PLoS ONE (Jan 2022)

Large-scale serosurveillance of COVID-19 in Japan: Acquisition of neutralizing antibodies for Delta but not for Omicron and requirement of booster vaccination to overcome the Omicron's outbreak.

  • Zhenxiao Ren,
  • Mitsuhiro Nishimura,
  • Lidya Handayani Tjan,
  • Koichi Furukawa,
  • Yukiya Kurahashi,
  • Silvia Sutandhio,
  • Kaito Aoki,
  • Natsumi Hasegawa,
  • Jun Arii,
  • Kenichi Uto,
  • Keiji Matsui,
  • Itsuko Sato,
  • Jun Saegusa,
  • Nonoka Godai,
  • Kohei Takeshita,
  • Masaki Yamamoto,
  • Tatsuya Nagashima,
  • Yasuko Mori

DOI
https://doi.org/10.1371/journal.pone.0266270
Journal volume & issue
Vol. 17, no. 4
p. e0266270

Abstract

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Continuous appearance of SARS-CoV-2 variants and mass vaccination have been intricately influencing on the COVID-19 situation. To elucidate the current status in Japan, we analyzed totally 2,000 sera in August (n = 1,000) and December (n = 1,000) 2021 collected from individuals who underwent a health check-up. The anti-N seropositive rate were 2.1% and 3.9% in August and December 2021, respectively, demonstrating a Delta variant endemic during that time; it was approximately twofold higher than the rate based on the PCR-based diagnosis. The anti-S seropositive rate was 38.7% in August and it reached 90.8% in December, in concordance with the vaccination rate in Japan. In the December cohort, 78.7% of the sera showed neutralizing activity against the Delta variant, whereas that against the Omicron was much lower at 36.6%. These analyses revealed that effective immunity against the Delta variant was established in December 2021, however, prompt three-dose vaccination is needed to overcome Omicron's outbreak.