New Delhi: The BA.2 sub-variant of Omicron is far more transmissible than the BA.1 strain. However, there is no cause for alarm as it is no more severe than the original strain, said the World Health Organisation (WHO) on Tuesday, adding that it is closely monitoring the BA.2 sub-variant of Omicron.
“BA.2 sublineage should continue to be considered a variant of concern and that it should remain classified as Omicron,” the WHO said in a statement, calling on public health authorities to keep a strict vigil over the variant.
The BA.2 sub-variant is becoming dominant in Denmark, increasing in the UK and also cropping up elsewhere, including India and Pakistan.
“At a global level, the proportion of reported sequences designated BA.2 has been increasing relative to BA.1 in recent weeks, however the global circulation of all variants is reportedly declining,” the UN health agency said.
How is BA.2 different?
BA.2 differs from BA.1 in its genetic sequence, including some amino acid differences in the spike protein and other proteins. Studies have shown that BA.2 has a growth advantage over BA.1. According to WHO, studies are underway to understand the reasons for this growth advantage, but initial data suggest that BA.2 appears to spread faster than BA.1, which currently remains the most common Omicron sublineage reported.
However, this difference in transmissibility appears to be much smaller than the difference between BA.1 and Delta. Studies are evaluating the risk of reinfection with BA.2 compared to BA.1.While cases of Omicron infecting a person twice have been documented, however, initial data from population-level reinfection studies suggest that infection with BA.1 provides strong protection against reinfection with BA.2.
The WHO clarified that based on data from several countries, there was no reported difference in clinical severity between BA.2 and BA.1. This holds true in cases where immunity from vaccination or natural infection is high.
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