Omicron subvariants BA.4, BA.5 and the future of coronavirus variants

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

A relatively new ommicron subvariant – BA.2.12.1 – is now responsible 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 in the coming 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 represents only 9% of cases. In early May, BA.2 and BA.2.12.1 were each responsible for about half of U.S. coronavirus infections, CDC data shows. And in March, BA.1 (the original omicron strain) was still in the lead.

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

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

That rapid conversion into variants is believed to be due to the mutations of each strain, particularly in the spike protein, which allow the virus to evade immune protection. In the case of BA.2.12.1, “it is believed to help bypass some of the antibodies generated by previous infections or vaccines,” Bill Hanage, Ph.D., associate professor of epidemiology at Harvard TH Chan School of Health, told TODAY.

But how much of BA.2.12.1’s success “is due to this, as opposed to being inherently more transmissible,” said Hanage, who is also co-director of Harvard’s Center for Communicable Disease Dynamics.

Does BA.2.12.1 cause more serious disease? “Parts of the country have had a relatively big bump (in cases) with BA.2.12.1, and that hasn’t really translated into extremely high rates of hospitalizations or deaths,” Hanage said.

But it is challenging to evaluate the true severity of the disease because of this subvariant. “The vast majority of the population is either vaccinated or has had a previous COVID infection, and that will affect the severity of the disease because there is some basic immunity,” Dr. Anna Durbin, an associate professor at Johns Hopkins University School of Medicine, told TODAY.

“The good news we can take from that is that we are still seeing protective effects of the vaccine against the more serious 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 currently dominant in the US, other emerging ommicron sub-variants – called BA.4 and BA.5 – are starting to gain ground. First discovered in South Africa, BA.4 now accounts for about 11% of US cases, and BA.5 accounts for nearly 24%, the CDC data shows.

“They’re not rising at the same rate everywhere,” Hanage said, noting that the two new species seem to be emerging in Texas and Florida, and that BA.5 cases are also on the rise in Washington state.

“In general, and it’s not clear if there’s a reason for that, they take off faster in places where BA.2 hasn’t been seen much,” he explained. That could be because BA.2 specifically provides some level of protection against these new variants or because having a more recent infection — of any variant — would provide some coverage, he said.

Hahn said she expects the new variants to “probably take over by the end of the summer”, noting that Portugal is currently experiencing a major surge, fueled by BA.5 cases. That’s “very concerning because this is one of the most vaccinated populations in the world, especially when it comes to boosters,” she added.

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

This week, the company shared new clinical trial data in a press release, stating that the injection offers better protection against BA.4 and BA.5 than the original vaccine. The booster was even more effective against the original Omicron strain.

What variants can we expect in the future?

All experts agreed that new variants are pretty much self-evident. And since the last few dominant variants have all been in the omicron family, it’s a good bet – but no guarantee – that the next ones will be too.

“You never want to bet that you’ll be surprised by this thing, but there seems to have been a shift,” Hanage said. And at this point, experts don’t expect another drastically new variant to pop up out of nowhere and quickly dominate as omicron did, Hahn said.

Previous variants, including alpha, delta, omicron (BA.1) and BA.2 “all began to evolve in the first few months after the virus entered the human population. They are not derived from each other,” Hanage explained. “But the things we’re seeing now are derived from ommicron, which is new.”

At the same time, however, it is important to recognize that the omicron subvariants are not identical to each other: “We call it the omicron family, but if you really look at the genetic distance of these relatives, they are just so different from each other. like alpha was for delta, for example,” Hahn said.

Ultimately, variants will “keep coming, they won’t stop,” Durbin said. “What do we know about other seasonal coronaviruses? They keep coming back, they keep mutating and we keep getting infected.”

The key points scientists will look at are whether the virus is starting to cause more serious illness, whether we should continue to get boosters to protect ourselves, and whether those vaccines should be regularly updated to better suit the strains that are circulating. , she said. Moderna and Pfizer are both working on booster shots, expected in the fall, targeting the ommicron variant.

How to protect yourself and your community

We may never be able to completely eradicate all variants of the coronavirus, Hanage said. But there are things we can do to reduce the chances that more will emerge and reduce the chances they have of taking over.

  • Keep wearing a mask. Yes, face masks still work – especially higher quality ones like 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 will protect you no matter what the people around you are doing,” Hanage said.
  • If you qualify, make a plan to get your second booster. While Durbin noted that booster protection seems to last less and less — “We’re looking at one to two months,” she said — if you’re over age 65 or have underlying conditions that make you more likely to get severe COVID-19, it’s worth getting the second booster. But it’s also worth planning when you need that extra protection most, such as before a trip or an event.
  • Check the details of the local health department. Because COVID-19 spreads differently in different parts of the country, it’s useful to keep an eye on the situation in your area. There are some on the CDC website, Durbin said, but she usually refers people to their local health department’s website for current information about their community.
  • If you’re sick and can stay home, you should. Even if you tested negative with a rapid home COVID-19 test, don’t assume you’re clear. “If you can be sick for a day, don’t go to the office where you sneeze, cough and have a fever,” Durbin said. Preventing the virus from spreading to others and “reducing the overall caseload is our best bet against the emergence of new variants,” Hahn agrees.
  • Vaccinating young children protects them and further reduces the population prone to infection, Durbin said. That can have consequences for the transmission, but also for the emergence of new variants.
  • Look out for next-generation boosters. The next crop of vaccines, designed to target specific variants or multiple variants, will be a significant step forward, the experts said. “Current vaccines are designed against a strain that is two years old or older,” Durbin said. “We know that the virus has mutated extensively.”


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