Anti-SARS-CoV-2 Receptor-Binding Domain Total Antibodies Response in Seropositive and Seronegative Healthcare Workers Undergoing COVID-19 mRNA BNT162b2 Vaccination

Factors influencing antibody response after COVID-19 recombinant protein vaccination in adults: A cross-sectional observational study, in Chongqing, China

The factors affecting the antibody responses to the ZF2001 vaccine remain unknown. To address this, we conducted a cross-sectional serological study in the real world. Adults with no prior SARS-CoV-2 infection history and received three doses of ZF2001 vaccine were invited to our study in the early stages of the COVID-19 epidemic in Chongqing between 7 April 2021 and 17 November 2021. A questionnaire survey was conducted to obtain demographic characteristics, health information, and the frequency of lifestyles at the time of enrollment. A total of 266 eligible subjects aged 18 to 86 years, with a median age of 56.00 (IQR: 34-66) participated. 68.80% of them were female. Hypertension (13.16%) and diabetes (6.02%) were common comorbidities. Serum samples were collected at one month after the third dose of ZF2001 vaccination, and serological testing was conducted using the Pseudovirus-Based Neutralization Assay. The chi-square test was employed to compare seropositivity rates, and the Mann-Whitney U test or the Kruskal-Wallis test was used to analyze the neutralizing antibodies level in stratified groups. Subsequently, univariate and multivariate linear regression analyses were conducted to identify the influencing factors. We observed that seropositivity rates was 76.32%, with 95% confidence interval (95%CI) 70.85%-81.03%, and geometric mean titer (GMT) was 120.26, with 95%CI 100.38-144.08. Age, diabetes, and frequently of alcohol were negative associations with antibody response (β = -0.2021, 95% CI: -0.2507 to -0.1535, β = -0.2873, 95% CI: -0.5590 to -0.0155, β = -0.2082, 95% CI: -0.3419 to-0.0746, P < 0.0001, P = 0.0384, P = 0.0024). Conversely, the -interval between 1 and 2 dose and frequently of tea were positive associations with antibody response (β = 0.1369, 95% CI: 0.0463 to 0.2275, β = 0.0830, 95% CI: 0.0106 to 0.1554, P = 0.0032, P = 0.0247). Overall, the ZF2001 vaccine-induced antibody response was influenced by a multifactor that may provide a reference for the development of personalized antigen vaccines and vaccination strategies in the future.

Anti-SARS-CoV-2 total immunoglobulin and neutralising antibody responses in healthy blood donors throughout the COVID-19 pandemic: a longitudinal observational study

INTRODUCTION

Quantifying antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and neutralising antibodies may help to understand protection at the individual and population levels. Determination of neutralising antibodies using classical virus neutralisation tests (VNT) is considered the gold standard, but they are costly and time-intensive. Enzyme-linked immunosorbent assay (ELISA)-based surrogate VNTs (sVNT) or anti-SARS-CoV-2 spike protein receptor binding domain immunoglobulins (anti-S-RBD Ig) may be suitable alternatives to VNTs. We aimed to (a) explore the correlations between anti-S-RBD Ig, VNT, and sVNT measurements and (b) describe humoral immunity against SARS-CoV-2 after vaccination, natural infection, and vaccine breakthrough infection in healthy blood donors.

METHODS

We measured total anti-SARS-CoV-2 Ig in 5714 serum samples from 2748 healthy individuals visiting the Swiss Red Cross Blood Donation Centre in Basel from 03/2020 to 04/2022. We used the Elecsys® Anti-SARS-CoV-2 immunoassay (Roche) against the N- and S-receptor binding domain (RBD) proteins. In a subset of 548 samples from 123 donors, we conducted sVNTs against the Wuhan wild-type SARS-CoV-2 (SARS-CoV-2 Neutralizing Antibodies Detection Kit; Adipogen™). In 100 samples from 40 donors, we correlated sVNT and VNTs against the wild-type (D614G WU1) virus. Surveys were sent to the blood donors to collect data on their SARS-CoV-2 infection and vaccination status. Using this data, donors were categorised as "vaccination only", "infection before vaccination", "post-vaccine breakthrough infection", and "natural infection only".

RESULTS

Our longitudinal observation study cohort consisted of 50.7% males with a median age of 31 years (range 18-75 y). Anti-SARS-CoV-2 N protein positivity rates per month indicate 57.1% (88/154) of the cohort was infected up to 04/2022. No differences in seropositivity were found between sexes, age groups, blood types (AB0 or RhD), and cytomegalovirus serostatus. We observed a high correlation between anti-S-RBD Ig and inhibition percentage (Spearman's ρ = 0.92, Kendall's τ = 0.77, p <0.0001). We determined the sensitivity and specificity for the manufacturers' thresholds for detecting virus-neutralising effects and computed the "best" cut-off based on our real-world data. We categorised 722/1138 (63.5%) donors as vaccination only (82.3%), post-vaccine breakthrough infection (7.8%), infection before vaccination (5.8%), and natural infection only (4.2%). We observed a lower inhibition percentage in the natural infection-only group than in all other vaccinated groups. The infection before vaccination group had higher anti-S-RBD Ig titres after the first vaccine dose than the other vaccinated groups.

CONCLUSION

In total, 57.1% of healthy blood donors were infected with SARS-CoV-2, but natural infection without evidence of vaccination seems to result in substantially lower neutralising antibody levels. An estimate of antibody neutralisation may be helpful to assess reinfection risk. Total anti-S-RBD Ig correlates with surrogate virus neutralisation test results, a surrogate for neutralisation; therefore, we suggest that total anti-S-RBD Ig may estimate the level of neutralising antibodies. The threshold for protection from an unfavourable clinical outcome must be evaluated in prospective clinical cohorts.

Follow-up SARS-CoV-2 serological study of a health care worker cohort following COVID-19 booster vaccination

BACKGROUND

Studies have shown that Omicron breakthrough infections can occur at higher SARS-CoV-2 antibody levels compared to previous variants. Estimating the magnitude of immunological protection induced from COVID-19 vaccination and previous infection remains important due to varying local pandemic dynamics and types of vaccination programmes, particularly among at-risk populations such as health care workers (HCWs). We analysed a follow-up SARS-CoV-2 serological survey of HCWs at a tertiary COVID-19 referral hospital in Germany following the onset of the Omicron variant.

METHODS

The serological survey was conducted in January 2022, one year after previous surveys in 2020 and the availability of COVID-19 boosters including BNT162b2, ChAdOx1-S, and mRNA-1273. HCWs voluntarily provided blood for serology and completed a comprehensive questionnaire. SARS-CoV-2 serological analyses were performed using an Immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA). Antibody levels were reported according to HCW demographic and occupational characteristics, COVID-19 vaccination and SARS-CoV-2 infection history, and multivariate linear regression was used to evaluate these associations.

RESULTS

In January 2022 (following the fourth COVID-19 wave in Germany including the onset of the Omicron variant), 1482/1517 (97.7%) HCWs tested SARS-CoV-2 seropositive, compared to 4.6% in December 2020 (second COVID-19 wave). Approximately 80% had received three COVID-19 vaccine doses and 15% reported a previous laboratory-confirmed SARS-CoV-2 infection. SARS-CoV-2 IgG geometric mean titres ranged from 335 (95% Confidence Intervals [CI]: 258-434) among those vaccinated twice and without previous infection to 2204 (95% CI: 1919-2531) among those vaccinated three times and with previous infection. Heterologous COVID-19 vaccination combinations including a mRNA-1273 booster were significantly associated with the highest IgG antibody levels compared to other schemes. There was an 8-to 10-fold increase in IgG antibody levels among 31 HCWs who reported a SARS-CoV-2 infection in May 2020 to January 2022 after COVID-19 booster vaccination.

CONCLUSIONS

Our findings demonstrate the importance of ongoing COVID-19 booster vaccination strategies in the context of variants such as Omicron and despite hybrid immunity from previous SARS-CoV-2 infections, particularly for at-risk populations such as HCWs. Where feasible, effective types of booster vaccination, such as mRNA vaccines, and the appropriate timing of administration should be carefully considered.

Seroprevalence of anti-SARS-CoV-2 IgG antibodies pre- and post-COVID-19 vaccination in staff members of Bandar Abbas Children's Hospital

BACKGROUND

Healthcare workers (HCWs) have a higher risk of contracting coronavirus disease 2019 (COVID-19) compared to the general population due to their frontline role and direct contact with the infected patients. Accordingly, they were among the first groups to receive vaccination against COVID-19. A higher risk of COVID-19 infection may also exist among hospital staff members other than HCWs. In this study, we assessed the seroprevalence of anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG pre- and post-COVID-19 vaccination in hospital staff members.

METHODS

This cross-sectional study included 228 staff members of Bandar Abbas Children's Hospital, Bandar Abbas, Iran, who were recruited from 2020 to 2021. Staff members were vaccinated with vector and inactivated vaccines. Anti-SARS-CoV-2 spike protein IgG was measured in their blood samples pre- and post-COVID-19 vaccination.

RESULTS

Of the 228 hospital staff members evaluated in this study (mean age: 37.59 ± 8.70 years), 204 (89.5%) were female and 210 (92.1%) were HCWs. Only one staff member was not vaccinated, the rest received one dose (99.6%), and 224 (98.7%) two doses. Vector vaccines were administered to 71.4% of staff members and 72.9% of HCWs. Anti-SARS-CoV-2 IgG antibody was positive in 8.8% of staff members before vaccination, 9.3% after the first dose, and 50% after the second dose. The corresponding percentages were 9.5%, 9.5%, and 48.8% in HCWs. Being a HCW was not associated with the seroprevalence of anti-SARS-CoV-2 IgG after the second dose; however, multivariable binary logistic regression analysis revealed that the interval between two vaccine doses (adjusted odds ratio [aOR] = 0.595, 95% confidence interval [CI] 0.434; 0.816, P = 0.001) and age (aOR = 1.062, 95% CI 1.021; 1.105, P = 0.003) were associated with seroprevalence.

CONCLUSIONS

After receiving a second dose of vector or inactive virus vaccines, our hospital's staff members and HCWs had a seroprevalence of anti-SARS-CoV-2 IgG antibodies of around 50%. Seroprevalence increased with increasing age and shorter intervals between doses.

