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BA.2 variant takes over. What’s known about it?

Laura Ungar

AP – In the latest battle of the coronavirus mutants, an extra-contagious version of Omicron has taken over the world.

The coronavirus version known as BA.2 is now dominant in at least 68 countries, including the United States (US).

The World Health Organization (WHO) said it makes up about 94 per cent of sequenced Omicron cases submitted to an international coronavirus database in the most recent week.

And the Centers for Disease Control and Prevention (CDC) said it was responsible for 72 per cent of new US infections last week.

Pathologist at Houston Methodist in Texas Dr Wesley Long said he’s seen BA.2 quickly become dominant in his medical system.


BA.2 has lots of mutations. It’s been dubbed “stealth Omicron” because it lacks a genetic quirk of the original Omicron that allowed health officials to rapidly differentiate it from the Delta variant using a certain PCR test.

One reason BA.2 gained ground, scientists said, is that it’s about 30 per cent more contagious than the original Omicron. In rare cases, research showed it can sicken people even if they’ve already had an Omicron infection – although it doesn’t seem to cause more
severe disease.

Vaccines appear equally effective against both types of Omicron. For both, vaccination plus a booster offers strong protection against severe illness and death.


Coronavirus cases rose in parts of Europe and Asia when BA.2 became dominant, and some scientists are concerned that the variant could also push up cases across the US.

Besides being more contagious, it’s spreading at a time when governments are relaxing restrictions designed to control COVID-19. Also, people are taking off their masks and getting back to activities such as travelling, eating indoors at restaurants and attending crowded events.

Long said he feels “very certain” that cases will eventually go back up in the US, whether that’s because of BA.2 or some future variant. “If it’s BA.2, it may be more of a wave or a speed bump than a surge.”


As the coronavirus continues to evolve, the WHO is tracking other mutants, including hybrids known as “recombinants”.

These include combinations of Delta and Omicron and hybrids of BA.2 and the original Omicron, also known as BA.1.

One recombinant that health authorities are tracking closely is a BA.1-BA.2 hybrid called XE, which was first detected in the United Kingdom (UK) in January.Scientists believe it may be about 10 per cent more contagious than BA.2.


The advice from experts remains the same: Take precautions to avoid getting COVID-19.

“The virus is still out there circulating,” Long said.

“Vaccination is still your best defence.”

Get the shots if you haven’t already, and get the second booster if you’re eligible because you are 50 or older or have a compromised immune system.

“If cases start going up in your community, think about assessing your risk level,” Long said.