When the Spanish flu struck the world in 1918, one leading physician, a former president of the American Medical Association, thought he was seeing the end of civilization. It was a reasonable conclusion. The virus rampaged throughout the world, leaving morgues overstuffed with bodies. In 1917, the year before the flu hit, life expectancy in the U.S. was 51 years. In 1918, it was 39 years—a drop that was due almost entirely to the flu. Worldwide, 100 million or more may have died from the Spanish flu, including 20 million in India alone. And with avian influenza, it could happen all over again.

Bird flu has already killed 32 of the 44 people infected in Asia this year, and the news isn´t getting better. Fortunately the only way the disease seems to spread to humans is through close contact with infected birds, although rare cases of human-to-human transmission have occurred. But if bird flu mutates and gains the ability to transmit as easily as normal flu—and scientists say that is a real possibility—it could trigger a worldwide pandemic similar to that in 1918. That prospect was raised last week, when Dr. Shigeru Omi, the World Health Organization´s (WHO) regional director for the Western Pacific, estimated that such a pandemic could infect 25-30% of the world´s population and kill up to 100 million people. Omi´s number is higher than earlier estimates, but even in the best-case scenarios millions might die. That would make SARS, which cost Asia billions in 2003 and virtually shut down the region for weeks, look like a slight case of the sniffles.
What is being done to defend us against that fate? Far too little. Work on the one tool that can make the biggest difference in the severity of a pandemic—an effective vaccine—has been underfunded. Thanks to a new technique called reverse genetics, researchers were able to create a vaccine strain from the H5N1 virus in record time—yet the candidate vaccine is just now entering clinical trials, because drug companies have been loathe to invest in a vaccine that may never be used, and governments have been reluctant to fully fund the work. The vaccine won´t be ready for five or six months, well after the high-risk winter flu season, and it would take even longer to produce enough to vaccinate a significant part of the world´s population. Tamiflu, the one drug that seems to be effective against bird flu, is in perilously short supply. In a pandemic, doctors in much of the world could do little more than watch their patients die.

That´s assuming they weren´t sick themselves. If the bird-flu virus spread at the rate Omi estimated, nearly a third of the world´s population could become ill. That means a third of the world´s police officers, government officials, soldiers, technicians—and medical workers—could be knocked out for weeks. Even the temporary loss of such a large part of the work force could lead to severe disruptions of public services—and complicate efforts to fight the pandemic. Countries and businesses need contingency plans in place now, yet in Asia only Japan has any real pandemic scheme. The poor Southeast Asian countries that will be the world´s front line against bird flu are almost totally unprepared. They will suffer first, and they will suffer the most.

That´s why preparations for a bird-flu pandemic need to be truly international, with wealthy developed countries leading the way. They need to budget real money now to stockpile bird-flu vaccine and antiviral drugs—and allow the WHO to channel some of those supplies to countries that can´t afford them. In the long run, Asia´s age-old backyard-farming practices—whereby animals and human beings live in close proximity, giving rise to new viruses like H5N1—need to be moved toward modern methods of slaughtering and food preparation. That will take resources that nations like Vietnam don´t have, so again, those funds need to come from developed countries. In turn, Asian countries need to be fully open and cooperative about allowing disease surveillance and scientific studies within their borders—and to invest in their public-health systems. We´ve come a long way since the secrecy of SARS, but too many countries still act as if an infectious disease is a source of shame that has to be kept inside its boundaries. But like the weather, infectious disease doesn´t respect international borders.

Seven million dead, or 50 million, or 100 million. The estimates thrown around are so high and the disease itself so seemingly hard to treat that there´s a temptation to hope it all just goes away. Rarely have so many brilliant scientists so fervently wished to be proven wrong. But a flu pandemic is inevitable, today or some time in the future. Unlike in 1918, national leaders have the experience and the science to prepare the world. They should do so.