Sensitivity of rapid antigen tests for COVID-19 during the Omicron variant outbreak among players and staff members of the Japan Professional Football League and clubs: a retrospective observational study.

Objectives: Rapid antigen tests have been used to prevent the spread of the COVID-19; however, there have been concerns about their decreased sensitivity to the Omicron variant. In this study, we assessed the sensitivity and specificity of the rapid antigen test compared with the PCR test among the players and staff members of the Japan Professional Football League and clubs. Furthermore, we evaluated the relationship between the sensitivity and the duration from the onset of symptoms to testing or vaccine status.
Design: This was a retrospective observational study.
Methods: We used 656 results from both the rapid antigen and PCR tests for COVID-19 using samples collected on the same day from 12 January to 2 March 2022, during the Omicron variant outbreak in Japan.
Results: The sensitivity of the rapid antigen test compared with the PCR test was 0.63 (95% CI: 0.53 to 0.73) and the specificity was 0.998 (95% CI: 0.995 to 1.000). There were no significant associations between the sensitivity and the duration from the onset of symptoms to testing (including asymptomatic cases in the category) or vaccination status (p>0.05) with small effect sizes (Cramer's V or φ: ≤0.22).
Conclusions: Even during the Omicron outbreak, the sensitivity of the rapid antigen tests did not depend on the duration from the onset of symptoms to testing.
Competing Interests: Competing interests: HS and TI received salaries from the Japan Professional Football League. WN and TY have received financial support from the Japan Professional Football League, the Yomiuri Giants, Tokyo Yakult Swallows, the Japan Professional Basketball League and the Kao Corporation in the context of measures at mass-gathering events. MM, MK, WN, TY and SI have attended the New Coronavirus Countermeasures Liaison Council jointly established by the Nippon Professional Baseball Organization and the Japan Professional Football League as experts without any reward. WN and TY were/are advisors to the Japan National Stadium and Japan Professional Football League. The data used in this study were provided from the Japan Professional Football League. Otherwise, these institutions had no role in study design. The findings and conclusions of this article are solely the responsibility of the authors and do not represent the official views of any institution.
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