TY - JOUR
T1 - Age-Stratified Seroprevalence of SARS-CoV-2 Antibodies before and during the Vaccination Era, Japan, February 2020–March 2022
AU - Yamayoshi, Seiya
AU - Iwatsuki-Horimoto, Kiyoko
AU - Okuda, Moe
AU - Ujie, Michiko
AU - Yasuhara, Atsuhiro
AU - Murakami, Jurika
AU - Duong, Calvin
AU - Hamabata, Taiki
AU - Ito, Mutsumi
AU - Chiba, Shiho
AU - Kobayashi, Ryo
AU - Takahashi, Satoshi
AU - Mitamura, Keiko
AU - Hagihara, Masao
AU - Shibata, Akimichi
AU - Uwamino, Yoshifumi
AU - Hasegawa, Naoki
AU - Ebina, Toshiaki
AU - Izumi, Akihiko
AU - Kato, Hideaki
AU - Nakajima, Hideaki
AU - Sugaya, Norio
AU - Seki, Yuki
AU - Iqbal, Asef
AU - Kamimaki, Isamu
AU - Yamazaki, Masahiko
AU - Kawaoka, Yoshihiro
AU - Furuse, Yuki
N1 - Funding Information:
This work was supported by Research Program on Emerging and Re-emerging Infectious Diseases (grant nos. JP19fk0108166 and JP20fk0108451s0301) and Japan Program for Infectious Diseases Research and Infrastructure (grant no. JP22wm0125002) from the Japan Agency for Medical Research and Development. The funder of the study had no role in study design, data collection, data analysis, data interpretation, or writing
Publisher Copyright:
© 2022 Centers for Disease Control and Prevention (CDC). All rights reserved.
PY - 2022/11
Y1 - 2022/11
N2 - Japan has reported a relatively small number of COVID-19 cases. Because not all infected persons receive diagnostic tests for COVID-19, the reported number must be lower than the actual number of infections. We assessed SARSCoV-2 seroprevalence by analyzing >60,000 samples collected in Japan (Tokyo Metropolitan Area and Hokkaido Prefecture) during February 2020–March 2022. The results showed that ≈3.8% of the population had become seropositive by January 2021. The seroprevalence increased with the administration of vaccinations; however, among the elderly, seroprevalence was not as high as the vaccination rate. Among children, who were not eligible for vaccination, infection was spread during the epidemic waves caused by the SARS-CoV-2 Delta and Omicron variants. Nevertheless, seroprevalence for unvaccinated children <5 years of age was as low as 10% as of March 2022. Our study underscores the low incidence of SARS-CoV-2 infection in Japan and the effects of vaccination on immunity at the population level.
AB - Japan has reported a relatively small number of COVID-19 cases. Because not all infected persons receive diagnostic tests for COVID-19, the reported number must be lower than the actual number of infections. We assessed SARSCoV-2 seroprevalence by analyzing >60,000 samples collected in Japan (Tokyo Metropolitan Area and Hokkaido Prefecture) during February 2020–March 2022. The results showed that ≈3.8% of the population had become seropositive by January 2021. The seroprevalence increased with the administration of vaccinations; however, among the elderly, seroprevalence was not as high as the vaccination rate. Among children, who were not eligible for vaccination, infection was spread during the epidemic waves caused by the SARS-CoV-2 Delta and Omicron variants. Nevertheless, seroprevalence for unvaccinated children <5 years of age was as low as 10% as of March 2022. Our study underscores the low incidence of SARS-CoV-2 infection in Japan and the effects of vaccination on immunity at the population level.
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U2 - 10.3201/eid2811.221127
DO - 10.3201/eid2811.221127
M3 - Article
C2 - 36198306
AN - SCOPUS:85140855360
VL - 28
SP - 2198
EP - 2205
JO - Emerging Infectious Diseases
JF - Emerging Infectious Diseases
SN - 1080-6040
IS - 11
ER -
