By Bhanvi Satija and Sriparna Roy

(Reuters) – Advisers to the U.S. Food and Drug Administration on Thursday unanimously recommended that updated COVID-19 shots being developed for a fall vaccination campaign target one of the currently dominant XBB coronavirus variants.

The panel voted 21-0 in favor of XBB-targeted shots, and the committee’s discussion indicated that the XBB.1.5 Omicron subvariant would be preferred.

FDA official Dr. Peter Marks indicated the agency was likely to settle on XBB.1.5, which manufacturers suggested could be ready for inoculations soonest.

COVID vaccine makers Pfizer/BioNTech, Moderna and Novavax are already developing versions of their respective vaccines targeting XBB.1.5 and other currently circulating subvariants. Preclinical data from all three was presented at the meeting.

“It seems like it’s the most feasible to get across the finish line early without resulting in delays in availability,” Melinda Wharton, vaccine policy official at U.S. Centers for Disease Control and Prevention (CDC) said of a shot aimed at XBB.1.5.

If XBB.1.5 is chosen as the target for this year’s campaign, it would be especially helpful to Novavax, as their protein-based vaccine takes longer to manufacture than rival mRNA-based shots. If the FDA chose a different target, Novavax could again find itself playing catch up to rivals.

“The fact that most of the manufacturers are ready to work on XBB.1.5 is an added reason to select this strain or this variant given the immunologic data,” said meeting chair Dr. Arnold Monto.

After the meeting, Novavax issued a release saying it expects to be able to deliver its XBB-targeted COVID shot this fall.

FDA staff reviewers in documents released this week said available evidence suggests this year’s shots should target an XBB subvariant. XBB and its offshoots, which now account for most U.S. infections, are descendents of the Omicron variant that caused COVID cases to surge to record levels early last year.

U.S. health regulators are looking to bring the next COVID shots more closely in line with the circulating virus.

Pfizer, in its presentation, said it could supply its monovalent shots targeting the XBB.1.5 subvariant by the end of July, while Moderna said it was prepared to supply a new variant-containing shot for fall season.

A so-called monovalent, or single target, vaccine would be a change from the most recent bivalent COVID boosters that targeted both the original strain of the coronavirus and Omicron.

The FDA takes recommendations from its outside experts into consideration before making a final decision on composition of the shots.

Thursday’s proceedings comes after an advisory group to the World Health Organization (WHO) last month recommended the next wave of COVID booster shots be updated to target XBB subvariants. Europe’s medicine regulators have also backed that recommendation.

The CDC recommended booster shots broadly last year. But panel member Dr. Paul Offit questioned whether the shots needed to be recommended for “everybody every season,” noting that the highest risk groups are those most likely to benefit from an annual booster.

Only about 17% of the U.S. population – some 56.5 million people – received a COVID booster during the 2022-2023 vaccination season, according to government data through early May. Older Americans were boosted at a higher rate than the general population.

Between Moderna and Pfizer, Morningstar analyst Karen Andersen expects 75 million doses to be sold in the United States during the 2023-2024 campaign.

Moderna last month said it continues to expect the U.S. annual COVID-19 market to be 100 million doses, largely in line with Pfizer’s view of 102 million.

COVID deaths and hospitalizations have declined in 2023, and the U.S. government in May ended its COVID Public Health Emergency, which had allowed millions of Americans to receive vaccines, tests and treatments at no cost.

(Reporting by Bhanvi Satija and Sriparna Roy in Bengaluru; Editing by Michael Erman and Bill Berkrot)

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