https://www.siliconvalley.com/2021/02/25/covid-outbreaks-tied-to-maskless-gym-workouts-cdc-reports-say/

(CNN) — Two COVID-19 outbreaks have been linked to maskless exercise classes at gyms in Chicago and Honolulu, according to new reports from the Centers for Disease Control and Prevention.

In the Chicago report, 60% of the 81 people who attended in-person fitness classes at one facility between August 24 and September 1 tested positive for coronavirus. Another 7% were considered probable cases: They reported symptoms consistent with the disease but did not test positive.