As residents of Los Angeles County enter their first week of being required to wear face masks because of rising numbers of coronavirus cases among unvaccinated people, new cases are increasing in all 50 states.

The nationwide increase on Sunday was the fourth day in a row on a rolling seven-day average, a run not seen since the spring 2020 surge, according to health officials. The weekly rolling average for cases has nearly tripled in the last month. The death rate is also up 24.7 percent from its low point two weeks ago.

Florida now leads the nation in coronavirus cases, with its biggest spike since last summer, according to the Tampa Bay Times. Most of the state's new cases are driven by the more infectious Delta variant, epidemiologist Dr Vincent Hsu told the NBC affiliate WFLA.

A YouGov poll showed that 90 percent of respondents who reject vaccination fear possible side effects from the vaccine more than they fear COVID-19 itself.

Less than 1 in 10 of the vaccine rejectors trust medical advice from Dr Anthony Fauci, and only 1 in 5 trusts the Centers for Disease Control and Prevention (CDC). And 1 in 5 believe the government is using vaccines to microchip the population.

On Fox News Sunday, Louisiana Republican Senator Bill Cassidy, who is also a physician, said it was unsurprising some citizens didn't trust the message coming from the White House, which he said they saw as "uber partisan". He said people would be more likely to listen to local medical professionals "they see at the PTA meeting".

The order in LA County, the most populous county in the US, requires that masks be worn in all indoor public settings, such as theaters, stores, gyms, offices and workplaces and in restaurants when not eating and drinking. Those exempted include children younger than 2. Indoor restaurant dining is still allowed, but patrons are asked to wear masks when they are not eating or drinking.

More California counties followed with mask recommendations Friday, including San Francisco and the City of Berkeley, recommending both vaccinated and unvaccinated people wear masks indoors in public spaces.

LA County public health officials reported that on Sunday there were 1,635 new coronavirus cases and four related deaths, bringing the total number of deaths to 24,583. Currently, there are 507 people hospitalized with COVID-19.

"This is very disturbing. And, of course, as responsible elected officials, we have to do something," said Hilda Solis, chairwoman of the LA County Board of Supervisors.

"I'm not pleased that we have to go back to using the masks in this manner," she said Sunday on ABC News' This Week. "But nonetheless, it's going to save lives. And right now, that to me is what's most important, and really getting more people to understand that they have to get vaccinated."

US Surgeon General Vivek H. Murthy said Sunday that he supports individual counties reinstating mask mandates to combat local surges of the coronavirus among unvaccinated people .

"It's very reasonable for counties to take more mitigation measures like the mask rules you see coming out in LA,'' he said on ABC News' This Week. Murthy said such local orders are consistent with federal guidelines that permit local authorities to require prevention measures.

Nevada's public health district on Friday recommended people wear masks in crowded indoor public places — including Las Vegas casinos — regardless of vaccination status.

The daily coronavirus case count has been climbing in Nevada, especially in southern Nevada where the Delta variant is the dominant strain and cases returned to levels not seen since February. More than half of the state's eligible population isn't fully vaccinated.

Clark County — the home of Las Vegas casinos — continues to account for the bulk of coronavirus cases in the state as well as the highest incidence rate. Nearly 78 percent of Nevada cases occurred there.

"Our numbers are trending in the wrong direction," said Brian Labus, an epidemiologist at the University of Nevada, Las Vegas. "Our recommendations have to change to match what the virus is doing."