Serologic Response to Vaccine for COVID-19 in Patients with Hematologic Malignancy: A Prospective Cohort Study

BACKGROUND

Patients with hematological cancers have increased COVID-19 morbidity and mortality, and these patients show attenuated vaccine responses. This study aimed to characterize the longitudinal humoral immune responses to COVID-19 vaccination in patients with hematological malignancies.

PATIENTS AND METHODS

We conducted a prospective cohort study, collecting samples from March 2021 to July 2022, from patients seen at a cancer treatment center in London, Ontario, Canada, who met the following eligibility criteria: age ≥18 years, diagnosed with a hematological malignancy, recipient of a COVID-19 vaccine during the study period, and able to provide informed consent.

RESULTS

Median anti-S titers (MST) were 0.0, 64.0, and 680.5 U/mL following first (V1), second (V2), and third (V3) vaccine doses, respectively. Patients with lymphoid malignancies' response to vaccination was attenuated compared to myeloid malignancy patients after V2 and V3 (P < .001, P < .01). Active treatment was associated with lower antibody titers (MST 10) compared to treatment 12-24 months (MST 465, P = .04367) and >24 months (MST 1660.5, P = .0025) prior to vaccination. V3 significantly increased antibody titers compared to V2 for patients less than 3 months from treatment. Increasing age was associated with smaller antibody response following V2 (P < .05), but not following V3. Patients receiving anti-CD20 therapy did not demonstrate increased antibody titer levels after V3 (V2 MST 0, V3 MST 0; P > .05).

CONCLUSION

We report an attenuated serologic response to COVID-19 vaccination in our study population of patients with hematological malignancy. The immune response to vaccination was affected by patient age, diagnosis, treatment, and timing of treatment exposure.

Association between sleep duration and antibody acquisition after mRNA vaccination against SARS-CoV-2

Introduction

Sleep enhances the antibody response to vaccination, but the relationship between sleep and mRNA vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is not fully understood.

Methods

In this prospective observational study, we investigated the influence of sleep habits on immune acquisition induced by mRNA vaccines against SARS-CoV-2 in 48 healthy adults (BNT-162b2, n=34; mRNA-1273, n=14; female, n=30, 62.5%; male, n=18, 37.5%; median age, 39.5 years; interquartile range, 33.0-44.0 years) from June 2021 to January 2022. The study measured sleep duration using actigraphy and sleep diaries, which covered the periods of the initial and booster vaccinations.

Results

Multivariable linear regression analysis showed that actigraphy-measured objective sleep duration 3 and 7 days after the booster vaccination was independently and significantly correlated with higher antibody titers (B=0.003; 95% confidence interval, 0.000-0.005; Beta=0.337; p=0.02), even after controlling for covariates, including age, sex, the type of vaccine, and reactogenicity to the vaccination. Associations between acquired antibody titer and average objective sleep duration before vaccination, and any period of subjective sleep duration measured by sleep diary were negligible.

Discussion

Longer objective, but not subjective, sleep duration after booster vaccination enhances antibody response. Hence, encouraging citizens to sleep longer after mRNA vaccination, especially after a booster dose, may increase protection against SARS-CoV-2.

Study registration

This study is registered at the University Hospital Medical Information Network Center (UMIN: https://www.umin.ac.jp) on July 30, 2021, #UMIN000045009.

Comparative Analysis of IgG Antibody Titers Induced by Three Different SARS-COV-2 Vaccines in Healthy Adults of Pakistan

Covid-19 is a contagious disease caused by severe acute respiratory syndrome corona virus 2 (SARS-CoV-2). In order to control this disease, different effective vaccines have been developed. This study is an attempt to determine the strength and duration of immunogenicity of various established vaccines. This cross-sectional, observational study was conducted to compare the efficacy of three different vaccines; Pfizer BNT 162b2, Sinovac, and CanSino, respectively, after a duration of 3 months, in the healthy adult population of Pakistan. In this study 371 healthy participants (aged 12-25 years) of both genders (male and females) were enrolled. The blood sample was drawn 90 days after the complete vaccination process. The humoral response (IgG) was analyzed by electrochemiluminescence immunoassay (ECLIA) method with Roche Anti-SARS-CoV-2 S analyzer kit. Descriptive statistical analysis was performed using IBM SPSS statistics version 22 and P < 0.05 was considered significant. The mean antibody titer in Pfizer-group was 12,536.35 U/mL, followed by 5168.68 U/mL in the Sinovac group and 4284.32 U/mL in the CanSino group. The Pfizer-group showed gender-specific significant differences, with higher antibody levels in males (P = 0.006) as compared to Sinovac and Cansino groups. The Mean IgG antibody levels of the Pfizer-vaccinated group were significantly higher than the Sinovac-vaccinated group and the CanSino-vaccinated group (P = 0.000, each). However, the mean difference between the Sinovac-vaccinated group and the CanSino-vaccinated group was not significant. Vaccine-induced seropositivity was found in the whole cohort. The mRNA-based vaccine produced the highest immune response, and thus, it is recommended for future application.

Antibody Response against Severe Acute Respiratory Syndrome Coronavirus 2 Messenger Ribonucleic Acid Vaccines in Infected Individuals: A Systematic Review

Individuals with a history of coronavirus disease 2019 (COVID-19) exhibit memory immunity acquired during natural infection. However, a decline in immunity after infection renders these individuals vulnerable to re-infection, in addition to a higher risk of infection with new variants. This systematic review examined related studies to elucidate the antibody response in these infected individuals after messenger ribonucleic acid (mRNA) vaccination. Hence, the focus of this review was to ascertain differences in the concentration of binding and neutralising antibodies of previously infected individuals in comparison to those of infection-naïve individuals after administration of two doses of mRNA vaccination through available case-control and cohort studies. Positive reverse transcriptase-polymerase chain reaction (RT-PCR) test or detectable anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies at the baseline in included studies showed categorisation of infected and uninfected individuals. This review utilised three online databases: PubMed, Scopus and Cochrane with the following keywords: (COVID-19 OR 'Coronavirus Disease 2019' OR SARS-CoV-2) AND Immun* AND (Pfizer OR BioNTech OR BNT162b2 OR Comirnaty OR Moderna OR mRNA-1273) from January 2019 to July 2021. Following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocol (PRISMA-P) 2020 guidelines and assessment based on the Crowe Critical Appraisal Tool (CCAT), we included 13 related qualified papers of observational studies discerning the binding and neutralising antibody concentrations of infected and uninfected individuals after administration of mRNA vaccines, such as the BNT162b2 and mRNA-1273 vaccine. The mRNA vaccines induced robust binding and neutralising antibody responses in both groups. However, infected individuals showed induction of higher antibody responses in a shorter time compared to uninfected individuals. Hence, a single dose of mRNA vaccination for infected individuals may be sufficient to reach the same level of antibody concentration as that observed in uninfected individuals after receiving two doses of vaccination.

Anti-SARS-CoV-2 receptor binding domain antibodies after the second dose of Sinovac and AstraZeneca vaccination

Purpose

The Sinovac and AstraZeneca vaccines are the primary coronavirus disease 2019 vaccines in Indonesia. Antibody levels in vaccine-injected individuals will decline substantially over time, but data supporting the duration of such responses are limited. Therefore, this study aims to quantitatively evaluate antibody responses resulting from the completion of Sinovac and AstraZeneca administration in Indonesian adults.

Materials and Methods

Participants were divided into two groups based on their vaccine type. Both groups were then assessed on the anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor binding domain (anti-SRBD) concentrations. The anti-SRBD level was measured using Elecsys anti-SARS-CoV-2 S assay and analyzed every month until 3 months after the second vaccination.

Results

The results presented significant differences (p=0.000) in immunoglobulin G (IgG) titers among the vaccines' measurement duration, where all samples observed a decrease in IgG titers over time. The mean titer levels of anti-SRBD IgG in the group given Sinovac were high in the first month after vaccination and decreased by 55.7% in 3 months. AstraZeneca showed lesser immune response with a slower decline rate. Adverse effects following immunization (AEFI) showed that systemic reactions are the most reported in both vaccines, with a higher percentage in the second dose of AstraZeneca type vaccines.

Conclusion

Sinovac induced more significant titers of anti-SRBD IgG 1 month after the second dose but generated fewer AEFIs. In contrast, AstraZeneca generated more AEFIs, in mild to moderate severity, but provided lower levels of anti-SRBD IgG.

Assessment of humoral and cellular immunity after bivalent BNT162b2 vaccination and potential association with reactogenicity

OBJECTIVES

This study investigated the feasibility and clinical value of using a novel, automated and high-throughput SARS-CoV-2 Interferon Gamma Release Assay (IGRA), combined with total anti-SARS-CoV-2 antibodies assessment, for evaluating the immune response after bivalent BNT162b2 vaccination.

METHODS

A cohort of healthcare workers, who already underwent primary vaccination and boosting with monovalent BNT162b2 vaccine, received a booster dose of the new BNT162b2 bivalent formulation. Blood samples were taken immediately before vaccination (T0) and 1 month afterwards (T1). Humoral and cellular immunity were assayed with Roche Elecsys Anti-SARS-CoV-2 and Roche Elecsys IGRA SARS-CoV-2, respectively.

RESULTS

The study population consisted of 51 subjects (median age: 43 years; 51% females). Total anti-SARS-CoV-2 antibodies and IGRA SARS-CoV-2 values increased at T1 from 9,050 to 25,000 BAU/mL (p<0.001), and from 0.44 to 0.78 IU/mL (p=0.385), accounting for median increase of 2.0 and 1.6 folds, respectively. Increased T1 values of total anti-SARS-CoV-2 antibodies and IGRA SARS-CoV-2 were recorded in 100% and 68.6% subjects, respectively. In those with baseline values below the median, post-vaccine levels displayed larger increases of 3.3 and 5.1 folds for anti-SARS-CoV-2 total antibodies and IGRA SARS-CoV-2, respectively. The variation of total anti-SARS-CoV-2 antibodies was inversely associated with their T0 values (r=-0.97; p<0.001), whilst that of IGRA SARS-CoV-2 was inversely associated with its T0 value (r=-0.58; p<0.001). No other signifcant associations were found with demographical or clinical variables, including side effects.

