COVID-19: Current vaccines may need to be updated, WHO warns

World Health Organisation (WHO) Technical Advisory Group has warned that current COVID-19 vaccines may need to be updated to ensure their continued effectiveness against Omicron and future variants.

The opinion is contained in an interim statement from the WHO Technical Advisory Group on COVID-19 Vaccine Composition, an expert group appointed by the UN health agency, which was established in September, 2021.

Amid increased Omicron circulation, members have called for “urgent and broad access” to current vaccines globally, both for protection and to mitigate the emergence of new variants of concern, or VOCs.

The 18 experts are developing a framework to analyse the evidence on emerging VOCs “in the context of criteria that would trigger a recommendation to change COVID-19 vaccine strain composition and will advise WHO on updated vaccine compositions, as required.”

They said vaccines that had a high impact on prevention of infection and transmission, in addition to prevention of severe disease and death, were needed and should be developed.

“Until such vaccines are available, and as the SARS-CoV-2 virus evolves, the composition of current COVID-19 vaccines may need to be updated, to ensure that COVID-19 vaccines continue to provide WHO-recommended levels of protection against infection and disease by VOCs, including Omicron and future variants.’’

The Technical Advisory Group will consider a change in vaccine composition to ensure doses continue to meet WHO criteria, including protection against severe disease, and to improve vaccine-induced protection.

Vaccines need to be “based on strains that are genetically and anti-genetically close” to circulating variants.

Additionally, they must protect against severe disease and death, and be more effective against infection, thus lowering virus transmission and the need for stringent public health and social measures.

The expert group has encouraged COVID-19 vaccine manufacturers to generate and provide data on the performance of current and Omicron-specific vaccines, which will inform any decision when changes to vaccine composition may be required.

The SARS-CoV-2 virus first emerged in Wuhan, China, in December 2019, and has continued to evolve. WHO has so far designated five variants of concern: Alpha, Beta, Gamma, Delta and Omicron.

“While the Omicron variant is spreading rapidly across the world, the evolution of SARS-CoV-2 is expected to continue and Omicron is unlikely to be the last VOC,” the experts said.