Key points:
- The WHO Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC) held its twice-yearly decision-making meeting in May 2026 to review the evolution of SARS-CoV-2, the effectiveness of currently approved COVID-19 vaccines and the implications for COVID-19 vaccine antigen composition.
- The objective of any update to COVID-19 vaccine antigen composition is to enhance vaccine-induced immune responses to circulating SARS-CoV-2 variants, when needed.
- Following this meeting, the TAG-CO-VAC advises vaccine manufacturers that monovalent LP.8.1 is the recommended vaccine antigen.
- Other antigens (e.g. XFG, NB.1.8.1) or other approaches that demonstrate broad and robust neutralizing antibody responses or efficacy against currently circulating SARS-CoV-2 variants could also be used.
- Vaccination remains an important public health countermeasure against COVID-19 and vaccination should not be delayed in anticipation of access to vaccines with an updated antigen composition. As per the March 2026 WHO Strategic Advisory Group of Experts on Immunization (SAGE) recommendations , Member States should consider routine COVID-19 vaccination of groups at highest risk of severe COVID-19 disease.
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 effectiveness 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. In December 2025, the TAG-CO-VAC advised vaccine manufacturers that monovalent LP.8.1 is the recommended vaccine antigen . Multiple manufacturers (using mRNA or recombinant protein-based vaccines) have updated COVID-19 vaccine antigen composition to monovalent LP.8.1 formulation. Several of these vaccines have been approved for use by regulatory authorities and have been introduced into vaccination programmes. Previous statements from the TAG-CO-VAC can be found on the WHO website .
The TAG-CO-VAC reconvened on 7-8 May 2026 to review the genetic and antigenic evolution of SARS-CoV-2; immune responses to SARS-CoV-2 infection and/or COVID-19 vaccination; the effectiveness of currently approved vaccines against circulating SARS-CoV-2 variants; and the implications for COVID-19 vaccine antigen composition.
Evidence reviewed
The published and unpublished evidence reviewed by the TAG-CO-VAC included: (1) SARS-CoV-2 genetic evolution, with additional support from the WHO Technical Advisory Group on Virus Evolution (TAG-VE); (2) Antigenic characterization of previous and emerging SARS-CoV-2 variants using virus neutralization tests with animal antisera and further analysis of antigenic relationships using antigenic cartography; (3) Immunogenicity data on the breadth of neutralizing antibody responses elicited by currently approved vaccine antigens against circulating SARS-CoV-2 variants using animal and human sera, with additional support from WHO Coronavirus Network
