcome the pandemic. Recent evidence has shown that response to vaccination in some vulnerable patients may be diminished, and it has been proposed a booster dose. We tested the kinetic of development of serum antibodies to the SARS-CoV-2 Spike protein, their neutralizing capacity, the CD4 and CD8 IFN-γ T-cell response in 328 subjects, including 131 immunocompromised individuals (cancer, rheumatologic, and hemodialysis patients), 160 health-care workers (HCW) and 37 subjects older than 75 yr, after vaccination with two or three doses of mRNA vaccines. We stratified the patients according to the type of treatment. We found that immunocompromised patients, depending on the type of treatment, poorly respond to SARS-CoV-2 mRNA vaccines. However, an additional booster dose of vaccine induced a good immune response in almost all of the patients except those receiving anti-CD20 antibody. Similarly to HCW, previously infected and vaccinated immunocompromised individuals demonstrate a stronger SARS-CoV-2–specific immune response than those who are vaccinated without prior infection.

Diminished and waning immunity to COVID-19 vaccination among hemodialysis patients in Israel: the case for a third vaccine dose

Background

Humoral responses to coronavirus disease 2019 (COVID-19) vaccines in hemodialysis (HD) patients can direct vaccination policy.

Methods

We compared 409 COVID-19-naïve HD patients from 13 HD units in Israel to 148 non-dialysis-dependent COVID-19-naïve controls. Twenty-four previously infected (antinucleocapsid positive) HD patients were analysed separately. Blood samples were obtained ≥14 days post-vaccination (BNT162b2, Pfizer/BioNTech) to assess seroconversion rates and titers of anti-spike (anti-S) and neutralizing antibodies.

Results

The median time from vaccination to blood sample collection was 82 days [interquartile range (IAR) 64-87] and 89 days (IQR 68-96) for HD patients and controls, respectively. Seroconversion rates were lower in HD patients compared with controls for both anti-S and neutralizing antibodies (89% and 77% versus 99.3%, respectively; P < 0.0001). Antibody titers were also significantly lower in HD patients compared with controls {median 69.6 [IQR 33.2-120] versus 196.5 [IQR 118.5-246], P < 0.0001; geometric mean titer [GMT] 23.3 [95% confidence interval (CI) 18.7-29.1] versus 222.7 [95% CI 174-284], P < 0.0001, for anti-S and neutralizing antibodies, respectively}. Multivariate analysis demonstrated dialysis dependence to be strongly associated with lower antibody responses and antibody titers waning with time. Age, low serum albumin and low lymphocyte count were also associated with lower seroconversion rates and antibody titers. HD patients previously infected with sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had no difference in their seroconversion rates or antibody titers compared with COVID-19-naïve patients.

Conclusion

This study demonstrates diminished and waning humoral responses following COVID-19 vaccination in a large and diverse cohort of HD patients, including those previously infected with SARS-CoV-2. Considering these results and reduced vaccine effectiveness against variants of concern, in addition to continued social distancing precautions, a third booster dose should be considered in this population.

Antibody Response to SARS-CoV-2 Infection and Vaccination in COVID-19-naïve and Experienced Individuals

Understanding the magnitude of responses to vaccination during the ongoing SARS-CoV-2 pandemic is essential for ultimate mitigation of the disease. Here, we describe a cohort of 102 subjects (70 COVID-19-naïve, 32 COVID-19-experienced) who received two doses of one of the mRNA vaccines (BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna)). We document that a single exposure to antigen via infection or vaccination induces a variable antibody response which is affected by age, gender, race, and co-morbidities. In response to a second antigen dose, both COVID-19-naïve and experienced subjects exhibited elevated levels of anti-spike and SARS-CoV-2 neutralizing activity; however, COVID-19-experienced individuals achieved higher antibody levels and neutralization activity as a group. The COVID-19-experienced subjects exhibited no significant increase in antibody or neutralization titer in response to the second vaccine dose (i.e., third antigen exposure). Finally, we found that COVID-19-naïve individuals who received the Moderna vaccine exhibited a more robust boost response to the second vaccine dose (p = 0.004) as compared to the response to Pfizer-BioNTech. Ongoing studies with this cohort will continue to contribute to our understanding of the range and durability of responses to SARS-CoV-2 mRNA vaccines.

Targeted isolation of panels of diverse human protective broadly neutralizing antibodies against SARS-like viruses

The emergence of current SARS-CoV-2 variants of concern (VOCs) and potential future spillovers of SARS-like coronaviruses into humans pose a major threat to human health and the global economy 1-7 . Development of broadly effective coronavirus vaccines that can mitigate these threats is needed 8, 9 . Notably, several recent studies have revealed that vaccination of recovered COVID-19 donors results in enhanced nAb responses compared to SARS-CoV-2 infection or vaccination alone 10-13 . Here, we utilized a targeted donor selection strategy to isolate a large panel of broadly neutralizing antibodies (bnAbs) to sarbecoviruses from two such donors. Many of the bnAbs are remarkably effective in neutralization against sarbecoviruses that use ACE2 for viral entry and a substantial fraction also show notable binding to non-ACE2-using sarbecoviruses. The bnAbs are equally effective against most SARS-CoV-2 VOCs and many neutralize the Omicron variant. Neutralization breadth is achieved by bnAb binding to epitopes on a relatively conserved face of the receptor binding domain (RBD) as opposed to strain-specific nAbs to the receptor binding site that are commonly elicited in SARS-CoV-2 infection and vaccination 14-18 . Consistent with targeting of conserved sites, select RBD bnAbs exhibited in vivo protective efficacy against diverse SARS-like coronaviruses in a prophylaxis challenge model. The generation of a large panel of potent bnAbs provides new opportunities and choices for next-generation antibody prophylactic and therapeutic applications and, importantly, provides a molecular basis for effective design of pan-sarbecovirus vaccines.

