An Omicron-specific booster could be ready by August, the CEO of US biotech firm Moderna has told Reuters, but the firm is still gathering clinical data to determine whether that vaccine would offer better protection than a new dose of the existing jab.

Moderna chief executive Stephane Bancel said in an interview the company aimed to have a booster ready by August 2022, before next autumn when he said more vulnerable people may need it.

"We believe a booster will be needed. I don't know yet if it is going to be the existing vaccine, Omicron-only, or bivalent: Omicron and existing vaccine, two mRNA in one dose."

He said a decision would be made in the coming months when clinical data becomes available.

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