Antibody responses to BNT162b2 mRNA COVID-19 vaccine and their predictors among healthcare workers in a tertiary referral hospital in Japan

Objectives: This study aimed to determine antibody responses in healthcare workers who receive the BNT162b2 mRNA COVID-19 vaccine and identify factors that predict the response. Methods: We recruited healthcare workers receiving the BNT162b2 mRNA COVID-19 vaccine at the Chiba University Hospital COVID-19 Vaccine Center. Blood samples were obtained before the 1st dose and after the 2nd dose vaccination, and serum antibody titers were determined using Elecsys (R) Anti-SARS-CoV-2S, an electrochemiluminescence immunoassay. We established a model to identify the baseline factors predicting post-vaccine antibody titers using univariate and multivariate linear regression analyses. Results: Two thousand fifteen individuals (median age 37-year-old, 64.3% female) were enrolled in this study, of which 10 had a history of COVID-19. Before vaccination, 21 participants (1.1%) had a detectable antibody titer (>0.4 U/mL) with a median titer of 35.9 U/mL (interquartile range [IQR] 7.8 - 65.7). After vaccination, serum anti-SARS-CoV-2S antibodies (>0.4 U/mL) were detected in all 1774 participants who received the 2nd dose with a median titer of 2060.0 U/mL (IQR 1250.0 - 2650.0). Immunosuppressive medication (p < 0.001), age (p < 0.001), time from 2nd dose to sample collection (p < 0.001), glucocorticoids (p = 0.020), and drinking alcohol (p = 0.037) were identified as factors predicting lower antibody titers after vaccination, whereas previous COVID-19 (p < 0.001), female (p < 0.001), time between 2 doses (p < 0.001), and medication for allergy (p = 0.024) were identified as factors predicting higher serum antibody titers. Conclusions: Our data demonstrate that healthcare workers universally have good antibody responses to the BNT162b2 mRNA COVID-19 vaccine. The predictive factors identified in our study may help optimize the vaccination strategy. (C) 2021 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study aimed to determine antibody responses in healthcare workers following the BNT162b2 mRNA COVID-19 vaccine and identified factors that predict the response. Results showed that healthcare workers have good antibody responses to the vaccine, with factors like immunosuppressive medication, age, and time from vaccination affecting antibody titers.