With flu vaccine running short, antiviral medications may emerge as the most useful, and least well-known, weapon in what's shaping up to be a nasty flu season.
The drugs can reduce symptoms and shorten the duration of the flu if they're started within 48 hours of the first sign of illness.
They also can be given to prevent the flu in people who know they have been exposed to it. For example, if a child has been diagnosed, other family members can take an antiviral medication to greatly reduce their risk of infection.
Antivirals have been around for years, but mostly they have been ignored in typical flu seasons. This year, however, looks to be unusually harsh, and the drugs -- there are four on the market -- could help curb the scope of the flu outbreak, health experts say.
"Influenza is underappreciated as a threat, and antivirals are underutilized. But I think this year will change all that," said Dr. Donald Perlman, an assistant clinical professor of pediatrics at the University of Medicine and Dentistry of New Jersey.
At a media briefing on the flu outbreaks last week, a federal health official consoled people who could not get the vaccine -- the best flu preventive -- with the option of antivirals.
"If people do get ill or require a visit to the physician, or hospitalization, in particular, with a severe case of the flu, treatments are available, and that can make a big difference," said Dr. Julie Gerberding, director of the national Centers for Disease Control and Prevention.
Although this year's unmet demand for the flu vaccine has some wondering whether supplies of antiviral medications will run low, Gerberding said the nation should have enough. "In the past, the problem has been that a lot of physicians aren't aware that the drug is available," said Terence Hurley, a spokesman for Roche Pharmaceuticals, maker of the newest drug, Tamiflu. "But we're seeing more demand already this year."
One reason antivirals may have been ignored is that, at first glance, they don't appear to do much. The drugs' labeling says they can shorten the flu's duration by a day or two; for most people, that may not be worth the effort to visit their physicians. But many doctors report that people who start taking an antiviral early in the illness are much less sick, said Perlman, who participated in clinical trials of Tamiflu. "Patients are generally up and about in 24 hours and able to go back to work. So it does more than just shorten the illness by a day or so. It dramatically changes the severity of the disease more often than not," he said.
Other patients may not know whether they have the flu or a cold (for which antivirals don't work), so they may not see a doctor within 48 hours of the onset of symptoms, Perlman said. For those unsure of the difference, he gives this advice: Typically, the flu will hit hard and fast, while a cold comes on slowly.
A more practical use for antivirals is to quickly protect people in close contact with someone who's just been diagnosed with the flu. Antivirals have been used most commonly in nursing homes. Although not 100% effective, studies show they significantly reduce the risk of getting the disease.
The four antiviral drugs are not interchangeable. All four drugs are effective against type A flu strains (this year's troublesome strain is Fujian A) and are considered safe; the two oldest drugs, Symmetrel and Flumadine, are less expensive. They typically cost about $25 per prescription, while Tamiflu and Relenza cost about $60. Insurers typically don't cover antivirals.
The two older drugs have slightly more side effects, including nervousness, anxiety, lightheadedness, nausea and diarrhea. Relenza and Tamiflu are in a different class -- called neuraminidase inhibitors -- and generally cause fewer side effects.
Symmetrel, Flumadine and Tamiflu can be used for prevention and treatment. But Relenza, which is a powder that is inhaled, is for treatment only. Relenza should not be used by people with asthma or other respiratory ailments. Antivirals, in general, are not recommended for pregnant or nursing women.