(CNN)The 2020 Boston Marathon has been canceled, and it will become a virtual race for the first time in the event's history.
Mayor Marty Walsh made the announcement Thursday at a news conference.
The Boston Athletic Association has determined that the traditional one day running of the 124th Boston marathon will not be feasible this year, given the coronavirus pandemic, he said.
"There's no way to hold this usual race format without bringing large numbers of people into close proximity," Walsh said. "This kind of event would not be responsible or realistic on September 14th or anytime this year."
The event had previously been postponed from April 20 to September 14.
All registered participants will be offered a full refund for their entry fee, and the race will be replaced by a virtual event in which participants can earn their finisher's medal by verifying that they ran 26.2 miles on their own within a six-hour time period.
People are able to participate virtually from September 7-14, and all athletes that complete the virtual race will receive a T-shirt, medal and runner's bib.
Walsh called this a "difficult adjustment," but said that "meeting tough challenges is what the Boston Marathon is all about."
Massachusetts currently has the fifth-most coronavirus cases in the United States, with 94,220, and it has the third-most deaths with 6,547, according to a Johns Hopkins University tally.
The city made the right decision by "erring on the side of caution," Gov. Charlie Baker said.