High SARS-CoV-2 infection rate after resuming professional football in São Paulo, Brazil.

OBJECTIVE: To examine the SARS-CoV-2 infection rate in a cohort of 6500 professional athletes and staff during the 2020 football (soccer) season in São Paulo, Brazil.

METHODS: This retrospective cohort study included 4269 players (87% male, age: 21.7±4.2 years) and 2231 staff (87% male, age: 42.6±11.9 years) from 122 teams (women: n=16) involved in eight leagues (women: n=2), which took place in São Paulo, Brazil. Between 4 July 2020 and 21 December 2020, swab samples were collected weekly (n=29 507) and tested for SARS-Cov-2 via reverse transcription-PCR by an accredited laboratory commissioned by the São Paulo Football Federation. We contacted the medical staff of each team with positive cases to collect information on disease severity.

RESULTS: Among 662 PCR-confirmed cases, 501 were athletes and 161 were staff. The new infection rate was 11.7% and 7.2% for athletes and staff, respectively. Athletes were more susceptible to infection than staff (OR: 1.71, 95% CI: 1.42, 2.06, p<0.001), although with lower chance for moderate to severe disease (OR: 0.06, 95% CI: 0.01, 0.54, p=0.012). Six teams had ≥20 individuals testing positive for SARS-CoV-2, whereas 19 teams had ≥10 confirmed cases. Twenty-five mass outbreaks were identified (≥5 infections within a team in a 2-week period). The prevalence of SARS-CoV-2 infections was similar in athletes and staff as the general population in São Paulo.

CONCLUSION: Despite weekly testing and other preventive measures, we found a high SARS-CoV-2 infection rate in athletes and staff after resuming football, which coincides with the high prevalence of infection in the community during the same period. These data may assist policy-makers and sports federations for determining if and when it is safe to resume competitions.