Omicron’s new variant cousin, BA.2, has arrived in the US. But don’t panic yet, experts say. – USA TODAY

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  • Cases of omicron BA.2 have been reported in at least four states – California, New Mexico, Texas and Washington – and on three other continents.
  • The newer variant, like the original omicron, has lots of mutations, including about 20 in the region targeted by most COVID-19 vaccines.

Yes, a new variant of omicron is spreading on at least four continents. But, no, it shouldn’t be a cause for panic, Massachusetts scientists said Tuesday.

Unlike two years ago when everyone was first learning about COVID-19, there are now many tools to combat the disease, and, like its cousin, omicron BA.2 is expected to remain relatively mild.

“I don’t think it’s going to cause the degree of chaos and disruption, morbidity and mortality that BA.1 did,” said Dr. Jacob Lemieux, an infectious disease specialist at Massachusetts General Hospital in Boston. “I’m cautiously optimistic that we’re going to continue to move to a better place and, hopefully, one where each new variant on the horizon isn’t news.”

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While COVID-19 cases have begun to decline in places like Massachusetts, where omicron hit hard late last year, cases of BA.2 are on the rise in the Philippines, India, Denmark and South Africa, Lemieux said. Cases have been reported in the United States, too – so far in California, New Mexico, Texas and Washington state.

It’s not clear yet whether BA.2 is pushing out the original omicron variant, now referred to as BA.1, he said.

In Denmark, for instance, the rise of BA.2 is coming as BA.1 falls, but they’re currently split about 50-50, so “it’s not clear which of these variants is driving the outbreak,” Lemieux said.

Meanwhile, in South Africa, where cases had fallen dramatically after a huge surge around Thanksgiving, BA.2 is now more prevalent than BA.1.

“What we don’t know and still have almost no information on is what impact this will have on case counts, on hospitalizations, on deaths,” he said.

Scientists still know very little about the transmissibility of BA.2 compared to BA.1, said Jeremy Luban, a professor of molecular medicine, biochemistry & molecular pharmacology at UMass Medical School.

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Lemieux, Luban and other medical experts made their comments Tuesday on a weekly call with media organized by the Massachusetts Consortium on Pathogen Readiness.

It’s also too early to say whether BA.2 will escape the protection provided by vaccines or existing medications, Luban said. 

The newer variant, like the original omicron, has lots of mutations, including about 20 in the region targeted by most vaccines. BA.2 also has mutations not found in BA.1, which could limit the effectiveness of monoclonal antibodies, he said.

“We don’t know what the significance of these mutations are going to be, especially in a population that has already encountered BA.1,” said Luban, adding that BA.2 may acquire its own Greek name, to distinguish it from omicron.

Many people caught omicron even after being infected with the delta variant, but it’s not clear whether someone who caught omicron remains vulnerable to BA.2, said Dr. Daniel Kuritzkes, chief of the division of infectious diseases at Brigham and Women’s Hospital and a professor at Harvard Medical School. 

T cells, the immune soldiers that seem to prevent severe disease after vaccination, will likely still be effective against BA.2, said Dr. Bruce Walker, director of the Ragon Institute of MGH, MIT and Harvard, which focuses on immunology research.

“It’s T cells that probably have a major effect on the disease course once somebody does become infected,” he said. “It’s encouraging that at least from the T cell side – they may not be protected from getting infected but (vaccines) should help mitigate disease.”

It’s not known when or where first BA.2 emerged, though it appears to have diverged from BA.1 a number of months ago, Lemieux said.

Although both variants first appeared in southern Africa, it’s not clear whether they originated there or simply came to public attention in that region, which has provided extensive genetic sequencing during the pandemic to track variants.

In order to spread, a new variant must be more transmissible – or just get lucky. 

“We don’t know what the factors are that are promoting the spread of BA.2, whether it’s chance, whether it’s intrinsically more transmissible, whether it’s more transmissible in the context of natural immunity against BA.1 – those are answers we’ll start to get over the coming weeks,” Lemieux said. 

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“It will take time to figure out as we watch it in different contexts as it spreads,” Luban added.

The reality, Lemieux said, is that while BA.2 is likely to keep spreading at least for a few weeks in places around the world, “we have an ability to combat the virus that is orders of magnitudes different from where we were two years ago.”

“Yes, we have some hard decisions. We have some evidence to collect. We can’t predict the future,” said Lemieux, noting that vaccines and drugs like monoclonal antibodies and antivirals have reduced the risk tenfold of becoming severely ill or dying from COVID-19.  “But I think we are in a tremendously optimistic place, despite all the transmission, despite all the challenges ahead.”

Contact Karen Weintraub at 

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