(WTNH) — The Centers for Disease Control and Prevention (CDC) classified Tolland County as an area with high COVID-19 community transmission this week, the seventh county in Connecticut to be classified under that category.

The CDC recently reported New Haven County, Hartford County, Middlesex, New London, Litchfield and Fairfield counties are now classified as areas of high COVID-19 community transmission, with Tolland County now on the list too.

One more Connecticut county is still classified as being in the “substantial transmission” category. Substantial community transmission is classified by the CDC as 50-99 cumulative cases per 100,000 people in the past seven days. High transmission is classified as places with more than 100 cases per 100,000 in a seven-day period.

In a statement, the state Department of Public Health said, “Vaccination remains the most important defense against illness and hospitalization from COVID-19. So-called ‘vaccine breakthrough’ cases have occurred in Connecticut, but they remain rare, and the vast majority of hospitalizations and deaths in Connecticut and around the country are in unvaccinated individuals. DPH strongly recommends that unvaccinated individuals get vaccinated as soon as possible to help stop the ongoing spread of the Delta variant.”

Health experts are warning residents to take the contagious Delta variant seriously.

“This Delta variant is not a joke, it’s highly contagious and it’s something we have not seen before,” said Maritza Bond, Health Director for the City of New Haven. “The fact that we went from substantial risk to a high transmission rate is really alarming. It’s basically letting us know as a county we are doing poor.”

Gov. Lamont issued an executive order on Aug. 5, allowing municipalities to implement universal masking requirements.

For New Haven Mayor Justin Elicker, that was the next step for the Elm City. Many other communities followed suit.

The state Department of Public Health is also recommending people ages 2 and up to wear a mask, despite vaccination status.

You can view all of this information and more data from the CDC here.