Handicapping the Flu Pandemic
A little scientific background is necessary to understand the threat and its possible consequences. The exterior of the flu virus consists of a lipid envelope from which project two surface proteins, hemagglutinin (H) and neuraminidase (N). The virus constantly mutates, which may cause significant alterations in either or both of these, enabling the virus to elude detection and neutralization by the human immune system.
A minor change is called genetic drift; a major one, genetic shift. The former is the reason that flu vaccines need to be updated from year to year; an example of the latter was the change in subtype from H1N1 to H2N2 that gave rise to the 1957 pandemic. This new variant was sufficiently distinct that people had little immunity to it. The rate of infection of symptomatic flu that year exceeded 50% in urban populations, and 70,000 died from it in the United States alone.
During the past several years, an especially virulent strain of avian flu, designated H5N1, has ravaged flocks of domesticated poultry in Asia and spread to migratory birds and (rarely) to humans. It has been detected in much of East and Southeast Asia, as well as in Russia, Turkey and parts of Eastern Europe, and it continues to spread. Since 2003, more than 60 human deaths have been attributed to H5N1.
Public-health experts and virologists are concerned about the potential of this strain because it already possesses two of the three characteristics needed to cause a pandemic: It can jump from bird to human and can produce a severe and often fatal illness. If additional genetic evolution makes H5N1 highly transmissible among humans, the third characteristic of a pandemic strain, a devastating world-wide outbreak could become a reality. Although it isn't possible to predict the timing of that last evolutionary step, because mutations occur each time the virus replicates, the more H5N1 viruses are produced the more likely it is that a "human H5N1" will emerge.
If the Turkish outbreak had been the beginning of a real pandemic -- which appears not to be the case -- we would expect to see illness spreading through families and among both health-care workers and patients in hospitals where the victims were treated. The rapidity of such spread would depend on the infectiousness of the pandemic strain, another variable that we can't predict. Before long, infected persons, perhaps even asymptomatic carriers, would introduce it to Istanbul, Tbilisi, Baghdad and beyond.
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Yet what if Turkey was the real thing -- do public policy makers have any good options? In theory, it is possible to contain a flu pandemic in its early stages by performing "ring prophylaxis," using antiflu drugs and quarantine aggressively to circumscribe and isolate relatively small outbreaks of a human-to-human transmissible strain of H5N1. According to Johns Hopkins University virologist Donald S. Burke, "Models show that it may be possible to identify a human outbreak at the earliest stage, while there are fewer than 100 cases, and deploy international resources -- such as a [World Health Organization] stockpile of antiviral drugs -- to rapidly quench it. This 'tipping point' strategy is highly cost-effective."
Of course, a strategy can be "cost-effective" only if it's actually feasible. Ring prophylaxis might work in Minneapolis, Toronto or Zurich, but in the parts of the world where flu pandemics begin the probability of success approaches zero. In places like Vietnam, Indonesia and China -- where the pandemic strain will likely originate -- animal husbandry practices that place billions of poultry and swine in close proximity to humans, combined with unsanitary conditions, poverty and grossly inadequate public-health infrastructure, make it highly unlikely to prevent or contain a pandemic at the source.
China's prodigious but chaotic effort to vaccinate 14 billion chickens annually has been compromised by the appearance of significant amounts of counterfeit vaccines. The absence of protective gear for vaccination teams, who might spread disease by carrying fecal material on their shoes from one farm to another, isn't helping either. In Turkey, local officials in the region where the bird flu was first detected warned the federal government on Dec. 16 of a surge in bird deaths, yet it took another 12 days for an investigation to begin. And when in early January a 14-year-old boy became Turkey's first avian flu mortality, followed soon by two siblings, a government spokesman criticized doctors for mentioning the disease because they were "damaging Turkey's reputation." These responses ominously resemble the passivity and denial by the Chinese government during the SARS outbreak of 2003.
We do need good surveillance in Europe, Asia and Africa in order to obtain the earliest possible warning that a strain of H5N1 flu transmissible from human to human has been detected. That would allow nations around the world rapidly to initiate a variety of public-health measures. Not the least of which would be to begin an emergency program to produce large amounts of vaccine.
In reality, with no effective vaccine available and supplies of antiviral drugs limited, little could be done to attenuate significantly the first wave of infections. If we're able to rush the pandemic strain into a crash program to manufacture vaccine, we could possibly blunt the second wave, however.
The U.N.'s World Health Organization is probably best equipped to perform surveillance, but its role is better left limited. Dr. David Nabarro, the U.N. coordinator on avian and human influenza, who has wide experience as a public-health bureaucrat but none in the highly specialized field of influenza, is busily raising money from countries around the world to finance efforts to combat the disease. However, we cannot ignore the dismal record of the scientifically challenged, politically correct, unaccountable U.N. Any component of it is inherently incapable of keeping politics out of scientific and medical decisions.
A flu pandemic will require hard-headed calls at many levels, including judgments about which patients are likely to benefit from scarce commodities such as drugs, vaccines and ventilators, as well as broader public-policy choices about how best -- among, literally, a world of possibilities -- to expend resources. To prepare for a possible catastrophe, we need to be aggressive, innovative and, above all, resilient. In society, as in biology, survival requires nothing less.