tetano
Editor, Senior Moderator
Emerg Infect Dis
. 2022 Oct 5;28(11).
doi: 10.3201/eid2811.221127. Online ahead of print.
Age-Stratified Seroprevalence of SARS-CoV-2 Antibodies before and during the Vaccination Era, Japan, February 2020-March 2022
Seiya Yamayoshi, Kiyoko Iwatsuki-Horimoto, Moe Okuda, Michiko Ujie, Atsuhiro Yasuhara, Jurika Murakami, Calvin Duong, Taiki Hamabata, Mutsumi Ito, Shiho Chiba, Ryo Kobayashi, Satoshi Takahashi, Keiko Mitamura, Masao Hagihara, Akimichi Shibata, Yoshifumi Uwamino, Naoki Hasegawa, Toshiaki Ebina, Akihiko Izumi, Hideaki Kato, Hideaki Nakajima, Norio Sugaya, Yuki Seki, Asef Iqbal, Isamu Kamimaki, Masahiko Yamazaki, Yoshihiro Kawaoka, Yuki Furuse
Abstract
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 SARS-CoV-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.
Keywords: COVID-19; Japan; SARS-CoV-2; antibody; coronavirus disease; epidemiology; incidence; respiratory infections; seroprevalence; severe acute respiratory syndrome coronavirus 2; vaccine; vaccine-preventable diseases; viruses; zoonoses.
. 2022 Oct 5;28(11).
doi: 10.3201/eid2811.221127. Online ahead of print.
Age-Stratified Seroprevalence of SARS-CoV-2 Antibodies before and during the Vaccination Era, Japan, February 2020-March 2022
Seiya Yamayoshi, Kiyoko Iwatsuki-Horimoto, Moe Okuda, Michiko Ujie, Atsuhiro Yasuhara, Jurika Murakami, Calvin Duong, Taiki Hamabata, Mutsumi Ito, Shiho Chiba, Ryo Kobayashi, Satoshi Takahashi, Keiko Mitamura, Masao Hagihara, Akimichi Shibata, Yoshifumi Uwamino, Naoki Hasegawa, Toshiaki Ebina, Akihiko Izumi, Hideaki Kato, Hideaki Nakajima, Norio Sugaya, Yuki Seki, Asef Iqbal, Isamu Kamimaki, Masahiko Yamazaki, Yoshihiro Kawaoka, Yuki Furuse
- PMID: 36198306
- DOI: 10.3201/eid2811.221127
Abstract
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 SARS-CoV-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.
Keywords: COVID-19; Japan; SARS-CoV-2; antibody; coronavirus disease; epidemiology; incidence; respiratory infections; seroprevalence; severe acute respiratory syndrome coronavirus 2; vaccine; vaccine-preventable diseases; viruses; zoonoses.