https://techcrunch.com/2020/03/17/faa-temporarily-closes-tower-at-chicagos-midway-airport-after-employees-test-positive-for-covid-19/

In another example for the farreaching effects of the coronavirus outbreak, the FAA today said that it is temporarily closing the tower at Midway Airport, the second largest airport in the Chicago area. In a statement, the FAA says that that several technicians at the facility tested positive for COVID-19. For a while, there was a ground stop in effect for Midway and no flights could take off to land at the airport.

In its statement, FAA notes that the airport remains open and that operations will continue at a reduced rate.