Healthcare Workers in South Korea Maintain a SARS-CoV-2 Antibody Response Six Months After Receiving a Second Dose of the BNT162b2 mRNA Vaccine

Abstract

BackgroundEffective vaccines against coronavirus disease 2019 (COVID-19) are available worldwide; however, the longevity of vaccine effectiveness is not known.ObjectiveWe performed a prospective observational study to assess the antibody response of healthcare workers against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after BNT162b2 mRNA COVID-19 vaccination.MethodsSARS-CoV-2 neutralizing antibody (nAb) and spike (S) protein-IgG (S-IgG) antibody titers were examined in participants who received two doses of the BNT162b2 mRNA COVID-19 vaccine in a single center between March 1, 2021, and October 11, 2021. Antibody levels were analyzed at four times: before vaccination (visit 1), 4 weeks after the first vaccination (visit 2), 3 months after the second vaccination (visit 3), and 6 months after the second vaccination (visit 4).ResultsA total of 249 healthcare workers at Jeju National University Hospital were enrolled in this study, and 982 blood samples were analyzed. The mean age was 38.1 ± 9.5 years, and 145 (58.2%) participants were females. Positive nAbs (inhibition rates ≥ 20%) were measured in 166/249 (66.7%) subjects at visit 2, 237/243 (97.5%) subjects at visit 3, and 150/237 (63.3%) subjects at visit 4. A S-IgG (≥50 AU/mL) positivity was detected in 246/249 (98.8%) subjects at visit 1, and all participants had positive S-IgG antibody levels at visits 3 and 4 after being fully vaccinated. Further analysis of S-IgG levels revealed a median quantitative antibody level of 1275.1 AU/mL (interquartile range [IQR] 755.5–2119.0) at visit 2, 2765.9 AU/mL (IQR 1809.8–4138.4) at visit 3, and 970.1 AU/mL (IQR 606.0–1495.9) at visit 4. Patient characteristics, such as age, body mass index, and comorbidity, had no relationship with nAb or S-IgG levels at any of the visits. Considering the change in antibody levels over time, both nAb and S-IgG levels at visit 4 decreased compared with the corresponding levels at visit 3. No evidence of SARS-CoV-2 infection was found among any of the participants throughout the study.ConclusionsThe BNT162b2 mRNA vaccine was effective in protecting healthcare personnel working in COVID-19-related departments. While the level of S-IgG antibodies was maintained for 6 months after the second vaccination, nAb levels waned over this 6-month period, indicating the need for a booster vaccination in some healthcare workers 6 months after full vaccination. Herein, we suggest that further studies are needed to evaluate the need for an interval of booster vaccination after full vaccination.

Longitudinal Dynamics of SARS-CoV-2 IgG Antibody Responses after the Two-Dose Regimen of BNT162b2 Vaccination and the Effect of a Third Dose on Healthcare Workers in Japan

“…These results agree with the recent report by Choi J.H. et al, showing the maintenance of SARS-CoV-2 antibody responses in healthcare workers in South Korea 6 months after receiving a second dose of the BNT162b2 mRNA vaccine [23]. This long-term persistence of antibodies, with the assumed contribution of memory B cells and long-lived plasma cells, may explain, in part, why the mRNA vaccine remains highly effective in preventing severe disease, even after the decline of antibody titers over time and increase in mild breakthrough infections.…”

Evaluation of S1RBD-Specific IgG Antibody Responses following COVID-19 Vaccination in Healthcare Professionals in Cyprus: A Comparative Look between the Vaccines of Pfizer-BioNTech and AstraZeneca

“…Regardless of vaccine type, all participants presented with positive levels of antibodies 3 weeks after the second vaccination dose, which remained positive 3 months after the second vaccine. These results agree with other studies showing that antibody levels can indeed last for months following vaccination [ 10 , 11 , 12 , 13 , 14 ]. Additionally, our findings are in line with other similar international studies, highlighting the decline of S1RBD-specific antibodies over time [ 10 , 11 , 12 , 13 , 14 , 15 ].…”

“…These results agree with other studies showing that antibody levels can indeed last for months following vaccination [ 10 , 11 , 12 , 13 , 14 ]. Additionally, our findings are in line with other similar international studies, highlighting the decline of S1RBD-specific antibodies over time [ 10 , 11 , 12 , 13 , 14 , 15 ]. Nevertheless, the immunogenic capacity of the antibodies present needs to be investigated further in order to determine their effectiveness in case of an infection with any of the emerging SARS-CoV-2 variants of concern.…”

Investigation of Possible Factors Influencing the Neutralizing Anti-SARS-CoV-2 Antibody Titer after Six Months from the Second Vaccination Dose in a Sample of Italian Nursing Home Personnel

“…With regards to the role of previous SARS-CoV-2 infection, it is well documented that HCW who had a SARS-CoV-2 infection plus a vaccination reach higher anti-SARS-CoV-2 antibody titer one month after the vaccination when compared to subjects with no infection history, and our results are in agreement with these findings [ 11 , 24 , 28 ]. Moreover, we found that these subjects with previous infection reported a significantly lower decay of the titer six months later.…”

“…Our results are a further confirmation of the relevant decline of the anti-SARS-CoV-2 IgG titer six months after the second dose of anti-COVID-19 vaccination [ 1 , 2 , 3 , 4 , 5 , 6 ]. Nevertheless, at the same time, the results we obtained represent also a further demonstration that, six months after completing the vaccination, there is still a positive antibody response, possibly indicating a protective effect [ 27 , 28 , 29 ], which in our case was identified in 100% of the sample. In fact, the IgG titer remained indicative of a positive neutralizing antibody response (i.e., according to the manufacturer ≥ 36 BAU/mL, for all the 63 subjects, even after six months from the second dose).…”