Geneva: At a global level, BA.1 has been the predominant Omicron lineage, however, the proportion of reported sequences designated as BA.2 has been increasing relative to BA.1 in recent weeks, and is the predominant Omicron lineage in several countries, the World Health Organization stated today.
It may be noted that Omicron is comprised of several genetically related sublineages, including BA.1, BA.2 and BA.3, each of which is being monitored by WHO and partners. WHO said BA.1 and BA.2 have some genetic differences, which may make them antigenically distinct.
Reinfection with BA.2 following infection with BA.1 has been documented, however, initial data from population-level studies suggest that infection with BA.1 provides substantial protection against reinfection with BA.2, at least for the limited period for which data are available, it said.
The current global epidemiological situation is characterized by rapid and relatively synchronous dominance of Omicron variant in all regions.
“While global cases are declining, there are reduced testing resources and capacities in some areas and the epidemiological situation remains heterogeneous, with a number of regions and countries reporting increases in new weekly cases, while others are now reporting declines,” WHO stated.
It may be mentioned that current vaccines are based on the virus that circulated early in the pandemic (ancestral virus e.g. GISAID: hCoV-19/Wuhan/WIV04/2019). Since then, there has been continuous and substantial virus evolution and it is likely that this evolution will continue, resulting in the emergence of new variants.
In light of this, WHO recommended that the composition of current COVID-19 vaccines may therefore need to be updated. “Any update to current COVID-19 vaccine composition would aim to, at a minimum, retain protection against severe disease and death, while ensuring the breadth of the immune response against circulating and emerging variants, which may be antigenically distinct,” it stated.
The World Health Organization, with the support of the Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC), continues to review and assess the public health implications of emerging SARS-CoV-2 Variants of Concern (VOC) on the performance of COVID-19 vaccines.
It said that since the publication of the interim statement on COVID-19 vaccines on January 11, 2022, Omicron became the dominant Variant Of Concern globally, rapidly replacing other circulating variants.
“The public health goal of COVID-19 vaccination prioritizes protection against severe disease and death. Current vaccines appear to confer high levels of protection against severe disease outcomes associated with Omicron infection. The TAG-CO-VAC therefore strongly supports urgent and broad access to current COVID-19 vaccines for primary series and booster doses, particularly for groups at risk of developing severe disease,” it said.
– global bihari bureau