Long-term analysis of antibodies elicited by SPUTNIK V: A prospective cohort study in Tucumán, Argentina

BACKGROUND

Gam-COVID-Vac (SPUTNIK V) has been granted emergency use authorization in 70 nations and has been administered to millions worldwide. However, there are very few peer-reviewed studies describing its effects. Independent reports regarding safety and effectiveness could accelerate the final approval by the WHO. We aimed to study the long-term humoral immune response in naïve and previously infected volunteers who received SPUTNIK V.

METHODS

Humoral immune responses, assayed by anti-SARS-CoV-2-spike-RBD IgG ELISA and neutralization assays, were measured in 602 healthcare workers at 0, 14, 28, 60 and 180 days after receiving SPUTNIK V between December 2020 and July 2021 in Tucumán, Argentina.

FINDINGS

Seroconversion was detected in 97% of individuals after 28 days post-vaccination (dpv) (N = 405). Anti-RBD titers began to decrease after 60 dpv (N = 328), but remained detectable in 94% at 90 dpv (N = 224). At 180 dpv, anti-RDB titers persisted in 31% (N = 146). Previous infection triggered an increased immune response to the first dose and increased neutralization activity against variants of concern (VOC). Second doses in previously infected individuals further increased titers, even 90 dpv (N = 75). Basal antibody titers had more influence on post-vaccination anti-RBD responses than the time elapsed between diagnosis and vaccination (N = 274).

INTERPRETATION

Data presented herein provides essential knowledge regarding the kinetics of antibodies induced by SPUTNIK V up to six months after immunization, and suggests that when considering one-dose vaccination policies for individuals with previous SARS-CoV-2 infection, serological studies to determine basal titers may be important, independent of when diagnosis occurred.

FUNDING

Tucumán Public Health System (SIPROSA), Argentinean National Research Council (CONICET), National University of Tucumán (UNT).

Real-world effectiveness of the mRNA-1273 vaccine against COVID-19: Interim results from a prospective observational cohort study

Background

Phase 3 trials found mRNA-1273 was highly effective in preventing COVID-19. We conducted a prospective cohort study at Kaiser Permanente Southern California (KPSC) to determine the real-world vaccine effectiveness (VE) of mRNA-1273 in preventing COVID-19 infection and severe disease.

Methods

For this planned interim analysis, individuals aged ≥18 years receiving 2 doses of mRNA-1273 ≥24 days apart (18/12/2020-31/03/2021) were 1:1 matched to randomly selected unvaccinated individuals by age, sex, and race/ethnicity, with follow-up through 30/06/2021. Outcomes were COVID-19 infection (SARS-CoV-2 positive molecular test or COVID-19 diagnosis code) or severe disease (COVID-19 hospitalization and COVID-19 hospital death). Adjusted hazard ratios (aHR) and confidence intervals (CI) for COVID-19 outcomes comparing vaccinated and unvaccinated individuals were estimated by Cox proportional hazards models accounting for multiple comparisons. Adjusted VE was calculated as (1-aHR)x100. Whole genome sequencing was performed on SARS-CoV-2 positive specimens from the KPSC population.

Findings

This analysis included 352,878 recipients of 2 doses of mRNA-1273 matched to 352,878 unvaccinated individuals. VE (99·3% CI) against COVID-19 infection was 87·4% (84·8–89·6%). VE against COVID-19 hospitalization and hospital death was 95·8% (90·7–98·1%) and 97·9% (66·9-99·9%), respectively. VE was higher against symptomatic (88·3% [98·3% CI: 86·1–90·2%]) than asymptomatic COVID-19 (72·7% [53·4–84·0%]), but was generally similar across age, sex, and racial/ethnic subgroups. VE among individuals with history of COVID-19 ranged from 8·2–33·6%. The most prevalent variants were Alpha (41·6%), Epsilon (17·5%), Delta (11·5%), and Gamma (9·1%), with Delta increasing to 54·0% of variants by June 2021.

Interpretation

These interim results provide reassuring evidence of the VE of 2 doses of mRNA-1273 across age, sex, and racial/ethnic subgroups, and against asymptomatic and symptomatic COVID-19, and severe COVID-19 outcomes. Among individuals with history of COVID-19, mRNA-1273 vaccination may offer added protection beyond immunity acquired from prior infection. Longer follow-up is needed to fully evaluate VE of mRNA-1273 against emerging SARS-CoV-2 variants.

Funding

Moderna Inc.

Comparing COVID-19 vaccines for their characteristics, efficacy and effectiveness against SARS-CoV-2 and variants of concern: a narrative review

BACKGROUND

Vaccines are critical cost-effective tools to control the coronavirus disease 2019 (COVID-19) pandemic. However, the emergence of variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may threaten the global impact of mass vaccination campaigns.

AIMS

The objective of this study was to provide an up-to-date comparative analysis of the characteristics, adverse events, efficacy, effectiveness and impact of the variants of concern for 19 COVID-19 vaccines.