CONCLUSIONS

The bivalent BNT162b2 vaccine booster enhances humoral and cellular immunity against SARS-CoV-2, especially in recipients with lower baseline biological protection.

Are anti-SARS-CoV-2 S/N IgG/IgM antibodies always predictive of previous SARS-CoV-2 infection?

Objectives

We planned this study to verify whether immunoassays for quantifying anti-SARS-CoV-2 IgG/IgM antibodies against both spike (S) and nucleocapsid (N) proteins may be used for identifying previous SARS-CoV-2 infections.

Methods

The study population consisted of a cohort of fully vaccinated healthcare workers. All study subjects underwent regular medical visits and molecular testing for diagnosing SARS-CoV-2 infections every 2-4 weeks between 2020-2022. Venous blood was drawn for measuring anti-SARS-CoV-2 antibodies with MAGLUMI 2019-nCoV lgG/IgM CLIA Assays directed against both SARS-CoV-2 S and N proteins.

Results

Overall, 31/53 (58.5%) subjects had tested positive for SARS-CoV-2 by RT-PCR throughout the study (24 once, 7 twice). No positive correlation was found between anti-SARS-CoV-2 S/N IgM antibodies and molecular test positivity. In univariate regression analysis, both a molecular test positivity (r=0.33; p=0.015) and the number of positive molecular tests (r=0.43; p=0.001), but not vaccine doses (r=-0.12; p=0.392), were significantly correlated with anti-SARS-CoV-2 S/N IgG antibodies. These two associations remained significant in multiple linear regression analysis (p=0.029 and p<0.001, respectively) after adjusting for sex, age, body mass index, and vaccine doses. In ROC curve analysis, anti-SARS-CoV-2 S/N IgG antibodies significantly predicted molecular test positivity (AUC, 0.69; 95% CI; 0.55-0.84), with the best cutoff of 0.05 AU/mL displaying 67.9% accuracy, 0.97 sensitivity, and 0.27 specificity.

Conclusions

Although anti-SARS-CoV-2 S/N IgG antibodies provide helpful information for identifying previous SARS-CoV-2 infections, a lower cutoff than that of sample reactivity should be used. Anti-SARS-CoV-2 S/N IgM antibodies using conventional cutoffs seem useless for this purpose.

Immunogenicity of SARS-CoV-2 mRNA intramuscular vaccination in patients with muscular disorders

Backgrounds

Little clinical data is available on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in patients with muscular disorders (MDs). The immunogenicity of SARS-CoV-2 vaccines against MDs, in particular, remains unknown. Thus, this study aimed to confirm the immunogenicity and safety of the SARS-CoV-2 vaccine against MDs.

Methods

All participants were vaccinated with two doses of mRNA vaccines (BNT162b2, Pfizer-BioNTech). The serum samples were collected from each patient on the day of second dose of vaccination, and then, consecutively, after one month, three months, and six months. Anti-SARS-CoV-2 IgG levels were determined using the Abbott SARS-CoV-2 IgG II Quant assay.

Results

We evaluated 75 individuals, including 42 patients with MDs and 33 patients with non-muscular disorders (non-MDs). Non-MD patients primarily include those with severe motor and intellectual disabilities. The median age of the patients was 32 years (range 12-64 years). After one and three months following the second immunization, patients with MDs had lower antibody responses. Furthermore, three months following the second immunization, the proportion of high responders among patients with MDs decreased significantly compared to that among patients without MDs (p-value of less than 0.01). No serious adverse events were observed in patients with or without MDs.

Conclusion

Intensity and latency of antibody response were suppressed in patients with MDs. Although MDs may be a key contributor in predicting the antibody response to SARS-CoV-2 vaccination, SARS-CoV-2 immunization in MDs needs extensive research.

Comprehensive assessment of SARS-CoV-2 antibodies against various antigenic epitopes after naive COVID-19 infection and vaccination (BNT162b2 or ChAdOx1 nCoV-19)

Comprehensive assessment of SARS-CoV-2 antibodies against antigenic epitopes and cross-neutralization on variants is essential to monitor after infection or vaccination. From 32 COVID-19 patients and 40 vaccinated individuals [20 Oxford-AstraZeneca (AZ) and 20 Pfizer-BioNTech (BNT)], 348 serial sera are collected until 40 days after infection and 3 months after homologous booster vaccination. Antibody levels were monitored using a multiplex-bead assay including variant spike antigens, Roche (S1/RBD total) and a surrogate virus neutralization test (GenScript). Anti-S/S1/RBD levels were higher than anti-S2/N levels from 2 weeks after infection and were higher in severe infection (P < 0.05). Vaccination showed highest antibody levels after 1-month booster and had consistently high levels in the order of anti-full S, anti-RBD, anti-S1 and anti-S2. Infection induced higher anti-S2/N levels than prime vaccination (P < 0.05). Three months after BNT/BNT vaccination, antibody levels against S1/RBD and 23 variant antigens were higher than post-infection or AZ groups (P < 0.05). Regarding intraindividual changes from post-prime to post-boost vaccination, boost induced a 1.1- to 3.9-fold increase on multiplex-bead assay, 22.8- to 24.2-fold on Roche assay and 22.8- to 24.2-fold on GenScript assay. Post-prime levels by multiplex-bead assay predicted post-boost levels, but Roche and GenScript results were not predictive in the AZ group. The kinetics of SARS-CoV-2 antibody levels vary depending on the antigenic epitopes, assay kit, disease severity or vaccine type. Assessing seroconversion using multiplex-bead assays may contribute to monitoring the disease course, adjusting vaccination strategies, and accelerating vaccination efficacy.

The risk factors of SARS-CoV-2 antibody level differences in healthcare workers post vaccination in Siloam hospitals: A nationwide multicenter study

Background

Several vaccines have been approved against COVID-19, and 5 have been used in Indonesia. Due to the decrease in antibody levels 3 to 6 months after the second dose of CoronaVac, healthcare workers received the third booster of mRNA vaccine (mRNA-1273) to increase the antibody level. This study aimed to evaluate the risk factors of anti-S-RBD IgG levels differences in healthcare workers.

Methods

This study is a retrospective cohort study of 576 healthcare workers without previous SARS-CoV-2 infection who received 2 doses of CoronaVac and the third dose of mRNA-1273 6 months after the second dose. Blood samples were obtained 2nd, 6th, 12th, and 24th weeks after the second dose of CoronaVac vaccine administration, with mRNA-1273 booster on week 20. Quantitative measurements of IgG antibodies were performed with Elecsys Anti-SARS-CoV-2 S immunoassay. We identify the baseline factors predicting post-vaccination antibody titers using univariate and multivariate linear regression analysis.

Results

This study comprised 576 participants aged 32 years old, 72.05% female, and 45.84% from high-risk occupation subgroups. The median antibodies titer level on the 2nd, 6th, 12th, and 24th weeks after the second vaccine dose administration were 40.99 u/mL, 42.01 u/mL, 54.78 u/mL, and 23,225 u/mL. Antibody levels trended highest in female and younger age group (20-29 years old).

Conclusions

The third dose of vaccine increased the quantitative SARS-CoV-2 spike IgG antibody titers and eliminated differences in antibodies titer by gender.

COVID-19 Breakthrough Infections among Patients Aged ≥65 Years in Serbia: Morbidity and Mortality Overview

BACKGROUND: Vaccines against severe acute respiratory syndrome coronavirus 2 have shown effectiveness in the prevention of COVID-19. Breakthrough infections occur, and age has been shown to be one of the dominant risk factors for poorer outcome. This research focuses on characteristics of breakthrough infections in older adults. METHODS: This retrospective study was conducted for four months (March−June 2021) in the autonomous province of Vojvodina in Serbia on 11,372 patients using reverse-transcription polymerase chain reaction or antigen-detection rapid diagnostic tests verifying COVID-19 in those aged ≥65 years. Demographics, comorbidities, disease severity, and final outcomes were evaluated in fully vaccinated compared to unvaccinated individuals. Individuals were divided into younger-old (65−74 years) and older-old (≥75 years) age groups and differences between those groups were further evaluated. Binary logistic regression was performed to identify independent predictors of poor outcome. RESULTS: By the end of the research, 51.3% of the population of APV 65−74 years, as well as 46.2% of those older than 74 years, were vaccinated. From the acquired sample, 17.4% had breakthrough infection. Asymptomatic forms were higher in both age groups of vaccinated vs. unvaccinated (3.9%—younger-old, 6.3%—older-old vs. 2.9%—younger-old, 3.9%—older-old). The same results were registered with mild symptoms (82.1%—younger-old, 68.1%—older-old vs. 76.3%—younger-old, 57.5%—older-old) (p < 0.001). The case fatality ratio of the vaccinated population was smaller than the unvaccinated population in both groups (3.1% vs. 7.9%—younger-old; 11.4% vs. 22.5%—older-old) (p < 0.001). The odds ratio for poor outcome in unvaccinated individuals was 2.3 (95% confidence interval, p < 0.001) for the total sample. CONCLUSIONS: An increase in asymptomatic and mild forms, as well as decrease in severe or critical forms and poor outcomes, were noted in the vaccinated population. Choosing to avoid vaccination against SARS-CoV-2 may increase the chance of poor outcome in older individuals.

