PandemicPreparedness

In an update on the Omicron variant,  World Health Organization advises "recent trends from India, South Africa, the United Kingdom, and Denmark suggest that BA.2 is increasing in proportion. Drivers of transmission and other properties of BA.2 are under investigation but remain unclear to date." The Omicron BA.2 variant does not have the same deletion of the S gene that the BA.1 variant has. The presence of the deletion in the original Omicron variant allows labs to identify on routine PCR testing which specimens are likely to have Omicron, which is confirmed on full genetic testing. As the BA.2 variant does not have this signal, as BA.2 increases, a rise in Omicron might not be evident unless more specific analysis is done.

In Denmark, the BA.2 subvariant made up 45% of all COVID-19 cases in the 2nd week of January. "Initial analysis shows no differences in hospitalisations for BA.2 compared to BA.1.".

South Africa's National Institute for Communicable Diseases Genomic Surveillance update of 14 January shows a "BA.2 increase recently observed and to be confirmed by additional data". In January, 85% of COVID-19 cases are due to Omicron BA.1, while Omicron BA.2 accounts for 14% of cases.  

The Indian SARS-CoV-2 Genomics Consortium (INSACOG) stated on 10 January report that "BA.2 lineage is a substantial fraction in India and Sgene dropout based screening is thus likely to give high false negatives" and has become the dominant strain in multiple metros.

The United Kingdom has designated the sub-lineage as a variant under investigation. In late-January, the UK Health Security Agency (UKHSA) has published (PDF) an updated risk assessment for the variant noting that the BA.2 sub-lineage appears to have evidence of a growth advantage over BA.1 in more than one country. It is not clear whether this is due to increased transmissibility or immune evasion although the agency points out that it is probably too early to know what is driving the growth advantage. More detail is examined in the accompanying Technical Briefing (PDF) of 28 January.