SOURCES

References for this review were identified through searches of PubMed, Google Scholar, BioRxiv, MedRxiv, regulatory drug agencies and pharmaceutical companies' websites up to 22nd September 2021.

CONTENT

Overall, all COVID-19 vaccines had a high efficacy against the original strain and the variants of concern, and were well tolerated. BNT162b2, mRNA-1273 and Sputnik V after two doses had the highest efficacy (>90%) in preventing symptomatic cases in phase III trials. mRNA vaccines, AZD1222, and CoronaVac were effective in preventing symptomatic COVID-19 and severe infections against Alpha, Beta, Gamma or Delta variants. Regarding observational real-life data, full immunization with mRNA vaccines and AZD1222 seems to effectively prevent SARS-CoV-2 infection against the original strain and Alpha and Beta variants but with reduced effectiveness against the Delta strain. A decline in infection protection was observed at 6 months for BNT162b2 and AZD1222. Serious adverse event rates were rare for mRNA vaccines-anaphylaxis 2.5-4.7 cases per million doses, myocarditis 3.5 cases per million doses-and were similarly rare for all other vaccines. Prices for the different vaccines varied from $2.15 to $29.75 per dose.

IMPLICATIONS

All vaccines appear to be safe and effective tools to prevent severe COVID-19, hospitalization, and death against all variants of concern, but the quality of evidence greatly varies depending on the vaccines considered. Questions remain regarding a booster dose and waning immunity, the duration of immunity, and heterologous vaccination. The benefits of COVID-19 vaccination outweigh the risks, despite rare serious adverse effects.

Waning antibody responses in COVID-19: what can we learn from the analysis of other coronaviruses?

OBJECTIVES

The coronavirus disease 2019 (COVID-19), caused by the novel betacoronavirus severe acute respiratory syndrome 2 (SARS-CoV-2), was declared a pandemic in March 2020. Due to the continuing surge in incidence and mortality globally, determining whether protective, long-term immunity develops after initial infection or vaccination has become critical.

METHODS/RESULTS

In this narrative review, we evaluate the latest understanding of antibody-mediated immunity to SARS-CoV-2 and to other coronaviruses (SARS-CoV, Middle East respiratory syndrome coronavirus and the four endemic human coronaviruses) in order to predict the consequences of antibody waning on long-term immunity against SARS-CoV-2. We summarise their antibody dynamics, including the potential effects of cross-reactivity and antibody waning on vaccination and other public health strategies. At present, based on our comparison with other coronaviruses we estimate that natural antibody-mediated protection for SARS-CoV-2 is likely to last for 1-2 years and therefore, if vaccine-induced antibodies follow a similar course, booster doses may be required. However, other factors such as memory B- and T-cells and new viral strains will also affect the duration of both natural and vaccine-mediated immunity.

CONCLUSION

Overall, antibody titres required for protection are yet to be established and inaccuracies of serological methods may be affecting this. We expect that with standardisation of serological testing and studies with longer follow-up, the implications of antibody waning will become clearer.

Three exposures to the spike protein of SARS-CoV-2 by either infection or vaccination elicit superior neutralizing immunity to all variants of concern

Infection-neutralizing antibody responses after SARS-CoV-2 infection or COVID-19 vaccination are an essential component of antiviral immunity. Antibody-mediated protection is challenged by the emergence of SARS-CoV-2 variants of concern (VoCs) with immune escape properties, such as omicron (B.1.1.529) that is rapidly spreading worldwide. Here, we report neutralizing antibody dynamics in a longitudinal cohort of COVID-19 convalescent and infection-naive individuals vaccinated with mRNA BNT162b2 by quantifying anti-SARS-CoV-2-spike antibodies and determining their avidity and neutralization capacity in serum. Using live-virus neutralization assays, we show that a superior infection-neutralizing capacity against all VoCs, including omicron, developed after either two vaccinations in convalescents or after a third vaccination or breakthrough infection of twice-vaccinated, naive individuals. These three consecutive spike antigen exposures resulted in an increasing neutralization capacity per anti-spike antibody unit and were paralleled by stepwise increases in antibody avidity. We conclude that an infection-plus-vaccination-induced hybrid immunity or a triple immunization can induce high-quality antibodies with superior neutralization capacity against VoCs, including omicron.

Dynamics of antibody response to CoronaVac vaccine

CoronaVac was the first vaccine approved in Brazil for use in healthcare workers (HCWs). However, there is limited information about it, with little long‐term evidence on post‐vaccination antibody persistence. This study evaluated the antibody response to SARS‐CoV‐2 in 1237 HCWs after the first (1D), second dose (2D), and 6 months postvaccination (6mA2D) with CoronaVac. The seropositivity was 88% at 1D, increasing to 99.8% at 2D, but decreasing to 97.9% at 6mA2D, which was also observed at the analyzed antibody levels. Interestingly, the levels in females were higher than males, and we found a positive correlation with previous SARS‐CoV‐2 infection. Participants with comorbidities had lower levels suggesting the need to monitor for a potential booster dose. Our findings suggest that CoronaVac induced a robust antibody response that wanes significantly over time. Further longitudinal studies are needed to identify whether the antibodies will decline or plateau at a lower level.

Our findings suggest that CoronaVac induced a robust antibody response that wanes significantly over time.

