Researchers say there is little evidence that Tamiflu and related medications prevent seasonal flu complications in healthy people, despite the prevailing wisdom.
Researchers at the Cochrane Review, an international non-profit group that reviews health information, set out to update its 2005 review of the drugs in preventing or improving flu symptoms, reducing flu transmission, and reduction in flu complication rates in healthy people, as well as to examine side effects.
They looked at previously published papers on the antiviral medications called neuraminidase inhibitors, which includes Tamiflu. But they say they found a disturbing scarcity of good data.
That was in part because they had to eliminate eight studies from the review that were never fully published, even though they were included in the previous review. The researchers dropped them for this review, they said, because they could not verify the results independently.
The researchers, led by Dr. Chris Del Mar, dean of medicine at Bond University in Australia, found insufficient data to prove whether the drugs reduce complications such as pneumonia in otherwise healthy people, calling the available evidence "confusing."
And they concluded the drugs have "modest effectiveness against the symptoms of influenza in otherwise healthy adults," noting they reduce the duration of illness by about a day.
The researchers conclude that not only are the benefits of the drugs small, there wasn't adequate information on the drugs side effects.
While the reviewed studies looked only at Tamiflu use for seasonal flu, the experts said their conclusions raised questions about the widespread use of the drug for any flu-like illness, including H1N1.
The research is published in BMJ Online.
Fiona Godlee, BMJ's editor, said the review casts doubt on the drug regulatory system that approved the medications.
"Governments around the world have spent billions of pounds (dollars) on a drug that the scientific community now finds itself unable to judge," she said in a statement.
But the World Health Organization disagreed with the reviewers. They said data from countries around the world show that when given early, Tamiflu can reduce the severity of swine flu symptoms. But the agency recommends the drug be saved for patients at risk of complications, such as pregnant women, the elderly, children, and those with underlying medical problems.
"This will not change our (Tamiflu) guidelines," said Charles Penn, a WHO antivirals expert.
And Roche, the maker of Tamiflu, defended the drug, saying in a statement that they "firmly believe in the robustness of the data."
While the researchers said their investigation was hampered by a scarcity of good data from Roche, the company that makes Tamiflu, Roche said that if the Cochrane researchers had simply signed a confidentiality agreement to protect the anonymity of clinical trial patients, they could have had the data.
