The world's top health official cast doubt over plans to vaccinate millions of people against the "unstoppable" swine flu pandemic, saying immunisations would not be available for months.
The comments by World Health Organization chief Margaret Chan came as Australia reported a spike in cases and Argentina dramatically upped its toll of those killed by the virus from 94 to 137 over the last three days.
Chan told the Guardian newspaper that a vaccine would not be available for several months, despite statements from health officials in Britain that the first stocks would start arriving in August.
"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 said.
"Clinical trial data will not be available for another two to three months," she added.
With the global death toll from A(H1N1) now reaching at least 429, WHO director of vaccine research Marie-Paul Kieny had said Monday that a swine flu vaccine should be available as early as September.
Chan's comments cast doubt on plans announced by countries around the world to start vaccinating those most at risk of contracting swine flu as early as next month.
Germany said it envisioned having to order some 25 million doses of a vaccine now under development to immunise nearly a third of its population.
Australia, the Asia-Pacific region's worst-hit country, was bracing to immunise the entire population against swine flu and has already placed an advance order for 21 million courses of a vaccine.
Currently in the southern hemisphere's traditional winter flu season, Australia said its number of cases had risen to over 10,000 and warned that the real number could be much higher.
Meanwhile, Italy predicted it may have to deal with between three and four million cases of swine flu by March 2010, the country's deputy health minister Ferruccio Fazio said.
He added that by the end of this year some 8.6 million Italians would have been vaccinated against the A(H1N1) virus, with the most vulnerable and those working in the emergency services given priority.
Argentina said its death toll rose to 137, making it the worst-hit in terms of fatalities after the United States, which has 211 fatalities and 37,000 confirmed infections according to the latest tally by US health officials.
Mexico, the third worst-hit country with 124 deaths and 12,521 infections according to the latest numbers, said late Tuesday that swine flu cases were picking up in the southeast, especially in Chiapas state near Guatemala.
Health ministers from six South American countries were to meet Wednesday to seek a coordinated response to fighting the epidemic. Argentina will host the meeting of ministers from Bolivia, Brazil, Chile, Uruguay and Paraguay.
Elsewhere on the continent, now in its winter season, Ecuador reported the disease has spread to 14 of the country's 24 provinces, with the total number of infections at 264 with three deaths.
And in Peru, some 15,000 doctors called for a nationwide protest on Wednesday to demand better prevention against swine flu, which has claimed at least five lives and infected around 2,000 people there.
"We demand addressing adequately the needs of hospitals in order to prevent further mistakes in the treatment of swine flu and to avoid more deaths," Leoncio Diaz, president of the Peruvian Medical Federation (FMP), told AFP.
A boy died in a Madrid hospital due to a medical error after his mother died from swine flu. She was Spain's first fatality from the disease.