SCIENTISTS AT THE Centers for Disease Control and Prevention in Atlanta announced last week that they had reconstructed the genetic code of the flu virus that killed at least 50 million people in 1918. Meanwhile, administration officials are preparing a plan to bolster U.S. preparedness for another pandemic. These two facts are related: The more that is understood about the 1918 flu virus, the more similar it appears to the avian flu that has recently killed millions of birds, as well as some 60 people, in Asia. So far, the avian flu virus has jumped from birds to humans, but not from person to person. If that changes, this flu could be as deadly as -- or, given the speed of modern travel, more deadly than -- its predecessor. This is a potential disaster that, like the hurricane that devastated New Orleans and the Gulf Coast, has long been anticipated. Also as with Hurricane Katrina, it is one for which the U.S. government is not prepared, as Mike Leavitt, the Health and Human Services secretary, acknowledged last week.

It's a good thing that Mr. Leavitt recognizes the problem. Unfortunately, it isn't clear that everyone in the administration understands it. It was disturbing to hear the president ruminate on the use of military troops for mass quarantines. That comment -- conjuring images of soldiers shooting as sick people try to cross a cordon sanitaire -- could have been a scare tactic. In fact, there is no legal, let alone ethical, means of enforcing mass quarantine in this country, and flu viruses, which don't always produce symptoms in the early stages, wouldn't obey them if there were.

So far the administration has concentrated on buying quantities of Tamiflu, an antiviral that looked as if it would be effective against avian flu but now, as the virus has mutated, might not be. There is also talk of U.S. help for surveillance teams in Asia, which is a good thing -- Mr. Leavitt is off to Asia this week -- but still insufficient, given the scant resources of the World Health Organization. Though many people assume otherwise, the WHO does not have thousands of employees who can be deployed to Asia on short notice, and it does not have vast stockpiles of Tamiflu or anything else.

The solution lies not in antivirals but in a vaccine that could be tailored, relatively quickly, to whatever form the virus takes, as well as help for U.S. hospitals, which are filled to capacity. The administration is aware of the former problem; the president met Friday with vaccine manufacturers, and the National Institutes of Health has been conducting vaccine research. But legislation is needed to facilitate research and rapid production of vaccines. That's a difficult task, given that American pharmaceutical companies, scared off by liability issues and low profits, no longer make vaccines at all.

Some in Congress have been working on a successor to last year's failed Bioshield legislation, which was intended to break the vaccine deadlock. Sens. Orrin G. Hatch (R-Utah) and Joseph I. Lieberman (D-Conn.) have introduced Bioshield II, which would absolve vaccine manufacturers of liability and give them patent incentives to produce vaccines. Sen. Richard Burr (R-N.C.), chairman of the bioterrorism and public health preparedness subcommittee, has announced his intention to introduce an innovative bill that would set up an agency, similar to the Defense Advanced Research Projects Agency, to invest in early research into drug and vaccine development in conjunction with the private sector.

The president should embrace this idea. It is also time to look again at the nation's medical emergency response systems, to examine again how doctors would be sent around the country and to involve hospital administrators in the discussion. Even if the avian flu never produces a pandemic, the country would be better prepared for whatever virus comes next.