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

• Published in: Frontiers in immunology Vol. 13; p. 827306
• Main Authors: Choi, Jae Hong, Kim, Young Ree, Heo, Sang Taek, Oh, Hyunjoo, Kim, Misun, Lee, Hyang Ran, Yoo, Jeong Rae
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 31.01.2022
• Subjects: Adult; Aged; Antibodies, Neutralizing - blood; Antibodies, Viral - blood; antibody; Antibody Formation - immunology; BNT162 Vaccine - immunology; COVID-19; COVID-19 - prevention & control; Female; Health Personnel - statistics & numerical data; Humans; Immunization, Secondary; Immunoglobulin G - blood; Immunologic Tests; Immunology; Korea; Male; Middle Aged; neutralizing antibody; Prospective Studies; Republic of Korea; SARS-CoV-2; SARS-CoV-2 - immunology; Spike Glycoprotein, Coronavirus - immunology; Vaccine Efficacy - statistics & numerical data; Young Adult; Republic of Korea; COVID-19; neutralizing antibody; SARS-CoV-2; antibody; Korea
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2022.827306

Effective vaccines against coronavirus disease 2019 (COVID-19) are available worldwide; however, the longevity of vaccine effectiveness is not known. We 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. SARS-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). A 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. The 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.