London : The World Health Organization(WHO) does not believe the monkeypox outbreak 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.

Richard Pebody, who leads the high-threat pathogen team at WHO Europe, also told Reuters in an interview that 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.

Germany's government said on Monday that it was assessing options for vaccinations, while Britain has offered them to some healthcare workers.

The primary measures to control the outbreak are contact tracing and isolation, Pebody said, noting that it is not a virus that spreads very easily, nor has it so far caused serious disease. The vaccines used to combat monkeypox can have some significant side-effects, he added.

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.

Most of the confirmed cases have not been linked to travel to Africa, which suggests there may be large amounts of undetected cases, said Pebody. Some health authorities suspect there is some degree of community spread.