A subvariant of the Omicron coronavirus strain that some studies have shown may be more contagious than the original version has been detected in 57 countries, the World Health Organization (WHO) has announced, which has requested that studies are carried out on the characteristics of the virus.
In its weekly epidemiological bulletin, published Tuesday evening, the World Health Organization explains that the Omicron variant, which accounts for more than 93% of all coronavirus specimens collected over the past month, has several sub-variants: BA. 1, BA.1.1, BA.2 and BA.3.
BA.1 and BA.1.1 – the earliest identified versions – still constitute over 96% of the Omicron sequences uploaded to the global GISAID database.
However, the WHO notes a marked increase in the number of cases involving BA.2, which has several different mutations from the original version, in particular on the spike protein marking the surface of the virus and which is essential for entering human cells.
“Sequences designated BA.2 have been submitted to GISAID by 57 countries to date,” the WHO points out, adding that in some countries this subvariant now accounts for more than half of the Omicron sequences collected.
The WHO said little is still known about the differences between the subvariants and called for studies to be carried out on the characteristics of the virus, including its transmissibility, its ability to evade immune protections and its virulence.
Several recent studies have suggested that BA.2 is more contagious than the original Omicron.
In a statement to the press, Maria Van Kerkhove, one of the WHO’s leading experts on Covid, said on Tuesday that information on the subvariant was limited, but some initial data indicated that BA.2 had “a slight increase in growth rate compared to BA.1”.
Omicron generally causes less severe disease than previous coronavirus variants and Van Kerkhove said there was no evidence so far that the BA.2 subvariant was more severe.
Ahmed Achour
