COVID-19 Outbreak Among Attendees of an Exercise Facility

Chicago, Illinois, August-September 2020

Frances R. Lendacki, MPH; Richard A. Teran, PhD; Stephanie Gretsch, MPH; Marielle J. Fricchione, MD; Janna L. Kerins, VMD


Morbidity and Mortality Weekly Report. 2021;70(9):321-325. 

In This Article

Abstract and Introduction


On September 8, 2020, the Chicago Department of Public Health (CDPH) was notified of a potential outbreak of coronavirus disease 2019 (COVID-19) at an exercise facility. COVID-19 cases were identified among 55 (68%) of 81 attendees of in-person classes held during August 24–September 1, 2020, including 49 (60%) cases confirmed by real-time reverse transcription–polymerase chain reaction (RT-PCR) testing and six (7%) probable cases among attendees who had compatible symptoms but negative or no RT-PCR test results. Overall, 43 (78%) attendees with COVID-19 participated in multiple classes while potentially infectious.* Twenty-two (40%) attendees with COVID-19 attended on or after the day of symptom onset. Among 58 exercise class attendees who provided information on in-class behaviors, 44 (76%) reported infrequent mask use, including 32 of 38 (84%) attendees with COVID-19 and 12 of 20 (60%) without COVID-19. The increased respiratory exertion that occurs in the enclosed spaces of indoor exercise facilities facilitates transmission of SARS-CoV-2, the virus that causes COVID-19, in these settings.[1,2] To reduce SARS-CoV-2 transmission in exercise facilities, employees and patrons should wear a mask, even during high-intensity activities when ≥6 ft apart. In addition, facilities should provide engineering and administrative controls including 1) improving ventilation; 2) enforcing consistent and correct mask use and physical distancing (maintaining ≥6 ft of distance between all persons and limiting physical contact, class size, and crowded spaces); 3) reminding infected employees and patrons to stay home and away from others for ≥10 days after symptom onset or, if asymptomatic, after a positive test result, as well as to observe quarantine guidance after close contact with a person with COVID-19 and while awaiting test results; and 4) increasing opportunities for hand hygiene. Conducting exercise activities entirely outdoors or virtually could further reduce SARS-CoV-2 transmission risk.

*The infectious period was presumed to begin 2 days before symptom onset or positive SARS-CoV-2 test result, whichever was known to be first, and presumed to end ≥10 days after symptom onset or positive test result as long as other symptoms (except loss of taste or smell) were improving and the patient had been fever-free for 24 hours without fever-reducing medication.