The WHO Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC) continues to closely monitor the genetic and antigenic evolution of SARS-CoV-2 variants, immune responses to SARS-CoV-2 infection and COVID-19 vaccination, and the performance of COVID-19 vaccines against circulating variants. Based on these evaluations, WHO advises vaccine manufacturers and regulatory authorities on the implications for future updates to COVID-19 vaccine antigen composition. The next decision-making meeting of the TAG-CO-VAC is scheduled for December 2026, after which a statement on COVID-19 vaccine antigen composition and an accompanying data annex will be published on the WHO website. These meetings are timed to balance the availability of the latest epidemiological, immunological, and virological data, with the kinetics of vaccine-induced protection and the lead time manufacturers need to update the antigen composition of authorized COVID-19 vaccines.

The purpose of this statement is to guide the scientific community and vaccine manufacturers as to which data should be generated ahead of the December 2026 TAG-CO-VAC deliberations. It is an update to the previous statement on the types of data requested in March 2026.1