抄録
Objective: To investigate the status of asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in medical facilities.
Methods: A cross-sectional study survey was conducted among healthcare workers toward the end of the eighth wave of the coronavirus disease 2019 (COVID-19) epidemic in Japan. Participants completed a self-administered questionnaire providing details their COVID-19 and COVID-19 vaccination history and provided a blood sample for SARS-CoV-2 nucleocapsid (N) antibody testing as evidence of past SARS-CoV-2 infection. Participants were categorized into four groups, according to whether they had received 0–2, 3, 4, or 5 doses of vaccine. The prevalence of N antibodies was compared between groups.
Results: Of 494 participants, 288 reported no history of SARS-CoV-2 infection, of whom 185 accepted serological testing for past infection. Of the 185, 14 (7.6%) showed serological evidence of past infection, indicating asymptomatic infection. The risk of asymptomatic COVID-19 was inversely associated with the number of doses of COVID-19 vaccine received.
Conclusions: The cumulative effect of vaccination on preventing asymptomatic COVID-19, suggests that repeated COVID-19 vaccination of healthcare workers may serve as an infection control measure.
