Feb 26, 2021 -- Gyms can be hotspots for COVID-19 outbreaks if people don’t wear face masks, even if they follow social distancing guidelines, according to new research from the CDC.

The agency released findings on Wednesday from outbreaks at gyms that had a high “attack rate” last summer — in one report from Hawaii and another report from Chicago.

In Hawaii, 21 people contracted COVID-19 in July after an infected cycling instructor taught classes for 3 days and later tested positive. The cycling stations were spaced more than 6 feet apart, but no one wore masks. One of the participants was another instructor, who later taught kickboxing classes and held personal training sessions without a mask, which also led to several COVID-19 cases.

In Chicago, 55 of 81 people who attended high-intensity fitness classes during the last week of August contracted COVID-19. The classes were limited to 10-15 people, and people were stationed more than 6 feet apart. The facility required masks upon gym entry, conducted temperature checks and screened for symptom, but people were allowed to remove their masks during exercise.

“The increased respiratory exertion that occurs in the enclosed spaces of indoor exercise facilitates transmission of SARS-CoV-2,” the CDC team wrote in the Chicago report.

No deaths were linked to the outbreaks, according to the CDC reports. In Hawaii, two people were hospitalized, and one was treated in an intensive care unit. In Chicago, one person was hospitalized, and two people visited the emergency room with COVID-19 symptoms.

The major factor in both outbreaks was a lack of mask use, the CDC researchers wrote. The Hawaii cycling class didn’t mandate mask use at the time, and the gym users in Chicago rarely used masks.

The Hawaii facility also kept doors and windows closed during classes, which may have increased the risk of transmission. The CDC researchers encouraged gyms and exercise facilities to require masks and physical distancing, improve ventilation, decrease class sizes and remind staff and customers to stay home when sick.

After the initial outbreak, the Chicago facility closed for 2 weeks and notified people who took classes of possible exposure. The facility asked people to provide proof of a negative COVID-19 test before returning to class and began to emphasize mask use. The Hawaii facility has also installed plexiglass barriers between cycling stations, removed four stations from the cycling room and limited class sizes.

“Exercising outdoors or virtually could further reduce SARS-CoV-2 transmission risk,” the CDC wrote in both reports.

WebMD Health News Brief

Sources

CDC Morbidity and Mortality Weekly Report: “Community Transmission of SARS-CoV-2 at Three Fitness Facilities — Hawaii, June-July 2020,” “COVID-19 Outbreak Among Attendees of an Exercise Facility — Chicago, Illinois, August-September 2020.”

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