WHO says health workers priority for H1N1 vaccine

Marie-Paule Kieny, WHO director of the Initiative for Vaccine Research, also said vaccine production yields so far had been "poor" but manufacturers were studying alternative strains which may increase output.

She also confirmed obesity as a risk factor for severe H1N1, or swine flu, complications.

"The (group of experts) recommended first that healthcare workers should be immunised in all countries in order to retain a functional health system as the virus evolves," she told a news conference.

"In terms of the other groups it depends on the strategy a country wants to follow."