The Connecticut Department of Public Health "strongly recommends" that anyone over the age of 2 wear a mask indoors regardless of vaccination status.
The department said there has been a rapid increase in cases of COVID-19 in Connecticut over the last 14 days due to the spread of the Delta variant.
Two days earlier, the DPH issued guidance recommending the use of masks in areas with significant COVID-19 transmission but has since expanded that guidance to include all of Connecticut.
This comes after four more counties were added to the latest Centers for Disease Control and Prevention (CDC) list of "substantial" or "high" COVID-19 transmission levels.
Get top local stories in Connecticut delivered to you every morning. >Sign up for NBC Connecticut's News Headlines newsletter.
Middlesex County is the latest county in the state to reach the CDC's recommended threshold for universal indoor masking, according to the latest data from the agency's COVID Data Tracker. Fairfield, Tolland and Windham counties reached the level a few days ago and Hartford, New Haven and New London counties reached it earlier in the week.
Litchfield County is the only one that hasn't yet reached the CDC threshold, however the DPH expects that will soon change.
"The likelihood is high that they will soon meet the threshold, and therefore universal masking indoors is an important precaution," a DPH spokesperson said in a statement.
Local
The CDC classifies counties with greater than 50 COVID-19 cases per 100,000 residents over seven days as "substantial."
The latest CDC guidance encourages residents with underlying medical conditions or who live with high-risk or unvaccinated individuals to consider wearing a mask indoors, including those with young children who are not eligible for the vaccine.
“I think it was the right thing to do. You know, we relied so long on individuals doing the right thing by getting vaccinated and fortunately that brought us close to reaching our statewide goals, but not quite there, particularly in certain pockets of this state," said Dr. Anthony Santella, University of New Haven's COVID-19 coordinator.
Santella believes that wearing masks in a good ideas right now with mediocre vaccination rates, the more transmissible Delta variant being so widespread and people starting to head indoors more as kids start to go back to school.
The CDC guidance is not a mandate and it leaves policy decisions up to the state and local level. At present in Connecticut, an executive order remains in effect that requires those who are not fully vaccinated against COVID-19 wear a face mask in public indoor spaces where they cannot social distance, according to the DPH.
“The main reason I got vaccinated is I wouldn’t have to wear a mask," Cromwell resident Dalton Michaud said.
State officials continue to urge the public to get a COVID-19 vaccine. Connecticut has one of the highest vaccination rates in the country, with about 2.3 million residents having received at least one dose.
As of Thursday, the state was reporting 1,133 breakthrough cases of COVID-19 in vaccinated residents, with 27 deaths reported in breakthrough cases. That amounts to a .06% breakthrough case rate, DPH said, representing 3.2% of COVID-related deaths since February and less than .01% of deaths overall.
The state's positivity rate came in at 2.72% Friday, up from 2.44% the day before. There were 18,025 new tests reported, with 491 new cases. There are 116 people hospitalized with the virus, a net increase of four from the day before.
The state is reporting COVID-19 related deaths once a week, on Thursday. To date, there are 8,293 deaths reported in Connecticut, an increase of seven from last week.