A recently discovered subvariant of the highly contagious Omicron coronavirus strain has now been detected in 57 countries, the World Health Organization (WHO) says.
In its weekly epidemiological update, the United Nations’ health agency noted on Tuesday that in some countries, the sub-variant now accounts for more than half of all sequenced Omicron cases.
It said little was known yet about the differences between the sub-variants but several studies have suggested that BA.2, also known as the “stealth variant”, was more infectious than the original sub-lineage.
Maria Van Kerkhove, an epidemiologist and the WHO’s technical lead on the coronavirus pandemic, told reporters that initial data indicated BA.2 had “a slight increase in growth rate over BA.1”, the first version of the Omicron variant.
The highly transmissible Omicron is generally known to cause less severe disease than previous variants such as Delta.
The WHO said Omicron, which accounts for more than 93 percent of all coronavirus specimens collected in the past month, has several sub-lineages: BA.1, BA.1.1, BA.2 and BA.3.
The first versions identified as BA.1 and BA.1.1 still account for more than 96 percent of all Omicron cases submitted to GISAID, it added, referring to the public virus tracking database.