Cumulative and undiagnosed SARS-CoV-2 infection among the staff of a medical research centre in Tokyo after the emergence of variants. (8th March 2023)

• Record Type: Journal Article
• Authors: Mizoue, Tetsuya; Yamamoto, Shohei; Oshiro, Yusuke; Inamura, Natsumi; Nemoto, Takashi; Horii, Kumi; Okudera, Kaori; Konishi, Maki; Ozeki, Mitsuru; Sugiyama, Haruhito; Aoyanagi, Nobuyoshi; Sugiura, Wataru; Ohmagari, Norio
• Is Part Of: Epidemiology and infection. Volume 151(2023)
• Publication Date: 2023-03-08
• Subjects: COVID-19 -- healthcare workers -- Japan -- SARS-CoV-2 -- seroprevalence; Communicable diseases -- Periodicals; Epidemiology -- Periodicals; 614.4
• DOI: 10.1017/S0950268823000353
• Languages: English
• ISSNs: 0950-2688

Abstract

Abstract: To describe the trend of cumulative incidence of coronavirus disease 19 (COVID-19) and undiagnosed cases over the pandemic through the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants among healthcare workers in Tokyo, we analysed data of repeated serological surveys and in-house COVID-19 registry among the staff of National Center for Global Health and Medicine. Participants were asked to donate venous blood and complete a survey questionnaire about COVID-19 diagnosis and vaccine. Positive serology was defined as being positive on Roche or Abbott assay against SARS-CoV-2 nucleocapsid protein, and cumulative infection was defined as either being seropositive or having a history of COVID-19. Cumulative infection has increased from 2.0% in June 2021 (pre-Delta) to 5.3% in December 2021 (post-Delta). After the emergence of the Omicron, it has increased substantially during 2022 (16.9% in June and 39.0% in December). As of December 2022, 30% of those who were infected in the past were not aware of their infection. Results indicate that SARS-CoV-2 infection has rapidly expanded during the Omicron-variant epidemic among healthcare workers in Tokyo and that a sizable number of infections were undiagnosed.