In our study, two doses of CoronaVac were capable of induction an antibody response in people ≥51 years old.

The seropositivity and the levels of antibodies were higher in females when compared to males.

We found a positive correlation with previous SARS‐CoV‐2 infection, previously infected participants had a significantly higher antibody response than previously uninfected participants.

Our findings suggest that patients with chronic diseases may need a booster shot of CoronaVac vaccine.

Individuals with immune‐mediated diseases developed a significant humoral response following the administration of two doses of CoronaVac, albeit with lower antibody titers.

A single mRNA vaccine dose in COVID-19 patients boosts neutralizing antibodies against SARS-CoV-2 and variants of concern

The urgent need for, but limited availability of, SARS-CoV-2 vaccines worldwide has led to widespread consideration of dose-sparing strategies. Here, we evaluate the SARS-CoV-2-specific antibody responses following BNT162b2 vaccination in 150 previously SARS-CoV-2-infected individuals from a population-based cohort. One week after first vaccine dose, spike protein antibody levels are 27-fold higher and neutralizing antibody titers 12-fold higher, exceeding titers of fully vaccinated SARS-CoV-2-naive controls, with minimal additional boosting after the second dose. Neutralizing antibody titers against four variants of concern increase after vaccination; however, overall neutralization breadth does not improve. Pre-vaccination neutralizing antibody titers and time since infection have the largest positive effect on titers following vaccination. COVID-19 severity and the presence of comorbidities have no discernible impact on vaccine response. In conclusion, a single dose of BNT162b2 vaccine up to 15 months after SARS-CoV-2 infection offers higher neutralizing antibody titers than 2 vaccine doses in SARS-CoV-2-naive individuals.

SARS-CoV-2 BNT162b2 vaccine-induced humoral response and reactogenicity in individuals with prior COVID-19 disease

BACKGROUND

Most individuals with prior COVID-19 disease manifest long-term protective immune responses against reinfection. Accordingly, we tested the hypothesis that humoral immune and reactogenicity responses to a SARS-CoV-2 mRNA vaccine differ in individuals with and without prior COVID-19 disease.

METHODS

Health care workers (n = 61) with (n = 30) and without (n = 31) prior COVID-19 disease received two 30 μg doses of Pfizer BNT162b2 vaccine 3 weeks apart. Serum IgG antibody against the spike receptor-binding domain; serum neutralizing activity; and vaccine reactogenicity were assessed longitudinally every 2 weeks for 56 days after the first injection.

RESULTS

The COVID-19 group manifested more rapid increases in spike IgG antibody and serum neutralizing activity after the first vaccine dose but showed little or no increase after the second dose compared with the infection-naive group. In fact, spike IgG was at its maximum level after the first dose in 36% of the COVID-19 group versus 0% of the infection-naive group. Peak IgG antibody levels were lower but appeared to fall more slowly in the COVID-19 group versus the infection-naive group. Finally, adverse systemic reactions, e.g., fever, headache, and malaise, were more frequent and lasted longer after both the first and second injection in the COVID-19 group than in the infection-naive group.

CONCLUSION

Individuals with prior COVID-19 disease demonstrate a robust, accelerated humoral immune response to the first dose but an attenuated response to the second dose of BNT162b2 vaccine compared with controls. The COVID-19 group also experienced greater reactogenicity. Humoral responses and reactogenicity to BNT162b2 differ qualitatively and quantitatively in individuals with prior COVID-19 disease compared with infection-naive individuals.

FUNDING

This work was supported by Temple University institutional funds.

Population homogeneity for the antibody response to COVID-19 BNT162b2/Comirnaty vaccine is only reached after the second dose across all adult age ranges

While mRNA vaccines are administrated worldwide in an effort to contain the COVID-19 pandemic, the heterogeneity of the humoral immune response they induce at the population scale remains unclear. Here, in a prospective, longitudinal, cohort-study, including 1245 hospital care workers and 146 nursing home residents scheduled for BNT162b2 vaccination, together covering adult ages from 19 to 99 years, we analyse seroconversion to SARS-CoV-2 spike protein and amount of spike-specific IgG, IgM and IgA before vaccination, and 3-5 weeks after each dose. We show that immunogenicity after a single vaccine dose is biased to IgG, heterogeneous and reduced with increasing age. The second vaccine dose normalizes IgG seroconversion in all age strata. These findings indicate two dose mRNA vaccines is required to reach population scale humoral immunity. The results advocate for the interval between the two doses not to be extended, and for serological monitoring of elderly and immunosuppressed vaccinees.

SARS-CoV-2 Variants, Vaccines, and Host Immunity

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a new beta coronavirus that emerged at the end of 2019 in the Hubei province of China. SARS-CoV-2 causes coronavirus disease 2019 (COVID-19) and was declared a pandemic by the World Health Organization (WHO) on 11 March 2020. Herd or community immunity has been proposed as a strategy to protect the vulnerable, and can be established through immunity from past infection or vaccination. Whether SARS-CoV-2 infection results in the development of a reservoir of resilient memory cells is under investigation. Vaccines have been developed at an unprecedented rate and 7 408 870 760 vaccine doses have been administered worldwide. Recently emerged SARS-CoV-2 variants are more transmissible with a reduced sensitivity to immune mechanisms. This is due to the presence of amino acid substitutions in the spike protein, which confer a selective advantage. The emergence of variants therefore poses a risk for vaccine effectiveness and long-term immunity, and it is crucial therefore to determine the effectiveness of vaccines against currently circulating variants. Here we review both SARS-CoV-2-induced host immune activation and vaccine-induced immune responses, highlighting the responses of immune memory cells that are key indicators of host immunity. We further discuss how variants emerge and the currently circulating variants of concern (VOC), with particular focus on implications for vaccine effectiveness. Finally, we describe new antibody treatments and future vaccine approaches that will be important as we navigate through the COVID-19 pandemic.

