Jackson and Williamson counties both exceeded 1,000 cases of COVID-19 late last week, as measured since the pandemic began.
Jackson County has been listed by IDPH at a warning level in the past, but had fallen off the list for several weeks running.
Williamson County has been listed at a warning level for several consecutive weeks as the county has experienced a recent spike in cases.
A county enters a warning level when two or more COVID-19 risk indicators that measure the amount of COVID-19 increase.
The other Illinois counties reported at a warning level this week are: Bond, Bureau, Cass, Clinton, Coles, Crawford, DeKalb, DuPage, Effingham, Greene, Grundy, Hancock, Henderson, Jasper, Jersey, Lawrence, Madison, McLean, Monroe, Morgan, Schuyler, Shelby, Stark, St.