WHO experts group lays out COVID-19 vaccine update decision process

The World Health Organization’s (WHO) expert group on COVID-19 vaccine composition is evaluating current evidence on SARC-CoV-2 variants to decide whether the vaccines need to be updated.

Members of WHO’s Technical Advisory Group on COVID-19 Vaccine Composition, an independent body of experts, laid out their work on this process in a Nature Medicine commentary, noting, “Entering the fourth year of the COVID-19 pandemic, index virus-based vaccines across several different platforms continue to provide high levels of protection against severe disease caused by all variants of SARS-CoV-2, including Omicron.”

“However, there has been continuous and substantial evolution of SARS-CoV-2 since the virus emerged, posing challenges to the ongoing public health response, including ensuring that vaccines continue to provide protection,” the authors add.

Vaccines are a critical tool available to fight this pandemic, and ensuring they remain effective is a top concern for WHO. A high priority is that vaccines should continue to be effective at preventing severe disease and death from COVID-19.

The article describes how the advisory group evaluates evidence to inform its advice on COVID-19 vaccine composition, and outlines remaining challenges and evidence gaps that the scientific community needs to address to allow for future, timely decisions on modifications.

The experts said, “Sustained community transmission of SARS-CoV-2 applies selective pressure on the virus, leading to further evolution. The trajectory and timeline of further virus evolution are uncertain, and delays between recommendations to update vaccine antigen composition and roll-out of updated vaccines are inevitable.”

Looking at future prospects, the commentary in Nature noted, “The current approach to vaccine antigen composition may not be sustainable in the long term, given the length of time for vaccine development, the paucity of surveillance data globally and the regulatory requirements in different countries. Enhanced mucosal immunity may improve protection against infection and transmission of SARS-CoV-2, and the TAG-CO-VAC encourages vaccine development in this area.”

The authors include the members of the technical advisory group, and Rebecca Grant, Jilian A. Sacks, Maria D. Van Kerkhove, Marie-Ange Wambo, Homa Attar Cohen, Samuel Mesfin, James R. Otieno, Lorenzo Subissi and Sylvie Briand from WHO. See this link for details: https://www.who.int/groups/technical-advisory-group-on-covid-19-vaccine-composition-(tag-co-vac)/about