Following a surge in COVID-19, influenza, and respiratory syncytial virus (RSV) infections, case counts are dropping, suggesting that "the worst of the winter resurgence is over." However, experts warn that COVID-19 still poses "a significant public health threat," Rob Stein writes for NPR's "Shots."

Is 'the worst' of the 'tripledemic' over?

While this winter's COVID-19 surge was not expected to be as bad as in previous years, both influenza and RSV spiked early this fall. In addition, XBB.1.5 started spreading rapidly during the holidays. With many people behaving like the pandemic was over, all three viruses spread quickly, resulting in a "tripledemic."

"So there were big fears of hospitals getting completely overwhelmed again, with many people getting seriously ill and dying," Stein writes. "But that's not what happened."

Now, the COVID-19 surge seems to be dissipating before becoming as severe as many experts expected. "I think the worst of the winter resurgence is over," said David Rubin, who has been tracking the pandemic at the PolicyLab at Children's Hospital of Philadelphia.

"This virus continues to throw 210-mile-per-hour curve balls at us. And it seems to defy gravity or logic sometimes," said Michael Osterholm, who heads the Center for Infectious Disease Research and Policy at the University of Minnesota.

"People all assumed we would see major transmission. Well, every time we think we have some reason to believe we know what it's going to do, it doesn't do that," Osterholm said.

At the beginning of the year, infections, hospitalizations, and deaths from COVID-19 increased in the United States. However, these numbers soon started to decline and have all been declining since, according to CDC.

In addition, the fall flu and RSV surges are also slowing, suggesting that the winter surges are likely over.

"I'm glad to say that we didn't have as much of a crush of infections as many thought was possible, which is very welcome news," said Jennifer Nuzzo, who leads the Pandemic Center at Brown University.

Why are cases declining?

According to Stein, several factors may have played a role in this decline. "One possibility could be that people avoided crowds, wore a mask and took other precautions morethan public health experts had expected they would," he writes. "But that doesn't really appear to be the case."

Another theory is that "viral interference" protected individuals infected with one virus from getting infected with another virus. "So maybe RSV and flu crowded out COVID in the same way COVID crowded out those other viral infections at various times over the last two years," Stein writes.

"At this point, I think that's more of a guess rather than very solid evidence," Nuzzo said. "But if it's true, that might mean we might be more susceptible to seeing a rise in infections when those viruses are not around."

However, Nuzzo and other experts suspect that the primary reason the COVID-19 surge is waning is because of the increased immunity most people have built up from prior infections and vaccinations.

"We have what I would call now a better immunity barrier," said Carlos Del Rio, an infectious disease specialist at Emory University who leads the Infectious Disease Society of America.

"Between vaccinations and prior infection I think all of us are in a different place than we were before," Del Rio said. "All of us, if not totally protected, we are somewhat better protected. And that immunologic wall is real."

COVID-19 still poses 'a significant public health threat'

Ultimately, the decline in cases does not mean Americans should stop worrying about COVID-19. "More than 400 people are still dying every day from COVID-19," Stein notes. "That's far fewer than the thousands who died during the darkest days of the last two winter surges. But it's still many more people than die from the flu each day, for example."

"Make no mistake: COVID-19 remains a significant public health threat," Nuzzo said. "That has not changed. And the fact that we are still losing hundreds of people a day to this virus is deeply troubling. So we shouldn't have to accept that level of disease and death that we are seeing."

William Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health, agreed, saying, "It's beyond question that society has moved into a stage where the pandemic is for most of us if not over then certainly quiet. And that's a great thing. Long may it remain so."

"Is it the case that there is no preventable suffering? No. There is still preventable suffering and death," Hanage noted.

Most COVID-19 deaths are among the elderly, many of whom have not received an updated COVID-19 booster. "So getting them boosted could help a lot. And the immunity the rest of us have built up could keep fading," Stein writes. "That means many of the rest of us may at some point need to get another booster to help further reduce the threat from COVID."

In addition, experts have noted that there could be another surge of the flu this year or the emergence of another dangerous variant of the coronavirus.

"This virus isn't done with us yet," Osterholm said. (Stein, "Shots," NPR, 2/3)