Immunity to SARS-CoV-2 induced by infection or vaccination

Adaptive immune responses play critical roles in viral clearance and protection against re-infection, and SARS-CoV-2 is no exception. What is exceptional is the rapid characterization of the immune response to the virus performed by researchers during the first 20 months of the pandemic. This has given us a more detailed understanding of SARS-CoV-2 compared to many viruses that have been with us for a long time. Furthermore, effective COVID-19 vaccines were developed in record time, and their rollout worldwide is already making a significant difference, although major challenges remain in terms of equal access. The pandemic has engaged scientists and the public alike, and terms such as seroprevalence, neutralizing antibodies, antibody escape and vaccine certificates have become familiar to a broad community. Here, we review key findings concerning B cell and antibody (Ab) responses to SARS-CoV-2, focusing on non-severe cases and anti-spike (S) Ab responses in particular, the latter being central to protective immunity induced by infection or vaccination. The emergence of viral variants that have acquired mutations in S acutely highlights the need for continued characterization of both emerging variants and Ab responses against these during the evolving pathogen-immune system arms race.

A report of two cases of myocarditis following mRNA coronavirus disease 2019 vaccination

BACKGROUND

Vaccination is the most important measure to control the coronavirus disease 2019 (COVID-19) pandemic. Myocarditis has been reported as a rare adverse reaction to COVID-19 vaccines. The clinical presentation of myocarditis in such cases can range from mild general symptoms to acute heart failure.

CASE SUMMARY

We report the cases of two young men who presented with chest pain and dyspnoea following the administration of the mRNA COVID-19 vaccine. Cardiac investigations revealed findings typical of acute myocarditis.

DISCUSSION

Myocarditis is a rare complication following mRNA COVID-19 vaccination. In this case series, the temporal proximity of the development of acute myocarditis and the administration of the mRNA COVID-19 vaccine was acknowledged. In the absence of other causative factors, myocarditis in these patients potentially occurred due to an adverse reaction to the mRNA COVID-19 vaccine. However, a causal relationship remains speculative. Clinical suspicion of myocarditis should be high if patients present with chest pain or dyspnoea after receiving COVID-19 vaccination.

Large inter-individual variability of cellular and humoral immunological responses to mRNA-1273 (Moderna) vaccination against SARS-CoV-2 in health care workers

PURPOSE

Studies on the immune responses to severe acute respiratory syndrome coronavirus 2 vaccines are necessary to evaluate the ongoing vaccination programs by correlating serological response data and clinical effectiveness data. We performed a longitudinal immunological profiling of health care workers vaccinated with mRNA-1273 (Moderna, Cambridge, MA, USA). Half of these vaccinees had experienced a mild coronavirus disease 2019 (COVID-19) infection in the spring of 2020 ("COVID-recovered" cohort), whereas the other half of the vaccinees had no previous COVID-19 infection ("COVID-naive" cohort).

MATERIALS AND METHODS

Serum was drawn at multiple time points and subjected to assays measuring anti-Spike immunoglobulin G (IgG), avidity of anti-Spike IgG, avidity of anti-receptor binding domain (RBD) IgG, virus neutralizing activity, and interferon-γ release from stimulated lymphocytes.

RESULTS

Between both cohorts and within each cohort, we found remarkable inter-individual differences regarding cellular and humoral immune responses to the Moderna mRNA-1273 vaccine.

CONCLUSION

First, our study indicates that the success of mRNA-1273 vaccinations should be verified by serological assays in order to identify "low-responders" to vaccination. Second, the kinetics of anti-S IgG and neutralizing activity correlate well with clinical effectiveness data, thus explaining incipient protection against infection 2 weeks after the first dose of mRNA-1273 in COVID-naive vaccinees. Third, our IgG-avidity data indicate that this incipient protection is mediated by low-avidity anti-RBD IgG and low-avidity anti-S IgG.

Side effects of messenger RNA vaccines and prior history of COVID-19, a cross-sectional study

BACKGROUND

There are concerns regarding immunogenicity with coronavirus disease 2019 (COVID-19) mRNA vaccines among persons with prior history of COVID-19 (PHC). This study was to analyze the short-term side effects of mRNA vaccines among health care workers (HCWs) with and without PHC.

METHODS

A cross-sectional study was performed using an independent online survey questionnaire that gathered responses from HCWs.

RESULTS

Among 1,475 HCWs, 1268 (85.97%) completed the survey, 102/1268 (44/447 in Moderna group and 58/821 in Pfizer-BioNTech group) reported PHC during pre-vaccination period. Symptoms of flushing/P = .05, brain fogging/P= .005, vertigo/P= .041, numbness/P= .023, diarrhea/P= .047, hives/P= .028, itching/P= .028, swelling of lips/mouth/P= .001, shortness of breath/P= .022, and anxiety/P= .048 have greater occurrence among Pfizer-BioNtech group with PHC when compared to Pfizer-BioNtech group with no PHC. Symptoms of chills/P= .027, flushing/P= .045, tremor/P= .05, muscle spasm/P= .039, vomiting/P= .031, diarrhea/P= .015, and cough/P= .011 have higher occurrence among Moderna group with PHC when compared to Moderna group with no PHC.

