Doubts raised about flu drugs' efficacy

September 22, 2005|By New York Times News Service

ROME -- As governments around the world stockpile millions of doses of flu vaccine and anti-viral drugs in anticipation of a possible influenza pandemic, two research papers have found that such treatments are far less effective than had been thought.

The studies, which could have implications for the fall flu season, are to be published online today by The Lancet, a London-based medical publication.

In one paper, international researchers analyzed data from flu vaccine studies over the past 37 years and discovered that vaccines showed at best a "modest" ability to prevent influenza or its complications in elderly people.

In the second paper, researchers from the Centers for Disease Control and Prevention in Atlanta found that influenza viruses, particularly those from the bird flu strain, had developed high rates of resistance to older and cheaper anti-viral drugs and that the rates have risen rapidly since 2003, particularly in Asia.

Before 2000, almost no virus was resistant to the drug Amantadine. By last year, 15 percent of influenza A viruses collected in South Korea, 70 percent of those from Hong Kong and 74 percent of those from China were impervious to it.

During the first six months of this year, 15 percent of the influenza A viruses in the United States were resistant, up from 2 percent the year before.

All human cases of the bird flu A(H5N1) strain - which is rare in humans - have been resistant, the researchers said.

The immediate implications of the finding are most ominous for the developing world. Wealthier nations have been stockpiling newer and vastly more expensive anti-viral medicines.

Even so, the research is alarming because it demonstrates how quickly and unexpectedly flu viruses can become impervious to medicines once the drugs are put into common use, as they would be in the case of a pandemic.

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