That study, which involved a five-year campaign for the release of full clinical trial data, found Tamiflu reduced the time to first alleviation of symptoms by 16.8 hours in adults when compared with placebo use, but there was no difference in hospital admission rates.
The researchers for the Lancet study, from universities in Michigan and Alabama and a London medical institute, said their work using data made available by Roche was independent.
But one of the BMJ paper's authors, Assistant Professor Peter Doshi, of Maryland University, told US science news site sciencemag.org that it was troubling that the new study was funded by the Multiparty Group for Advice on Science, which received financial support from Roche.
The BMJ article's authors said their findings gave reason to question the stockpiling of Tamiflu, its inclusion on the World Health Organisation's list of essential drugs and its use as an anti-flu medicine.
The New Zealand Ministry of Health said, after the BMJ paper, that it would maintain its $32 million stockpile of Tamiflu as this was international best practice.
Virus expert Associate Professor Lance Jennings told the Herald the Lancet findings supported the general recommendation for the use of Tamiflu in severe influenza, especially for patients who were likely to be admitted to hospital.
"Tamiflu is an important part of our armamentarium against influenza, however it does not replace vaccination, which currently provides our best protection against seasonal influenza."
Tamiflu
• Anti-influenza medication.
• Can be bought from pharmacists without a prescription.
• An online pharmacy offers it for $66.45 for 10 75mg capsules; doctor's prescription required.
• There is scientific debate about its effectiveness.
• Latest study found it reduced duration of serious symptoms on average to about four days, compared with about five for those taking a placebo.
Tamiflu saved me: patient
Belinda van den Bos. Photo / Richard Robinson
Belinda van den Bos says she owes her life to Tamiflu.
"From what the doctors say, without Tamiflu I never would have survived."
The 55-year-old from Torbay on Auckland's North Shore spent much of last March dangerously ill with influenza and pneumonia. She was in an Auckland City Hospital intensive care unit for 12 days and in North Shore Hospital for 10.
She was connected to an "ECMO" machine that adds oxygen to the blood outside the body and was given antibiotics and the anti-viral Tamiflu medication.
Mrs van den Bos had been unwell since December 2013. She now knows that she had pneumonia and later caught the flu, the opposite of the thinking at the time.
A senior manager at accountancy firm Crowe Horwath, Mrs van den Bos had
been vaccinated against the strain of flu she caught, the 2009 A(H1N1) pandemic virus, and the value she places on flu vaccination is undiminished by its failure in her case. She plans to get a jab this flu season.
