Covid: What is Omicron subvariant BA.2 and is there cause for concern?

The highly transmissible omicron variant is now responsible for half of the world’s Covid-19 infections. But omicron is an umbrella term for several strains closely related to SARS-Cov-2, the most common being the BA.1 strain.

Now, more countries, mainly in Asia and Europe, are seeing an increase in cases caused by BA.2.

BA.2 is sometimes called the “stealth” subvariant because it lacks the genetic marker that the researchers were using to quickly identify whether an infection was a “regular” (BA.1) or delta case.

As with other variants, a BA.2 infection can be detected by PCR and antigen tests, but they only indicate whether the case is positive or negative for Covid – they cannot distinguish the variants. For this, further checks are needed.

BA-2 appears to be more transmissible than previous variants, but fortunately, no data to date suggests it is more serious.

So how concerned should we be with this emerging variant? Check out what we know about her.

What is BA.2?

As viruses mutate into new variants, they sometimes split or branch into sub-lineages. The delta variant, for example, is made up of 200 different subvariants.

The same movement occurred with the ômicron, which includes the BA.1, BA.2, BA.3 and B.1.1.529 lineages.

BA.1 is responsible for most cases. According to the WHO (World Health Organization), nearly 99% of the viral DNA submitted to the global GISAID database (as of January 25, 2022) has been sequenced as this subvariant.

It is unclear where it originated, but BA.1 was first detected in November in sequences uploaded to the Philippine database.

Where is BA.2 spreading?

Since November, 40 countries have added thousands of BA.2 sequences to their databases.

According to the WHO, the subvariant is already becoming dominant in the Philippines, Nepal, Qatar, India and Denmark. In some places, its growth was marked.

According to Denmark’s State Serum Institute, about half of the country’s new Covid-19 cases are caused by BA.2.

India is another country where BA.2 is rapidly replacing the delta and omicron variants BA.1, according to a survey conducted by molecular biologist Bijaya Dhakal.

The Philippine Department of Health (DOH) said the BA.2 subline was already predominant in samples received in late January.

And in England, more than 1,000 confirmed cases of BA.2 have been identified, according to the UK Health Safety Agency (UKHSA).

She has been designated as an “under investigation variant” by the British health authorities, which means they are following her closely, but are not too concerned about her at this point.

BA.2 infections in Germany are also growing faster than BA.1 and delta, according to Meera Chand, UKHSA’s Covid-19 director.

Is BA.2 more transmissible?

A study of 8,500 families and 18,000 individuals conducted by the State Serum Institute of Denmark found that BA.2 was “significantly” more transmissible than BA.1. It more easily infected vaccinated and booster-dose individuals than previous variants, the study found, although vaccinated people were less likely to transmit it.

Another study, from the United Kingdom, also found greater transmissibility for BA.2 compared to BA.1.

But a preliminary evaluation found no evidence that the vaccines would be less effective against symptomatic diseases for any of the subvariants.

Is BA.2 more dangerous?

There are no data to suggest that BA.2 leads to more severe disease than the previous subvariants of omicron.

“Looking at other countries where BA.2 is now overtaking (BA.1), we are not seeing any greater increases in hospitalization than expected,” said Boris Pavlin, WHO’s Covid-19 Response Team, on Tuesday. thursday (2).

Pavlin added that even if BA.2 replaces BA.1, it may have little effect on the trajectory of the pandemic and the way people are treated.

“Its impact is unlikely to be substantial, although more data is needed,” he said.

As with previous variants, experts believe the vaccines will continue to be highly effective against serious illness, hospitalization and death.

“Vaccination offers profound protection against severe cases, including the micron,” Pavlin said.

Chand from the UK added: “So far, there is not enough evidence to determine whether BA.2 causes more severe disease than BA.1, but data are limited and the UKHSA is continuing to investigate.”

“We must remain vigilant and get the vaccines. We must all continue to test ourselves if symptoms appear.”