SARS-CoV-2 seroprevalence among healthcare workers in a highly vaccinated Japanese medical center from 2020–2023

Infection-induced SARS-CoV-2 seroprevalence has been studied worldwide. At Juntendo University Hospital (JUH) in Tokyo, Japan, we have consistently conducted serological studies using the blood residue of healthcare workers (HCWs) at annual health examinations since 2020. In this 2023 study (n = 3,5...

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Main Authors: Yan Yan, Kanami Ito, Hiroshi Fukuda, Shuko Nojiri, Wataru Urasaki, Takamasa Yamamoto, Yuki Horiuchi, Satoshi Hori, Kazuhisa Takahashi, Toshio Naito, Yoko Tabe
Format: Article
Language:English
Published: Taylor & Francis Group 2024-12-01
Series:Human Vaccines & Immunotherapeutics
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Online Access:https://www.tandfonline.com/doi/10.1080/21645515.2024.2337984
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author Yan Yan
Kanami Ito
Hiroshi Fukuda
Shuko Nojiri
Wataru Urasaki
Takamasa Yamamoto
Yuki Horiuchi
Satoshi Hori
Kazuhisa Takahashi
Toshio Naito
Yoko Tabe
author_facet Yan Yan
Kanami Ito
Hiroshi Fukuda
Shuko Nojiri
Wataru Urasaki
Takamasa Yamamoto
Yuki Horiuchi
Satoshi Hori
Kazuhisa Takahashi
Toshio Naito
Yoko Tabe
author_sort Yan Yan
collection DOAJ
description Infection-induced SARS-CoV-2 seroprevalence has been studied worldwide. At Juntendo University Hospital (JUH) in Tokyo, Japan, we have consistently conducted serological studies using the blood residue of healthcare workers (HCWs) at annual health examinations since 2020. In this 2023 study (n = 3,594), N-specific seroprevalence (infection-induced) was examined while univariate and multivariate logistic regression analyses were performed to compute ORs of seroprevalence with respect to basic characteristics of participants. We found that the N-specific seroprevalence in 2023 was 54.1%—a jump from 17.7% in 2022, and 1.6% in 2021—with 37.9% as non-PCR-confirmed asymptomatic infection cases. Those younger than 50 (adjusted OR = 1.62; p < .001) and recipients with 4 doses or less of vaccine had a higher risk to be N-positive, ranging from 1.45 times higher for the participants with 4 doses (p < .001) to 4.31 times higher for the participants with 1 dose (p < .001), compared to those with 5 or more doses. Our findings indicate that robust vaccination programs may have helped alleviate symptoms but consequently caused asymptomatic spread in this hospital, especially among younger HCWs. Although having four doses or less was found to be associated with higher risk of infection, the optimal constitution and intervals for effective booster vaccines warrant further investigations.
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spelling doaj-art-784b8f4cd26041b6b81906cf18b877bd2025-08-20T03:12:41ZengTaylor & Francis GroupHuman Vaccines & Immunotherapeutics2164-55152164-554X2024-12-0120110.1080/21645515.2024.2337984SARS-CoV-2 seroprevalence among healthcare workers in a highly vaccinated Japanese medical center from 2020–2023Yan Yan0Kanami Ito1Hiroshi Fukuda2Shuko Nojiri3Wataru Urasaki4Takamasa Yamamoto5Yuki Horiuchi6Satoshi Hori7Kazuhisa Takahashi8Toshio Naito9Yoko Tabe10Department of General Medicine, Juntendo University Faculty of Medicine, Tokyo, JapanDepartment of Safety and Health Promotion, Juntendo University, Tokyo, JapanDepartment of General Medicine, Juntendo University Faculty of Medicine, Tokyo, JapanMedical Technology Innovation Center, Juntendo University, Tokyo, JapanClinical Research and Trial Center, Juntendo University, Tokyo, JapanDepartment of Clinical Laboratory, Juntendo University Hospital, Tokyo, JapanDepartment of Clinical Laboratory Medicine, Juntendo University Faculty of Medicine, Tokyo, JapanInfection Control Science, Juntendo University Graduate School of Medicine, Tokyo, JapanDepartment of Respiratory Medicine, Juntendo University Faculty of Medicine, Tokyo, JapanDepartment of General Medicine, Juntendo University Faculty of Medicine, Tokyo, JapanDepartment of Clinical Laboratory, Juntendo University Hospital, Tokyo, JapanInfection-induced SARS-CoV-2 seroprevalence has been studied worldwide. At Juntendo University Hospital (JUH) in Tokyo, Japan, we have consistently conducted serological studies using the blood residue of healthcare workers (HCWs) at annual health examinations since 2020. In this 2023 study (n = 3,594), N-specific seroprevalence (infection-induced) was examined while univariate and multivariate logistic regression analyses were performed to compute ORs of seroprevalence with respect to basic characteristics of participants. We found that the N-specific seroprevalence in 2023 was 54.1%—a jump from 17.7% in 2022, and 1.6% in 2021—with 37.9% as non-PCR-confirmed asymptomatic infection cases. Those younger than 50 (adjusted OR = 1.62; p < .001) and recipients with 4 doses or less of vaccine had a higher risk to be N-positive, ranging from 1.45 times higher for the participants with 4 doses (p < .001) to 4.31 times higher for the participants with 1 dose (p < .001), compared to those with 5 or more doses. Our findings indicate that robust vaccination programs may have helped alleviate symptoms but consequently caused asymptomatic spread in this hospital, especially among younger HCWs. Although having four doses or less was found to be associated with higher risk of infection, the optimal constitution and intervals for effective booster vaccines warrant further investigations.https://www.tandfonline.com/doi/10.1080/21645515.2024.2337984SARS-CoV-2COVID-19seropositivemRNA vaccinehealthcare workerJapan
spellingShingle Yan Yan
Kanami Ito
Hiroshi Fukuda
Shuko Nojiri
Wataru Urasaki
Takamasa Yamamoto
Yuki Horiuchi
Satoshi Hori
Kazuhisa Takahashi
Toshio Naito
Yoko Tabe
SARS-CoV-2 seroprevalence among healthcare workers in a highly vaccinated Japanese medical center from 2020–2023
Human Vaccines & Immunotherapeutics
SARS-CoV-2
COVID-19
seropositive
mRNA vaccine
healthcare worker
Japan
title SARS-CoV-2 seroprevalence among healthcare workers in a highly vaccinated Japanese medical center from 2020–2023
title_full SARS-CoV-2 seroprevalence among healthcare workers in a highly vaccinated Japanese medical center from 2020–2023
title_fullStr SARS-CoV-2 seroprevalence among healthcare workers in a highly vaccinated Japanese medical center from 2020–2023
title_full_unstemmed SARS-CoV-2 seroprevalence among healthcare workers in a highly vaccinated Japanese medical center from 2020–2023
title_short SARS-CoV-2 seroprevalence among healthcare workers in a highly vaccinated Japanese medical center from 2020–2023
title_sort sars cov 2 seroprevalence among healthcare workers in a highly vaccinated japanese medical center from 2020 2023
topic SARS-CoV-2
COVID-19
seropositive
mRNA vaccine
healthcare worker
Japan
url https://www.tandfonline.com/doi/10.1080/21645515.2024.2337984
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