Masks will be required at any indoor spaces at Grant Park starting Saturday, Lollapalooza organizers said, explaining the new mandate is based on the latest advice from the Chicago Department of Public Health.
On Friday evening, CDPH revealed the recommendation for all residents over the age of 2 wear masks in public indoor settings, regardless of vaccination status. Wearing a face covering remains optional in outdoor settings "where the risk of COVID-19 transmission is lower."
Lollapalooza's organizers encourage all fans to bring a mask for the remaining two days of the festival.
The four-day event, billed as the largest musical festival happening in the world this year, saw massive crowds and little to no social distancing at multiple concerts on opening day.
To enter, concert-goers must provide a printed copy of their COVID vaccine card, vaccine record or negative coronavirus test within 72 hours of entering.
While Chicago Mayor Lori Lightfoot has said CDPH and Lollapalooza's own health experts decided it was safe to move forward with the event, some infectious disease specialists say they're bracing for a jump in COVID-19 infections following the festival.
Along with suburban Cook County, Chicago is considered an area of "substantial" COVID transmission by the U.S. Centers for Disease Control and Prevention, a move that triggered federal recommendation to resume indoor masking under its new guidance released Tuesday.
The CDC updated its guidance to recommend that fully vaccinated people should wear masks in indoor settings again in areas of the U.S. that are seeing "substantial" or "high" transmission of COVID-19. Illinois' health department later said it would align with the CDC guidance.