As the United States faces a rising number of Covid-19 cases and hospitalizations from the omicron subvariant BA.5, some are wondering if it's better to get a booster now or wait for reformulated vaccines in the fall, Sam Whitehead and Arthur Allen write for Kaiser Health News.

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According to CDC data, BA.5 is now the dominant subvariant in the United States, accounting for more than 60% of all new Covid-19 cases. Many health experts have voiced concern about the subvariant's increased contagiousness and ability to evade both vaccine and natural immunity.

"The key feature of BA.5, that we know about, is its immune evasiveness—you can be fully vaccinated and boosted and still have a risk of a breakthrough infection," said Ashish Jha, the White House Covid-19 response coordinator. "You can be previously infected—even as recent as the last couple of months—and have a very high rate of reinfection."

To combat BA.5, which has contributed to a rise in Covid-19 hospitalizations over the past few weeks, federal health officials are strongly urging people, especially those who are age 50 or older and have an increased risk for severe illness, to get a Covid-19 booster dose.

Currently, people ages five and older are eligible for a booster dose five months after their initial vaccine series. According to CDC, only around half of U.S. adults have received a booster shot, and only 28% of those ages 50 and older have received a second booster dose as recommended.

"If you've not gotten a vaccine shot this year, go get one now," Jha said. "It could save your life."

However, other health experts say it may be better for eligible individuals, particularly those who are not at high risk of severe Covid-19, to wait until the fall to get a second booster when reformulated vaccines targeting the BA.4 and BA.5 subvariants are expected to be available.

"I think that we have all been asking that same question," said Kathryn Edwards, scientific director of the Vanderbilt Vaccine Research Program. "What's the benefit of getting another booster now when what will be coming out in the fall is a bivalent vaccine and you will be getting BA.4/5, which is currently circulating? Although whether it will be circulating in the fall is another question."

Rapidly evolving variants add to health officials' communication challenges

According to Carlos del Rio, a professor of infectious diseases at the Emory University School of Medicine, trying to keep up with rapidly evolving coronavirus variants has made it difficult for health officials to effectively communicate information about the vaccine and boosters to the public.

"What we're seeing now is a little bit of an information void that is not helping people make the right decision," del Rio said, noting that public mistrust can also grow as health officials change their message to address new coronavirus variants.

Consistent messaging around boosters has also been further complicated by differing opinions from experts. "When experts have different views based on the same science, why are we surprised that getting the message right is confusing?" said Bruce Gellin, chief of global public health strategy at the Rockefeller Foundation.

To improve communication around boosters, David Brett-Major, an infectious disease specialist at the University of Nebraska Medical Center, said trusted, local sources—not just federal health officials—need to tell patients about their value.

"Access happens locally," Brett-Major said. "If your local systems are not messaging and promoting and enabling access, it's really problematic."

However, Georges Benjamin, executive director of the American Public Health Association, said the public's interest in getting another booster is unlikely to increase even after new vaccines are made available and eligibility is expanded. In areas with high vaccine coverage, people will largely be protected from new coronavirus variants, but people living in areas with low vaccine coverage could face a "rude awakening" in the future, he said.

"Nothing is simple with Covid, is it? It's just whack-a-mole," Edwards said. "This morning I read about a new variant in India. Maybe it'll be a nothingburger, but who knows? Maybe something big, and then we'll wonder, 'Why did we change the vaccine strain to BA.4/5?'" (Whitehead/Allen, Kaiser Health News, 7/18)