The state Department of Public Health on Sunday issued an alert that strongly recommends all Connecticut residents over 2 years old wear face masks in indoor public spaces, whether they're vaccinated or not, given the rapid increase in COVID-19 cases over the past two weeks because of the delta variant.

The warning came as all but one of the state's eight counties were classified by the U.S. Centers for Disease Control as having “substantial transmission" of COVID-19. The state's only county with moderate transmission, Litchfield County, has a high likelihood of meeting the substantial threshold soon, the state department said.

DPH on Sunday also urged both vaccinated and unvaccinated residents at high risk for complications of COVID-19, such as individuals with diabetes, compromised immune systems, pregnancy, obesity and asthma, to avoid large indoor gatherings that could include a mix of vaccinated and unvaccinated people.

The agency stressed how vaccination “remains the most important defense against illness and hospitalization.” More than 59% of the population of Connecticut has been fully vaccinated against the coronavirus with more than 64% having received at least one shot of a vaccine.

— Associated Press