CONCLUSIONS

Few short-term side effects among mRNA vaccine recipients with PHC may have necessitated transient time-off from work. The PHC can be considered as a predictor for severity of side effects. While the vaccination program continues in the United States, a future COVID legislation that mandates vaccination among employees along with paid time off provision may help with higher compliance and acceptance.

Kinetics of SARS-CoV-2-Neutralising Antibodies of Residents of Long-Term Care Facilities

INTRODUCTION

Elderly residents of nursing homes (NHs) and long-term care units (LTCUs) have been shown to have a high risk of mortality and morbidity in cases of SARS-CoV-2 infection. The objective of this study was to examine the kinetics of neutralizing antibodies (NAbs) directed against the SARS-CoV-2 virus in residents of the NH and LTCU units of our University Hospital who were identified with positive serology after the first epidemic outbreak.

MATERIALS AND METHODS

The participants included were sampled every three months for qualitative serological testing, as well as quantitative testing by neutralization tests using retroviral particles containing the S glycoprotein of SARS-CoV-2. Vaccination using the Comirnaty (Pfizer BNT162b2) vaccine begun before the last serological follow-up.

RESULTS

The median NAb titer in June 2020 was 80 [40; 60] versus 40 [40; 160] three months later, showing a statistically significant decline (p < 0.007), but remained stable between the three- and six-month timepoints (p = 0.867). By nine months after vaccination, we observed a significant difference between vaccinated residents known to have positive serology before vaccination (SERO+, Vacc+) and those vaccinated without having previously shown COVID-19 seroconversion (SERO-, Vacc+), the latter group showing similar titers to the SERO+, Vacc- participants (p=0.166). The median antibody titer in SERO+, Vacc+ patients increased 15-fold following vaccination.

DISCUSSION

Humoral immunity against SARS-CoV-2 appears to be persistent in elderly institutionalized patients, with a good post-vaccination response by residents who had already shown seroconversion but a notably diminished response by those who were seronegative before vaccination. To evaluate immunity in its entirety and elaborate a sound vaccination strategy, the cellular immune response via T cells specific to SARS-CoV-2 merits analysis, as this response is susceptible to being affected by immunosenescence.

Antibody response after one and two jabs of the BNT162b2 vaccine in nursing home residents: The CONsort-19 study

Background

The humoral immune response following COVID‐19 vaccination in nursing home residents is poorly known. A longitudinal study compared levels of IgG antibodies against the spike protein (S‐RBD IgG) (S‐RDB protein IgG) after one and two BNT162b2/Pfizer jabs in residents with and without prior COVID‐19.

Methods

In 22 French nursing homes, COVID‐19 was diagnosed with real‐time reverse‐transcriptase polymerase chain reaction (RT‐PCR) for SARS‐CoV‐2. Blood S‐RDB‐protein IgG and nucleocapsid (N) IgG protein (N‐protein IgG) were measured 21–24 days after the first jab (1,004 residents) and 6 weeks after the second (820 residents).

Results

In 735 residents without prior COVID‐19, 41.7% remained seronegative for S‐RDB‐protein IgG after the first jab vs. 2.1% of the 270 RT‐PCR‐positive residents (p < 0.001). After the second jab, 3% of the 586 residents without prior COVID‐19 remained seronegative. However, 26.5% had low S‐RDB‐protein IgG levels (50–1050 UA/ml) vs. 6.4% of the 222 residents with prior COVID‐19. Residents with an older infection (first wave), or with N‐protein IgG at the time of vaccination, had the highest S‐RDB‐protein IgG levels. Residents with a prior COVID‐19 infection had higher S‐RDB‐protein IgG levels after one jab than those without after two jabs.

Interpretation

A single vaccine jab is sufficient to reach a high humoral immune response in residents with prior COVID‐19. Most residents without prior COVID‐19 are seropositive for S‐RDB‐protein IgG after the second jab, but around 30% have low levels. Whether residents with no or low post‐vaccine S‐RDB protein IgG are at higher risk of symptomatic COVID‐19 requires further analysis.

Protective Immunity after Natural Infection with Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) - Kentucky, USA, 2020

BACKGROUND

As vaccine supply and access remain limited in many parts of the world, understanding the duration of protection from reinfection after natural infection is important.

METHODS

Distinct individuals testing positive and negative for SARS-CoV-2 between March 6, 2020, and August 31, 2020, in Kentucky, USA, were identified using the Kentucky National Electronic Disease Surveillance System. Individuals were followed for occurrence of a positive test for SARS-CoV-2 from 91 days after their initial test result through December 31, 2020. Protection from reinfection provided by a prior infection was calculated and additional analyses evaluated impact of age, sex, symptom status, long-term care facility connection, testing occurrence and frequency, and time from initial infection.

RESULTS

The protective effect from prior infection was 80.3% (95% CI, 78.2%-82.2%) for those aged 20-59 years and 67.4% (95% CI, 62.8%-71.4%) for those aged ≥60 years. At 30-day time periods through 270 days (with limited exceptions), protection was estimated to be >75% for those aged 20-59 years and >65% for those aged ≥60 years. Factors associated with repeat positive testing included a connection to a long-term care facility, duration of potential exposure, and absence of symptoms during initial infection.

