President Biden's declaration that "the pandemic is over" could complicate the administration's effort to battle COVID-19, public health experts say.

Biden made the remarks in a Sunday broadcast of 60 Minutes. "We still have a problem with COVID. We're still doing a lot of work on it. But the pandemic is over," he said. "If you notice, no one's wearing masks. Everybody seems to be in pretty good shape. And so I think it's changing."

The president's comments come as public health officials are trying to convince Americans to get a new booster shot, and as the White House has worked unsuccessfully for months to convince Congress to provide more than $22 billion in new funding for the COVID-19 response. Since Sunday night, Republicans have already used his words to question vaccine mandates that are still in place for the nation's military and other federally funded programs.

At the same time, nearly 400 Americans are dying each day of COVID, according to the Centers for Disease Control and Prevention.

Multiple public health experts called Biden's remarks "unfortunate."

"When you have the president of the U.S. saying the pandemic is over, why would people line up for their boosters? Why would Congress allocate additional funding for these other strategies and tools?" said Dr. Celine Gounder, an epidemiologist and senior fellow with the Kaiser Family Foundation. "I am profoundly disappointed. I think this is a real lack of leadership."

The remarks could cause political difficulties

The White House is currently fighting an uphill battle in Congress to secure $22.4 billion in emergency COVID-19 funding to support vaccinations, testing and further research. Some Republican support is needed in the Senate to secure the funding, which the administration has been seeking since the spring. It has been hard to come by as some GOP lawmakers argue that there is still unspent money from earlier COVID-19 funding measures that can be used.

In announcing the funding request earlier this month, an official told reporters on a briefing call that there is not currently "enough funding to get through a surge in the fall." The administration has already stopped the program to send free test kits to Americans because of a lack of funds.

The president's words could undercut the effort to get this money further.

Republicans are already using the statement to question the justification for ongoing pandemic measures, including the military's vaccine requirement and mandates for vaccines and masks in federally funded Head Start education programs.

"Biden admitted last night that the COVID pandemic is over. In other words, there is no 'ongoing emergency' to justify his proposal for student loan handouts," said Sen. Marsha Blackburn of Tennessee.

Some public health experts agreed with Biden's characterization of a "change" in the pandemic. "It is a reasonable thing to do as we collectively move on from this emergency footing that we've been on for the last couple of years, and try to navigate a new normal," said Dr. Bob Wachter, chair of UCSF's Department of Medicine. "It's an appropriate way of thinking about the threat as it stands today."

Acknowledging the shift shouldn't stand in the way of funds for COVID-related efforts, said Dr. Tom Frieden, who led the CDC during the Obama administration.

"We don't have a pandemic of Alzheimer's disease or influenza or heart disease. But Congress still needs to fund programs to address those problems," he said.

The ongoing booster campaign could face challenges

The Biden administration's public health leaders have sometimes struggled at times to present a clear, unified message about COVID-19. His administration has at times been criticized for a lack of communication or issuing guidance that seemingly conflicts with available data.

Now, the president's remarks have thrown another wrench into the mix at a crucial moment.

The administration has just rolled out a new bivalent booster shot designed to target the omicron subvariants that have dominated caseloads in the country in recent months, and the agency is working to convince Americans to go out and get it. (Since the CDC recommended the shot earlier this month, hundreds of thousands of Americans have received it.)

But health officials have long struggled to convince Americans to get their shots. Only 68% of Americans completed their original vaccine course, and fewer than half of those have gotten any booster shot.

Most troubling are booster rates for people over 65, said Jennifer Nuzzo, the director of Brown University's Pandemic Center. Data from the CDC show that while the vast majority of older Americans got the original vaccines, far fewer — only about a quarter — have also taken the two original boosters.

"If we do nothing else to reduce the number of deaths from COVID, we need to make sure that people who are at the greatest risk of severe illness and death — and that's people over the age of 65 — that they get their booster," Nuzzo said. "I don't want to inadvertently send the signal that that's not something they need to do anymore."

She and other public health experts pointed to the winter, when a surge of new cases is likely as cold weather pushes socialization indoors, and holidays prompt people to travel to visit family and friends. A winter wave of cases will require tests, vaccines and other efforts to combat COVID, they said.

"I would say, let's not declare the pandemic over," said Dr. Carlos Del Rio, an infectious disease specialist at Emory University. "Let's say that we're in a very good place, and we need to continue working hard in order to stay in that good place."

NPR's Arnie Seipel contributed reporting.