Surveillance Found Low SARS-CoV-2 Attack Rates Among Tokyo Games Athletes

Researchers reviewed cases linked to the Tokyo 2020 Olympic and Paralympic Games reported to the Tokyo Metropolitan Government from 1 July to 19 September 2021. The analysis included 804 infections among Games participants and in-person contributors. Attack rates were calculated for athletes and team officials, and investigators used enhanced case-based surveillance with genomic sequencing to examine transmission patterns.

Among athletes and team officials, 65 of 11,400 people at the Olympic Games and 30 of 4,800 at the Paralympic Games tested positive, an attack rate of 0.6% at each event. Most of these 95 cases were among overseas travellers; 85 were diagnosed within 14 days of arriving in Japan. Sequencing results were available for 304 cases with sufficient viral load. Delta accounted for 285 (94%) of those sequences. Overseas Delta strains were common among athletes and team officials diagnosed within 14 days of entry, while domestic AY.29 strains predominated in resident cases and among some organisers and media diagnosed later.

The authors concluded that layered risk-reduction measures likely minimised transmission to athletes. The findings are observational and cannot establish the effect of specific measures. Sequencing was available for only a subset of cases, particularly fewer than one in five cases in the remaining contributor groups, which limits comparisons across groups.