WHO to Revise Definition of Global Pandemic

Emma Hitt, PhD

May 22, 2009

May 22, 2009 — The World Health Organization (WHO) announced today that it is revising the criteria that will cause a move to pandemic alert level phase 6, the final alert phase, indicating that a global pandemic of influenza A (H1N1) is under way.

Phase 6 in the current structure of the pandemic alert levels had been defined as "community level outbreaks in at least one other country in a different WHO region in addition to the criteria defined in Phase 5." Phase 5 is defined as human-to-human transmission of the virus in at least 2 countries in a single WHO region.

Keiji Fukuda, MD, MPH, assistant director-general ad. interim for health security and environment at the WHO, spoke during a WHO media briefing in Geneva today.

Dr. Fukuda described 3 types of transmission that are taking place. In North America, there is widespread community transmission. In Europe and Asia, there is a "mixed" picture, including both travel-related cases as well as community transmission. The third level consists of travel-related cases only, he said.

Community outbreak in more than 1 WHO region would ordinarily have been grounds for raising the pandemic alert level to phase 6. But the WHO stopped short of making that recommendation today, even though community-level outbreaks are occurring in Europe.

"In the here and now, I cannot tell you what the new criteria for phase 6 are," he said. According Dr. Fukuda, there would need to be a change in severity or transmission that would affect countries.

"To give you an example, if the virus moved into the southern hemisphere and caused significant outbreaks...and [if] we see patterns that are different than we are seeing in North America, and [if] it appears clear that there is a much more severe effect or a change in how the virus is behaving — these are the kinds of things that would signal that there is an increased risk for people getting harmed," he said. Or if "something is changing and that you really need to increase your state of alertness, your state of preparation even to a higher level than it is now."

"It's a little bit early to give the exact words about what [the new criteria] might be," he said.

According to the WHO, currently 42 countries are reporting 11,168 laboratory-confirmed cases including 86 deaths.


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