The opinion is contained in an interim statement from the WHO Technical Advisory Group on COVID-19 Vaccine Composition, which was established last September.

Broader access

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 analyze 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 have a high impact on prevention of infection and transmission, in addition to prevention of severe disease and death, are 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,” they wrote.

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.

Appeal to manufacturers

Vaccines need to be “based on strains that are genetically and antigenically 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,” said the expert group.