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 variant of concern (VOC). The WHO Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC) is 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. The TAG will advise WHO on updated vaccine compositions, as required.

Vaccines that have received WHO Emergency Use Listing, across several vaccine platforms, provide a high level of protection against severe disease and death caused by VOCs. For the Omicron variant, the mutational profile and preliminary data indicate that vaccine effectiveness is reduced against symptomatic disease caused by this variant, but protection against severe disease is more likely to be preserved.

More data on vaccine effectiveness, particularly against hospitalization, severe disease, and death are needed, including for each vaccine platform and for various vaccine dosing and product regimens, before recommendations can be made with respect to possible new vaccine compositions.