The New York City Fire Department announced Sunday that 61-year-old Joseph Ferrugia is its first active firefighter to have died of COVID-19.

He is the 13th member of the FDNY to die of coronavirus.

“This horrific illness has taken far too many lives, and now it has killed a man who bravely served New Yorkers for three decades," Fire Commissioner Daniel A. Nigro said in a statement Sunday. "He ran toward danger his entire career, searching for those trapped by flames and doing all he could to save them. Our entire Department mourns his loss.”

Ferrugia joined FDNY in 1990 and was a World Trade Center first responder, the department said.

FDNY said he is survived by his three adult children and three siblings.

Chicago Public Schools pushed back the return of in-person classes for kindergarten through eighth-grade students by one day as negotiations continue between the city and the Chicago Teachers Union.

While the district and union leadership agree on some items of contention in principle, Mayor Lori Lightfoot said at a press conference Sunday that the union has refused to put those agreements in writing and instead has added more items to the negotiating table that are not related to the public safety issues associated to reopening some classrooms during the COVID-19 pandemic.

Just minutes before Lightfoot was expected to appear in a presser Sunday, CTU sent a series of tweets that hinted there was not going to be a deal just yet.

The mayor said she still expects CPS teachers to show up to their classrooms despite the dispute. Last week she said that if they do not, she would be forced to take further action, but did not specify what that action would be.

The U.S. Centers for Disease Control and Prevention released its latest update Sunday on the country's coronavirus vaccine rollout.

There have been close to 50 million doses distributed around the country, according to the agency's online tracker. Of those doses, 31 million, roughly 62%, have been administered, according to the CDC.

About 25 million people have received their first dose and 5.6 million have received two doses, the CDC said.

A city on Florida’s panhandle put on its Mardi Gras parade as planned, despite its high positivity rate.

Prior to the parade on Saturday, Milton Mayor Heather Lindsay advised residents to take their temperature before attending the event and for everyone who attends the party after the parade and participates in the kid’s zone to wear a mask.

"I would love to focus only on the fun and pageantry of it all because I love Mardi Gras, but we must accept life on life's terms," Lindsay wrote. "Presently we are in the midst of a widespread outbreak of a virus that is not just the flu."

The city currently has a positivity rate of 18%, "well above" the state average of 6.62%, Lindsay wrote. Households affected in Milton reduced from a high of 102 to 90 this week, but the local positivity rate has been as high as 28% and "never lower" than 16%, she added. The population in Milton is about 10,000.

It is unclear how many people attended the event.

Americans should now assume there's already more contagious variants of the novel coronavirus circulating in their communities, according to Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention.

"I think we should be treating every infection as if it's a variant," Walensky told ABC News chief anchor George Stephanopoulos in an interview Friday on "Good Morning America."

"That is the way we're going to control this pandemic," she added. "Quite honestly, we know that these viruses are going to mutate. They generally mutate to the advantage of the virus and that's how we get these more dominant strains."

Walensky's remarks come a day after the United States confirmed its first cases of the B1351 variant, which was first identified in South Africa and has since spread to dozens of other countries.

"We had always been worried that they were here and we hadn't yet detected them," she said.

The B1351 variant was discovered in two people in South Carolina who were not in contact with one another and haven't traveled recently, which concerns Walensky.

"So the presumption is here that they became infected from other people in the community and that there's community spread of this variant," she said.

Walensky explained that it "takes a while" for scientists to detect a variant.

"From the time of symptoms to somebody getting a test to that test being positive and to us being able to sequence it, that turnaround time could be up to 10 to 14 days," she said.

Although the CDC has "done an enormous amount of scaling up of our surveillance of these variants," Walensky said researchers are essentially starting from the ground up because "there has not been a public health infrastructure to track these variants."

"There has not been money, resources to be able to do mass sequencing at the level of infection that we have in this country right now," she said. "That is part of the American Rescue Plan, is to be able to use resources to finance a mass scale-up of surveillance for these variants."

There are concerns that the variants wield increased transmissibility and mortality, or that existing treatments and vaccines won't work as well against them.

"The current vaccines we're still studying against these variants," Walensky said. "What I will say though is we have a 95% efficacious vaccine against the current strain. Even if we have some diminution of that efficacy against the South Africa strain, I still think we need to really go ahead, push the vaccination, because this just is still yet another tool in our toolbox to fight this pandemic."