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The Omicron subvariant, BA.2, is not only more transmissible than the original Omicron strain, BA.1, but may cause more severe disease, a lab study from Japan says.
"Our multiscale investigations suggest that the risk of BA.2 for global health is potentially higher than that of BA.1," the researchers said in the study published on the preprint server bioRxiv. The study has not been peer-reviewed yet.
The researchers infected hamsters with BA.1 and BA.2. The hamsters infected with BA.2 got sicker, with more lung damage and loss of body weight. Results were similar when mice were infected with BA.1 and BA.2.
"Infection experiments using hamsters show that BA.2 is more pathogenic than BA.1," the study said.
BA.1 and BA.2 both appear to evade immunity created by COVID-19 vaccines, the study said. But a booster shot makes illness after infection 74% less likely, CNN said.
What's more, therapeutic monoclonal antibodies used to treat people infected with COVID didn't have much effect on BA.2.
BA.2 was "almost completely resistant" to casirivimab and imdevimab and was 35 times more resistant to sotrovimab, compared to the original B.1.1 virus, the researchers wrote.
"In summary, our data suggest the possibility that BA.2 would be the most concerned variant to global health," the researchers wrote. "Currently, both BA.2 and BA.1 are recognised together as Omicron and these are almost undistinguishable. Based on our findings, we propose that BA.2 should be recognised as a unique variant of concern, and this SARS-CoV-2 variant should be monitored in depth."
If the World Health Organization recognized BA.2 as a "unique variant of concern," it would be given its own Greek letter.
But some scientists noted that findings in the lab don't always reflect what's happening in the real world of people.
"I think it's always hard to translate differences in animal and cell culture models to what's going on with regards to human disease," Jeremy Kamil, PhD, an associate professor of microbiology and immunology at Louisiana State University Health Shreveport, told Newsweek. "That said, the differences do look real."
"It might be, from a human's perspective, a worse virus than BA.1 and might be able to transmit better and cause worse disease," Daniel Rhoads, MD, section head of microbiology at the Cleveland Clinic in Ohio, told CNN. He reviewed the Japanese study but was not involved in it.
Another scientist who reviewed the study but was not involved in the research noted that human immune systems are evolving along with the COVID variants.
"One of the caveats that we have to think about, as we get new variants that might seem more dangerous, is the fact that there's two sides to the story," Deborah Fuller, PhD, a virologist at the University of Washington School of Medicine, told CNN. "Our immune system is evolving as well. And so that's pushing back on things."
Scientists have already established that BA.2 is more transmissible than BA.1. The Omicron subvariant has been detected in 74 countries and 47 U.S. states, according to CNN. About 4% of Americans with COVID were infected with BA.2, the outlet reported, citing the CDC, but it's now the dominant strain in other nations.
It's not clear yet if BA.2 causes more severe illness in people. While BA.2 spreads faster than BA.1, there's no evidence the subvariant makes people any sicker, an official with the World Health Organization said, according to CNBC.
BioRxiv: "Virological characteristics of SARS-CoV-2 BA.2 variant."
Newsweek: "Stealth Omicron BA.2 COVID Variant Could Be More Dangerous, Immune-Resistant Than BA.1 — Study."
CNN: "As BA.2 subvariant of Omicron rises, lab studies point to signs of severity."
CNBC: "WHO says the new omicron subvariant doesn't appear to be more severe than the original."
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Cite this: Subvariant May Be More Dangerous Than Omicron: Study - Medscape - Feb 18, 2022.