Team-to-team transmission of COVID-19 in ice hockey games - a case series of players in Finnish ice hockey leagues

Background: The COVID-19 pandemic suspended nearly all team sports globally. The pro series have resumed playing by creating safe bubbles or massive testing protocols. Amateur level sports have also restarted seasons without possibility for such precautions. Our aim was to report the epidemiology of COVID-19 in an amateur ice hockey team and the team-to-team transmission during two games. Methods: A descriptive brief report based on public statements by the local health authorities and the teams involved. Results: An asymptomatic carrier of COVID-19 in a U-20 ice hockey team infected 22 of 28 team mates. The day before the first players had symptoms, the team had returned from a two games away trip. A few days later COVID-19 was detected in both opposing teams and they were ordered to quarantine. During the two weeks quarantine a total of 24 players from the two opposing teams tested positive. Some of these players were training with senior teams and three additional infected players were detected in two senior teams. In total, 49 infections were detected in five ice hockey teams, and six teams were in quarantine for two weeks. Conclusion: An asymptomatic player can potentially endanger the whole season of a team and put opponents in danger as well. We report massive team-to-team transmission of COVID-19 in the U-20 Finnish National Hockey League. In order to prevent spread of COVID-19 in amateur-level team sports, suitable protocols should be established and adopted into daily use.