ST. LOUIS (AP) — The St. Louis area has become one of the first in the United States to reinstate mask requirements amid a rise in cases that health officials are blaming on low vaccination rates and the highly contagious delta variant.

Despite pushback from some elected officials, face coverings became mandatory today in indoor public places and on public transportation in St. Louis city and St. Louis County for everyone ages 5 or older — even for those who are vaccinated. Wearing masks outdoors is strongly encouraged, especially in group settings.

“For those who are vaccinated this may feel like punishment, punishment for doing the right thing,” St. Louis County Executive Sam Page, a Democrat, said at a news conference today. “I’ve heard that and I feel that frustration. While the vaccination can protect against serious illness, it can’t protect you from being infected with COVID-19 and passing it onto someone else, someone who may be more vulnerable.”

The decision comes as both of Missouri’s urban areas see a big uptick in coronavirus hospitalizations that began in rural areas of the state, especially in southwestern Missouri.

Missouri ranks fourth nationally in the most new cases per capita in the past 14 days, according to data collected by Johns Hopkins University Center for Systems Science and Engineering to measure outbreak caseloads and deaths across the United States.