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SARS-CoV-2 Antibody Status after the BNT162b2 Vaccine in Healthcare Workers

Shinsuke ONISHI1), Akinori YAMAZAKI2), Koki KIKUCHI3), Yoshinosuke SHIMAMURA4), Fumiko SUGAYA5) and Yoshiyasu ANBO6)
1)Department of Emergency Medicine, Teine Keijinkai Hospital, 2)Department of Pharmacy, Teine Keijinkai Hospital, 3)Department of Infectious Diseases, Teine Keijinkai Hospital, 4)Department of Nephrology, Teine Keijinkai Hospital, 5)Department of Respiratory Medicine, Teine Keijinkai Hospital, 6)Department of Surgery, Teine Keijinkai Hospital

This study conducted a survey on healthcare workers (HCWs) who received two doses of the BNT162b2 coronavirus disease 2019 (COVID-19) vaccine. It aimed to determine their postvaccination severe acute respiratory syndrome 2 (SARS-CoV-2) antibody status.
The study enrolled a total of 307 HCWs. Blood samples, which were obtained 2 weeks after receiving the second vaccination dose, were analyzed using a lateral flow test, the Wondfo SARS-CoV-2 antibody test, which outputs results in the form of lines. We developed a visual scoring system for the quantification of test line intensity, with scores ranging from 0 to 5.
Among individuals with a history of previous SARS-CoV-2 infection, 85.7% (12/14) scored 5 (strongly positive) in comparison with 22.9% (67/293) of individuals with no history of previous SARS-CoV-2 infection. A score of 5 was associated with prior SARS-CoV-2 infection and postvaccination fever (adjusted odds ratios, 19.6 and 2.6; 95% confidence intervals, 5.0-131 and 1.3-4.9, respectively). In addition, we conducted an enzyme-linked immunosorbent assay on some of the blood samples to evaluate the anti-spike protein antibody levels. Anti-SARS-CoV-2 antibodies were identified in 99.7% (306/307) of fully vaccinated HCWs. The final analysis included the results of previous antibody tests conducted before and after the initial vaccine dose of the HCWs. We confirmed that a higher score in the quantifying test corresponds to higher antibody titers. The average anti-spike protein antibody levels before and after the vaccination showed the following results: 1132±1007 AU/mL in previously infected HCWs before vaccination; 18070±4183 AU/mL in previously infected HCWs after the first vaccination; 7819±3822 AU/mL in previously uninfected HCWs after the second vaccination; and 30206±9740 AU/mL in previously infected HCWs after the second vaccination. Significant differences were observed between each group (P < 0.01).

Key words:COVID-19, SARS-CoV-2, vaccine, antibody, lateral flow test


Received: August 20, 2021
Accepted: October 22, 2021

37 (1):10─17,2022

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