Two weeks after the four-day Lollapalooza music festival finished in the city, Chicago public health officials said there was “no evidence” the event was a super-spreader for Covid-19.

With up to 400,000 people having attended the event, just 203 coronavirus cases had been identified since the festival began on 29 July. There has been no hospitalisations or deaths reported.

At a news conference, Chicago Department of Public Health commissioner Allison Arwady said there had been no unexpected findings following the festival: “There’s no evidence at this point of a super spreader event, and there’s no evidence of substantial impact to Chicago’s Covid epidemiology.”

Arwady suggested four in 10,000 vaccinated attendees, or 0.0004%, reported testing positive, while 16 in 10,000 unvaccinated guests reported testing positive.

Lollapalooza attendees were required to show evidence of being fully vaccinated or a negative Covid test result, taken within 72 hours, to gain entry to the festival. Unvaccinated attendees were asked to wear masks at outdoors parts of the site, while all had to wear masks at indoor venues.

Lollapalooza said that 90% of the event’s attendees, an estimated 385,000 not including artists, staff and crew, were vaccinated.