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April 27, 2009 -- Swine flu has prompted the World Health Organization to heighten its pandemic alert level from phase 3 to phase 4.
That means that the swine flu outbreak has taken a "significant step" toward becoming a pandemic, but "we're not there yet," says Keiji Fukuda, MD, assistant director-general for health,security, and environment at the World Health Organization (WHO).
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Like people, pigs can get influenza (flu), but swine flu viruses aren't the same as human flu viruses. View the slideshow.
Speaking at a late-night news conference in Geneva, Fukuda noted that a swine flu pandemic may not be inevitable because the situation is "fluid" and the virus could change -- something flu viruses are notorious for doing -- and it's unpredictable whether the virus will worsen or fade away.
Fukuda says because the swine flu virus is already in several countries, containment "is not feasible," so countries should focus on mitigating the virus.
Those efforts are already under way in the U.S., where the federal government has declared swine flu to be a public health emergency.
At a news conference earlier today, CDC Acting Director Richard Besser, MD, was asked what it would mean in the U.S. if the WHO raised the pandemic alert level.
"It doesn't really matter, from our perspective, what you call this," Besser replied. "We are acting aggressively," and heightening the WHO?pandemic alert level "may have more relevance for a country that has yet to see cases."?
Here are the key steps health officials want you to take to protect yourself and others from swine flu:
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Here is how the World Health Organization defines its pandemic alert phases:?
Phase 1: No viruses circulating among animals have been reported to cause infections in humans.
Phase 2: An animal influenza virus is known to have caused infection in humans.
Phase 3: An animal or human-animal influenza virus has caused sporadic cases or small clusters of disease in people, but it has not resulted in human-to-human transmission sufficient to sustain community-level outbreaks.
Phase 4: There is verified human-to-human transmission of an animal or human-animal influenza virus able to cause community-level outbreaks. Phase 4 indicates a significant increase in risk of a pandemic but does not mean that a pandemic is a foregone conclusion.
In phase 4, sustained person-to-person transmission "is limited to one relatively contained geographic area, and it is felt that there is a possibility of a containment effort being successful" with antiviral drugs and vaccines, if there are any (there aren't for the new swine flu virus), WHO spokesman Gregory Hartl told reporters earlier today.