Researchers are rushing to understand the H1N1 swine flu virus and its future impact.

Despite the growing number of infections globally, the World Health Organization said Thursday the situation hasn't changed fundamentally since the alert level was increased to five yesterday.

Scientists are starting to believe this virus won't kill the tens of millions of people many expected from the next pandemic.

"We do not have any evidence to suggest that we should move to phase six today, or any such move is imminent right now," said Dr. Keiji Fukuda, WHO's acting assistant director-general for health security and environment.

To reach level six, a declared pandemic, the virus would need to spread into the community in one country outside of North America.

"Certainly from what we're seeing now, it doesn't seem to be the scary virus of 1918 that we were predicting would be the next pandemic, or that we were preparing for anyway, which is the good news," said Dr. Todd Hatchette, director of virology and immunology at Dalhousie University in Halifax.

Researchers are studying the virus to learn how efficiently it spreads and to see if it mutates, knowing the more it circulates in the population, the greater the chances it will change.

If it becomes more virulent, public health agencies in North America are better prepared now than ever, said Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, and a member of the U.S. National Science Advisory Board on Biosecurity.

Supply chains vulnerable

But Osterholm is worried about how infections could affect developing and densely populated countries that supply many lifesaving drugs such as insulin and heart medications to North Americans.

"Most of those are generic drugs and they're made in countries like India and China," Osterholm said. "The supply chains are very thin, very vulnerable to any disruption, whether it be border closings or even widespread illness in those countries where they're made."

So far, pharmaceutical companies in India and China have said they are ready to ramp up production of antiviral drugs if needed.

Work also continues on developing a vaccine.

Once that happens, likely in late fall or early winter, Canada will be in better shape than many other countries since there is a vaccine manufacturing facility in Quebec and a deal with its owner, GlaxoSmithKline, that guarantees supply for Canadians.