(Reuters) - The U.S. Food and Drug Administration on Thursday recommended that booster doses of COVID-19 vaccines be modified beginning this fall to include components tailored to combat the currently dominant Omicron BA.4 and BA.5 lineages.
The FDA said manufacturers would not need to change the vaccine for the primary vaccination series, saying the coming year will be "a transitional period when this modified booster vaccine may be introduced."
The new booster shots would be bivalent vaccines, meaning doses would target both the original virus as well as Omicron.
The decision follows a recommendation by the agency's outside advisers to change the design of the shots this fall in order to combat more prevalent versions of the coronavirus.
BA.4 and BA.5 are now estimated to account for more than 50% of U.S. infections, according the U.S. Centers for Disease Control and Prevention (https://bit.ly/3sdkZE6), and have also become dominant elsewhere.
The FDA said in a statement on Thursday that it hoped the modified vaccines could be used in early to mid-fall.
Pfizer and Moderna have been testing versions of their vaccines modified to combat the BA.1 Omicron variant that caused the massive surge in cases last winter.
Although they have said those vaccines worked against BA.1 and the more recently circulating lineages, they did see a lower immune response against BA.4 and BA.5.
The companies had already been manufacturing their BA.1 vaccines, and said on Tuesday that swapping to a BA.4/BA.5 version could slow the rollout.
Pfizer/BioNTech, which on Wednesday announced a $3.2 billion contract to supply more COVID vaccine doses to the United States, said they would have a substantial amount of BA.4/BA.5 vaccine ready for distribution by the first week of October.
Moderna said it would be late October or early November before it would have the newly modified vaccine ready.
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