The world's top health official said on Wednesday that a vaccine to combat the surging swine flu pandemic would not be readily available for months as the number of deaths from the virus spiralled.
The comments by World Health Organization chief Margaret Chan came as Australia and Japan reported a surge in cases of the A(H1N1) virus, and Argentina dramatically upped its death toll from 94 to 137 in just three days.
"There's no vaccine. One should be available soon, in August. But having a vaccine available is not the same as having a vaccine that has proven safe," Chan told Britain's Guardian newspaper.
"Clinical trial data will not be available for another two to three months," she added, contradicting health officials in Britain and elsewhere who said the first stocks would start arriving in August.
WHO director of vaccine research Marie-Paul Kieny, calling the pandemic "unstoppable", had said on Monday that a swine flu vaccine should be available as early as September.
Germany said it envisaged having to order some 25 million doses of vaccine to immunise nearly a third of its population.
Australia, the Asia-Pacific region's worst-hit country, has already placed an advance order for 21 million doses, enough to immunise its entire population.
Australia and Argentina are now in the southern hemispheric winter, and officials fear a major rise in infections when the northern hemisphere enters the colder months and regular influenza becomes rampant.