The Swedish government is tightening countrywide coronavirus restrictions on the number of people who can gather in a restaurant and making face masks mandatory on public transportation.

Sweden has not gone into lockdowns or closed businesses, relying instead on citizens' sense of civic duty to control infections.

However, the country has seen a recent rapid increase in confirmed cases that is straining the health care system.

"The situation continues to be very serious," Swedish Prime Minister Stefan Lofven said Friday.

The virus has spread quickly among medical personnel, pushing the government to back more restrictions. They include a nationwide ban on bars and restaurants selling alcohol after 10 p.m., a curfew that was pushed back to 8 p.m. on Friday.