Influenza , or the flu, is an upper respiratory infection that spreads through droplets when an infected person sneezes or coughs. Many countries, including the United States, have been stockpiling the antiviral drug oseltamivir (Tamiflu) in the event of a flu pandemic (perhaps one triggered by bird flu, as some fear). Doctors prescribe Tamiflu and zanamivir (Relenza) along with two older antiviral drugs to relieve symptoms, shorten flu duration, and reduce the risk of complications. But could these drugs effectively contain the virus from spreading during a pandemic?

In an article published on January 19, 2006 in the online edition of The Lancet , researchers caution that antiviral drugs would not effectively combat a flu pandemic. They report that the older antiviral drugs are ineffective and have led to the emergence of resistant flu strains. Tamiflu and Relenza do ease symptoms and reduce their duration. However, they do not make infected individuals less contagious; nor do they treat “influenza-like illnesses,” which are similar to the flu, but are not caused by the influenza virus.

About the Study

The researchers analyzed 51 randomized, controlled trials published through October 2005 that examined the effects of antiviral drugs on influenza. The antiviral drugs studied were the older M2 ion channel blocking drugs (amantadine and rimantadine) and the newer neuraminidase inhibitors (Tamiflu and Relenza). The studies analyzed how well the antiviral drugs prevented and treated influenza, and whether they had any unpleasant side effects.

The older antiviral drugs, amantadine and rimantadine, helped relieve some flu symptoms, but did not protect against infection or help prevent flu transmission (by reducing the amount of virus shed through the nose). In addition, these drugs had some serious side effects, including hallucinations and led to the rapid emergence of drug-resistant flu strains.

The newer antiviral drugs, Tamiflu and Relenza, effectively reduced flu symptoms if taken within 48 hours of their onset. They also reduced the likelihood of flu complications, such as pneumonia and bronchitis . However, they did not effectively treat influenza-like illnesses or prevent an infected individual from spreading the virus. They were also ineffective at preventing the spread of infection from infected individuals without symptoms (who could unknowingly infect others).

How Does This Affect You?

This analysis found that although the neuraminidase inhibitors relieved flu symptoms and shortened flu duration, they could not single-handedly prevent the spread of flu during a pandemic. The researchers warn that at the very least, the use of Tamiflu and Relenza must be accompanied by public health measures such as vigilant hand washing and quarantine of infected individuals.

The best way to reduce your risk of getting the flu is to get a yearly flu shot. If you are at high risk for getting the flu or developing a complication from the flu, wash your hands often, and if possible, avoid crowded areas during flu season, which peaks from late December through March. If you have the flu, stay home from work or school to avoid infecting others.