Are the new omicron subvariants more infectious or more deadly? What to know

As we head into another summer with COVID-19, the landscape of coronavirus variants is changing yet again.

A relatively new omicron subvariant — BA.2.12.1 — now accounts for the majority of COVID-19 cases in the country. But experts say two other variants, BA.4 and BA.5, are picking up steam and could very well take over within the next few months.

As of June 18, subvariant BA.2.12.1 is responsible for about 56% of all COVID-19 cases in the US, according to the most recent data from the Centers for Disease Control and Prevention.

Meanwhile, the previously dominant BA.2 now only accounts for 9% of cases. Back in early May, BA.2 and BA.2.12.1 were each responsible for about half of US coronavirus infections, the CDC data show. And in March, BA.1 (the original omicron strain) was still in the lead.

In some areas of the country, BA.2.12.1 has taken over even more: “I’m in Connecticut, and it’s like 80% of all sequences that we see right now,” Anne Hahn, Ph.D., a postdoctoral researcher at the Yale School of Public Health, told TODAY.

“And that turnover between BA.1, then BA.2 and now BA.2.12.1 was very fast, which is kind of unexpected,” said Hahn, whose work is investigating the viral evolution of SARS-CoV-2. “We are now at BA.5, and it’s June 2022. The first of this whole family emerged in November 2021. So that’s really concerning.”

That 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,” Bill Hanage, Ph.D., associate professor of epidemiology at the Harvard TH Chan School of Public Health, told TODAY.

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, who is also the co-director of Harvard’s Center for Communicable Disease Dynamics.

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 it’s challenging to evaluate the true severity of disease due to this subvariant. “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.

On the horizon: BA.4 and BA.5

While BA.2.12.1 is dominant right now in the US, other emerging omicron subvariants — called BA.4 and BA.5 — are beginning to gain ground. First detected in South Africa, BA.4 now accounts for about 11% of cases in the US, and BA.5 is responsible for nearly 24%, the CDC data show.

“They’re not taking off at the same rate everywhere,” Hanage said, noting that the two new strains seem to be popping up in Texas and Florida, and that BA.5 cases are 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,” he explained. 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 expects 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.

Companies are working on the next generation of COVID-19 boosters, which will target specific omicron-related variants. For instance, Moderna is planning to release a bivalent vaccine this fall that targets the original coronavirus strain, as well as the omicron variant.

This week, the company shared new clinical trial data in a press release, which said that the shot provides better protection against BA.4 and BA.5 than the original vaccine. The booster was even more effective against the original omicron strain.

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 omicron variant.

How to protect yourself and your community

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 feverish,” Durbin said. Avoiding spreading the virus to others and “reducing the overall caseload is our best bet against new emerging variants,” 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.”


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