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Omicron BA.2 in the U.S.: What we know about the emerging ‘stealth’ variant of COVID-19

The strain has already reached U.S. shores, with cases in California, New Mexico, Texas, and elsewhere. Here’s what experts know so far.

Omicron BA.2 in the U.S.: What we know about the emerging ‘stealth’ variant of COVID-19
[Photo: Getty Images]

Much of the world’s still fixated on COVID’s original omicron variant—omicron BA.1, in virologist terms—but now its stealth-variant sibling, BA.2, is creeping into the spotlight.

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You may or may not have heard of it, depending on your news junkiness and your surviving tolerance for pandemic-watching two years into the long-running horror show. What exactly is omicron BA.2? If you’re here, you’re about to find out.

Well? What is it?

It’s a newer strain of the COVID-19 virus—which mutated into the omicron BA.1 variant, which then mutated into the omicron BA.2 sub-variant. It’s unclear when or where BA.2 first emerged, but scientists believe it diverged from BA.1 at least several months ago.

Ok, where is it now? Here?

As of last week, there were over 8,000 cases of BA.2 identified since November 2021, with cases rising early in the Philippines, India, U.K., Denmark, and Germany. It has been detected in at least 40 countries and several U.S. states, including California, New Mexico, Texas, and Washington State, where two confirmed cases were reported this past week.

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What do the experts say? Should I be worried?

There are two big questions: Is BA.2 more contagious, and is it deadlier?

Since it’s still emerging, and researchers are in the discovery stage, there are no clear answers yet. But, regarding transmissibility, there are signs that BA.2 is spreading fast: In Denmark, it now accounts for roughly half of all omicron cases; and in South Africa, where the original omicron variant was first detected, BA.2 is now more prevalent than BA.1. According to a tweet from Tom Peacock, a researcher at Imperial College’s Department of Infectious Disease, “[Consistent] growth across multiple countries is evidence BA.2 may be some degree more transmissible than BA.1.”

As for whether it’s deadlier, experts have very limited data to be able to tell yet. But early evidence from India and Denmark suggests it does not cause more severe illness than BA.1 (phew, but again—it’s very early, so maybe don’t fling off the mask and rush Tivoli Gardens just yet).

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Am I safe if I’m vaccinated? Or if I already caught the original omicron?

Again, too early to tell . . . but certainly, experts are watching. As James Musser, an infectious diseases research director at Houston Methodist Hospital, told the Washington Post, “We know omicron can clearly evade preexisting immunity” from both vaccines and exposure to other virus variants. “What we don’t know yet is whether son-of-omicron does that better or worse than omicron.” Stay tuned.

Why is it called the stealth omicron?

“Stealth” variant might scream silent killer, but it’s no scarier than the last omicron. Its nickname refers to its impact on testing: It has genetic traits that elude classification as an omicron variant in polymerase chain reaction assays. Typically, samples of omicron virus leave a hallmark trace in PCR results, called an s-gene target failure; however, BA.2 lacks the spike gene deletion responsible for the signature pattern.

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