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Omicron variant BA.5 is now dominant in US, and it evades immune protection more easily

Experts share tips to stay safe as the BA.5 coronavirus variant now accounts for more than half of all COVID-19 cases in the country.

A relatively new omicron subvariant — BA.5 — now accounts for the majority of COVID-19 cases in the country. And experts say two other variants, BA.4 and the previously dominant BA.2.12.1, are still concerning.

As of July 7, BA.5 is causing nearly 54% of COVID-19 cases in the U.S., according to the most recent data from the Centers for Disease Control and Prevention. Meanwhile, BA.4 is responsible for about 17% of cases and the previously dominant BA.2.12.1 is still responsible for 27% of cases.

Just a month ago, the landscape of coronavirus variants looked very different: In the first week of June, BA.2.12.1 accounted for 62% of COVID-19 cases while BA.4 and BA.5 were just picking up steam and each caused less than 10% of cases.

The quick turnover of variants is "kind of unexpected," Anne Hahn, Ph.D., a postdoctoral researcher at the Yale School of Public Health, told TODAY. “We are now at BA.5," which started to gain ground in June, said Hahn, whose work is investigating the viral evolution of SARS-CoV-2. "The first of this whole family emerged in November 2021. So that’s really concerning.”

What to know about omicron subvariant BA.5

Previously, experts did predict that BA.4 and/or BA.5 would likely become dominant. “They’re not taking off at the same rate everywhere,” Bill Hanage, Ph.D., associate professor of epidemiology at the Harvard T.H. Chan School of Public Health, told TODAY in mid-June.

He noted the two new strains, which were initially discovered in South Africa, seemed to be popping up first in Texas and Florida. And BA.5 cases were ticking up in Washington state as well.

“In general, and it’s not clear whether there’s a reason for this, they’re taking off more quickly in places that did not see a lot of BA.2,” said Hanage, who is also the co-director of Harvard’s Center for Communicable Disease Dynamics. That may be because BA.2 specifically offers some level of protection against these new variants or because simply having a more recent infection — of any variant — would provide some coverage, he said.

Hahn said she expected the new variants to “take over probably towards the end of the summer,” and noted that Portugal is seeing a major surge fueled by BA.5 cases right now. That’s “very concerning because this is one of the most highly vaccinated populations worldwide, especially when it comes to boosters,” she added.

BA.5 may be uniquely adept at evading vaccine protection, experts told NBC News. And just last week, an advisory panel to the Food and Drug Administration directed vaccine manufacturers to include protection against BA.4 and BA.5 in new COVID-19 vaccines to be released this fall.

Those companies, including Pfizer and Moderna, are already working on the next generation of COVID-19 boosters, which will target those specific omicron-related variants in addition to the original strain.

Still holding on: BA.2.12.1

The quick turnover in variants is thought to be due to each strain's mutations, particularly in the spike protein, which may allow the virus to evade immune protection. In the case of BA.2.12.1, "that's believed to help it sidestep some of the antibodies that have been generated by previous infections or vaccines," Hanage said.

But how much of the success of BA.2.12.1 "is due to that as opposed to it just being inherently more transmissible isn't clear," said Hanage.

Does BA.2.12.1 cause more severe illness? "Parts of the country have had a relatively big bump (in cases) with BA.2.12.1, and that's not really been translated into extremely large amounts of hospitalizations or deaths," Hanage said.

But, at this stage in the pandemic, it's challenging to evaluate the true severity of disease due to specific subvariants. "The vast majority of the population has either been vaccinated or has had a previous COVID infection, and that's going to affect the severity of disease because there's some baseline immunity," Dr. Anna Durbin, associate professor in the Johns Hopkins University School of Medicine, told TODAY.

"The good news that we can take from that is that we're still seeing protective effects of the vaccine against the more severe forms of disease," said Durbin, whose research focuses on evaluating vaccines for infectious diseases.

What kinds of variants can we expect to see in the future?

All of the experts agreed that new variants are pretty much a given. And, considering the last few dominant variants have all been in the omicron family, it's a good bet — but not a guarantee — the next ones will be, too.

"You never want to bet against being surprised by this thing, but there does look to have been a shift," Hanage said. And, right now, experts don’t expect another drastically new variant to pop up out of nowhere and quickly dominate the way omicron did, Hahn said.

Previous variants, including alpha, delta, omicron (BA.1) and BA.2 "all started evolving in the first few months after the virus entered the human population. They're not derived from each other," Hanage explained. "But the things we're seeing now are derived from within omicron, which is a new thing."

At the same time, though, it's important to recognize that the omicron subvariants are not identical to each other: "We call it the omicron family, but when you actually look at the genetic distance of these family members, they are as different to each other as alpha was to delta, for example," Hahn said.

Ultimately, variants "will keep coming; they're not going to stop," Durbin said. "What do we know from other seasonal coronaviruses? They continue to come back, they continue to mutate and we continue to be infected."

The key points scientists will be looking for are whether the virus begins to cause more severe disease, whether we'll need to continue to get boosters to protect ourselves and whether those vaccines will need to be regularly updated to better match the strains that are circulating, she said. Moderna and Pfizer are both working on booster shots, expected in the fall, that target the BA.4 and BA.5 omicron subvariants.

How to protect yourself and your community from BA.5

We may never be able to completely stamp out all coronavirus variants, Hanage said. But there are things we can do to lower the odds that more will emerge and reduce the opportunities they have to take over.

  • Keep wearing a mask. Yes, face masks still work — especially those that are higher quality, such as KN95, KF94 and N95 respirators. Wearing masks is especially useful in higher-risk situations, such as crowded indoor events. "If it's a good mask, it'll protect you regardless of what people around you are doing," Hanage said.
  • If you're eligible, make a plan to get your second booster. While Durbin noted that protection from boosters seems to be lasting for less and less time — "We're looking at one to two months," she said — if you're over 65 or have underlying conditions that make you more likely to develop severe COVID-19, it's worth getting the second booster. But it's also worth planning out when you're most likely to want that extra protection, like before travel or an event.
  • Check local health department data. Because COVID-19 is spreading differently in different areas of the country, it's helpful to keep an eye on the situation near you. There is some on the CDC website, Durbin said, but she usually directs people to their local health department website for up-to-date information on their community.
  • If you're sick and are able to stay home, you should. Even if you've tested negative with an at-home rapid COVID-19 test, don't assume you're in the clear. "If you can take a sick day, you shouldn't go into the office where you're sneezing and coughing and febrile," Durbin said. Avoiding spreading the virus to others and "reducing the overall caseload is our best bet against new variants emerging," Hahn agreed.
  • Getting young kids vaccinated will help protect them and further reduce the population susceptible to infection, Durbin said. That may affect transmission, as well as the emergence of new variants.
  • Look forward to next-generation boosters. The next crop of vaccines, designed to target specific variants or multiple variants, will be a key step forward, the experts said. "The current vaccines were designed against a strain that's two years old or more," Durbin said. "We know the virus has mutated extensively."