WHO says the new omicron BA.2 subvariant will rise globally, but scientists don't know if it can reinfect people

February 10, 2022: -The World Health Organization expects a more transmissible version of omicron to increase circulation worldwide. However, it’s not yet clear if the subvariant can reinfect people who caught an earlier version of the omicron strain.

Maria Van Kerkhove, the WHO’s Covid-19 technical lead, said Tuesday the global health agency is tracking four different versions of omicron. Van Kerkhove said the BA.2 subvariant, more contagious than the currently dominant BA.1 version, will likely become more common.

“BA.2 is more transmissible than BA.1, so we expect to see BA.2 increasing in detection around the world,” Van Kerkhove said during a question-and-answer session live-streamed on the WHO’s social media platforms Tuesday.

The WHO is monitoring BA.2 to see if the subvariant causes an increase of new infections in countries that saw a rapid rise and then a sharp decline in omicron cases, she said.

Van Kerkhove emphasized that there’s no indication of a difference in the severity of infections caused by either subvariant, though she noted that research is ongoing. Omicron generally doesn’t make people as sick as the alpha and delta variants, though it does spread faster.

Researchers in Denmark have found that BA.2 is about 1.5 times more transmissible than BA.1, and it is more adept at infecting vaccinated and even boosted people. However, fully vaccinated people are less likely to spread it than unvaccinated.

Van Kerkhove said the shots remain highly effective at preventing severe disease and death, though they don’t control all infections. She called on people to get vaccinated and wear masks indoors.

Dr. Abdi Mahamud, the WHO’s Covid incident manager, said it’s unclear whether BA.2 can reinfect people who previously had BA.1.

That could have a significant impact on how much the virus can spread. A study in the U.K. found that two-thirds of people who caught omicron said they had Covid before.

Most states in the U.S. have confirmed the presence of BA.2. However, it’s circulating at a low level, with 460 total cases confirmed so far, according to an international database that tracks Covid variants.