A health worker takes a swab sample from a man for the COVID-19 coronavirus test at a 24-hour testing facility in Chennai, the city of India on January 20, 2022. Media reported that more than 9,000 people have been infected with the Omicron virus in India. Photo: AFP

Scientists are keeping a close watch on a recently discovered sub-variant of the Omicron version of the COVID-19 virus to determine how its emergence could effect pandemic spread.

The initial Omicron variant has become the dominant virus strain in recent months but British health authorities have notably identified hundreds of cases of the latest version, dubbed BA.2, while international data suggest it could spread relatively quickly.

The UK Health Security Agency (UKHSA) identified over 400 cases in Britain in the first 10 days of February in 2021 and the latest variant has been detected in some 40 other countries, accounting for a majority of recent cases in India, Denmark and Sweden. 

The UKHSA indicated Friday it had designated the BA.2 sub-lineage as a variant under investigation (VUI) as cases of it were on the increase even if, in Britain, the BA.1 lineage currently remains dominant.

The authority underlined that "there is still uncertainty around the significance of the changes to the viral genome," which required surveillance as, cases in recent days showed a sharp rise in BA.2 incidence notably in India and Demark.

"What surprised us is the rapidity with which this sub-variant, which has been circulating to a great extent in Asia, has taken hold in Denmark," French epidemiologist Antoine Flahault told AFP.

BA.2 has yet to be a variant of concern, but Flahault says countries have to be alert to the latest development as scientists ramp up surveillance.

"[France] expected a spike in contaminations in mid-January: It didn't happen and perhaps that is due to this sub-variant, which seems very transmissible but not more virulent" than BA.1, he observed.

"What interests us is if this [sub-variant] possesses different characteristics" from BA.1 in terms of contagiousness and severity, France's public health agency said Friday. 

Only a handful of BA.2 cases have emerged in France, but the country is monitoring developments as they spread across the Channel. "Very early observations from India and Denmark suggest there is no dramatic difference in severity compared to BA.1," tweeted Tom Peacock, a virologist at Imperial College,  adding the latest variant should not call into question the effectiveness of existing vaccines.

Peacock also stressed that "we do not currently have a strong handle on... how much more transmissibility BA.2 might have over BA.1. However, we can make some guesses, early observations."

AFP