Fauci says US is out of the ‘full-blown’ pandemic phase. But experts warn the virus still poses a threat.

As Dr. Anthony Fauci, the nation’s top infectious disease expert, declared that the United States is “out of the full-blown, explosive pandemic phase,” some public health experts cautioned Wednesday that the unpredictable virus that causes COVID-19 still poses a threat.

“The SARS-CoV-2 virus has surprised us again and again,” said Andrew Lover, an assistant professor of epidemiology in the School of Public Health and Health Sciences at the University of Massachusetts Amherst. “We should be wary of declaring victory too soon.”

In an interview Tuesday on “PBS NewsHour,” Fauci said, “We are certainly right now in this country out of the pandemic phase. Namely, we don’t have 900,000 new infections a day and tens and tens and tens of thousands of hospitalizations and thousands of deaths. We are at a low level right now. So if you’re saying, are we out of the pandemic phase in this country? We are.”

Fauci said he didn’t think the virus could be eradicated but hoped levels could be kept “very low” with “intermittent vaccinations.”

Fauci, President Biden’s chief medical adviser, clarified his views Wednesday in an interview with The Washington Post, saying, “Right now we’re at a low enough level that I believe that we’re transitioning into endemicity. ... We’re not in the full-blown, explosive pandemic phase. That does not mean that the pandemic is over.”

“The world is still in a pandemic,” he said. “There’s no doubt about that.” But the United States is “transitioning into more of a controlled endemicity,” he said.

Yet Lover warned that a resurgence of the virus could catch the country off guard.

“The [US Centers for Disease Control and Prevention] has shifted to pandemic metrics that focus solely on hospitalizations, and in this regard most of the US is controlling the virus pretty well,” he said by e-mail. “However, as home testing has become more routine, and many states shift to irregular reporting schedules, our barometer of transmission is getting less and less reliable.

“We may be setting ourselves up for serious situations as many public health interventions are relaxed and protection from boosters begins to wane,” he said.

Dr. Sandro Galea, an epidemiologist and dean at the Boston University School of Public Health, said in an e-mail that while the situation had improved, “the question is whether we are entering an endemic phase, one where we are at a level of transmission that we manage on a regular basis.”

“I am not sure we are there yet as our familiarity with the virus transmission patterns evolve,” Galea said.

Dr. Peter J. Hotez, a vaccine expert at the Baylor College of Medicine in Houston, said on Twitter that he was concerned about a possible wave of COVID-19 in the South this summer.

“I feel it’s still possible we could see a new variant of concern rip across Texas and US Southern states this summer, just as we did in 2020 and 2021,” he wrote.

I feel it’s still possible we could see a new variant of concern rip across Texas and US Southern states this summer just as we did in 2020 and 2021. Reasons: 1) too few vaccinated in this part of the country, 2) immunity from omicron not durable https://t.co/eKazEXxLXV
— Prof Peter Hotez MD PhD (@PeterHotez) April 27, 2022

“The pandemic continues & policies to address it should continue,” Julia Raifman, an assistant professor of health law, policy and management at Boston University School of Public Health, said in a tweet, pointing to recent increases in hospitalizations in Massachusetts, the spread of new variants, and possible “harmful seasonal surges” ahead.

Nationally, cases and hospitalizations are rising again, although they are far lower than the heights seen earlier in the pandemic. Restrictions are easing as many Americans appear to be putting the pandemic behind them. Masking requirements have been lifted across most of the country, and a federal mask mandate in transportation settings was lifted after a judge struck down the requirement.

In a reminder that the coronavirus is still a threat, Fauci said Tuesday that he wouldn’t attend the White House Correspondents’ Association dinner “because of my individual assessment of my personal risk,” and Vice President Kamala Harris said she had tested positive for COVID-19.

Dr. Philip Landrigan, director of Boston College’s global public health program, said he agreed with Fauci’s assessment that the pandemic is in a “deceleration” phase. Barring the emergence of a new variant, there is reason for optimism, he said.

“The infection is still with us. It’s probably going to be with us a long time,” he said. “But it’s not causing the large numbers of cases and hospitalizations and deaths” it did before.

He said that vaccines had been key in preventing hospitalizations and deaths.

“The vaccine doesn’t necessarily protect you against an upper respiratory infection,” he said. “But it certainly keeps you out of the hospital and keeps you alive.” A recent study estimated that COVID-19 vaccinations by the end of last month had averted more than 2.2 million deaths in the United States.

Matthew Fox, professor of epidemiology and global health at the Boston University School of Public Health, said he believed the nation is likely past the phase at which “we will see (barring a new, evasive variant) large-scale waves of hospitalizations and deaths.”

“That’s in part because we have so much prior infection leading to immunity and also because we have lots of vaccination making people less susceptible and far less likely to have severe infection,” he said.

But vigilance remains necessary, he said. “We do still need to take care to protect the vulnerable,” he said in an e-mail. “Watching for increasing infection rates will allow us to take steps when the risk goes up and hopefully bring things back down reasonably quickly.”

Material from Globe wire services was used in this report.

Martin Finucane can be reached at martin.finucane@globe.com.