Anti-Spike and Neutralizing Antibodies after Two Doses of COVID-19 Sinopharm/BIBP Vaccine

Host response to COVID-19 vaccines is partially evaluated through the estimation of antibody response, specifically the binding anti-spike (anti-S) and the neutralizing antibodies (nAbs) against SARS-CoV-2. Vaccine-induced humoral response affects decisions on the choice of vaccine type, vaccine acceptance, and the need for boosting. Identification of risk factors for poor antibody response helps to stratify individuals who might potentially require booster doses. The primary objective of this cross-sectional study was to investigate the antibody response after receiving two Sinopharm vaccine doses. Factors affecting antibody response were additionally studied. Moreover, a predictive cutoff for anti-S was generated to predict positivity of nAbs. Blood samples were collected from 92 adults and relevant data were recorded. Antibody levels (anti-S and nAbs) against SARS-CoV-2 were tested one month following the second dose of Sinopharm vaccine using two commercial ELISA tests. Among the 92 participants, 88 tested positive for anti-S (95.7%), with a median level of 52.15 RU/mL (equivalent to 166.88 BAU/mL). Fewer participants (67.4%) were positive for nAbs, with a median percentage of inhibition (%IH) of 50.62% (24.05−84.36). A significant positive correlation existed between the titers of both antibodies (correlation coefficient = 0.875, p < 0.001). When the anti-S titer was greater than 40 RU/mL (128 BAU/mL), nAbs were also positive with a sensitivity of 80.6% and a specificity of 90%. Positive nAbs results were associated with a higher anti-S titers (62.1 RU/mL) compared to negative nAbs (mean anti-S titer of 18.6 RU/mL). History of COVID-19 infection was significantly associated with higher titers of anti-S (p = 0.043) and higher IH% of nAbs (p = 0.048). Hypertensive participants were found to have significantly higher median titers of anti-S (101.18 RU/mL) compared with non-hypertensive ones (42.15 RU/mL), p = 0.034. Post-vaccination headache was significantly higher among those with higher anti-S than those with relatively lower titers (98.82 versus 43.69 RU/mL, p = 0.048). It can be concluded that the Sinopharm vaccine produced high levels of binding antibodies but with low neutralizing abilities. Also, levels of anti-S titer greater than 40 RU/mL could adequately predict positivity of nAbs without need for their testing.

Variation of Total Anti-SARS-CoV-2 Antibodies After Primary BNT162b2 Vaccination and Homologous Booster

BACKGROUND

In this serosurveillance study, we investigated the variation of total anti-SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) antibodies in healthcare workers receiving primary BNT162b2 vaccination and homologous booster.

METHODS

A total number of 524 subjects (median age, 46 years; 65.3% females), were studied. All received primary BNT162b2 vaccination (two doses) and homologous booster (one dose) >8 months after completing the primary cycle. Blood samples were collected before the first and second vaccine doses, at 1, 3 and 6 months after the second dose, as well as before and 1 month after booster. Total anti-SARS-CoV-2 neutralizing antibodies were assayed with Roche Elecsys Anti-SARS-CoV-2 S chemiluminescent immunoassay.

RESULTS

Overall, 65.1% subjects were baseline (i.e., pre-vaccination) SARS-CoV-2 seronegative and always tested SARS-CoV-2 negative ("N/N"), 16.2% were baseline SARS-CoV-2 seronegative but tested SARS-CoV-2 positive after receiving the vaccine booster dose ("N/P"), whilst 18.7% were baseline SARS-CoV-2 seropositive and always tested SARS-CoV-2 negative afterwards ("P/N"). All groups displayed a similar trend of total anti-SARS-CoV-2 S antibodies throughout the study period, though the P/N cohort exhibited higher values compared to the other two groups until receiving the booster, after which the levels become similar in all cohorts. Significant differences in total anti-SARS-CoV-2 S antibodies values were not found between N/N and N/P groups, neither 1 month after booster. The rate of subjects with protective antibodies values become 100% in all groups after booster.

CONCLUSIONS

Although baseline seropositivity is associated with more pronounced humoral immune response following primary vaccination compared to never infected subjects, SARS-CoV-2 infection after booster does not significantly foster antibody titers.

Evaluation of the Anti-Spike (RDB) IgG Titer among Workers Employed at the University of Pisa Vaccinated with Different Types of SARS-CoV-2 Vaccines

With the development of SARS-CoV-2 vaccines, many authors started evaluating the immunization efficacy of the available vaccines mainly through sero-positivity tests or by a quantitative assessment of the IgG against the spike protein of SARS-CoV-2 virus in vaccinated subjects. In this work, we compared the titers resulting from vaccination and tried to understand the potential factors affecting the immune response to the available SARS-CoV-2 vaccines. This study was conducted on 670 volunteers employed at the University of Pisa and undergoing a health surveillance program at the University Hospital of Pisa. For each participant, 10 mL of blood, information about contacts with confirmed cases of COVID-19, age, sex, SARS-CoV-2 vaccination status, previous SARS-CoV-2 infection and symptoms, type of vaccine and the date of administration were collected. In the multivariate analysis, the type of vaccine, the presence of symptoms in SARS-CoV-2 positive individuals, and the distance from the second dose significantly affected the antibody titer; the combined vaccination resulted in a faster decay over time compared with the other types of vaccination. No significant differences were observed between Spikevax and Comirnaty (p > 0.05), while the antibody levels remain more stable in subjects undergoing Vaxzevria vaccination (p < 0.01) compared with mRNA-based ones.

Predictors of seroconversion after coronavirus disease 2019 vaccination

BACKGROUND

Vaccine nonresponse during the coronavirus disease 2019 (COVID-19) pandemic has considerable individual and societal risks.

OBJECTIVE

To investigate the clinical characteristics of patients with lack of seroconversion after vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

METHODS

Demographic and clinical data were collected from 805 patients who had validated antibody assays against the SARS-CoV-2 spike protein at least 14 days after completion of their COVID-19 vaccination. Clinical characteristics from patients with a negative (< 0.4 U/mL) antibody response were assessed and summarized.

RESULTS

A total of 622 (77.3%) patients attained seroconversion as defined by a titer of greater than or equal to 0.4 U/mL, whereas 183 out of 805 (22.7%) patients exhibited no seroconversion after vaccination against SARS-CoV-2. Univariately, older age (P = .02) and male sex were associated with a lower likelihood of seroconversion (P = .003). Therapy with immunosuppressive drugs was noted in 93 (50.8%) of seronegative patients with most (n = 83/93, 89.2%) receiving ongoing immunosuppressive therapy at the time of vaccination. Among the 134 (73.2%) seronegative patients with immunodeficiency, 110 (82.1%) had primary immunodeficiency. Cancer (n = 128, 69.9%), B cell depletion therapy (n = 90/115, 78.3%), and immunosuppressant steroid use (n = 71/93 on immunosuppressants, 76.3%) were the other common characteristics among the vaccine nonresponders. More importantly, our study did not evaluate the actual efficacy of COVID-19 vaccination.

CONCLUSION

Vaccine responses vary by age and sex, with men showing lower rates of seroconversion as compared with women. Primary immunodeficiency along with active malignancy and ongoing immunosuppression with steroids or B cell depletion therapy appeared to be the most common characteristics for those with a lack of vaccine seroconversion after COVID-19 vaccination.

Serum Antibodies SARS-CoV-2 Spike (S) Protein Receptor-Binding Domain in OBGYN Residents and Effectiveness 3 Months after COVID-19 Vaccination

BACKGROUND: The health care workers are considered as vulnerable people who had higher infecting dose of SARS-CoV-2 infection compared to other society. Among more than 500 deaths of Indonesians physicians, obstetrics and gynecologist (OBGYN) has become the most specialists who died in this pandemic. AIM: The objective of our study is to evaluate the antibodies of SARS-CoV-2 in serum OBGYN residents post-vaccination as well as the presence of infection 3 months after the vaccination. METHODS: A prospective cohort study was conducted in OBGYN residents Universitas Indonesia. Serum antibodies SARS-CoV-2 spike (S) protein receptor-binding domain (RBD) was measured using electrochemiluminescence immunoassay, 21 days after Sinovac vaccination, with basic characteristics being recorded. Within 3 months follow-up, the participants were monthly checked related to post-vaccination infection. RESULTS: The median antibodies SARS-CoV-2 for all participants were 50.72 (19.09–98.57) U/mL. There were 20 residents (24.1%) who had post-vaccination infection within 3 months and dominated by asymptomatic to mild symptoms. Body mass index (r = –0.221, p = 0.044) and sleep hours (r = –0.225, p = 0.041) were found to be inversely correlated with antibodies SARS-CoV-2 S RBD. CONCLUSION: Antibodies SARS-CoV-2 S RBD found to be correlated with BMI and sleep hours. The 3-month post-vaccine infection among OBGYN residents was almost similar to Jakarta’s positivity rate and the efficacy rate was higher than expected by National Agency of Drug and Food Control.

Characterization of the significant decline in humoral immune response six months post-SARS-CoV-2 mRNA vaccination: A systematic review

Accumulating evidence shows a progressive decline in the efficacy of coronavirus disease 2019 (COVID-19) (severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2]) messenger RNA (mRNA) vaccines such as Pfizer-BioNTech (mRNA BNT161b2) and Moderna (mRNA-1273) in preventing breakthrough infections due to diminishing humoral immunity over time. Thus, this review characterizes the kinetics of anti-SARS-CoV-2 antibodies after the second dose of a primary cycle of COVID-19 mRNA vaccination. A systematic search of the literature was performed and a total of 18 articles (N = 15 980 participants) were identified and reviewed. The percent difference of means of reported antibody titers was then calculated to determine the decline in humoral response after the peak levels postvaccination. Findings revealed that the peak humoral response was reached at 21-28 days after the second dose, after which serum levels progressively diminished at 4-6-month postvaccination. Additionally, results showed that regardless of age, sex, serostatus, and presence of comorbidities, longitudinal data reporting antibody measurement exhibited a decline of both anti-receptor binding domain immunoglobulin G (IgG) and anti-spike IgG, ranging from 94% to 95% at 90-180 days and 55%-85% at 140-160 days, respectively, after the peak antibody response. This suggests that the rate of antibody decline may be independent of patient-related factors and peak antibody titers but mainly a function of time and antibody class/molecular target. Hence, this study highlights the necessity of more efficient vaccination strategies to provide booster administration in attenuating the effects of waning immunity, especially in the appearance of new variants of concerns.

