The World Health Organisation's annual assembly in Geneva has been told that developing countries in Africa, Asia and Latin America are ill-equipped for a H1N1 swine flu pandemic.
Poor nations are doing all they can but it might not be enough
WHO Director-General Margaret Chan said the virus, which has so far killed 74 people, mostly in Mexico, and infected nearly 9,000 others in 40 mainly affluent countries, could leave poor nations "bearing the brunt", if its spread widens.
Chan's comments were supported by delegates from the regions themselves.
Viliami Tangi, health minister of the Pacific Island of Tonga, said poor countries like his simply lack adequate medical staff, laboratories and drug-stockpiles.
He said the initial outbreaks in wealthy countries such as the United States and Japan, which prompted rapid research, had "helped all of us".
A Nigerian delegate said African countries were "far from being ready", while Sri Lanka's health minister Nimal Siripala de Silva, who is president of this year's WHO assembly, said he hoped delegates would reach a deal about how vaccine manufacturers should share viral samples.
Chan also said it was essential governments cooperate and openly share information.
Health experts warn that the current onset of winter in the southern hemisphere could provide fertile conditions for the new viral strain alongside seasonal flu.
WHO reluctant to declare pandemic
Residents in Mexico, where the flu broke out, are still exercising caution
At the meeting in Geneva, which has been shortened from nine days to five so those attending can return home to deal with the influenza crisis, ministers and experts are also discussing what would trigger the WHO to declare a full pandemic.
WHO's Margaret Chan is still cautioning against doing so at this stage.
"We remain in phase five," she said.
That level indicates only that a pandemic is imminent. Chan said it was a difficult "balancing act" between warning the public but also providing reassurance.
Britain's Health Secretary Alan Johnson also led calls in Geneva for caution. "We need more time to study this," he said, referring to data being gathered world-wide.
Greece has become the latest country to confirm its first case of swine flu. A 19 year-old student, who recently returned from the United States, has been hospitalized in Athens.
Children and teens vulnerable
Young people seem to be especially at risk, according to the US Centers for Disease Control and Prevention, the CDC.
CDC spokeswoman, Dr. Anne Schuchat said most of the 200 Americans hospitalized so far were younger people, in contrast to the elderly who are normally the hardest hit by seasonal flu.
Dr. Schuchat said one hypothesis researchers are examining is that adults aged over 65 may have some protection due to their exposure to a distantly related virus a long time ago.
Editor: Nick Amies