The effectiveness of the swine flu antiviral Tamiflu has been questioned after a major review found there was no evidence that it could prevent complications such as pneumonia.
Research published in the British Medical Journal found the antiviral could shorten the bout of illness by a day or so but concluded that the lack of published data meant it was impossible to know whether it prevents severe disease.
"Governments around the world have spent billions of pounds on a drug that the scientific community now finds itself unable to judge," said Dr Fiona Godlee, editor of the BMJ.
Roche, the manufacturer of Tamiful, has made huge profts from the drug, with sales of £1.6bn this year alone. The government has stockpiled enough for half the population.
The review criticised Roche for withholding the evidence the company has gained from trials, making it impossible to judge the drug's effectiveness.
The research team were forced to drop eight trials from their review of 20 existing studies because they were unable to independently verify the findings.
In a statement, Roche insisted that governments and licensing authorities had been given access to all the trial information and defended the reliability of the data.