Evaluation of the Roche SARS-CoV-2 Rapid Antibody Test in Samples from Vaccinated Individuals

The study aimed to establish the performance of the SARS-CoV-2 Rapid Antibody Test (IgG and IgM) and the Elecsys Anti-SARS-CoV-2 S assay in vaccinated individuals. A panel of serum samples from Boca Biolistics was utilized to assess antibodies following vaccination, consisting of samples drawn prior to vaccination, after the first dose, or at least 14 days after the second dose of Moderna mRNA-1273 or Pfizer-BioNTech BNT162b2 COVID-19 vaccines. Agreement between the two methods was measured and stratified by test evaluator and assay lot. Agreement between the SARS-CoV-2 Rapid Antibody Test (IgG) and Elecsys Anti-SARS-CoV-2 S assay qualitative measurements at the different assessment points for both mRNA-1273 and BNT162b2 ranged between 97.06% (95% confidence interval [CI] 84.67, 99.93) to 100% (95% CI 82.35, 100). Agreement of the SARS-CoV-2 Rapid Antibody Test (IgG) with the Elecsys Anti-SARS-CoV-2 S assay was not highly influenced by either lot or evaluator. There was a medium-to-strong correlation between the semiquantitative SARS-CoV-2 Rapid Antibody Test (IgG) result and quantitative Elecsys Anti-SARS-CoV-2 S assay in samples taken after both doses of the vaccines, with higher intensity bands being associated with higher total anti-S antibody titer (mRNA-1273, P = 0.0019; BNT162b2, P < 0.0001). Conclusion Semiquantitative SARS-CoV-2 Rapid Antibody Test (IgG) and quantitative Elecsys Anti-SARS-CoV-2 S assay correlated well, suggesting that the SARS-CoV-2 Rapid Antibody Test (IgG) is helpful in understanding the immune response postvaccination. The current data support the use of the SARS-CoV-2 Rapid Antibody Test (IgG) in the vaccinated population.

IMPORTANCE Serologic assays are an essential tool for seroprevalence surveys, for quality control of vaccines, and to determine the response to vaccination. Although a correlate of immunity has not yet been established for COVID-19 vaccines, antibody titers after natural infection and vaccination have been associated with protection from symptomatic SARS-CoV-2 infection. Rapid point-of-care assays can be of use in this context with advantages over centralized testing, such as speed and ease of use. The point-of-care SARS-CoV-2 Rapid Antibody Test (IgG) compared favorably to the Elecsys Anti-SARS-CoV-2 S assay with agreement rates above 97.06%, after one or two doses of Moderna mRNA-1273 or Pfizer-BioNTech BNT162b2. Semiquantitative SARS-CoV-2 Rapid Antibody Test (IgG) and quantitative Elecsys Anti-SARS-CoV-2 S assay results correlated well, suggesting that SARS-CoV-2 Rapid Antibody Test (IgG) is helpful in understanding the immune response postvaccination. The current data support the use of the SARS-CoV-2 Rapid Antibody Test (IgG) in the vaccinated population.

The role of neutralizing antibodies by sVNT after two doses of BNT162b2 mRNA vaccine in a cohort of Italian healthcare workers

OBJECTIVES

Evaluating anti-SARS-CoV-2 antibody levels is a current priority to drive immunization, as well as to predict when a vaccine booster dose may be required and for which priority groups. The aim of our study was to investigate the kinetics of anti-SARS-CoV-2 Spike S1 protein IgG (anti-S1 IgG) antibodies and neutralizing antibodies (NAbs) in an Italian cohort of healthcare workers (HCWs), following the Pfizer/BNT162b2 mRNA vaccine, over a period of up to six months after the second dose.

METHODS

We enrolled 57 HCWs, without clinical history of COVID-19 infection. Fluoroenzyme-immunoassay was used for the quantitative anti-S1 IgG antibodies at different time points T1 (one month), T3 (three months) and T6 (six months) following the second vaccine shot. Simultaneously, a commercial surrogate virus neutralization test (sVNT) was used for the determination of NAbs, expressed as inhibition percentage (% IH).

RESULTS

Median values of anti-S1 IgG antibodies decreased from T1 (1,452 BAU/mL) to T6 (104 BAU/mL) with a percent variation of 92.8% while the sVNT showed a percent variation of 34.3% for the same time frame. The decline in anti-S1 IgG antibodies from T1 to T6 was not accompanied by a loss of the neutralizing capacity of antibodies. In fact at T6 a neutralization percentage <20% IH was observed only in 3.51% of HCWs.

CONCLUSIONS

Our findings reveal that the decrease of anti-S1 IgG levels do not correspond in parallel to a decrease of NAbs over time, which highlights the necessity of using both assays to assess vaccination effectiveness.

Antibody response of smokers to the COVID-19 vaccination: Evaluation based on cigarette dependence

Smokers may have lower antibody titers after vaccination with a coronavirus disease 2019 (COVID-19) mRNA vaccine. However, to the best of our knowledge, no study has evaluated antibody titers after COVID-19 vaccination based on the level of smokers' cigarette dependence. In this study, we measured the level of serum anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) spike protein receptor-binding domain (S-RBD) immunoglobulin-G (IgG) by enzyme linked immunosorbent assay of 55 actively smoking Japanese social workers (firefighters, paramedics, and rescue workers) who had received two doses of the BNT162b2 vaccine. Further, we assessed their cigarette dependence using the Fagerstrom Test for Nicotine Dependence (FTND), measured their serum cotinine levels, and tested for their correlation with anti-RBD IgG levels. Serum anti-SARS-CoV-2 S-RBD protein IgG levels after BNT162b2 vaccination showed a significant negative correlation with FTND (ρ = -0.426, p = 0.001). In addition, serum cotinine level showed a significant positive correlation with FTND (ρ = 0.470, p = 0.000). However, no significant negative correlation was noted between serum cotinine and serum anti-SARS-CoV-2 S-RBD protein IgG levels (ρ = -0.156, p = 0.256). Our results suggest that smokers with strong cigarette dependence have inadequate anti-SARS-CoV-2 S-RBD protein IgG levels after COVID-19 mRNA vaccination.

Immunogenicity of COVID-19 Vaccines in Patients with Diverse Health Conditions: a Comprehensive Systematic Review

It remains unclear how effective COVID-19 vaccinations will be in patients with weakened immunity due to diseases, transplantation, and dialysis. We conducted a systematic review comparing the efficacy of COVID-19 vaccination in patients with solid tumor, hematologic malignancy, autoimmune disease, inflammatory bowel disease, and patients who received transplantation or dialysis. A literature search was conducted twice using the Medline/PubMed database. As a result, 21 papers were included in the review, and seropositivity rate was summarized by specific type of disease, transplantation, and dialysis. When different papers studied the same type of patient group, a study with a higher number of participants was selected. Most of the solid tumor patients showed a seropositivity rate of more than 80% after the second inoculation, but a low seropositivity was found in certain tumors such as breast cancer. Research in patients with certain types of hematological malignancy and autoimmune diseases has also reported low seropositivity, and this may have been affected by the immunosuppressive treatment these patients receive. Research in patients receiving dialysis or transplantation has reported lower seropositivity rates than the general population, while all patients with inflammatory bowel disease have converted to be seropositive. Meta-analysis validating these results will be needed, and studies will also be needed on methods to protect patients with reduced immunity from COVID-19. This article is protected by copyright. All rights reserved.

COVID-19 Vaccination in Health Care Workers in Italy: A Literature Review and a Report from a Comprehensive Cancer Center

The coronavirus disease 2019 pandemic still represents a global public health emergency, despite the availability of different types of vaccines that reduced the number of severe cases, the hospitalization rate and mortality. The Italian Vaccine Distribution Plan identified healthcare workers (HCWs) as the top-priority category to receive access to a vaccine and different studies on HCWs have been implemented to clarify the duration and kinetics of antibody response. The aim of this paper is to perform a literature review across a total of 44 studies of the serologic response to COVID-19 vaccines in HCWs in Italy and to report the results obtained in a prospective longitudinal study implemented at the Fondazione IRCCS Istituto Nazionale Tumori (INT) of Milan on 1565 HCWs. At INT we found that 99.81% of the HCWs developed an antibody response one month after the second dose. About six months after the first serology evaluation, 100% of the HCWs were still positive to the antibody, although we observed a significant decrease in its levels. Overall, our literature review results highlight a robust antibody response in most of the HCWs after the second vaccination dose. These figures are also confirmed in our institutional setting seven months after the completion of the cycle of second doses of vaccination.

Antibody response after two doses of the BNT162b2 vaccine among healthcare workers of a Greek Covid 19 referral hospital: A prospective cohort study

The global vaccination against SARS-CoV-2 has highlighted the need of assessing vaccines' immunogenicity against COVID-19. To evaluate humoral immunity induced by the BNT162b2 vaccine, we enrolled health care workers at AHEPA University Hospital of Thessaloniki, Greece to measure Anti-S SARS-CoV-2, anti-RBD SARS-CoV-2 and neutralizing antibodies. A total of 955 individuals with a median age of 50 years, were included in the study. Median values of antibodies were 1947.27 BAU/mL (Abbott SARS-CoV-2 IgG II Quant), 2064.98 BAU/mL (MAGLUMI SARS-CoV-2 S-RBD IgG) and 2464.63 IU/mL (MAGLUMI SARS-CoV-2 Neutralizing Antibodies). Individuals previously infected had greater antibody responses than infection naive ones and a 7-fold higher neutralizing antibodies titre. Antibodies degreased by age but not sex. Spearman's correlation coefficient among the three assays ranged from 0.903 to 0.969. The BNT162b2 vaccine was highly immunogenic in our cohort. Further research is needed to evaluate the vaccine's immunogenicity through time as well as in different populations.

An analysis of antibody response following the second dose of CoronaVac and humoral response after booster dose with BNT162b2 or CoronaVac among healthcare workers in Turkey

Limited data are available on the short- to midterm levels of antibodies to the CoronaVac vaccine and quantitative change in humoral response after homologous or heterologous booster doses. In this prospective cohort study, we evaluated the anti-receptor-binding domain (RBD) immunoglobulin G (IgG) levels after two doses of CoronaVac and heterologous/homologous booster administration among healthcare workers in a university hospital in Turkey. Quantitative anti-RBD IgG antibody levels were measured at first and fourth months in 560 healthcare workers who had completed two doses of CoronaVac vaccine, and within 2 months after the third dose of CoronaVac or BNT162b2. Participants were asked to complete a questionnaire during the first blood draw. The seropositivity rate was 98.9% and 89.1%, and the median antibody level was 469.2 AU/ml and 166.5 AU/ml at first and fourth month, respectively. In the fourth month, a mean reduction of 61.4% ± 20% in antibody levels was observed in 79.8% of the participants. The presence of chronic disease (odds ratio [OR]: 1.76, 95% confidence interval [CI]: 1.15-2.69) and being in the 36-50 age group (OR: 2.11, 95% CI: 1.39-3.19) were identified as independent predictors for low antibody response. The antibody level increased 104.8-fold (median: 17 609.4 vs. 168 AU/ml) and 8.7-fold (median: 1237.9 vs. 141.4 AU/ml) in the participants who received BNT162b2 and CoronaVac, respectively. During the follow-up, 25 healthcare workers (4.5%) were infected with severe acute respiratory syndrome coronavirus 2. Considering the waning immunity and circulating variants, a single booster dose of messenger RNA vaccine seems reasonable after the inactivated vaccine especially in risk groups.

