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Cochrane Review: Governments Wasted Money Stockpiling Tamiflu

No evidence that antiviral drug stops spread of influenza

According to an updated Cochrane evidence review, published April 10 by The Cochrane Collaboration and the British Medical Journal, the antiviral drug Tamiflu (oseltamivir, Genentech/Roche) shortens symptoms of influenza by about half a day, but there is no good evidence to support claims that it reduces hospital admissions or the complications of influenza.

Evidence from treatment trials confirms an increased risk of nausea and vomiting. Moreover, when Tamiflu was used in prevention trials, there was an increased risk of headaches, psychiatric disturbances, and renal events.

Although the drug — when used as a preventative treatment — can reduce the risk of people having symptomatic influenza, there is no proof that it can stop people carrying the flu virus and spreading it to others, the report says.

The latest updated Cochrane Review is based on internal reports of 20 trials of oseltamivir and 26 trials of zanamivir (Relenza, GlaxoSmithKline), which involved a total of more than 24,000 people. The review’s findings challenge the historical assumption that neuraminidase inhibitors are effective in combating influenza. The evidence also suggests there are insufficient grounds to support the use of Tamiflu in preventing person-to-person spread of the flu. This raises further questions about the most effective way to support drug regulation and public health policy decision-making, the authors suggest.

Claims about the effectiveness of Tamiflu against complications were a key factor in decisions made by governments around the world to stockpile these drugs in case of a pandemic. The U.S. has spent more than $1.3 billion buying a strategic reserve of antivirals, while in the U.K. the government has spent almost £424 million for a stockpile of about 40 million doses.

In 2009, a lack of access to available trial data hampered the efforts of Cochrane researchers to verify the safety and effectiveness of Tamiflu — and led to questions about decisions to stockpile the drug while its risks and benefits remained uncertain. Now, the BMJ and Cochrane have issued a joint call to government and health policy decision-makers around the world, asking: in light of the latest findings from the Cochrane Review, would you make the same recommendations today, choosing to stockpile Tamiflu?

Compared with placebo, taking Tamiflu led to a quicker alleviation of influenza-like symptoms of only half a day (from 7.0 days to 6.3 days) in adults, but the effect in children was more uncertain. There was no evidence of a reduction in hospitalizations or in serious influenza complications, confirmed pneumonia, bronchitis, sinusitis, or ear infections in either adults or children. Tamiflu also increased the risk of nausea and vomiting in adults by approximately 4% and in children by 5%. There was a reported increased risk of psychiatric events of around 1% when Tamiflu was used to prevent influenza. The evidence also suggests that Tamiflu prevented some people from producing sufficient numbers of their own antibodies to fight infection, the report says.

According to the Cochrane researchers, the worldwide use of Tamiflu has increased dramatically since the outbreak of the H1N1 virus (swine flu) in April 2009. It was initially believed that Tamiflu would reduce hospital admissions and the complications of influenza, such as pneumonia, during influenza pandemics. However, the original evidence presented to government agencies around the world was incomplete, the researchers claim.

The Cochrane Review has benefited from recent access to more complete reports of the original research, made available by Roche and GlaxoSmithKline. Although the authors confirmed small benefits on symptom relief, there was little to justify the belief that Tamiflu reduces hospital admissions or the risk of developing confirmed pneumonia, the new data suggest. Along with the evidence of harms from the medication, it raises the question of whether global stockpiling of the drugs is still justifiable given the lack of reliable evidence to support the original claims of its benefits, according to the authors.

Dr. David Tovey, Editor-in-Chief, Cochrane, said: “We now have the most robust, comprehensive review on neuraminidase inhibitors that exists. Initially thought to reduce hospitalizations and serious complications from influenza, the review highlights that Tamiflu is not proven to do this, and it also seems to lead to harmful effects that were not fully reported in the original publications. This shows the importance of ensuring that trial data are transparent and accessible.”

The review recommends that guidance on the use of both neuraminidase inhibitors — oseltamivir and zanamivir — in the prevention or treatment of influenza should be revised to take account of the evidence of a small benefit and an increased risk of harm.

Source: Cochrane Collaboration; April 10, 2014.

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