The World Health Organization (WHO) said on Saturday that the risk of a pandemic caused by the A/H1N1 virus is still very high and there is still the possibility to raise the alert level to Phase 6 from the current Phase 5.
"At the present time, I would still propose that a pandemic is imminent because we are seeing the disease spread," Michael Ryan, the agency's director for global alert and response, told a news briefing in Geneva.
"This is the time for us to prepare, and be ready," he said.
The WHO's current pandemic alert level remains at Phase 5, which is characterized by human-to-human spread of the virus in two or more countries in only one WHO region.
Currently the sustained spread of the virus is still confined to the region of North America, notably Mexico and the United States.
Although human cases have also been confirmed in Europe and Asia, there is still no evidence suggesting that sustained community outbreaks have occurred in the two regions, according to the WHO official.
But Ryan warned that the possibility to raise to pandemic alert Phase 6, which means sustained community outbreaks out of North America, cannot be ruled out.
"At this point, we have to expect that Phase 6 will be reached, and we have to hope that it is not reached," he said.
According to a latest WHO update, the world's total number of lab confirmed A/H1N1 infections has increased to 658, with 16 countries being affected.
Mexico, the epicenter of the outbreak, has officially reported 397 confirmed human cases of infection, including 16 deaths. The U.S. government has reported 160 laboratory confirmed human cases, including one death.
Governments that reported laboratory confirmed cases with no deaths include Austria (1), Canada (51), Hong Kong, China (1), Costa Rica (1), Denmark (1), France (2), Germany (6), Israel (3), Netherlands (1), New Zealand (4), Republic of Korea (1), Spain (13), Switzerland (1) and Britain (15).