The World Health Organization is expected to say an Omicron-targeted Covid-19 vaccine dose can be administered as a third shot in order to broaden immune responses in the face of a virus that is “likely” to continue to evolve.

The preliminary advice, as described by two people with knowledge of the matter and contained in documents seen by the Financial Times, marks a significant shift in the thinking of global health authorities. The recommendation, which comes from a technical group within the health body, is the first to back the use of a variant-specific vaccine since the heavily mutated and heavily infectious Omicron viral variant emerged late last year.

The interim advice could be published as early as Friday, according to the people. The WHO did not respond to specific questions and said it was “aware” that a statement from the technical group was “forthcoming”. The WHO would only make a real-world policy recommendation once safety and other data had become available for variant-specific vaccines, the people said.