Abstract
Introduction: Vaccine effectiveness against SARS-CoV-2 infections decreases due to waning immunity, and booster vaccination was therefore introduced. We estimated the anti-spike antibody (AS-ab) recovery by booster vaccination and analyzed the risk factors for SARS-CoV-2 infections.
Methods: The subjects were health care workers (HCWs) in a Chiba University Hospital vaccination cohort. They had received two doses of vaccine (BNT162b2) and a booster vaccine (BNT162b2). We retrospectively analyzed AS-ab titers and watched out for SARS-CoV-2 infection for 90 days following booster vaccination.
Results: AS-ab titer eight months after two-dose vaccinations had decreased to as low as 587 U/mL (median, IQR (interquartile range) 360-896). AS-ab titer had then increased to 22471 U/mL (15761-32622) three weeks after booster vaccination. There were no significant differences among age groups. A total of 1708 HCWs were analyzed for SARS-CoV-2 infection, and 48 of them proved positive. SARS-CoV-2 infections in the booster-vaccinated and non-booster groups were 1.8% and 4.0%, respectively, and were not significant. However, when restricted to those 20-29 years old, SARS-CoV-2 infections in the booster-vaccinated and non-booster groups were 2.9% and 13.6%, respectively (p = 0.04). After multivariate logistic regression, COVID-19 wards (adjusted odds ratio (aOR):2.9, 95% confidence interval (CI) 1.5-5.6) and those aged 20-49 years (aOR:9.7, 95%CI 1.3-71.2) were risk factors for SARS-CoV-2 infection.
Conclusions: Booster vaccination induced the recovery of AS-ab titers. Risk factors for SARS-CoV-2 infection were HCWs of COVID-19 wards and those aged 20-49 years. Increased vaccination coverage, together with implementing infection control, remains the primary means of preventing HCWs from SARS-CoV-2 infection.
Keywords: Anti-spike antibody; Booster vaccination; Healthcare worker; SARS-CoV-2; mRNA vaccine.
【저자키워드】 SARS-CoV-2, healthcare worker, mRNA vaccine., anti-spike antibody, booster vaccination, 【초록키워드】 COVID-19, infection control, Vaccine, vaccination, mRNA vaccine, SARS-COV-2 infection, risk factor, BNT162b2, Cohort, Coverage, HCWs, Effectiveness, Health care worker, age, group, university, SARS-CoV-2 infections, Booster vaccine, dose, waning immunity, HCW, interquartile range, Factor, adjusted odds ratio, not significant, 95%CI, no significant difference, 95% confidence interval, subject, multivariate logistic regression, positive, decrease, analyzed, eight, median, introduced, groups, Increased, IQR, 【제목키워드】 SARS-COV-2 infection, Antibody Response, Japan, BNT162b2 mRNA,