What to know about the omicron variant and subvariant BA.2

A more transmissible subvariant, BA.2, has become the dominant strain in the United States as the omicron surge has waned. Those most at risk are the unvaccinated and older than 75

The BA.2 “stealth” omicron variant is expected to soon become the dominant strain. Here is what you need to know about a possible new wave of infections. (Video: Brian Monroe, John Farrell/The Washington Post)

After emerging in November, the omicron variant spread rapidly across the globe because of mutations that allowed it to evade some of the immunity produced by vaccinations and previous infections. In midwinter, tens of millions of people in the United States, many of them fully vaccinated and boosted, were infected by omicron.

Now, a subvariant called BA.2, which has many mutations not seen in omicron, is posing a new threat and accounting for a swiftly growing share of cases in the United States, as it propels sharp case increases in Europe and Asia. Preliminary research suggests BA.2 is at least 30 percent more transmissible than omicron.

The Centers for Disease Control and Prevention estimated that, as of March 19, BA.2 accounted for 35 percent of new infections. The genomics company Helix, analyzing more current data, put its own estimate at 70 percent. Both estimates show a steady rise toward dominance of the subvariant.

The rise in BA.2 cases comes as federal health authorities have relaxed certain recommendations. On Feb. 25, the CDC updated its mask guidelines, which no longer recommend masking for most people in indoor public spaces in counties with low to medium levels of covid-19 community transmission and hospitalizations. Most of America is now classified at those lower levels. However, other prevention strategies, such as vaccinations, are still recommended.

Coronavirus: What you need to know

End of the public health emergency: The Biden administration ended the public health emergency for the coronavirus pandemic on May 11, just days after WHO said it would no longer classify the coronavirus pandemic as a public health emergency. Here’s what the end of the covid public health emergency means for you.

Tracking covid cases, deaths: Covid-19 was the fourth leading cause of death in the United States last year with covid deaths dropping 47 percent between 2021 and 2022. See the latest covid numbers in the U.S. and across the world.

The latest on coronavirus boosters: The FDA cleared the way for people who are at least 65 or immune-compromised to receive a second updated booster shot for the coronavirus. Here’s who should get the second covid booster and when.

New covid variant: A new coronavirus subvariant, XBB. 1.16, has been designated as a “variant under monitoring” by the World Health Organization. The latest omicron offshoot is particularly prevalent in India. Here’s what you need to know about Arcturus.

Would we shut down again? What will the United States do the next time a deadly virus comes knocking on the door?

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