By Karina Toledo | Agência FAPESP* – A study conducted at the University of São Paulo (USP) in Brazil shows that the incidence of infections by the novel coronavirus among professional soccer players in São Paulo state during the 2020 season was 11.7%, the same as among health workers in the front line of the response to the pandemic.
To arrive at this number, the researchers retrospectively analyzed almost 30,000 RT-PCR tests performed on swabs from 4,269 athletes during eight tournaments of the São Paulo State Soccer Federation (FPF), the league responsible for organizing official championships in the state – six for men (the São Paulo Cup, Under-23s, U-20s, and the three divisions of the São Paulo Championship) and two for women (the São Paulo Championship and U-17s). A total of 501 tests confirmed the presence of SARS-CoV-2. They also analyzed 2,231 tests on swabs from support staff (health workers, technical committees, directors, kitmen, etc.), and 161 (7%) were positive.
“It’s a much higher attack rate than has been seen in other countries. In Denmark, for example, only four out of 748 players tested positive [0.5%]. The Bundesliga [in Germany] found eight cases out of 1,702 players [0.6%]. Even in Qatar, where there’s a moderate risk of community transmission, the rate was far lower than ours: 24 out of 549 tested positive [4%]. Compared with the other reported rates, our players were infected between three and 24 times more,” Bruno Gualano, a professor at the University of São Paulo’s Medical School (FM-USP) and principal investigator for the study, told Agência FAPESP.
In an article published in the British Journal of Sports Medicine, the authors say the numbers are probably underestimated. The group had access to the database of the laboratory commissioned by FPF to test the athletes. However, players belonging to clubs that competed in national tournaments could choose to be tested by laboratories commissioned by the Brazilian Soccer Confederation (CBF), and these results were not included in the analysis.
In any event, the São Paulo data shows that the virus affected men and women equally among those tested. A comparison of the results for players and staff shows a high attack rate among players, but severe cases of COVID-19 were more frequent among staff, who are older on average and are not all in perfect health.
“This is a cause of concern,” Gualano said. “The few severe cases, one of which ended in death, were reported among members of staff. Although our data suggest players tend to manifest only mild symptoms or none at all, they can of course transmit the virus to others in the community. Most have a very active social life.”
Contact tracing has never been implemented in Brazil as a public health policy, he added, so it is not possible to measure the impact of the secondary infections caused by players in their households or social circles.