Swine Flu Pandemic Alert Level Raised

World Health Organization Raises Level From Phase 3 to Phase 4 -- Not Yet at Pandemic Level

Medically Reviewed by Louise Chang, MD on April 27, 2009
From the WebMD Archives

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).

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:

  • Wash your hands regularly with soap and water, especially after coughing or sneezing. Or use an alcohol-based hand cleaner.
  • Avoid close contact with sick people.
  • Avoid touching your mouth, nose, or eyes.
  • If you're sick, stay at home. Cover your nose and mouth with a tissue when you sneeze, and throw the tissue in the trash afterward.

Pandemic Alert Phases

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.

"Basically it's more of a very punctual, concentrated, local effort," Hartl said.

Phase 5: There has been human-to-human spread of the virus in at least two countries in one World Health Organization region (WHO regions are Africa, the Americas, the Eastern Mediterranean, Europe, Southeast Asia, and the Western Pacific). Phase 5 is a strong signal that a pandemic is imminent and that time is short to finalize mitigation measures.

In phase 5, sustained person-to-person transmission isn't just happening in one place; it's happening in several geographic areas.

"That means that the virus is much more widespread," Hartl said. "In that case, there would be decisions needed to be made" about vaccine production, antiviral drugs, and preventing health care systems from getting overloaded.

Phase 6: This is the pandemic phase, which is characterized by community-level outbreaks in at least one other country in a different WHO region than the countries involved at the phase 5 level.

The pandemic phase 6, which is the highest phase, basically means that it has spread across continents," Hartl says.

Today, Fukuda said that the WHO decided to raise the pandemic alert level to phase 4 because there was clear evidence of person-to-person transmission, but not to raise it to phase 5 until there was more information on the sustainability of the virus.

Although there has been a case in Spain, that person had recently traveled to Mexico, and there wasn't evidence that that patient's illness was spreading in Spain, Fukuda notes.

Swine Flu: Cases Rising

Here's a quick wrap-up of today's other swine flu news:

There are 40 lab-confirmed cases of swine flu in the U.S., according to the CDC.

  • New York City has 28 swine flu cases -- the most in the U.S. All New York cases occurred at a parochial school in Queens; 17 other students at that school have "probable" swine flu; the CDC will conduct lab tests on samples taken from the students.
  • The other lab-confirmed swine flu cases in the U.S. include seven people in California, two in Kansas, two in Texas, and one in Ohio.
  • 26 cases, including seven deaths, have been confirmed in Mexico. Six cases have been confirmed in Canada, and one case has been confirmed in Spain.
  • All swine flu cases in the U.S., Canada, and Spain have been mild; severe cases have only been seen in Mexico, for unknown reasons.
  • The CDC is advising U.S. residents to avoid "nonessential" travel to Mexico because of swine flu.

The World Health Organization is not recommending closing any borders or restricting travel because travel bans wouldn't be effective in preventing the spread of the swine flu virus. However, Fukuda says it would be "prudent" for people to delay travel if they are sick and to seek medical attention if they get sick after traveling to any part of the world.

Show Sources


Keiji Fukuda, MD, assistant director-general for health security and environment, World Health Organization. 

World Health Organization: "Current WHO Phase of Pandemic Alert."

World Health Organization: "Regional Offices."

Gregory Hartl, spokesman, World Health Organization.

WebMD Health News: "Swine Flu Cases Rising in U.S., World."

WebMD Health News: "Swine Flu FAQ."

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