Spread of flu in families reduced with new drug

By Catherine Seigerman

Families like to share a lot of things, but the flu shouldn't be one of them. A new study, published in the Nov. 2 issue of The New England Journal of Medicine, found that zanamivir can prevent the flu from making the rounds within a family when one member becomes infected.

"The close interaction of the typical family makes it easy for influenza to spread throughout a household," said Dr. Frederick Hayden, professor of internal medicine at the U.Va. Health System and lead investigator of the study.

Zanamivir, an inhaled neuraminidase inhibitor, received approval for treatment of influenza from the U.S. Food and Drug Administration in 1999.

The double-blind, placebo-controlled clinical trial was designed to examine the effectiveness of zanamivir in preventing the spread of influenza A and B from one infected family member to other members. During the influenza season, ill individuals with suspected influenza were randomized to receive either treatment with zanamivir or placebo. Their well family members not infected with the flu received the same blinded medication once daily for prevention of illness.

Results showed that zanamivir significantly reduced the risk of acquiring the flu by 79 percent. Out of 337 total families, 19 percent receiving placebo had one or more members who developed laboratory confirmed influenza during prophylaxis as compared with only 4 percent in the group receiving zanamivir.

"Families tell us that the spread of influenza in the household is a serious problem, and sometimes turns into weeks of illness that can significantly disrupt their day-to-day activities," Hayden said.

Health care professionals have been reluctant to use one anti-influenza agent for both treatment and prevention in the same household due to the resistance problems that were seen with the older drugs amantadine and rimantadine. However, in this study no resistance was observed with zanamivir.

Influenza or flu is a viral infection that affects approximately 25 million people each year in the U.S., the majority of whom are not vaccinated. During an average year, the flu causes over 20,000 excess deaths, results in as many as 300,000 hospitalizations, and is associated with combined direct and indirect healthcare costs of about $12 billion per year.