What we know about Omicron sub-variant BA.2

First identified in November 2021, the BA.2 sublineage of the Omicron variant has now become dominant worldwide, according to the World Health Organization.

The BA.2 represented nearly 86% of all sequenced cases between February 16 and March 17.

Initial data suggests that BA.2 appears inherently more transmissible than its highly contagious Omicron siblings BA.1 and BA.1.1 which currently remains the most common

The BA.1 was previously the most common Omicron sub-variant reported. So far, there is insufficient evidence to determine whether BA.2 causes more severe illness than BA.1. But, limited, early evidence suggests it may not be more severe than BA.1.

Omicron itself has been consistently found to have lower severity when compared to Delta.

Scientists say that, as with other Omicron variants, vaccines are less effective against BA.2 but booster shots can provide significant protection.

BA.2 has been held responsible for the recent surge in cases in China and European countries like the UK and Germany.

It is often called the ‘stealth variant’ because it is slightly harder to track. A missing gene in BA.1 allowed it to be tracked by default through a common PCR test, which uses three genes to detect coronavirus.

BA.2, on the other hand, can only be found by genomic sequencing since standard PCR tests could not tell it apart from the delta variant.

While BA.1 and BA.2 share around 30 mutations, BA.2 has eight unique mutations not found in BA.1 and lacks 13 mutations that BA.1 does have.

One of the key concerns about BA.2 was whether it could re-infect those who had already had the original BA.1 subvariant of Omicron.

A recent study by Danish scientists -- which is yet to be peer-reviewed -- suggested that people previously infected with BA.1 have strong protection against BA.2.

The study found that Omicron BA.2 re infections do occur shortly after BA.1 infections but are rare.