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CHICAGO — Cook and Will County health officials are recommending all residents to be wearing masks indoors in public as several area counties have entered the “substantial” transmission category as designated by the CDC.

They are the only area counties at this time to officially recommend masks inside for those who are vaccinated. Other area counties who have recently entered the “substantial transmission” category are McHenry, DuPage, Kendall, Grundy and LaSalle counties.

“Today, the CDC changed the classification for Cook County indicating that there is ‘substantial’ community transmission of COVID-19 in the County. As such, the CDC recommends that all fully vaccinated people wear a mask in public indoor settings. We strongly recommend that everyone follow the CDC recommendations and we will be issuing a new masking guidance tomorrow. The Delta variant is the strongest version of COVID-19 yet and we must contain it through both vaccinations and prevention measures such as mask wearing indoors and in crowded outdoor settings,” Cook County officials said.

Will County officials point to the vaccine as the greatest barrier against COVID-19.

“In the last few weeks we have seen positive COVID case numbers more than triple,” said WCHD Executive Director Sue Olenek.  “It is mostly due to the Delta variant, but it is still COVID-19, and those who are unvaccinated are at risk.  Please get your vaccination, and therefore limit the transmission of the virus.  As the number of vaccinated individuals increases, the virus has less people to infect, and therefore less of an opportunity to continue mutating.”

Health officials have not recommended any mask mandates or recommendations yet in the counties that have entered the “substantial risk” category besides Will and Cook.

On Tuesday, the CDC reserved course on some masking guidelines by saying that even vaccinated people return to wearing masks indoors in areas with “substantial” or “high” transmission.

Substantial transmission counties are described by the CDC as having 50 to 99 new cases per 100,000 people over a seven-day period.  Much of a recent substantial increase in Will County COVID-19 cases has been traced to the current Delta variant

Earlier this week, the Illinois Department of Public Health (IDPH) announced that they are aligning with the CDC’s updated recommendations for masking, as well as their updated recommendations for fully vaccinated people. 

1,691 new cases were reported in Illinois Thursday with 12 additional deaths.