How bizarre! The World Health Organization has declared swine flu a "pandemic," signaling governments worldwide to launch emergency response plans.
The mildest pandemics of the 20th century killed at least a million people worldwide, according to the WHO's data, while old-fashioned seasonal flu strikes every nation yearly and kills an estimated 250,000 to 500,000. As of Thursday, when the pandemic was declared, H1N1 swine flu had killed only 144 people total -- fewer than succumb daily to seasonal flu annually. And in Mexico, where the outbreak began and where it has been the most severe, cases peaked quickly, in just four weeks.
A pandemic declaration will be costly when we can least afford it and could prompt severe restrictions on human activities (think China). Perhaps most important, such a declaration could render the term "flu pandemic" essentially meaningless -- risking lethal public complacency if a bona fide one hits.
So how can the WHO say swine flu qualifies as a pandemic? And why?
The WHO definition for "influenza pandemic" once required "several, simultaneous epidemics worldwide with enormous numbers of deaths and illness." But in 2005, it promulgated a definition that virtually ignores the number of cases and completely ignores deaths. Now it requires "sustained chains of human-to-human transmission leading to community-wide outbreaks" in two parts of the world, with this addition: The cause must be an animal or human-animal flu virus; the latter is known as genetic reassortment.
Thus, under this definition, "community-wide outbreaks" of swine flu in two South American countries and somewhere in China could qualify as a pandemic. No deaths required. And a pure human flu that killed 20 million people would not qualify.
The obvious presumption is that viruses with animal genes pose a greater threat. But that's "a matter of faith more than science," says James Chin, a UC Berkeley epidemiologist who was in charge of surveillance and control of communicable diseases at the WHO in the late 1980s.
Indeed, the science indicates the presumption is false. The WHO first warned of an H5N1 avian flu pandemic in 2004, projecting up to 150 million deaths. Yet a 2007 study found H5N1 -- though detected in 1959 -- was many mutations away from the ability to become readily transmissible among humans.
We're also repeatedly warned that if H5N1 reassorted with human flu, it would produce a combination with the alleged severity of the bird virus and the infectiousness of the human one. Yet a 2006 Centers for Disease Control and Prevention study found the opposite: that a genetically engineered reassortment given to ferrets -- the best animal models for human flu -- produced milder and less infectious flu than did pure H5N1. Reassortment didn't create a "super flu" but rather a 98-pound weakling.
As to human-pig hybrids, a 1976 New Jersey swine flu outbreak in the dead of winter, when flu is most contagious, infected just 230 soldiers, killing one, on a crowded Army base.
At some level, the WHO knows its definition is faulty. The online "WHO Handbook for Journalists" still states: "A pandemic virus can emerge" by adapting "during human infections." And the WHO has warned that one way avian flu could become pandemic is through a purely human mutation.
But it's also true that the worst influenza pandemic in history, the Spanish flu of 1918-19, did involve an animal-human hybrid virus; that episode has become a popular obsession. Never mind that "each subsequent novel flu that sweeps through the world has been milder," Chin observes. "The public health community keeps waiting for the second coming" of Spanish flu, he says.
So, in 2005, the WHO apparently redefined "flu pandemic" to reflect the popular angst as well as its own.
A less generous observation is that the WHO's "when, not if" avian flu pandemic failed to materialize, and it has now put swine flu in its stead. In her pandemic announcement Thursday, WHO's director-general, Margaret Chan, declared: "The world can now reap the benefits of investments over the last five years in pandemic preparedness." Not really. Swine flu, being no more contagious and far milder than seasonal flu, calls for absolutely no actions that wouldn't apply to seasonal varieties.
"I think they're going to have to go back to the drawing board," says Chin of the WHO definition. For now, we'll pay in told and untold ways because the WHO has cried "havoc" and let slip the dogs of pandemic.