FDA Aims to Phase Out Original COVID-19 Vaccines

The FDA is considering switching completely to bivalent COVID-19 vaccines, including for primary series doses, according to briefing documents released ahead of an advisory committee meeting later this week, and the agency is planning to offer an updated booster each fall similar to the flu vaccine.

On Thursday, the Vaccines and Related Biological Products Advisory Committee (VRBPAC) will vote on whether to harmonize primary series and booster doses of all COVID-19 vaccines to a single bivalent composition containing components targeting BA.4/5 and the original SARS-CoV-2 strain.

The agency is also seeking feedback on simplifying the immunization schedule. To do this, the FDA proposes a two-dose annual series for certain young children, older adults, and people with immunocompromising conditions. All other individuals would receive a single dose.

Population-level data on hybrid immunity (from prior infection plus vaccination) could also one day play a role in simplifying schedules by helping determine risk levels for different age groups, as multiple studies have suggested durable protection in these individuals, the agency noted.

As outlined by the FDA, strain selection would become an annual process for VRBPAC each June (as was done last year to select the current bivalent vaccines), with an updated vaccine produced and deployed for use no later than September each year. If a more pathogenic vaccine-escape variant were to emerge, however, an ad-hoc strain-selection meeting would be convened.

The agency said this would simplify vaccine deployment, lead to fewer vaccine administration errors, and ease communication, which could “potentially” lead to better vaccine uptake and enhance public health.

“The existence of multiple COVID-19 vaccine compositions, immunization schedules, and differences in vaccine compositions for primary series and booster doses complicate vaccine administration, uptake, and communication,” FDA staff explained.

Studies have suggested that bivalent mRNA vaccines produce better neutralizing antibody responses to Omicron subvariants while maintaining neutralizing capability against the ancestral strain, according to the agency.

Ideally, the FDA noted, a new composition each year would be done in coordination with the World Health Organization (WHO), but “the FDA and VRBPAC may need to consider a change in COVID-19 strain composition for U.S. vaccines without a prior WHO strain recommendation.” Unlike influenza, the FDA said, there is currently no coordinated global infrastructure or governance of vaccine composition evaluations for SARS-CoV-2.