Chicago Med had to temporarily suspend production on Season 6 shortly after beginning in September due to a positive COVID-19 test from a member of the production team, although the Med halt didn’t affect production on Chicago Fire or Chicago P.D. More recently, Chicago Fire had to halt production shortly before the One Chicago fall premieres due to a positive COVID test from a crew member.
The One Chicago shows have run into some obstacles since returning to production for the new seasons, however.
Med and P.D. were apparently not affected by the temporary Fire suspension.