Abstract
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.
【초록키워드】 vaccination, Immunity, SARS-CoV-2 variant, Diagnosis, omicron, delta variant, Neutralizing activity, Cohort, Health, Concordance, SARS-CoV-2 variants, outbreak, sera, Japan, seropositive, Endemic, Analysis, mass vaccination, individual, COVID-19 situation, anti-S, vaccination rate, effective, analyzed, collected, overcome, reached, much lower, Continuous, 【제목키워드】 COVID-19, neutralizing antibody, Delta, outbreak, booster vaccination, overcome,