New cases of COVID-19 have been sweeping across the United States in recent weeks. On Thursday, President Joe Biden tested positive. His symptoms of tiredness, a runny nose and dry cough are considered mild.

The highly infectious and transmittable BA.5 subvariant of the coronavirus’s omicron variant is making up nearly 80% of new cases, according to the latest figures from the U.S. Centers for Disease Control and Prevention (CDC) COVID Data Tracker.

Although the initial vaccinations are effective at preventing hospitalization and death, their immunity weakens over time.

“So, more people, even those who might have protection from past infection or vaccination, have gotten COVID-19,” according to the CDC.

That’s why the CDC is recommending that immunized adults and children 5 years and older follow up with a vaccination booster in five months, and those 50 and older get a second booster shot for renewed protection. But so far, the CDC reports that only about half of adults have gotten a booster and just 28% of those age 50 and older have received a second dose, which provides even further protection from the illness.

This leaves millions of people more vulnerable to the most recent variants of omicron.

“It’s very concerning that many individuals who are eligible for boosters are choosing not to get them,” David Grabowski, a professor of health care policy at Harvard Medical School, told VOA. “There’s really strong research suggesting the protective effects of these boosters against COVID.”

The White House issued a warning this week about the spike in BA.5 subvariant cases and urged Americans over the age of 50 to get the booster shots.

“It could save your life,” said Dr. Ashish Jha, the administration’s COVID response coordinator.

Many health advocates are alarmed that public momentum over COVID-19 has waned.

Some people “don’t feel a sense of urgency to get booster shots even though they are available in most parts of the country,” Grabowski said.

Part of the reason may be a lack of communication by public health officials that is confusing to the public, said Dr. William Schaffner, a professor of infectious diseases at Vanderbilt University School of Medicine.

“Public health officials have not communicated clearly when you should get a booster and that it is an important step,” Grabowski told VOA.

Dr. David Aronoff, chair of the Department of Medicine at Indiana University’s School of Medicine, explained that in some instances, “people may have had a booster shot and not have realized they were eligible for another in several months.”

There is also the idea that since the symptoms from BA.5 are usually mild for people who are vaccinated, then why bother getting a booster, said Tina Runyan, a professor of family medicine and community health at the University of Massachusetts Medical School. With a highly contagious strain going around, some people think they will get COVID anyway, so getting a booster won’t protect them that much, she said.

But Dr. Anthony Fauci, the nation’s top infectious disease expert, said that’s not true.

“If you are not vaccinated to the fullest, namely, you have not gotten boosters according to what the recommendations are, then you’re putting yourself at an increased risk that you could mitigate against by getting vaccinated,” he said during a July 12 press briefing with the White House COVID-19 response team and public health officials.

Despite that warning, health experts say COVID-19 fatigue is causing a lack of response.

“People are ready to put COVID behind them and they just want to return to a more normal way of life,” explained Schaffner.

Going back to normal may be fleeting as new subvariants continue to pop up.

“We have to start thinking about the booster as something we might do annually to protect ourselves and others,” said Keri Althoff, an associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health in Maryland.

Meanwhile, new vaccines are in the works to target omicron subvariants BA.4 and BA.5.

“Getting vaccinated now will not preclude you from getting a variant-specific vaccine later this fall or winter,” said Jha, the White House COVID response coordinator.

“We’re hoping we get new vaccines in the future that will target particular variants as they come up,” Aronoff said, but the currently available vaccines, which include boosters, “are keeping people out of hospitals and from dying from COVID.”