The flu season usually lasts from October to May with peaks in December and January. This year, it got an early start with cases reported in September. In a typical year, 36,000 Americans die from the virus, and researchers worry the toll will be even higher this year.

Treatment often means easing the symptoms while the body mounts its own defense. Most cases of influenza clear up without treatment. But in thousands of cases annually, especially among the elderly, it can be deadly.

That´s why health experts conduct vigorous campaigns for people to get vaccinated annually.

With fear escalating, people have rushed to be vaccinated, causing shortages of the vaccine in some areas. The country´s two manufacturers say they have run out of supplies. The makers of FluMist, a more expensive inhaled version of the vaccine, remains widely available, said Jamie Lacey, spokeswoman for the manufacturer, MedImmune Vaccines.

For those who do get the flu, doctors no longer recommend carrying camphor or cucumbers, as some did in years past. But other traditional palliatives — chicken soup for example — remain popular.

Antiviral medications are available for flu, but their effect is only modest, said Dr. Debra Birnkrant, head of antivirals for the Food and Drug Administration.

There are four drugs on the market to combat flu, but they are only moderately helpful, she said. Birnkrant said even the most effective must be taken within 48 hours of the onset of symptoms, and then the medication shortens the illness´ duration only by a day or so.

Tamiflu and Relenza are the brand names of the two most recently approved antiviral drugs for flu, both directed at flu types A and B. The FDA says that Tamiflu can prevent flu if taken beforehand.

Tamiflu also can reduce the chances of complications in persons with the flu, but the drug is underused, contended Dr. Frederick G. Hayden of the University of Virginia.

Hayden, who has served as a consultant to antiviral drug makers, said the product can reduce the chance of lower respiratory infections.

Two older drugs also are on the market, Symmetrel and Flumadine, both of which are directed only at type A flu.

Beyond that, over-the-counter medications including pain relievers, decongestants and antihistamines, can ease symptoms, although they do not treat the virus.

Dr. Norman H. Edelman of the American Lung Association said his group focuses on getting vaccines because they are highly effective and even partial protection can make a big difference.

With the emphasis on vaccines, there has been little pressure toward the development of new antiviral drugs, experts said.

Hayden said the underuse of the currently available drugs reduces the incentive for the pharmaceutical industry to develop new ones to fight the flu, colds and other viruses.

A few potential drugs are being tested in animals but nothing close to being in clinical trials in people, Hayden said.

Researchers at Imperial College in London, for example, are testing a strategy for battling flu by adjusting the body´s sometimes exaggerated immune response to the virus. So far, their work is limited to mice.