Effect of COVID-19 on Anti-S Antibody Response in Healthcare Workers Six Months Post-Vaccination

Prevalence of neutralizing antibodies against SARS-CoV-2 using a rapid serological test in health workers of a Spanish Department of Health in Alicante (Spain) before the booster dose of the vaccine

AIM

To study the prevalence of neutralizing antibodies in healthcare workers and healthcare support personnel after the administration of the second dose of the BNT162b2 vaccine (Pfizer-BioNTech).

MATERIALS AND METHODS

In December 2021, we undertook a study in the Health Department in Orihuela, Alicante (Spain), which consists of 1500 workers. We collected demographic variables about the study participants, and we performed a "point-of-care" immunochromatography test to measure the presence of neutralizing antibodies (OJABIO® SARS-CoV-2 Neutralizing Antibody Detection Kit, manufactured by Wenzhou OJA Biotechnology Co., Ltd. Wenzhou, Zhejiang, China) before the administration of the third dose of the vaccine.

RESULTS

We obtained complete information about 964 (64%) workers, which consisted of 290 men and 674 women. The average age was 45,8 years (min. 18, max. 68) and the average time since the last dose of the vaccine was 40,5 weeks (min. 1,71, max. 47,71). A total of 131 participants (13,5%) had suffered infection by SARS-CoV-2 confirmed using RT-PCR. The proportion of participants who showed presence of neutralizing antibodies was 38,5%. In the multivariable analysis, the time since the last dose of the vaccine (aOR week: 1,07; 95%CI: 1,04; 1,09) and previous infection by SARS-CoV-2 (aOR: 3,7; 95CI: 2,39; 5,63) showed a statistically significant association with the presence of neutralizing antibodies.

CONCLUSIONS

The time since the administration of the last dose of the vaccine and the previous infection by SARS-CoV-2 determined the presence of neutralizing antibodies in 38,5% of the healthcare workers and support workers.

Immunogenicity of Two Doses of BNT162b2 mRNA COVID-19 Vaccine with a ChAdOx1-S Booster Dose among Navy Personnel in Mexico

Booster doses of the SARS-CoV-2 vaccine have been recommended to improve and prolong immunity, address waning immunity over time, and contribute to the control of the COVID-19 pandemic. A heterologous booster vaccine strategy may offer advantages over a homologous approach. To compare the immunogenicity of two doses of BNT162b2 mRNA COVID-19 vaccine with a ChAdOx1-S booster dose, immunoglobulin G (IgG) anti-spike (anti-S) and anti-nucleocapsid (anti-N) antibody titers (Ab) were compared over 1 year and post-booster vaccination. Results showed that, at 3- to 9-month assessments in vaccinated subjects, an-ti-N Ab were undetectable in participants with no history of COVID-19. In contrast, anti-S Ab measurements were lower than those with COVID-19, and a decrease was observed during the 9 months of observation. After booster vaccination, no differences were found in anti-S between participants who reported a history of COVID-19 and those who did not. Anti-S levels were higher after booster vaccination measurement vs. at 9 months in participants with COVID-19 and without COVID-19, i.e., independent of an infection history. Vaccine administration elicited a response of higher anti-S IgG levels in those infected before vaccination, although levels decreased during the first nine months. IgG anti-N titers were higher in participants with a history of declared infection and who were asymptomatic. The ChAdOx1-S booster increased anti-S Ab levels in participants regardless of whether they had been infected or not to a significantly higher value than with the first two vaccines. These findings underscore the importance of booster vaccination in eliciting a robust and sustained immune response against COVID-19, regardless of the prior infection status.

Impact of Health Workers' Choice of COVID-19 Vaccine Booster on Immunization Levels in Istanbul, Turkey

BACKGROUND

There are limited data regarding short- and medium-term IgG antibody levels after the CoronaVac and BNT162b2 vaccines. This study aimed to investigate the antibody responses of health workers who initially received two doses of CoronaVac one month apart followed by a booster dose of either CoronaVac or BNT162b2, as well as determine whether either vaccine provided superior results.

METHODS

This research represents the second phase of a mixed-methods vaccine cohort study and was conducted between July 2021 and February 2022. The participants (n = 117) were interviewed in person and blood samples were collected before and at 1 and 6 months after the booster vaccination.

RESULTS

BNT162b2 was found to have greater immunogenic potential than CoronaVac (p < 0.001). Health workers without chronic disease exhibited statistically significant increases in antibody levels after both vaccines (p < 0.001), whereas only BNT162b2 caused a significant increase in antibody levels in participants with chronic disease (p < 0.001). Samples obtained before and at 1 and 6 months after the booster vaccination revealed no age- or sex-based differences in IgG-inducing potential for either vaccine (p > 0.05). Antibody levels were comparable in both vaccine groups before the booster regardless of COVID-19 history (p > 0.05); however, antibody levels were significantly higher after the BNT162b2 booster at 1 month (<0.001) and at 6 months, except among participants who had a positive history of COVID-19 infection (p < 0.001).

CONCLUSIONS

Our results suggest that even a single booster dose of BNT162b2 after initial vaccination with CoronaVac provides a protective advantage against COVID-19, especially for risk groups such as health workers and those with chronic diseases.

