The Technical Advisory Group on COVID-19 Vaccine Composition of the World Health Organisation (WHO) has charged manufacturers to update the composition of current COVID-19 vaccines to match the protection demands of emerging variants.
The group on Tuesday said the current vaccines are based on the virus that circulated early in the pandemic which might not be adequate for potential variants.
It said there has been continuous and substantial virus evolution and it is likely that this evolution will continue, resulting in the emergence of new variants.
“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,” the Advisory Group said.
According to WHO, current vaccines appear to confer high levels of protection against severe disease outcomes associated with Omicron infection.
However, it is calling for 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 despite substantial increases in available vaccine supply, equity remains a challenge.
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The first interim statement from the advisory group highlighted the need for the development of vaccines that provide protection against infection and prevent transmission, in addition to the protection from severe disease and death, as a means to achieve a greater public health impact from COVID-19 vaccination.
The WHO also said that global cases of COVID-19 are declining along with testing rates in some regions but reporting of fresh rise in infections is also growing in some regions and countries.
Its epidemiological report shows that the Omicron variant remains dominant across the globe, comprising of several genetically related sub-variants, including BA.1, BA.2 and BA.3.
At a global level, WHO says the BA.1 sub-variant has been the predominant Omicron virus, but BA.2 has been increasing relative to BA.1 in recent weeks in several countries.
Data from population-level studies suggest that infection with BA.1 provides substantial protection against reinfection with BA.2.
Considerations
Some of the key issues the advisory group considered for update are that diverse levels of population immunity exist between countries due to different waves. It weighed the possibility that the performance of any updated vaccine(s) may vary depending on the nature and magnitude of previously acquired immunity.
And when updated vaccines become available, a substantial proportion of the global population might have been exposed to SARS-CoV-2, either as a result of vaccination or prior infection.
There are also considerable uncertainties as to how the virus will continue to evolve and the antigenic characteristics of future variants. Given widespread transmission of Omicron globally, the possibility of its continued evolution is high and a new variant may emerge before an updated vaccine can be produced and delivered at scale.
