A total of 203 people who attended Lollapalooza have since confirmed to health officials that they later tested positive for COVID-19, Chicago's top doctor said Thursday.
After an estimated 385,000 people attended the festival, a total of 58 Chicago residents, 138 non-Chicago Illinois residents and seven out-of-state residents have since tested positive, Chicago Department of Public Health Commissioner Dr. Allison Arwady said at a news conference in which she said there was "no evidence" that Lollapalooza was a superspreader event.
Arwady delivered the update exactly two weeks after the four-day Lollapalooza music festival kicked off in the city's Grant Park.
Chicago's largest annual event - canceled last year due to the coronavirus pandemic - was allowed to return this year from July 29 to Aug. 1 at full capacity and with new health protocols.
To enter Lollapalooza, concert-goers were required to show a printed copy of their COVID vaccine card, vaccine record or negative coronavirus test results obtained within 72 hours of entering.
City officials billed it as the largest music festival happening in the world this year, with massive crowds and little to no social distancing or masking in the crowds at multiple performances.
Get Tri-state area news delivered to your inbox. Sign up for NBC New York's News Headlines newsletter.
Multiple infectious disease experts warned that Lollapalooza could lead to an increase in already rising metrics like COVID-19 cases and hospitalizations - concerns Mayor Lori Lightfoot dismissed and that Chicago health officials now say did not come to fruition.
"So now 14 days post, as I said, we've had no unexpected findings at this point, there's no evidence at this point of a superspreader event and there's no evidence of substantial impact to Chicago's COVID epidemiology," Arwady said Thursday.
"We estimate approximately 385,000 people attended Lolla. Approximately 90% plus were vaccinated, based on measures that were taken at the site," she explained. "We used 88% vaccinated as a conservative estimate for our calculations."
Arwady said the city estimates that, of the vaccinated attendees, four in every 10,000 people were later diagnosed with COVID.
"Among unvaccinated attendees, we did as expected see a higher rate of COVID cases but it was still low," she said.
Among unvaccinated attendees, 16 in 10,000 reported testing positive, she said.
"And as of yesterday we had no hospitalizations or deaths reported, we do continue to follow up," Arwady said.
About 71% of the attendees who tested positive later were not Chicago residents, Arwady said, and 79% were under the age of 30. About 62% were white and 82% of them were symptomatic.
"Where we look at our Chicago cases, 58 of them at this point, really important to note, not just for Lolla but for everybody in Chicago: 13 of those cases, 22%, did report attending Lolla on or after the day their symptoms began," Arwady said. "This is a really important reminder, we need everybody in Chicago not to ignore symptoms, assume it's a summer cold, regardless of your vaccination status because we know vaccines are not 100% protective."
Arwady's update on Thursday came at a time when the average daily number of new cases in Chicago is up to 364 per day - a 39% increase over the previous week.
That figure is also more than 10 times the low of 34 that the city saw in late June but remains lower than the more than 700 cases per day the city was seeing earlier this year and last, before vaccines were widely available.
Hospitalizations in Chicago are up 6% from last week while deaths are up 29%, per the city's data. The positivity rate in testing is up to 3.8% as of Thursday, an increase from 3.5% last week, which has risen each week since it was at 1% a month ago.