CONCLUSIONS

Natural infection provides substantial and persistent immunologic protection for a period of several months for most individuals, although subpopulations may be at greater risk of repeat positive testing and potential poor outcomes associated with reinfection. These subgroups include individuals aged ≥60 years, residents and staff of long-term care facilities, and those who have mild or asymptomatic illness with initial infection. Continued emphasis on vaccination and infection prevention and control strategies remains critically important in reducing the risk of reinfection and associated severe outcomes for these groups.

A New Testing Platform Using Fingerstick Blood for Quantitative Antibody Response Evaluation after SARS-CoV-2 Vaccination

Testing and vaccination have been major components of the strategy for combating the ongoing COVID-19 pandemic. In this study, we have developed a quantitative anti-SARS-CoV-2 spike (S1) IgG antibody assay using a fingerstick dried blood sample. We evaluated the feasibility of using this high-throughput and quantitative anti-SARS-CoV-2 spike (S1) IgG antibody testing assay in vaccinated individuals. Fingerstick blood samples were collected and analyzed from 137 volunteers before and after receiving the Moderna or Pfizer mRNA vaccine. Anti-SARS-CoV-2 S1 IgG antibody could not be detected within the first 7 days after receiving the first vaccine dose, however, the assay reliably detected antibodies from day 14 onwards. In addition, no anti-SARS-CoV-2 nucleocapsid (N) protein IgG antibody was detected in any of the vaccinated or healthy participants, indicating that the anti-SARS-CoV-2 S1 IgG assay is specific for the mRNA vaccine-induced antibodies. The S1 IgG levels detected in fingerstick samples correlated with the levels found in venous blood plasma samples and with the efficacy of venous blood plasma samples in the plaque reduction neutralization test (PRNT). The assay displayed a limit of quantification (LOQ) of 0.59 μg/mL and was found to be linear in the range of 0.51-1000 μg/mL. Finally, its clinical performance displayed a Positive Percent Agreement (PPA) of 100% (95% CI: 0.89-1.00) and a Negative Percent Agreement (NPA) of 100% (95% CI: 0.93-1.00). In summary, the assay described here represents a sensitive, precise, accurate, and simple method for the quantitative detection and monitoring of post-vaccination anti-SARS-CoV-2 spike IgG responses.

Longitudinal Analysis of Antibody Responses to the mRNA BNT162b2 Vaccine in Patients Undergoing Maintenance Hemodialysis: A 6-Month Follow-Up

Background: Patients on hemodialysis (HD) are at higher risk for COVID-19, overall are poor responders to vaccines, and were prioritized in the Portuguese vaccination campaign. Objective: This work aimed at evaluating in HD patients the immunogenicity of BTN162b2 after the two doses induction phase, the persistence of specific antibodies along time, and factors predicting these outcomes. Methods: We performed a prospective, 6-month long longitudinal cohort analysis of 156 HD patients scheduled to receive BTN162b2. ELISA quantified anti-spike IgG, IgM, and IgA levels in sera were collected every 3 weeks during the induction phase (t0 before vaccine; t1, d21 post first dose; and t2 d21 post second dose), and every 3-4 months during the waning phase (t3, d140, and t4, d180 post first dose). The age-matched control cohort was similarly analyzed from t0 to t2. Results: Upon exclusion of participants identified as previously exposed to SARS-CoV-2, seroconversion at t1 was lower in patients than controls (29 and 50%, respectively, p = 0.0014), while the second vaccine dose served as a boost in both cohorts (91 and 95% positivity, respectively, at t2, p = 0.2463). Lower response in patients than controls at t1 was a singularity of the participants ≤ 70 years (p = 2.01 × 10-05), associated with immunosuppressive therapies (p = 0.013), but not with lack of responsiveness to hepatitis B. Anti-spike IgG, IgM, and IgA levels decreased at t3, with IgG levels further waning at t4 and resulting in >30% seronegativity. Anti-spike IgG levels at t1 and t4 were correlated (ρ = 0.65, p < 2.2 × 10-16). Conclusions: While most HD patients seroconvert upon 2 doses of BNT162b2 vaccination, anti-spike antibodies levels wane over the following 4 months, leading to early seroreversion in a sizeable fraction of the patients. These findings warrant close monitoring of COVID-19 infection in vaccinated HD patients, and advocate for further studies following reinforced vaccination schedules.

Impaired seroconversion after SARS-CoV-2 mRNA vaccines in patients with solid tumours receiving anticancer treatment

Background

Patients with solid tumours have high COVID-19 mortality. Limited and heterogeneous data are available regarding the immunogenicity of SARS-CoV-2 mRNA vaccines in this population.

