In September 2021, WHO established the Technical Advisory Group on COVID-19 Vaccine Composition (TAG-CO-VAC). This multidisciplinary group of 18 experts reviews and assesses the public health implications of emerging VOCs on the performance of COVID-19 vaccines and provides recommendations on COVID-19 vaccine composition.[1] The work of this group complements that of the Technical Advisory Group on SARS-CoV-2 Virus Evolution (TAG-VE), the Strategic Advisory Group of Experts on Immunization (SAGE) and its Working Group on COVID-19 Vaccines, and the working groups of the WHO R&D Blueprint for Epidemics.   

Since its emergence, the SARS-CoV-2 virus has continued to evolve and WHO has designated five variants as SARS-CoV-2 Variants of Concern (VOC) to date – namely Alpha, Beta, Gamma, Delta and Omicron – due to their impact on transmission, disease severity, or capacity for immune escape. 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 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 and will advise WHO on updated vaccine compositions, as required. This framework considers the global spread and transmissibility, clinical severity, genetic, antigenic and phenotypic characteristics of the VOC, including capacity for immune escape and assessments of vaccine effectiveness.[2]

Since the WHO classified the Omicron variant as a VOC on 26 November 2021, the TAG-CO-VAC has met regularly to review the evidence on the characteristics of the Omicron variant. This statement reflects the current understanding of the implications of the emergence of the Omicron variant on current COVID-19 vaccines and provides the TAG-CO-VACs current perspective on vaccine options for the future.

Global public health goals of COVID-19 vaccines

With available COVID-19 vaccines, the current focus remains on reducing severe disease and death, as well as protecting health systems. 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 will be reduced against symptomatic disease caused by the Omicron variant, but protection against severe disease is more likely to be preserved. However, 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.

Please click here to read the original article