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.
