-Original-

Pre-Vaccination Anti-Severe Acute Respiratory Syndrome Coronavirus 2 Antibody Seroprevalence in Workers at Three Japanese Hospitals

Yoko Takayama^1,2, Toshiaki Komatsu³, Tatsuhiko Wada⁴, Shin Nihonyanagi², Takayuki Hoshiyama^2,4, Tatsumi Moriya⁵, Shizue Shimamura⁶, Naoko Kajigaya⁷, Masanori Naito⁸, Osamu Takeuchi⁹, Yuki Bando^7,10, Masahiko Watanabe¹¹, Masatsugu Iwamura¹² and Hideaki Hanaki¹³

¹Department of Infection Control and Infectious Diseases, Research and Development Center for New Medical Frontiers, Kitasato University School of Medicine, Kanagawa, Japan
²Department of Infection Control and Prevention, Kitasato University Hospital, Kanagawa, Japan
³Department of Pharmacy, Kitasato University Hospital, Kanagawa, Japan
⁴Department of Rheumatology and Infectious Diseases, Kitasato University School of Medicine, Kanagawa, Japan
⁵Kitasato University Health Care Center, Kanagawa, Japan
⁶Department of Clinical Trial Center, Kitasato University Medical Center, Saitama, Japan
⁷Department of Infection Control and Prevention, Kitasato University Medical Center, Saitama, Japan
⁸Department of Gastroenterological and General Surgery, St. Marianna University School of Medicine, Kanagawa, Japan
⁹Biomedical Laboratory, Department of Research, Kitasato University Kitasato Institute Hospital, Tokyo, Japan
¹⁰Department of Pediatrics, Kitasato University Medical Center, Saitama, Japan
¹¹Department of Surgery, Kitasato University Kitasato Institute Hospital, Tokyo, Japan
¹²Department of Urology, Kitasato University School of Medicine, Kanagawa, Japan
¹³Infection Control Research Center, The Omura Satoshi Memorial Institution, Kitasato University, Tokyo, Japan

Background: Antibody testing is essential for accurately estimating the number of people infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This study aimed to investigate the influence of background factors on seroprevalence by testing for anti-SARS-CoV-2 antibodies in blood samples obtained from the staff of three hospitals.
Methods: This cross-sectional observational study was conducted from June 8 to July 4, 2020, as part of a mandatory health examination. Leftover blood samples collected during the health examinations at each hospital were used to test for the presence of anti-SARS-CoV-2 antibodies. The Elecsys Anti-SARS-CoV-2 RUO assay was used for antibody detection. The relationship between staff age, gender, body mass index, blood pressure, work environments with different exposure risks, place of residence, and campus location and seroprevalence was investigated. The data were anonymized prior to analysis.
Results: A total of 3,677 individuals were included in the study, comprising 2,554 females (69.5%) and 1,123 males (30.5%). Anti-SARS-CoV-2 antibody (immunoglobulin G) was detected in 13 participants (0.35%). Seroprevalence was slightly higher in males than females (0.62% vs. 0.23%, P=0.08). By occupation, anti-SARS-CoV-2 antibodies were found in 6 (0.75%) physicians, 6 (0.31%) nurses, and one individual (0.11%) in the medical personnel group, with slightly higher levels in physicians. No significant difference was noted in the seroprevalence in terms of all background factors.
Conclusions: Our study shows that the background factors do not impact seropositivity rates. Thorough daily infection control and adherence to recommended health guidelines were found to reduce infection risk.

J Nippon Med Sch 2022; 89: 513-519

Keywords
anti-severe acute respiratory syndrome coronavirus 2 antibody, seroprevalence, coronavirus disease, university hospitals, healthcare workers

Correspondence to
Yoko Takayama, Department of Infection Control and Infectious Diseases, Research and Development Center for New Medical Frontiers, Kitasato University School of Medicine, 1-15-1 Kitasato, Minami-ku, Sagamihara-shi, Kanagawa 252-0374, Japan
yoko@med.kitasato-u.ac.jp

Received, January 2, 2022
Accepted, April 13, 2022