GENEVA, SWITZERLAND - One dose of H1N1 vaccine should offer ample protection against the pandemic flu strain, the head of vaccine research at the World Health Organisation (WHO) said on Monday.

"All the data that we have seen show that one dose is sufficient," Marie-Paule Kieny told journalists in Geneva.

The WHO official said that the vaccines developed against the H1N1 flu strains are yielding larger volumes than first expected.

"Availability of vaccine will be higher than what was feared at one time," she said.

Donated vaccines will be provided from the WHO to about 100 low-income and middle-income countries to immunise their health workers from the spreading virus, Kieny added. --REUTERS