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The Ministry of Health yesterday said it would maintain its $32 million stockpile of Tamiflu despite the new evidence, as it was ''international best practice'' to do so.
The British Medical Journal and the Cochrane Collaboration yesterday issued a call to governments to reconsider policies on stockpiling Tamiflu in light of the findings.
While it shortened symptoms of influenza by half a day, there was no evidence to support claims it reduced hospital admissions, complications, or the spread of flu, the Cochrane Collaboration said in a press release.
The study also highlighted side effects, such as nausea and vomiting. The findings also applied to the antiviral drug Relenza.
University of Auckland, New Zealand, Cochrane Fellow Dr Vanessa Jordan said the latest research was like ''another chapter in a story which reads like a sensationalist script for a Hollywood movie''. The review used clinical trial data that had not been public before.
''The available data in 2009 suggested that antivirals, such as Tamiflu and Relenza, had potential benefits in reducing complications from influenza and as a result the length of hospital stays and ICU admissions.
''However, this information was incomplete and full trial evidence on the drugs' effectiveness was suppressed by the manufacturers.
''Through perseverance, the Cochrane authoring group have succeeded in obtaining information on 45 unpublished trials,'' Dr Jordan said.
Medsafe general manager Dr Stewart Jessamine said the study was insufficient for New Zealand to alter its position.
''In line with World Health Organisation advice, and with some 100 other countries around the world, New Zealand maintains just over 1 million doses of Tamiflu and more than 300,000 doses of Relenza. These stocks are periodically refreshed.''
The cost of the Tamiflu alone was about $32 million. The cost of the Relenza was unclear, but the entire stockpile, including medical supplies such as syringes, was worth about $46 million.
''As with all drugs and the assessment of their costs and benefits, it's important that regulators consider the widest possible range of research and information. This study should be placed in that context.
''Another recent study, in The Lancet, looked at the use of Tamiflu in patients suffering from influenza - as opposed to clinical controlled trials in the Cochrane study. This showed there were clear benefits from its use.
''New Zealand will continue to monitor literature on this subject and the considerations of other regulators,'' he said.