The FDA's vaccine advisors will meet Thursday to vote on whether an XFG monovalent vaccine should be preferred for COVID-19 shots for the 2026-2027 season. [MEDPAGE TODAY]

The Vaccines and Related Biological Products Advisory Committee (VRBPAC) will also discuss what circumstances would warrant a non-JN.1 lineage variant -- such as BA.3.2, also called "Cicada" -- for next season's vaccines.

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In an FDA briefing document, the agency noted that in the U.S., descendants of the JN.1 variant of Omicron remain prominent and have diversified into multiple lineages, including XFG, NB.1.8.1, and LF.7.

All major manufacturers (Pfizer, Moderna, Sanofi) have indicated they are "prepared to produce an XFG vaccine" for the 2026-2027 season, according to the agency.

While XFG variants remain dominant, the BA.3.2 variant began to pick up steam globally last fall and reached a prevalence of 30% in some European countries, even though it remains a minor variant in the U.S.

BA.3.2 has more than 70 substitutions and deletions in the spike protein relative to JN.1 descendants, according to FDA staff. Yet available phenotypic data suggest that its "limited expansion is consistent with reduced intrinsic fitness, including weaker ACE2 binding, lower infectivity ... and modest replication capacity relative to [JN.1 variants], despite substantial antigenic drift and antibody escape."

The FDA document also noted that datasets show a higher proportion of BA.3.2 sequences from pediatric patients.

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