An email sent Tuesday morning to the 35,000 runners in this October's Chicago Marathon outlined the safety measures event organizers will be taking.
Those who are not fully vaccinated by race day will need to provide a negative COVID test result, taken no more than 72 hours prior to the Oct. 10 event.
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Race organizers also said they are exploring how to accommodate those who cannot participate due to a positive COVID test within 14 days of the event.
Anyone with COVID symptoms is asked not to participate.
All attendees are required to wear face coverings while at indoor event venues and in Grant Park prior to starting the race, organizers said.