BA.4 and BA.5 Are New Omicron Subvariants: What to Know
ItIt took only about one month for Omicron subvariant BA.2.12.1 to infect most new COVID-19 victims in America. But even newer iterations of the Omicron variant are spreading rapidly through the U.S. and are poised to outcompete past versions of the virus, reinfect millions of Americans, and extend the country’s current COVID-19 surge.
As of June 11, U.S. Centers for Disease Control and Prevention estimates that BA.4 and BA.5 represent more than 21% each of the new cases. Experts say these two subvariants were created from Omicron lines to be even more contagious. They can also bypass vaccinations or immunity. People can become infected again even though they have had Omicron before.
Here’s what to know about the latest Omicron subvariants.
They’re built to escape immunity
Omicron BA.4 (and BA.5) were identified for the first time in South Africa in February 2022 and February 2022 respectively. BA.2.12.1 was a result of BA.2 in America, while scientists from the New York State Health Department identified the first cases in South Africa in April.
All three subvariants have a similar mutation that distinguishes them from older versions of Omicron, says Marc Johnson, a microbiology and immunology professor at the University of Missouri who leads the state’s wastewater surveillance program. “There’s clearly a convergence on how to get around the immune system,” he says.
Paul Bieniasz is a Rockefeller University professor who studies viral evolution. He says that these newer Omicron versions can overcome antibodies from prior vaccinations or previous infection. Several research groups—including a team at Columbia University, a consortium based in Japan, and an international group including South African scientists—have tested antibodies from prior Omicron infections against BA.4 and BA.5. The three research groups found that these antibodies provide protection several times greater against Omicron BA.1 (or BA.2), which are older variants.
While these studies have not yet been peer-reviewed, scientists like Bieniasz consider them part of an expected trend in the coronavirus’ continued evolution. Future variants will “acquire more and more mutations that enable them to evade the antibodies we’re generating in response to vaccination and infection,” he says.
Some treatments aren’t as effective against them
The newer subvariants can also bypass monoclonal antibody treatments, which use lab-made immune system proteins developed from earlier strains of SARS-CoV-2. “Most of those antibodies that have been made are now obsolete,” Bieniasz says. Eli Lilly has only one treatment that works against Omicron. It is the Eli Lilly Omicron-specific treatment. Other treatments, such as the antiviral drug Paxlovid, can be used to reduce severe Omicron infection symptoms.
They’re more contagious, but it’s still unclear whether they cause more severe disease
Although limited data is available on the severity and impact of these subvariants are not yet complete, scientists remain optimistic, based upon reports from South Africa which saw fewer deaths and hospitalizations. during its BA.4 and BA.5 wavesComparable to BA.1.
However, it’s clear that BA.4, BA.5, and BA.2.12.1 are more contagious than past versions of OmicronThey are spreading faster than ever. The CDC estimates that BA.4 or BA.5 caused approximately 1% of all new COVID-19 infections in May and then rose to cause 22% in June. BA.2.12.1 has similarly exploded: it’s now causing an estimated 64% of new infections in the U.S. and has caused the majority of new cases nationwide since mid-May.
Helix’s data shows Omicron is declining and BA.4 and BA.5 are gaining ground. Shishi Luo (associate director of bioinformatics, infectious diseases, Helix) says that the U.S. has already experienced a BA.1 surge and is currently in the middle of a BA.2 rise. She says that BA.4 or BA.5 might cause another wave to this surge of BA.2.
It’s unclear which strain will dominate the U.S. next
Luo, along with other experts, are trying to determine if one of the Omicron subvariants is going to outcompete another. BA.4 and BA.5 are driving new COVID-19 increases in other countries. However, the subvariants of Omicron have not been able to directly compete with BA.2.12.1. The U.K. has early evidence that BA.4 may be spreading slightly faster than BA.2.12.1. However, the future landscape is still unclear.
BA.4, BA.5, and BA.2.12.1 are all “competing for the same people, because they kind of have the same advantage,” Johnson says. His team’s Missouri wastewater surveillance network is showing that BA.4 and BA.5 are causing more cases in some places, while BA.2.12.1 is causing more cases in others. He says that the areas dominated by BA.184.108.40.206 have seen a greater increase in cases. These findings are contrary to reports that BA.4 (or BA.5) has taken over BA.2.12.12.
Bieniasz states that Omicron might be different in various parts of the nation. BA.4. and BA.5 could gain less ground in Northeast areas where there is a strong BA.220.127.116.11 surge, Bieniasz says. They will be more common in the South or West. People’s behavior, such as the choices to hold large gatherings or travel, can also play a role in which variant comes out on top when different strains are “closely matched in their fitness,” he says.
However, one thing is certain: many Americans can be reinfected by these subvariants. “We can expect to be reinfected,” Luo says. “And every time we’re infected, it’s at best a hassle. And at worst, it can lead to debilitating symptoms,” she adds, pointing to the risk of Long COVID—which, recent studies suggest, is common even among people who have been vaccinated.
“We didn’t really appreciate how slippery this virus would be,” Bieniasz says. He expects the coronavirus to continue evolving around the immune system’s defenses. Moderna has developed Omicron-specific booster vaccine that may increase the protection against future reinfections.
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