The FDA has until the early summer to decide whether vaccine makers need to change existing Covid shots to target different virus variants to avoid another possible surge in cases this fall, according to a top official at the drug regulator.

Dr. Peter Marks, who leads the Food and Drug Administration office responsible for vaccine safety and efficacy, told the agency’s advisory committee Wednesday that a decision would need to be made by June in order to have shots available in the fall. Marks said the U.S. could face another wave of infection at that time because the virus will continue to evolve as immunity from the current vaccines wanes.

Robert Johnson, a senior official at the Biomedical Advanced Research and Development Authority, said at the meeting that the biggest challenge in updating the shots will be coordinating across the vaccine makers to make sure they are focusing on the correct Covid variants.

Pfizer, Moderna and other vaccine makers are conducting clinical trials on omicron-based shots. However, the companies aren’t currently coordinating on their new vaccine formulas, according to Jerry Weir, head of the FDA’s division of viral products. Several FDA advisory panel members said public health authorities need to develop a unified approach across vaccine makers, similar to their work updating the flu vaccine to target new strains every year.

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