Once again, the U.S. is heading into what could be another COVID-19 surge, with cases rising nationwide and in most states after a two-month decline.

A big unknown? “We don’t know how tall this mountain is going to grow,” said Dr. Stuart Campbell-Ray, an infectious disease expert at Johns Hopkins University.

When the contagious omicron version of the coronavirus swept through the population, no one expected a spike as high as last time around.

But experts warn that the coming wave – driven by A mutant called BA.2 This is thought to be more than 30% contagious – and will sweep the country. They worry that hospitalizations, already rising in parts of the Northeast, will rise in a growing number of states in the coming weeks.They say the wave of cases will be bigger than it appears because the reported numbers are massively underestimated As more people test at home without reporting their infection or skipping testing altogether.

At the peak of the last omicron surge, hundreds of thousands of cases were reported each day. The seven-day rolling average of daily new cases rose to 39,521 as of Thursday from 30,724 two weeks earlier, according to Johns Hopkins University data collected by The Associated Press.

Dr Eric Topol, director of the Scripps Research Translational Institute, said the number will likely continue to grow until the surge reaches about a quarter of the last “huge” height. He said BA.2 could have the same impact in the US as it did in Israel, where it created a “bump” in the chart measurement case.

Experts say immunity to vaccinations or past infections in the U.S. is somewhat contained compared to early winter.

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But Wray said the U.S. could end up being like Europe, where the surge in BA.2 was “huge” in some places with comparable levels of immunity. “We’re probably going to have a big increase here,” he said.

Both experts said that BA.2 will gradually spread across the country. The Northeast has been hit the hardest so far – more than 90% of new infections last week were caused by BA.2, compared to 86% nationally. As of Thursday, Vermont, Rhode Island, Alaska, New York and Massachusetts had the highest per capita coronavirus infection rates over the past 14 days. In Washington, D.C., which also ranks in the top 10 for new case rates, Howard University announced it will move most of its undergraduate programs online for the remainder of the semester due to a “significant increase in COVID-19 positivity” in the region, and on campus.

Average daily new cases in some states, including Rhode Island and New Hampshire, rose by more than 100% in two weeks, according to data from Johns Hopkins University.

In New Hampshire, the rise in cases comes two weeks after all 11 state-managed vaccination sites closed, and some advocates are forcing the governor to reverse course.

Rhode Island Department of Health spokesman Joseph Windken said the metric they are most concerned about right now is the hospitalization rate, which remains relatively low. About 55 patients with COVID-19 were hospitalized, compared with more than 600 at one point in the pandemic.

Officials believe vaccination rates are high. State statistics show that 99 percent of Rhode Island adults were at least partially vaccinated, and 48 percent received booster doses, which scientists believe are key to preventing serious disease with omicron.

Vermont also has relatively high levels of vaccination and fewer hospitalizations compared to the peak of the first wave. But the health commissioner there, Dr Mark Levine, said there had been a slight rise in hospitalisations and the number of patients in intensive care units, although the number of deaths had not risen.

Data from the Centers for Disease Control and Prevention shows a slight rise in new hospital admissions with confirmed COVID-19 in the New England and New York areas.

On the West Coast, modelers at Oregon Health and Science University expect a slight increase in hospitalizations in the state over the next two months, as well as a sharp rise in cases in the state.

As the outbreak spreads across the country, states with low vaccination rates could face more infections and severe cases that end up in hospitals, experts said.

With COVID restrictions largely lifted, government leaders must be careful to use the right tone when talking to people about protecting themselves and others, Wray said. Philadelphia recently became The first major U.S. city to restore its indoor mask rules after a sharp rise in infections. But Levin of Vermont said there are no plans to reinstate any restrictions imposed earlier during the pandemic.

“It’s hard to enact restrictive draconian measures,” Wray said. “Fortunately, we have some tools that we can use to reduce risk. So I hope leaders can emphasize the importance of people looking at the numbers,” being aware of the risks and considering preventive measures such as wearing masks, getting vaccinated and boosting immunizations if They haven’t.

Lynne Richmond, a 59-year-old breast cancer survivor who lives in Silver Spring, Maryland, said she plans to get a second booster immunization and continue to wear a mask in public as cases rise in her state and nearby Washington, D.C.

“I’ve never really stopped wearing a mask…I’ve been on high alert,” she said. “I feel like I’ve come this far; I don’t want to get Covid-19.”

At the 250-bed New Hampshire Veterans Home in Tilton, staff are still wearing masks and practicing social distancing. Veterans are allowed limited tours of places like the antique racing museum and restaurants, where they can have a separate room with wait staff wearing masks.

Staying vigilant is a good strategy, experts say, as the coronavirus keeps throwing curveballs. One of the latest: More infectious sub-variants of BA.2, known as BA.2.12 and BA.2.12.1, have been discovered in New York State. Scientists warn that new and potentially dangerous variants could emerge at any time.

“We shouldn’t think the pandemic is over,” Topol said. “We still have to be vigilant.”