The World Health Organization (WHO) Technical Advisory Group on COVID-19 Vaccine Composition “has recommended that the next COVID vaccine formulations use a monovalent (single-strain) JN.1 lineage.” CIDRAP reported on the recommendations.

Experts with the group also noted that “the XBB lineage has been displaced by JN.1 and…circulating variants will likely be derived from JN.1.” The group had recommended a switch to XBB.1.5 for COVID vaccines a year ago, “but evidence from animal studies and human sera experiments suggests that XBB.1.5 and JN.1 are antigenically distinct.”

As far as the XBB.1.5 vaccine’s effectiveness against the JN.1 strain, experts said that studies show “some protection during the first 3 months after vaccination, but with a slight reduction in VE against JN.1 for protection against severe and symptomatic disease, similar to what neutralization antibody titer studies found. They added, however, that the ability for XBB.1.5 vaccination to protect against symptomatic disease may be less robust as SARS-CoV-2 evolution continues from JN.1.” A candidate monovalent JN.1 vaccine, on the other hand, produces higher neutralization antibodies against co-circulating JN.1 variants such as KP.2 than does the XBB.1.5 vaccine,” according to a single study.

For now, any emergency listed or prequalified COVID vaccines are still good to administer, urges the WHO. The U.S. Food and Drug Administration (FDA) Vaccines and Related Biological Products Advisory Committee (VRBPAC) “will meet on May 16 to discuss and make strain-selection recommendations for 2024-25 COVID vaccines.”