Immunosenescence and Altered Vaccine Efficiency in Older Subjects: A Myth Difficult to Change

Organismal ageing is associated with many physiological changes, including differences in the immune system of most animals. These differences are often considered to be a key cause of age-associated diseases as well as decreased vaccine responses in humans. The most often cited vaccine failure is seasonal influenza, but, while it is usually the case that the efficiency of this vaccine is lower in older than younger adults, this is not always true, and the reasons for the differential responses are manifold. Undoubtedly, changes in the innate and adaptive immune response with ageing are associated with failure to respond to the influenza vaccine, but the cause is unclear. Moreover, recent advances in vaccine formulations and adjuvants, as well as in our understanding of immune changes with ageing, have contributed to the development of vaccines, such as those against herpes zoster and SARS-CoV-2, that can protect against serious disease in older adults just as well as in younger people. In the present article, we discuss the reasons why it is a myth that vaccines inevitably protect less well in older individuals, and that vaccines represent one of the most powerful means to protect the health and ensure the quality of life of older adults.

An Association Study of HLA with the Kinetics of SARS-CoV-2 Spike Specific IgG Antibody Responses to BNT162b2 mRNA Vaccine

BNT162b2, an mRNA-based SARS-CoV-2 vaccine (Pfizer-BioNTech, New York, NY, USA), is one of the most effective COVID-19 vaccines and has been approved by more than 130 countries worldwide. However, several studies have reported that the COVID-19 vaccine shows high interpersonal variability in terms of humoral and cellular responses, such as those with respect to SARS-CoV-2 spike protein immunoglobulin (Ig)G, IgA, IgM, neutralizing antibodies, and CD4+ and CD8+ T cells. The objective of this study is to investigate the kinetic changes in anti-SARS-CoV-2 spike IgG (IgG-S) profiles and adverse reactions and their associations with HLA profiles (HLA-A, -C, -B, -DRB1, -DQA1, -DQB1, -DPA1 and -DPB1) among 100 hospital workers from the Center Hospital of the National Center for Global Health and Medicine (NCGM), Tokyo, Japan. DQA1*03:03:01 (p = 0.017; Odd ratio (OR) 2.80, 95%confidence interval (CI) 1.05-7.25) was significantly associated with higher IgG-S production after two doses of BNT162b2, while DQB1*06:01:01:01 (p = 0.028, OR 0.27, 95%CI 0.05-0.94) was significantly associated with IgG-S declines after two doses of BNT162b2. No HLA alleles were significantly associated with either local symptoms or fever. However, C*12:02:02 (p = 0.058; OR 0.42, 95%CI 0.15-1.16), B*52:01:01 (p = 0.031; OR 0.38, 95%CI 0.14-1.03), DQA1*03:02:01 (p = 0.028; OR 0.39, 95%CI 0.15-1.00) and DPB1*02:01:02 (p = 0.024; OR 0.45, 95%CI 0.21-0.97) appeared significantly associated with protection against systemic symptoms after two doses of BNT162b2 vaccination. Further studies with larger sample sizes are clearly warranted to determine HLA allele associations with the production and long-term sustainability of IgG-S after COVID-19 vaccination.

Reduced Magnitude and Durability of Humoral Immune Responses to COVID-19 mRNA Vaccines Among Older Adults

BACKGROUND

The magnitude and durability of immune responses to coronavirus disease 2019 (COVID-19) mRNA vaccines remain incompletely characterized in the elderly.

METHODS

Anti-spike receptor-binding domain (RBD) antibodies, angiotensin-converting enzyme 2 (ACE2) competition, and virus neutralizing activities were assessed in plasma from 151 health care workers and older adults (range, 24-98 years of age) 1 month following the first vaccine dose, and 1 and 3 months following the second dose.

RESULTS

Older adults exhibited significantly weaker responses than younger health care workers for all humoral measures evaluated and at all time points tested, except for ACE2 competition activity after 1 vaccine dose. Moreover, older age remained independently associated with weaker responses even after correction for sociodemographic factors, chronic health condition burden, and vaccine-related variables. By 3 months after the second dose, all humoral responses had declined significantly in all participants, and remained significantly lower among older adults, who also displayed reduced binding antibodies and ACE2 competition activity towards the Delta variant.

CONCLUSIONS

Humoral responses to COVID-19 mRNA vaccines are significantly weaker in older adults, and antibody-mediated activities in plasma decline universally over time. Older adults may thus remain at elevated risk of infection despite vaccination.

Factors Influencing Level and Persistence of Anti SARS-CoV-2 IgG after BNT162b2 Vaccine: Evidence from a Large Cohort of Healthcare Workers

We aimed at evaluating quantitative IgG response to BNT162b2 COVID-19 vaccine among health care workers (HCW), and exploring the role of demographic, clinical, and occupational factors as predictors of IgG levels. On May 2021, among 6687 HCW at the largest tertiary care University-Hospital of Northwestern Italy, at a median of 15 weeks (Interquartile range-IQR 13.6−16.0) after second-dose, serological response was present in 99.8%. Seropositivity was >97% in all the subgroups, except those self-reporting immunodeficiency (94.9%). Overall, the median serological IgG value was 990 BAU/mL (IQR 551−1870), with most of subjects with previous SARS-CoV-2 infection or with shorter time lapse (2−8 weeks) between vaccination and serology with values in the highest quintile (>2080). At multivariable analysis, significant predictors of lower values were increasing age, male, current smoking, immunodeficiency, recent occupational contacts, and increasing time lapse from vaccination; conversely, previous infection and recent household contacts were significantly associated with higher IgG levels. Subjects with previous infection kept a very high level (around 2000 BAU/mL) up to 120 days. These results, besides supporting a high serological response up to 4−5 months, suggest predictive factors of faster decay of IgG levels that could be useful in tailoring vaccination strategies.

Effects of age, sex, serostatus, and underlying comorbidities on humoral response post-SARS-CoV-2 Pfizer-BioNTech mRNA vaccination: a systematic review

With the advent of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic, several vaccines have been developed to mitigate its spread and prevent adverse consequences of the Coronavirus Disease 2019 (COVID-19). The mRNA technology is an unprecedented vaccine, usually given in two doses to prevent SARS-CoV-2 infections. Despite effectiveness and safety, inter-individual immune response heterogeneity has been observed in recipients of mRNA-based vaccines. As a novel disease, the specific immune response mechanism responsible for warding off COVID-19 remains unclear at this point. However, significant evidence suggests that humoral response plays a crucial role in affording immunoprotection and preventing debilitating sequelae from COVID-19. As such, this paper focused on the possible effects of age, sex, serostatus, and comorbidities on humoral response (i.e. total antibodies, IgG, and/or IgA) of different populations post-mRNA-based Pfizer-BioNTech vaccination. A systematic search of literature was performed through PubMed, Cochrane CENTRAL, Google Scholar, Science Direct, medRxiv, and Research Square. Studies were included if they reported humoral response to COVID-19 mRNA vaccines. A total of 32 studies were identified and reviewed, and the percent differences of means of reported antibody levels were calculated for comparison. Findings revealed that older individuals, male sex, seronegativity, and those with more comorbidities mounted less humoral immune response. Given these findings, several recommendations were proposed regarding the current vaccination practices. These include giving additional doses of vaccination for immunocompromised and elderly populations. Another recommendation is conducting clinical trials in giving a combined scheme of mRNA vaccines, protein vaccines, and vector-based vaccines.

Humoral response to the SARS-CoV-2 BNT162b2 mRNA vaccine: Real-world data from a large cohort of healthcare workers

BACKGROUND

The SARS-CoV-2 pandemic was responsible for the death of millions of people around the world, which accelerated the study of vaccines. The BNT162b2 mRNA COVID-19 is a messenger RNA vaccine that encodes the spike protein of the virus. However, the duration of the protection conferred by this vaccine and factors associated with immune responses require validation in large cohorts.

METHODS

Here, we present data of humoral immune response to vaccination in4264 healthcare workers, tested before (T0) and 15 and 90 days (T1 and T2, respectively) following vaccination.Peripheral blood was collected for immunological analysis using the Quant SARS-CoV-2 IgG II Chemiluminescent Microparticle Immunoassay (CMIA) to determine anti-spike IgG, receptor binding domain (RBD), S1 subunit of SARS-CoV-2.

FINDINGS

At T0, 96·8% (n = 4129) of participants had IgG antibodies non-reactive to anti-SARS-CoV-2. Fifteen days after completing the vaccination, the IgG overall median titer was significantly elevated (21·7x103AU/mL). Both for uni- and multivariate logistic regression analyses women presented higher antibody levels than men, independent of age. Titers were significantly altered among age groups, decreasing by each increase in 10-year of age. At 3 months after completing the vaccination, anti-SARS-CoV-2 IgG titers were 6·3-fold diminished. This real-world post-vaccination data confirmed production of a frequent and elevated anti-SARS-CoV-2 IgG titers, associated with high protection rates. Females and younger participants had higher titer 15 days after vaccination, and despite the significant reduction from 15-to-90 days, those with higher pre-vaccination titers maintained higher levels throughout the remaining timepoints.

INTERPRETATION

These findings support the need to track humoral immunity kinetics to uncover viral susceptibility and eventually implement re-vaccination, particularly in groups prone to lower humoral immune response.

FUNDING

No external funding was received to conduct this study.

Clinical Utility of Elecsys Anti-SARS-CoV-2 S Assay in COVID-19 Vaccination: An Exploratory Analysis of the mRNA-1273 Phase 1 Trial

Background

The ability to quantify an immune response after vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is essential. This study assessed the clinical utility of the quantitative Roche Elecsys® Anti-SARS-CoV-2 S assay (ACOV2S) using samples from the 2019-nCoV vaccine (mRNA-1273) phase 1 trial (NCT04283461).

