Vaccination rates, which have slowed in recent weeks across the United States, remain stubbornly low in many Southern states—a trend that health experts say could put those areas at risk of another Covid-19 surge later this summer.

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Why experts are concerned about a potential Covid-19 surge

Nationwide, vaccination rates have dropped from a peak of more than 3.3 million doses a day in mid-April to about 1.1 million doses per day now, according to the New York Times.

And while more than half of the populations are vaccinated in eight states, in some other states—including Alabama, Louisiana, and Mississippi—fewer than half of adults have been partially vaccinated. Many of these states are located in the South, the Times reports, where eight of the 10 states with the lowest vaccination rates are located.

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And some states and localities with low vaccination rates are seeing increases in Covid-related hospitalizations, the Times reports. In fact, the eight states in which hospitalizations are currently rising—which include Louisiana, Oklahoma, and Utah—also have persistently low vaccination rates.

For instance, in Newton County, Missouri, just 15% of people have been fully vaccinated, and local hospitals have seen a 47% increase in Covid-19 hospitalizations over the two weeks prior to June 3.

The challenge isn't only that so many people are unvaccinated, Ted Delbridge, executive director of the Maryland Institute for Emergency Medical Services Systems, said. Those who do get sick with Covid-19 now are "in most age groups, twice as likely to end up hospitalized as people who got the virus earlier in the course of the pandemic," he said—likely due to coronavirus variants that can cause more serious disease.

At a White House briefing, Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases and chief medical advisor to the White House, said the delta variant, first discovered in India, was becoming the dominant variant in the United Kingdom.

"We cannot let that happen in the United States," he said, adding that the variant accounts for just 6% of sequenced U.S. Covid-19 cases at the moment.

Fauci explained that the delta variant "may be associated with an increased disease severity, such as hospitalization risk, compared to" the alpha variant first discovered in the United Kingdom. He added that the best protection against a spread of the delta variant was vaccination, citing research indicating that the currently available vaccines protect against it.

Despite the emergence of new variants, experts said that if there is another Covid-19 surge in the South, it isn't likely to be as deadly as last summer's surge, since some people—especially among vulnerable groups such as the elderly—have been vaccinated and since treatments for Covid-19 have improved, the Times reports.

"The surge is not likely to end up tying up hospitals and causing lots of deaths," Edward Trapido, an epidemiologist and associate dean for research at the Louisiana State University School of Public Health, said. However, those who haven't been vaccinated—which disproportionately includes younger populations—would still be at risk, and it's in those populations that "we will expect to see a rise," he said.

Health officials push Americans to get vaccinated, but roadblocks remain

Peter Hotez, a vaccine expert at Baylor College of Medicine, said that to avoid a potential surge of Covid-19 cases, states in the South need to get closer to 70% of their population being partially vaccinated.

"We're not even close to that in the Southern states," he said.

In response to a slowing vaccination rate nationwide—and to the persistently low vaccination rates in the South in particular—health officials have been promoting vaccinations with a variety of incentive programs, including free tickets to sporting events, free air travel, and free tickets to amusement parks. CMS is also trying to incentivize providers to aid the effort, offering $150 to providers who go to people's homes to administer a two-dose Covid-19 vaccine.

Still, many people remain vaccine-hesitant. For instance, a recent Gallup poll found that 78% of Americans who said they're not planning to be vaccinated said they're unlikely to reconsider their plans, with 51% saying they're "not likely at all." Overall, just 20% of vaccine-hesitant people indicated a willingness to reconsider their stance.

Vaccine hesitancy is most common among middle-aged Americans than younger and older Americans, the poll found. Research suggests that some people who don't want to get vaccinated distrust the federal government's role in developing the vaccine, while others say they are too busy or are waiting for more information. Additionally, some Black individuals have said their vaccine hesitancy is rooted in broader concerns about the medical profession's historic maltreatment of people of color.

This reluctance to get vaccinated is particularly concerning, experts say, because Americans are increasingly returning to their pre-pandemic day-to-day lives. For instance, an Axios and Ipsos poll found that although 61% of Americans at the beginning of March said they felt there was a large to moderate risk in returning to pre-pandemic life, just 30% of Americans said the same last week.

"A lot of people have the sense of, 'Oh, dodged that bullet,'" Jeanne Marrazzo, director of the Division of Infectious Diseases at the University of Alabama at Birmingham, added. "I don't think people appreciate that if we let up on the vaccine efforts, we could be right back where we started" (Rojas/Smith, New York Times, 6/9; Elamroussi et al., CNN, 6/10; Jiménez et al., New York Times, 6/7; Nather, Axios, 6/8; Jiménez, New York Times, 6/9; Mastrangelo, The Hill, 6/7; Jones, Gallup, 6/7).