Experience of quantitative SARS-CoV-2 antibody screening of health-care workers in the southern part of Kyoto city during COVID-19 peri-pandemic period
Background: The coronavirus disease-2019 (COVID-19) pandemic is associated with a heavy burden on the mental and physical health of patients, regional healthcare resources, and global economic activity. While our understanding of the incidence and case-fatality rates increases, data on seroprevalence of antibodies against the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) in healthcare workers during the peri-pandemic period is insufficient. This study quantitatively evaluated seroprevalence of SARS-CoV-2 antibody in healthcare workers in the southern part of Kyoto city, Japan. Methods: We prospectively recruited healthcare workers from a single hospital between April 10 and April 20, 2020. We collected serum samples from these participants and quantitatively evaluated SARS-CoV-2 IgG antibody levels by enzyme-linked immunosorbent assay. Results: Five (5.4%), 15 (16.3%), and 72 (78.3%) participants showed positive, borderline, and negative serum SARS-CoV-2 IgG antibody status, respectively. We found the mean titer associated with each antibody status (overall, positive, borderline, and negative) was clearly differentiated. Participants working at the otolaryngology department and/or having a history of seasonal common cold symptoms had a significantly higher titer of SARS-CoV-2 IgG antibody (p=0.046, p=0.046, respectively). Conclusions: Five (5.4%) and 15 (16.3%) participants tested positive and borderline, respectively, for SARS-CoV-2 IgG antibody during the COVID-19 peri-pandemic period. These rates were higher than expected based on government situation reports. The present findings suggest that COVID-19 was already spread in the southern part of Kyoto city at the early stage of pandemic.