Methods

Samples from 30 healthy participants, aged 18-55 years, who received two injections with mRNA-1273 at a dose of 25 μg (n=15) or 100 μg (n=15), were collected at Days 1 (first vaccination), 15, 29 (second vaccination), 43 and 57. ACOV2S results (shown in U/mL - equivalent to BAU/mL per the first WHO international standard) were compared with results from ELISAs specific to antibodies against the Spike protein (S-2P) and the receptor binding domain (RBD) as well as neutralization tests including nanoluciferase (nLUC80), live-virus (PRNT80), and a pseudovirus neutralizing antibody assay (PsVNA50).

Results

RBD-specific antibodies were already detectable by ACOV2S at the first time point of assessment (d15 after first vaccination), with seroconversion before in all but two participants (25 μg dose group); all had seroconverted by Day 29. Across all post-baseline visits, geometric mean concentration of antibody levels was 3.27-7.48-fold higher in the 100 μg compared with the 25 μg dose group. ACOV2S measurements were highly correlated with those from RBD ELISA (Pearson's r=0.938; p<0.0001) and S-2P ELISA (r=0.918; p<0.0001). For both ELISAs, heterogeneous baseline results and smaller increases in antibody levels following the second vs first vaccination compared with ACOV2S were observed. ACOV2S showed absence of any baseline noise indicating high specificity detecting vaccine-induced antibody response. Moderate-strong correlations were observed between ACOV2S and neutralization tests (nLUC80 r=0.933; PsVNA50, r=0.771; PRNT80, r=0.672; all p ≤ 0.0001).

Conclusion

The Elecsys Anti-SARS-CoV-2 S assay (ACOV2S) can be regarded as a highly valuable method to assess and quantify the presence of RBD-directed antibodies against SARS-CoV-2 following vaccination and may indicate the presence of neutralizing antibodies. As a fully automated and standardized method, ACOV2S could qualify as the method of choice for consistent quantification of vaccine-induced humoral response.

Gut microbiota-derived metabolites confer protection against SARS-CoV-2 infection

The gut microbiome is intricately coupled with immune regulation and metabolism, but its role in Coronavirus Disease 2019 (COVID-19) is not fully understood. Severe and fatal COVID-19 is characterized by poor anti-viral immunity and hypercoagulation, particularly in males. Here, we define multiple pathways by which the gut microbiome protects mammalian hosts from SARS-CoV-2 intranasal infection, both locally and systemically, via production of short-chain fatty acids (SCFAs). SCFAs reduced viral burdens in the airways and intestines by downregulating the SARS-CoV-2 entry receptor, angiotensin-converting enzyme 2 (ACE2), and enhancing adaptive immunity via GPR41 and 43 in male animals. We further identify a novel role for the gut microbiome in regulating systemic coagulation response by limiting megakaryocyte proliferation and platelet turnover via the Sh2b3-Mpl axis. Taken together, our findings have unraveled novel functions of SCFAs and fiber-fermenting gut bacteria to dampen viral entry and hypercoagulation and promote adaptive antiviral immunity.

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.

Anti-SARS-CoV-2 Spike Protein RBD Antibody Levels After Receiving a Second Dose of ChAdOx1 nCov-19 (AZD1222) Vaccine in Healthcare Workers: Lack of Association With Age, Sex, Obesity, and Adverse Reactions

Response to vaccines generally varies according to individual factors of the vaccinated subjects such as demographics and immune status. While there are various reports of factors associated with immunogenicity of mRNA COVID-19 vaccines, little is known about those of adenovirus vector vaccines. We conducted a prospective observational study to assess the relationships of antibody level with age, sex, body mass index (BMI), and adverse reactions (ARs) to an adenovirus vector vaccine, ChAdOx1 nCoV-19. Healthcare workers who planned to receive both the first and second injections of the ChAdOx1 nCoV-19 vaccine at Hanyang University Hospital, Seoul, Korea, were enrolled in the study. Seven days after each injection, participants were asked to complete an online adverse reaction survey. In addition, anti-SARS-CoV-2 spike (S) protein receptor binding domain (RBD) antibody concentration was measured 4 weeks after the second injection. All participants (n = 447, 100%) showed serologic positivity (≥ 0.8 U/mL) 4 weeks after the second injection of ChAdOx1 nCoV-19 vaccine. Furthermore, the anti-SARS-CoV-2 S protein RBD concentration was similar among groups when stratified by age, sex, BMI, or presence and severity of AR; multivariable linear regression found no associations between antibody response to the ChAdOx1 nCoV-19 vaccine and age, BMI, sex, and vaccine-induced ARs. In conclusion, age, sex, obesity, and ARs were not associated with antibody responses after two doses of ChAdOx1 nCoV-19 vaccination.

Immunogenicity of BNT162b2 mRNA COVID-19 Vaccine in Patients with Cardiovascular Disease

Concern has been raised about the effectiveness of the coronavirus disease 2019 (COVID-19) vaccine in the population of patients with various comorbidities such as heart disease. We investigated the humoral response to the BNT162b2 mRNA COVID-19 vaccine in patients with cardiovascular disease (CVD). We measured IgG against severe acute respiratory syndrome coronavirus 2 spike receptor-binding domain (RBD-IgG) in 85 CVD patients and 179 healthcare workers (HCWs). Blood samples were collected from patients and HCWs three times: (1) before the first dose of vaccination, (2) two weeks after the first dose of vaccination, and (3) two weeks after the second dose of vaccination. Patients with CVD showed a significantly inferior serological response to the BNT162b2 mRNA COVID-19 vaccine at 14 days after the prime dose compared to HCWs (21% vs. 95%, p < 0.001). Median RBD-IgG titers of patients with CVD at 14 days after the second dose were significantly lower than those of HCWs (137.2 U/mL (80.6-200.4 U/mL) vs. 176.2 U/mL (123.9-260.0 U/mL), p < 0.001). In multivariable analyses, CVD is significantly associated with seropositivity after first vaccination and RBD-IgG titers after second vaccination. CVD patients may have a poor humoral response to the BNT162b2 mRNA COVID-19 vaccine, need to be closely monitored, and require earlier revaccination to ensure stronger immunity and protection against infection.

Anti-Spike SARS-CoV-2 IgG Assessment with a Commercial Assay during a 4-Month Course after COVID-19 Vaccination

We intended to assess the humoral response induced by the Pfizer/BioNTech Comirnaty COVID-19 vaccine with commercially available immunoassays: anti-spike (S) IgG and IgM, and anti-nucleocapsid (N) IgG antibodies, over a 4-month course. One hundred subjects, including 15 COVID-19 convalescents, comprised the study cohort. The SARS-CoV-2 antibodies concentrations were measured on day 0' and 10', 20', 30', 60', 90', and 120' after the first dose administration. Over the course of the study, 100% of the participants developed and sustained anti-SARS-CoV-2 S IgG antibodies. The highest concentration, exceeding the quantification range of the test (2080 BAU/mL), was reached by 67% of the subjects on day 30'. The concentration of the antibodies remained stable between days 30' and 90' but was followed by a significant decrease between days 90' and 120'. The stronger and more persistent humoral response was noted for women. The COVID-19 convalescents developed higher antibody levels, particularly 10 days after the first Comirnaty dose. Twenty-three out of the eighty-five naïve vaccinees failed to develop a detectable IgM response. LIAISON® SARS-CoV-2 TrimericS IgG (DiaSorin S.p.A, Saluggia, Italy) may be useful in the assessment of the humoral response to the Comirnaty vaccine. In contrast, Abbott's anti-S SARS-CoV-2 IgM has a limited utility in this context.

Human IgM and IgG Responses to an Inactivated SARS-CoV-2 Vaccine

Objective

The ongoing COVID-19 pandemic warrants accelerated efforts to test vaccine candidates. To explore the influencing factors on vaccine-induced effects, antibody responses to an inactivated SARS-CoV-2 vaccine in healthy individuals who were not previously infected by COVID-19 were assessed.

Methods

All subjects aged 18–60 years who did not have SARS-CoV-2 infection at the time of screening from June 19, 2021, to July 02, 2021, were approached for inclusion. All participants received two doses of inactivated SARS-CoV-2 vaccine. Serum IgM and IgG antibodies were detected using a commercial kit after the second dose of vaccination. A positive result was defined as 10 AU/mL or more and a negative result as less than 10 AU/mL. This retrospective study included 97 infection-naïve individuals (mean age 35.6 years; 37.1% male, 62.9% female).

Results

The seropositive rates of IgM and IgG antibody responses elicited after the second dose of inactivated SARS-CoV-2 vaccine were 3.1% and 74.2%, respectively. IgG antibody levels were significantly higher than IgM levels (P<0.0001). Sex had no effect on IgM and IgG antibody response after the second dose. The mean anti-IgG level in older persons (⩾42 years) was significantly lower than that of younger recipients. There was a significantly lower antibody level at > 42 days compared to that at 0–20 days (P<0.05) and 21–31 days (P<0.05) after the second dose.

Conclusion

IgG antibody response could be induced by inactivated SARS-CoV-2 vaccine in healthy individuals (>18 years), which can be influenced by age and detection time after the second dose of vaccination.

