WHO says the new omicron BA.2 variant will spread globally

The World Health Organization expects a more contagious version of omicron to increase circulation worldwide, but it is unclear whether the Covid variant can re-infect people infected with earlier versions of the omicron strain.

Maria Van Kerkhove, head of AI, speaks at a press conference on the COVID-19 pandemic at the United Nations in Geneva, Switzerland.

Maria Van Kerkhove, who is the World Health Organization's technical chief for Covid-19, said Tuesday that global health agencies are tracking four different versions of OMICRON. Van Kerkhove said the currently dominant BA.1 sub-variant may become more common than the ba.2 variant, which was already more contagious.

"BA.2 is more contagious than BA.1, so we expect BA.2 testing rates to increase worldwide," Van Kerkhove said during a Q&A session broadcast live on WHO social media platforms on Tuesday.

WHO is monitoring BA.2 to see if the sub-variant causes an increase in new infections in countries where Omicron cases rise rapidly and then decline sharply, she said.

Van Kerkhove stressed that there is no indication of a difference in the severity of infection caused by any one subvariate, though she notes that research is ongoing. Omicron doesn't usually make people as sick as alpha and delta variants, although it does spread faster.

Researchers in Denmark found that BA.2 is about 1.5 times more contagious than BA.1 and is better at infecting people who are vaccinated or even immunized. However, people who are fully vaccinated are less likely to transmit the virus than unvaccinated people.

Van Kerkhove said these vaccines are still very effective in preventing serious illness and death, although they do not prevent all infections. She called on people to be vaccinated indoors and wear masks.

Dr Abdi Mahamud, WHO's Event Manager for Covid, said it was unclear whether BA.2 could reinfect people who had previously been infected with BA.1.

This can have a significant impact on the extent to which the virus spreads. A UK study found that two-thirds of people infected with OMICRON said they had been infected with Covid before.

According to an international database that tracks variants of Covid, most U.S. states have confirmed the presence of BA.2, although its level of transmission is low, with 460 cases confirmed to date.