Serological Responses up to 9 Months following COVID-19 mRNA Vaccination in Residents and Health-Care Workers of Long-Term Care Facilities: A Multicenter Prospective Cohort Study in Northern Italy

Long-term care facilities (LTCFs) were severely affected by COVID-19, in particular in Northern Italy. We aimed to assess antibody responses among residents and healthcare workers (HCWs) of 13 LTCFs through serum samples collected at three time points: prior to, two weeks, and 9 months after receiving Pfizer/BNT162b2 SARS-CoV-2 mRNA vaccine (respectively t0, t1, and t2). IgG antibodies targeted towards the S1 domain of the spike protein were measured, and results were expressed in binding antibody units (BAU/mL). Friedman's average rank test was performed to compare antibody titres between the three time points. Two logistic regression models were built to identify independent predictors of (1) developing and (2) maintaining a significant antibody response to vaccination, using a previously identified threshold. In total, 534 subjects were enrolled (371 HCWs and 163 residents). The antibody titres at t1 were the highest; at t2, the IgG titres significantly decreased, remaining however 10 times higher compared to titres at t0. Previous infection was the only significant predictor of developing and maintaining a response over threshold in both models. Results of this study provided further insights on the humoral response elicited by vaccination, and on host factors determining variations in its magnitude and kinetics.

Immunogenicity evaluation after BNT162b2 booster vaccination in healthcare workers

Waning of the immune response upon vaccination in SARS-CoV-2 infection is an important subject of evaluation in this pandemic, mostly in healthcare workers (HCW) that are constantly in contact with infected samples and patients. Therefore, our study aimed to establish the specific humoral response of specific IgG and IgA antibodies upon vaccination, during the second year of pandemic and evaluating the booster shot with the same vaccine type. A group of 103 HCW with documented exposure to the virus were monitored for specific IgG and IgA levels prior to vaccination, after the first vaccination round, during the following 8 months and after the booster shot with the same vaccine type. After 8 months post-vaccination the humoral response in both IgG and IgA decreased, 2.4 times for IgG, and 2.7 times for IgA. Although the antibodies levels significantly decreased, no documented infection was registered in the group. After the booster shot, the entire group, displayed IgG increased levels, immediately after booster followed by the increase in specific IgA. IgG levels post-second round of vaccination are statistically higher compared to the first round, while IgA is restored at the same levels. Within the vaccination or booster routine for a multiple waves' pandemic that is generating new virus variants, populational immunity remains an important issue for future implementation of prevention/control measures.

Performance evaluation of an automatic chemiluminescence immune platform for SARS-CoV-2 neutralizing antibody after vaccination in real world

OBJECTIVE

Reliable high-throughput serological assays for SARS-CoV-2 antibodies present an important role in the strength and duration of immunity after vaccination. The study investigated the analytical and clinical performances of neutralizing antibodies (NTAb) assay by chemiluminescent (CLIA), and SARS-CoV-2 neutralizing antibody after vaccination in real world.

METHODS

The analytical performances of CLIA for SARS-CoV-2 NTAb were evaluated, followed by the sensitivity and specificity identified with a PRNT test from 50 volunteers. Then, a cohort of vaccine recipients (n = 37) were tracked with SARS-CoV-2 NTAb assay at prior to vaccination, one, three and six months post two doses. In real world, a total of 737 cases were recruited from physical examination center in Shenzhen Luohu People's Hospital (from Jun to August 2021) to analyze vaccination status.

RESULTS

Serological assays on the CLIA were found with excellent characteristics including imprecision, repeatability and linearity. Besides, it was robust to icterus, lipemia and hemolysis. The good sensitivity and specificity were obtained at 98% and 100%, respectively. NTAb results showed a high correlation with PRNT₅₀ titers (r 0.61). Until July 2021, the BBIBP-CorV (76.3%) and Sinovac CoronaVac (20.5%) were the predominant vaccines injection in Shenzhen, China. Adolescent less than 18 years was the main unvaccinated group (52.1%). The seropositive rate of inactive SRAR-CoV-2 vaccines exceeded 97% after inoculation. The NTAb generated by Sinovac CoronaVac with the schedule of 0-56 days was found significantly lower than that by BBIBP-CorV (P < 0.001). The follow-up of NTAb changes in a cohort and the dynamic variation of NTAb in real world disclosed steep downward by almost three times for NTAb level occurred at three months post twice vaccinations. The seropositive ratio was at least 50% over 6 months.

CONCLUSIONS

SARS-CoV-2 neutralizing antibodies assay show excellent analytical and clinical performances, and a high correlation with neutralizing activity. Anti-epidemic measures and the urgent trial of SARS-CoV-2 vaccine was calling for adolescents.

Decline of Anti-SARS-CoV-2 IgG Antibody Levels 6 Months after Complete BNT162b2 Vaccination in Healthcare Workers to Levels Observed Following the First Vaccine Dose

Research on post-vaccination antibody dynamics has become pivotal in estimating COVID-19 vaccine efficacy. We studied anti-SARS-CoV-2 Spike RBD IgG levels in 587 healthcare workers (2038 sera) who completed BNT162b2 vaccination. Average antibody titer 3 weeks after the first dose in COVID-19-naïve participants (median 873.5 AU/mL) was 18-fold higher than the test threshold, with a significant increase 1 month (median 9927.2 AU/mL) and an exponential decrease 3 (median 2976.7 AU/mL) and 6 (median 966.0 AU/mL) months after complete vaccination. Participants with a history of COVID-19 prior to vaccination showed significantly higher antibody levels, particularly after the first dose (median 14,280.2 AU/mL), with a slight decline 1 month (median 12,700.0 AU/mL) and an exponential decline in antibody titers 3 (median 4831.0 AU/mL) and 6 (median 1465.2 AU/mL) months after vaccination. Antibody levels of COVID-19-naïve subjects after the first dose were moderately correlated with age (r = −0.4). Multivariate analysis showed a strong independent correlation between IgG levels 6 months after vaccination and both IgG titers after the first dose and 1 month after vaccination (R² = 0.709). Regardless of pre-vaccination COVID-19 history, IgG levels 6 months after vaccination were comparable to antibody levels reached by COVID-19-naïve participants after the first vaccine dose.