Methods and findings

This is a prospective, single-centre cohort study aiming at evaluating seroconversion in terms of anti-spike antibodies in a population of patients with solid tumours undergoing cancer therapy within 2 months before the second vaccine dose, as compared with a cohort of controls. Subjects who were not SARS-CoV-2 naïve were excluded, and 171 patients were included in the final study population (150 vaccinated with BNT162b2, 87.7%; 21 with mRNA-1273, 12.3%) and compared with 2406 controls. The median follow-up time from the second dose of vaccination was 30 days (12–42; IQR: 26–34). Most patients had metastatic disease (138, 80.7%). Seroconversion rate was significantly lower in cancer patients than in controls (94.2% versus 99.8%, p < 0.001). At univariate logistic regression analysis, Odds ratio (OR) for seroconversion was also reduced in older individuals (>70 years). A multivariate logistic model confirmed cancer as the only significant variable in impairing seroconversion (OR 0.03, p < 0.001). In the cancer population, a multivariate analysis among clinical variables, including the type of cancer treatment, showed ECOG PS > 2 as the only one of impact (OR 0.07, p = 0.012).

Conclusions

There is a fraction of 6% of patients with solid tumours undergoing cancer treatment, mainly with poorer performance status, who fail to obtain seroconversion after SARS-CoV-2 mRNA vaccines. These patients should be considered for enhanced vaccination strategies and carefully monitored for SARS-CoV-2 infection during cancer treatment.

SARS-CoV-2 spike conformation determines plasma neutralizing activity

Numerous safe and effective COVID-19 vaccines have been developed that utilize various delivery technologies and engineering strategies. The influence of the SARS-CoV-2 spike (S) glycoprotein conformation on antibody responses induced by vaccination or infection in humans remains unknown. To address this question, we compared plasma antibodies elicited by six globally-distributed vaccines or infection and observed markedly higher binding titers for vaccines encoding a prefusion-stabilized S relative to other groups. Prefusion S binding titers positively correlated with plasma neutralizing activity, indicating that physical stabilization of the prefusion conformation enhances protection against SARS-CoV-2. We show that almost all plasma neutralizing activity is directed to prefusion S, in particular the S 1 subunit, and that variant cross-neutralization is mediated solely by RBD-specific antibodies. Our data provide a quantitative framework for guiding future S engineering efforts to develop vaccines with higher resilience to the emergence of variants and longer durability than current technologies.

Assessment of Post-Vaccination Antibody Response Eight Months after the Administration of BNT1622b2 Vaccine to Healthcare Workers with Particular Emphasis on the Impact of Previous COVID-19 Infection

At the end of 2020, COVID-19 vaccination programs were initiated in many countries, including Poland. The first vaccine approved in Poland was the BNT162b2 mRNA preparation (Pfizer/BioNTech), and the first vaccinated group were healthcare workers. The aim of the present study was to evaluate post-vaccine antibody titers 8 months after the second vaccine dose had been administered to a group of employees of the Hospital of the Ministry of the Interior and Administration in Olsztyn (Poland). The employees were divided into two groups: persons who had COVID-19 in the fourth quarter of 2020 and were vaccinated in January-February 2021, and persons without a history of COVID-19 who were vaccinated during the same period. The analyzed material was venous blood serum collected from 100 hospital employees on 23-28 September 2021. The level of anti-SARS-CoV-2 S antibodies was measured with a Roche Cobas e411 analyzer using the electrochemiluminescence (ECLIA) method. The study demonstrated that persons with a history of SARS-CoV-2 infection had significantly higher antibody levels (taking into account gender, age, type of work performed, and severity of post-vaccination symptoms) than employees without a history of COVID-19. The study also revealed that the type of work, age, gender, and the course of SARS-CoV-2 infection can influence the humoral immune response. The presented results may prove helpful in the context of administering additional vaccine doses.

CTN 328: immunogenicity outcomes in people living with HIV in Canada following vaccination for COVID-19 (HIV-COV): protocol for an observational cohort study

INTRODUCTION

Most existing vaccines require higher or additional doses or adjuvants to provide similar protection for people living with HIV (PLWH) compared with HIV-uninfected individuals. Additional research is necessary to inform COVID-19 vaccine use in PLWH.

METHODS AND ANALYSIS

This multicentred observational Canadian cohort study will enrol 400 PLWH aged >16 years from Montreal, Ottawa, Toronto and Vancouver. Subpopulations of PLWH of interest will include individuals: (1) >55 years of age; (2) with CD4 counts <350 cells/mm3; (3) with multimorbidity (>2 comorbidities) and (4) 'stable' or 'reference' PLWH (CD4 T cells >350 cells/mm3, suppressed viral load for >6 months and <1 comorbidity). Data for 1000 HIV-negative controls will be obtained via a parallel cohort study (Stop the Spread Ottawa), using similar time points and methods. Participants receiving >1 COVID-19 vaccine will attend five visits: prevaccination; 1 month following the first vaccine dose; and at 3, 6 and 12 months following the second vaccine dose. The primary end point will be the percentage of PLWH with COVID-19-specific antibodies at 6 months following the second vaccine dose. Humoral and cell-mediated immune responses, and the interplay between T cell phenotypes and inflammatory markers, will be described. Regression techniques will be used to compare COVID-19-specific immune responses to determine whether there are differences between the 'unstable' PLWH group (CD4 <350 cells/mm3), the stable PLWH cohort and the HIV-negative controls, adjusting for factors believed to be associated with immune response. Unadjusted analyses will reveal whether there are differences in driving factors associated with group membership.

ETHICS AND DISSEMINATION

Research ethics boards at all participating institutions have granted ethics approval for this study. Written informed consent will be obtained from all study participants prior to enrolment. The findings will inform the design of future COVID-19 clinical trials, dosing strategies aimed to improve immune responses and guideline development for PLWH.

TRIAL REGISTRATION NUMBER

NCT04894448.