The World Health Organization does not believe the outbreak of monkeypox outside of Africa requires mass vaccinations as measures like good hygiene and safe sexual behaviour will help control its spread, a senior official said on Monday.

In an interview with Reuters, Richard Pebody, who leads the high-threat pathogen team at WHO Europe, also said immediate supplies of vaccines and antivirals are relatively limited.

His comments came as the U.S. Centers for Disease Control and Prevention said it was in the process of releasing some Jynneos vaccine doses for use in monkeypox cases.

Public health authorities in Europe and North America are investigating over 100 suspected and confirmed cases of the viral infection in the worst outbreak of the virus outside of Africa, where it is endemic.

The primary measures to control the outbreak are contact tracing and isolation, he said, noting that it is not a virus that spreads very easily nor has it so far caused serious disease.

"We're not at a situation where we're moving to widespread vaccination of populations," he said.

It is unclear what is driving the outbreak, with scientists trying to understand the origin of the cases and whether anything about the virus has changed. There is no evidence the virus has mutated, a senior executive at the U.N. agency said separately on Monday.

Many - but not all - of the people who have been diagnosed in the current monkeypox outbreak have been men who have sex with men (MSM).

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