Pfizer-BioNTech and Sinopharm: A Comparative Study on Post-Vaccination Antibody Titers

COVID-19 (coronavirus disease 2019) vaccines induce immunity through different mechanisms. The aim of this study is to compare the titers of specific antibodies in subjects vaccinated with either the Pfizer-BioNTech COVID-19 vaccine or the Sinopharm vaccine. This prospective observational cohort included Jordanian adults vaccinated with two doses, 21 days apart, of either of the two aforementioned vaccines. Titers were collected 6 weeks after the administration of the second dose. Overall, 288 participants were included, of which 141 were administered the Pfizer-BioNTech vaccine, while 147 were administered the Sinopharm vaccine. Remarkably, 140 (99.3%) of the Pfizer-BioNTech vaccine recipients had positive IgG titers, while 126 (85.7%) of Sinopharm recipients had positive IgG (p < 0.001). The mean titer for IgG among Pfizer-BioNTech recipients was 515.5 ± 1143.5 BAU/mL, compared to 170.0 ± 230.0 BAU/mL among Sinopharm subjects (p < 0.001). Multivariable regression analysis showed that the Pfizer-BioNTech vaccine positively correlated with positive IgG titers (OR: 25.25; 95% CI: 3.25-196.15; p = 0.002), compared with a negative effect of cardiovascular diseases (OR: 0.33; 95% CI: 0.11-0.99; p = 0.48) on IgG titers. In conclusion, fully vaccinated recipients of the Pfizer-BioNTech vaccine had superior quantitative efficiency compared to Sinopharm recipients. A booster dose is supported for Sinopharm recipients, or those with chronic immunosuppressive diseases.

mRNA vaccination in people over 80 years of age induces strong humoral immune responses against SARS-CoV-2 with cross neutralization of P.1 Brazilian variant

Age is the major risk factor for mortality after SARS-CoV-2 infection and older people have received priority consideration for COVID-19 vaccination. However, vaccine responses are often suboptimal in this age group and few people over the age of 80 years were included in vaccine registration trials. We determined the serological and cellular response to spike protein in 100 people aged 80-96 years at 2 weeks after the second vaccination with the Pfizer BNT162b2 mRNA vaccine. Antibody responses were seen in every donor with high titers in 98%. Spike-specific cellular immune responses were detectable in only 63% and correlated with humoral response. Previous SARS-CoV-2 infection substantially increased antibody responses after one vaccine and antibody and cellular responses remained 28-fold and 3-fold higher, respectively, after dual vaccination. Post-vaccine sera mediated strong neutralization of live Victoria infection and although neutralization titers were reduced 14-fold against the P.1 variant first discovered in Brazil they remained largely effective. These data demonstrate that the mRNA vaccine platform delivers strong humoral immunity in people up to 96 years of age and retains broad efficacy against the P.1 variant of concern.

Waning of IgG, Total and Neutralizing Antibodies 6 Months Post-Vaccination with BNT162b2 in Healthcare Workers

Data about the long-term duration of antibodies after SARS-CoV-2 vaccination are still scarce and are important to design vaccination strategies. In this study, 231 healthcare professionals received the two-dose regimen of BNT162b2. Of these, 158 were seronegative and 73 were seropositive at baseline. Samples were collected at several time points. The neutralizing antibodies (NAbs) and antibodies against the nucleocapsid and the spike protein of SARS-CoV-2 were measured. At day 180, a significant antibody decline was observed in seronegative (-55.4% with total antibody assay; -89.6% with IgG assay) and seropositive individuals (-74.8% with total antibody assay; -79.4% with IgG assay). The estimated half-life of IgG from the peak humoral response was 21 days (95% CI: 13-65) in seronegative and 53 days (95% CI: 40-79) in seropositive individuals. The estimated half-life of total antibodies was longer and ranged from 68 days (95% CI: 54-90) to 114 days (95% CI: 87-167) in seropositive and seronegative individuals, respectively. The decline of NAbs was more pronounced (-98.6%) and around 45% of the subjects tested were negative at day 180. Whether this decrease correlates with an equivalent drop in the clinical effectiveness against the virus would require appropriate clinical studies.

Adverse Events following AstraZeneca COVID-19 Vaccine in Saudi Arabia: A Cross-Sectional Study among Healthcare and Nonhealthcare Workers

INTRODUCTION

Many COVID-19 vaccines have been emerging with different efficacy and safety profiles. So far, very little attention has been paid to severity and reactogenicity of COVID-19 vaccine among healthcare workers. Thus, the aim of this study is to investigate the side effects associated with the first dose of AstraZeneca COVID-19 vaccine among healthcare workers (HCWs) and nonhealthcare workers (non-HCWs).

METHOD

This is an observational cross-sectional study conducted at King Abdullah bin AbdulAziz University Hospital, Saudi Arabia, between February 28 and March 12, 2021. The major outcomes were the reported side effects of day 1, day 2, and day 3 after vaccination among HCWs and non-HCWs. Other outcomes included the onset and the duration of the reactions or the side effects that were reported.

RESULTS

A total of 526 participants completed the survey with 173 (32.8%) HCWs and the remaining majority were non-HCWs. Some of the most frequently reported side effects among the participants on the first day were muscle aches (49%), followed by fever (42%) and headache (40%). HCWs experienced more muscle aches, headache, sore throat, and abdominal pain, which were statically significant, compared to non-HCWs. The mean onset of symptoms was 16 (±15.3) h in the HCW arm compared with 12.2 (±10.2) h in non-HCWs (p = 0.0024). Furthermore, the mean duration of symptoms in the HCW group was 37 (±19) h compared with 32.3 (±13) h in the non-HCW group (p = 0.067).

CONCLUSION

The reported side effects were common but not pressing in both groups. HCW respondents appeared to have more COVID-19 vaccine-associated symptoms.

Antibody response and self-reported adverse reactions following vaccination with Comirnaty: a pilot study from a Croatian university hospital

This study aimed to determine antibody responses against SARS-CoV-2 spike (S) after both BioNTech-Pfizer Comirnaty vaccine doses and study the correlation with self-perceived adverse reactions. Antibodies determination with Elecsys anti-SARS-CoV-2 S assay was performed a day prior to or just before administration of the second dose and 8-13 days after the second dose. Participants selected from a predefined list of the experienced local (injection site reactions) and/or systemic (fatigue, headache, myalgia, arthralgia, chills and fever) post-vaccination adverse reactions. An average 100-fold increase in antibody titre in naive vaccinees was observed between the two time points (median 67 U/mL vs 2841 U/mL, p<0.001). Participants aged below 50 had higher antibody titres (median 99 U/mL vs 26 U/mL, p=0.003 after the first dose; median 3617 U/mL vs 2556 U/mL, p=0.026 after the second dose). All reported adverse reactions were mild-to-moderate, with more participants declaring systemic reactions after the second dose (p=0.001), without a clear correlation with antibody titre.

Performance evaluation of the Roche Elecsys Anti-SARS-CoV-2 S immunoassay

The Elecsys® Anti-SARS-CoV-2 S immunoassay (Roche Diagnostics International Ltd, Rotkreuz, Switzerland) has been developed for the detection of antibodies to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein. We evaluated the assay performance using samples from seven sites in Germany, Austria, and Switzerland. For specificity and sensitivity analyses, 7880 presumed negative pre-pandemic samples and 827 SARS-CoV-2 PCR-confirmed single or sequential samples from 272 different patients were tested, respectively. The overall specificity and sensitivity (≥14 days post-PCR) for the Elecsys Anti-SARS-CoV-2 S immunoassay were 99.95% (95% confidence interval [CI]: 99.87–99.99; 7876/7880) and 97.92% (95% CI: 95.21–99.32; 235/240), respectively. The Elecsys Anti-SARS-CoV-2 S immunoassay had significantly higher specificity compared with the LIAISON® SARS-CoV-2 S1/S2 IgG (99.95% [2032/2033] vs 98.82% [2009/2033]), ADVIA Centaur® SARS-CoV-2 Total (100% [928/928] vs 86.96% [807/928]), ARCHITECT SARS-CoV-2 IgG (99.97% [2931/2932] vs 99.69% [2923/2932]), iFlash-SARS-CoV-2 IgM (100.00% [928/928] vs 99.57% [924/928]), and EUROIMMUN Anti-SARS-CoV-2 IgG (100.00% [903/903] vs 97.45% [880/903]) and IgA (100.00% [895/895] vs 95.75% [857/895]) assays. The Elecsys Anti-SARS-CoV-2 S immunoassay had significantly higher sensitivity (≥14 days post-PCR) compared with the ARCHITECT SARS-CoV-2 IgG (98.70% [76/77] vs 87.01% [67/77]), iFlash-SARS-CoV-2 IgG (100.00% [76/76] vs 93.42% [71/76]) and IgM (100.00% [76/76] vs 35.53% [27/76]), and EUROIMMUN Anti-SARS-CoV-2 IgG (98.26% [113/115] vs 93.91% [108/115]) assays. Therefore, the Elecsys Anti-SARS-CoV-2 S assay demonstrated a reliable performance across various sample populations for the detection of anti-S antibodies.

Large-scale study of antibody titer decay following BNT162b2 mRNA vaccine or SARS-CoV-2 infection

BACKGROUND

Immune protection following either vaccination or infection with SARS-CoV-2 decreases over time.

OBJECTIVE

To determine the kinetics of SARS-CoV-2 IgG antibodies following administration of two doses of BNT162b2 vaccine, or SARS-CoV-2 infection in unvaccinated individuals.

METHODS

Antibody titers were measured between January 31, 2021, and July 31, 2021 in two mutually exclusive groups: i) vaccinated individuals who received two doses of BNT162b2 vaccine and had no history of previous infection with COVID-19 and ii) SARS-CoV-2 convalescents who had not received the vaccine.

RESULTS

A total of 2,653 individuals fully vaccinated by two doses of vaccine during the study period and 4,361 convalescent patients were included. Higher SARS-CoV-2 IgG antibody titers were observed in vaccinated individuals (median 1581 AU/mL IQR [533.8-5644.6]) after the second vaccination, than in convalescent individuals (median 355.3 AU/mL IQR [141.2-998.7]; p<0.001). In vaccinated subjects, antibody titers decreased by up to 40% each subsequent month while in convalescents they decreased by less than 5% per month. Six months after BNT162b2 vaccination 16.1% subjects had antibody levels below the seropositivity threshold of <50 AU/mL, while only 10.8% of convalescent patients were below <50 AU/mL threshold after 9 months from SARS-CoV-2 infection.

CONCLUSIONS

This study demonstrates individuals who received the Pfizer-BioNTech mRNA vaccine have different kinetics of antibody levels compared to patients who had been infected with the SARS-CoV-2 virus, with higher initial levels but a much faster exponential decrease in the first group.

FUNDING

This research was internally funded by Leumit Health Services (LHS) and was supported in part by the Intramural Research Program, National Institutes of Health, National Cancer Institute, Center for Cancer Research.The content of this publication does not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.

IMPACT STATEMENT

Large scale study display the kinetics of SARS-CoV-2 IgG antibodies present in individuals vaccinated with two doses of mRNA vaccine vs. unvaccinated patients who had recovered from the disease: initial levels of antibody are much higher in vaccinated patients, but decrease faster.