The World Health Organization (WHO) has recommended in a statement that future COVID-19 vaccines no longer include the original SARS-CoV-2 virus, but instead a different version that closely matches circulating variants.
The WHO’s Technical Advisory Group on COVID-19 Vaccine Composition on May 18 suggested including the XBB.1.5 variant, which is responsible for most new infections worldwide. The updated vaccine should focus on a single XBB variant rather than multiple versions.
Although not binding, this recommendation serves as a foundation for national vaccine decisions. Some experts have advocated for including multiple virus strains in the next shot, akin to the annual flu shot’s approach. The WHO group highlighted that slight differences exist among existing XBB variants and alternative formulations or platforms that generate strong neutralizing antibody responses against XBB descendent lineages may be considered.
The latest U.S. COVID-19 booster is bivalent, targeting the original SARS-CoV-2 version and two Omicron variants (BA.4 and BA.5). While these shots and previous vaccines remain effective against severe illness, hospitalization, and death, they offer less protection against infection as antibody levels decline over time. Updating the COVID-19 vaccine is crucial to address waning effectiveness, provided the strains in the vaccine closely match circulating ones. Targeting a single version of the virus may reduce the chances of achieving this alignment.