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http://online.wsj.com/public/article/0,,SB110512998255120225,00.html?mod=todays_free_featureJust How Deadly Is Bird Flu?
It Depends on Whom You Ask
January 13, 2005
This is the first installment of The Numbers Guy, a new column on the way numbers and statistics are used – and abused – in the news, business and politics. I welcome your questions and comments, and will post and respond to your letters soon. Write to me at numbersguy@wsj.com.
The World Health Organization has a big problem: It needs to alert the public to the dangers of a virus that has killed very few people, yet could, in some scenarios, devastate nations across the globe.
So, the group's doctors and scientists have lately been forecasting truly alarming numbers from the so-called Asian bird flu -- up to 100 million deaths. One researcher has gone much further, suggesting the toll could be up to a billion people.
But projecting death counts from such a bug isn't just an inexact science; it's more like educated guesswork. The truth is, scientists don't know the rates at which this hypothetical flu -- derived from a bird flu that so far in Asia doesn't spread well from human to human -- could infect and kill. They base guesses on prior flu pandemics, but there's no way to quantify how much better we're prepared in 2005, thanks to improved vaccine production and antiviral medication, than we were in 1968, when the last flu pandemic struck.
Then again, the next pandemic could be worse than that relatively mild one, and even worse than the deadliest of the past century, in 1918, which killed at least 20 million people at a time when the world had a smaller population which traveled less.
The most responsible answer, then, to the question of how many people the flu will kill is, "We don't know." But big numbers get headlines while honest uncertainty usually doesn't. And the WHO has been sharing big numbers, like two million to seven million people dead world-wide. At a press conference in Hong Kong two months ago, one official went further, saying this hypothetical pandemic could kill as many as 100 million people. The WHO always cautions that these aren't sure numbers, but the group shouldn't be surprised that the press often skips the complexity.
The 100 million figure was reported widely, including in the New York Times, The Wall Street Journal Online, CNN, Newsweek and the U.K.'s Observer; but without much caution about how arbitrary it is.
At issue is H5N1, a new strain of bird flu that so far has killed a few dozen people in Asia -- nearly three quarters of the number of people known to have been infected. Scientists fear the virus will spontaneously mutate or swap parts of its genetic code with another virus, and thereby become more transmissible. They hope that in doing so, it also will become less lethal. But there is no way to know. (Dutch researchers recently found that a different strain of bird flu had spread widely among humans in 2003, but killed few of those infected.)
Henry Niman, who studies viruses and criticizes the WHO for being underprepared, says that in the true worst-case scenario, one billion people could die. That figure was reported in the New York Times. Dr. Niman's reasoning: The current mortality rate among those known to have been infected is nearly 75% and the WHO is estimating that one billion to two billion could be infected world-wide. But Dr. Niman, a medical researcher in Pittsburgh whose company, Recombinomics Inc. seeks to develop vaccines for viruses, adds, "There are a lot of variables. The concept that you can't really put a number on
at this time, is certainly valid."............