Editor's note: Includes two new sections, on phase change considerations and on possible impact.
Apr 27, 2009 (CIDRAP News) – The World Health Organization (WHO) today raised its official pandemic alert level from the current phase 3 to phase 4 on its 6-phase scale, saying the newly identified swine influenza virus has made a pandemic more likely but not inevitable.
"We think we have taken a step in that [pandemic] direction, but a pandemic is not considered inevitable at this time," said Dr. Keiji Fukuda, the WHO's assistant director-general for health security and environment, at a press conference from Geneva.
By the WHO's definition, phase 4 means that a novel flu virus has become sufficiently transmissible to cause sustained community outbreaks. Phase 3 signals that a new virus is causing sporadic illness cases or small clusters of cases but is not spreading enough to cause larger outbreaks.
WHO Director-General Margaret Chan decided to raise the alert phase on the recommendation of the agency's Emergency Committee, which met today.
Fukuda said it was clear to the committee that person-to-person transmission of the swine flu virus is going on. Confirmed swine flu cases have been reported in Mexico, the United States, Canada, and Spain (one case).
"Given the widespread presence of the virus, the director-general considered that containment of the outbreak is not feasible," the WHO said in a statement. "The current focus should be on mitigation measures."
The WHO also recommended today that governments not close borders or restrict travel, saying those steps would likely cause major disruptions while doing little to keep the virus from spreading. However, the agency said it is prudent for sick people to delay international travel and for those who get sick after travel to seek medical attention.
In addition, the WHO advised that production of seasonal flu vaccine should not be interrupted in favor of making a swine flu vaccine at this point. The recommendation comes as flu season in the southern hemisphere is getting under way.
At the same time, Fukuda said the Emergency Committee advised the WHO "to take all steps to facilitate development of a vaccine that could protect people against this new virus." He estimated it will take 4 to 6 months to develop and begin producing such a vaccine, and several more months to make it in large quantities.
The WHO move came the same day the US swine flu count doubled to 40 cases with the addition of 20 more cases associated with a school in New York City and as federal health officials advised against nonessential travel to Mexico, the epicenter of the outbreaks.
Phase change considerations
In raising the alert phase, the WHO committee "felt that, given the rapidly evolving situation, it was important to send a strong signal to countries that now is a good time to strengthen preparedness for pandemic influenza if it continues to evolve in that direction," said Fukuda.
Although the WHO's official guidance on pandemic phases and related actions suggests that containment of a new virus may still be possible in phase 4, the agency made clear today that it does not believe it's still possible to contain the virus to a small geographic area. This agrees with what US health officials have been saying.
"The committee discussed the situation in depth and decided that . . . really this virus is too widespread to make containment a feasible consideration," Fukuda said.
The WHO ventured no predictions about how long the pandemic alert will remain at phase 4. "As further information becomes available, WHO may decide to either revert to phase 3 or raise the level of alert to another phase," the agency statement said.
When Fukuda was asked why the WHO didn't move the alert to phase 5, he indicated the committee had some doubts about the extent of community outbreaks. Phase 5 is defined as a situation involving sustained community outbreaks in two or more countries within one WHO region. Phase 6 means sustained community outbreaks in more than one WHO region.
In carefully reviewing the epidemiologic data, including the confirmed and suspected cases, the WHO committee was convinced that person-to-person transmission is going on, said Fukuda. "But there's a recognition that we'd really like more information on the sustainability of the virus, and one of the signs would be widespread community outbreaks. If you look at the case reported in Spain, this was a case in a traveler returning from Mexico, and we don't really have any evidence of community spread of infections occurring within a country."
Commenting on the recommendation against travel restrictions, he said, "At this point, with the virus widespread . . . closing borders or restricting travel really has very little effect if any effect at stopping the movement of this virus; however it would cause a great deal of disruption of countries." He said modeling studies have indicated it would take "very, very draconian restrictions on travel" to slow the virus's spread.
Possible impact of WHO move
Peter M. Sandman, PhD, a risk-communication expert and business consultant, welcomed the WHO's phase change as a step that may increase preparedness efforts by many countries and companies and should increase preparations by individuals.
Although the WHO has been criticized for not raising the alert level sooner, the system has worked much as expected, given that the agency had to get a consensus, Sandman commented by e-mail.
"It matters a lot that the WHO caught up this evening," he said. "US government officials have been saying for two days now that they're responding to conditions on the ground, not to any 'label' the WHO might decide to apply or not apply. That may be true for the CDC and other US agencies. But it's not true for health officials in countries without any confirmed cases so far, many of which have written pandemic plans that specify a different response to phase 4 than to phase 3. And it's not true for companies, especially multinational companies, many of which have their own pandemic plans keyed to the WHO stages. Ditto for cities and states with pandemic plans but no local cases; the WHO phase shift may trigger a response from them as well.
"And a lot of smaller companies and smaller communities without pandemic plans have been waiting for a signal to start taking precautionary action. This may be the signal they have been waiting for."
Sandman said that in their messages to the public, US health officials so far have recommended only hygiene practices, not more concrete preparedness steps such as stockpiling supplies. He said he hopes that the shift to phase 4 will inspire the public to do much more.
"We are losing precious preparedness time—time to go out and buy supplies before there's a real emergency, while the shelves are still full and the stores can still replenish; and time to think through what life might be like in a week or two if all schools are closed, most businesses are closed, and many people are very, very sick," Sandman said.
"The trick is to do all that preparing while bearing in mind that this swine flu outbreak may very well fizzle. In other words, we must prepare for the worst without committing ourselves to expecting the worst," he added.
Sandman concluded, "Here's the secret of preparedness that fearful government leaders tend to forget: It's a calming experience to prepare. People who have been working hard not to worry about the pandemic that might be looming, people who have spent today holding back that gathering knot in their guts, will feel more in control after they have taken some concrete steps to get themselves and their family ready. I hope they read tonight's WHO decision as advice to do that tomorrow."
Apr 27 WHO statement
HHS description of US pandemic response stages in relation to WHO alert phases
WHO press briefing page