In the July/August issue of Foreign Affairs, Laurie Garret, a senior fellow for global health at the Council on Foreign Relations, recounts how in March 1976, the Ford administration was convinced that the world was on the verge of an influenza pandemic. On national television, President Ford warned the nation that “unless we take effective counteractions, there could be an epidemic of this dangerous disease next fall and winter here in the United States.” The pandemic, however, never materialized. Mrs. Garret concludes by saying that “the experience weakened U.S. credibility in public health and helped undermine the stature of President Ford.”
But what if the pandemic did occur? Would the world have been prepared to deal with millions of infected people? Even with the advance warning, the answer is probably not. And so, as we face the probability of a pandemic of avian flu, the real lesson from 1976 is not to avoid being wrong, but how to properly prepare in the event that we are right.
Avian flu, otherwise known as H5N1, first appeared in humans in 1997, after a small epidemic broke out in Hong Kong killing six persons. The virus was contained, probably because it had not yet adapted for human-to-human transmission. As Mrs. Garret notes, in early 2004, the flu reappeared in a more virulent form known as “z+” virus. In the first few weeks of that year, “z+” killed 11 million chickens in Vietnam and Thailand. By April 2004, 120 million chickens had died of the flu or were deliberately exterminated to prevent its spreading. More troubling, in April 2005, H5N1 was discovered in pigs, whose respiratory system closely matches that of humans, indicating that the virus had adapted from an avian-based mutation to a mammalian one. A World Health Organization summary of known human “z+” cases worries that “the virus has become stealthier: Human cases are now occurring with no discernable exposure to H5N1 through contact with diseased or dead birds,” which is how scientists had linked past human outbreaks in Asia.
Of the 109 known human cases of avian flu, 54 have died, suggesting an astonishingly high mortality rate. But that’s slightly deceiving, as Mrs. Garret notes. The Hong Kong outbreak of 1997 killed 35 percent of those infected. When the virus re-emerged in its “z” form in 2003, it killed 68 percent of those infected. Since December 2004, however, the mortality rate for avian flu has dropped back to 36 percent. One explanation, according to Mrs. Garret, is that “H5N1 has begun adapting to its human hosts, becoming less deadly but easier to spread.” She notes that “leading flu experts argue that this sort of phenomenon has in the past been a prelude to human influenza epidemics.”
What would an avian flu pandemic look like? The WHO says that because nothing like H5N1 has circulated in humans before, we have virtually no immune defense, unlike most common flu viruses. The last universal flu outbreak was the Spanish flu of 1918-19, which killed between 50 million and 100 million people worldwide. If avian flu acts similarly, scientists estimate between 180 million and 360 million deaths worldwide, and close to 2 million in the United States. More conservative estimates, cited by the CDC as a “medium-level epidemic,” place U.S. deaths at 207,000. And these numbers of course don’t account for the panic that would grip the world economy, as quarantines shut down trade and markets. In short, the consequences of a pandemic of avian flu would be catastrophic.
Flu outbreaks normally are treated with vaccines, but the nature of vaccine production means that it could be up to six to eight months after avian flu appears before an effective vaccine is created, if at all. Millions would still die. Right now the only defense we have against avian flu is the antiviral drug Tamiflu, which studies have shown works reasonably well against the “z+” strain.
That doesn’t mean there isn’t anything we can do to prepare. The WHO is currently recommending that countries begin stockpiling Tamiflu, which is produced in the United States. Meanwhile, the Bush administration, aware of the potenial danger, is funding efforts to study the disease, and the Department of Homeland Security has prepared a pandemic flu plan. In April, President Bush issued an executive order authorizing the use of quarantines and permitting the isolation of those suspected of carrying the avian flu. The administration should also press Asian countries, like China and Vietnam, to better monitor their avian populations and impose stricter regulations on their poultry industries.
Despite these efforts, many scientists are doubtful that a pandemic can be avoided, much less contained. The goal now is to be vigilant and, as doctors vow, do no harm.