Flu drug Tamiflu is not as effective as Roche has made it out to be, a Cochrane Collaboration and BMJ review has concluded.
On the positive side, the antiviral was found to shorten symptoms of influenza by half a day and, when used as a preventative treatment, Tamiflu (oseltamivir) reduced the risk of people suffering from flu symptoms.
However, the Cochrane and BMJ review also found “there is no good evidence to support claims that it reduces admissions to hospital or complications of influenza”. In addition, “it is unproven that it can stop people carrying the influenza virus and spreading it to others”.
The review also revealed there was an increased risk of side effects, such as nausea, vomiting, headaches, psychiatric disturbances and renal events, when taking the drug.
The Cochrane Review: Neuraminidase inhibitors for preventing and treating influenza in healthy adults and children, is based on full internal reports of 20 Tamiflu and 26 Relenza (zanamivir – manufactured by GlaxoSmithKline) trials involving more than 24,000 people.
The findings have challenged the historical assumption the neuraminidase inhibitors are effective in combatting flu, which was a key factor in decisions made by governments around the world to stockpile these drugs in case of a pandemic.
Use of Tamiflu increased dramatically following the outbreak of the H1N1 swine flu virus in April 2009. The USA has spent more than $1.3 billion buying strategic reserve of antivirals, while in the UK the government has spent almost £424 million for a stockpile of about 40 million doses.
Now the review authors are asking governments whether they would make the same stockpiling decisions on the back of the review’s conclusions, which they claim, “raise 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”.
The review authors – Dr Tom Jefferson, Dr Carl Heneghan and Dr Peter Doshi – said this review showed the importance of trial transparency. “Drug approval and use cannot be based on biased or missing information any longer. We risk too much in our population’s health and economy… We urge people not to trust in published trials alone or on comment from conflicted health decision makers, but to view the information for themselves.” They call on the current guidance to be reviewed in light of the new findings.
The review follows a four-year battle to access the trial results. Tamiflu’s manufacturer Roche has been criticised for its lack of transparency with its data and its unwillingness to help provide access to the information. Roche has previously claimed patient and commercial confidentiality as the reason why it withheld some data.
In response to the review (see also YouTube link below), Roche said it “fundamentally disagrees” with the overall conclusions, adding that it “firmly stands” by the quality and integrity of the data as “reflected in decisions reached by 100 medicines regulators across the world and subsequent real-world evidence demonstrating that Tamiflu is an effective medicine in the treatment and prevention of influenza”. The drugmaker also says it does not consider the Cochrane Acute Respiratory Infections Group that authored the report “to be the final authority on the value of neuraminidase inhibitors”.
“Roche believes it is important that public health bodies and influenza experts provide their opinion on this review, alongside the totality of Tamiflu data, before any conclusions are drawn.”
Roche’s UK medical director Dr Daniel Thurly adds that the report’s conclusions “could potentially have serious public health implications”.
Furthermore, the company claims the review did not include patient-level data that Cochrane had requested, and says the National Audit Office has previously found the government’s stockpile to be cost-effective. The company also cites other trial data that has found the drug safe and effective.
The findings come just months after a report was published by MPs criticising the amount of money spent on stockpiling Tamiflu. The UK Parliament's Public Accounts Committee said it was “surprised and concerned to discover that information is routinely withheld from doctors and researchers about the methods and results of clinical trials on treatments currently prescribed in the UK”. It added: “None of the latest proposals from regulators or industry adequately addresses the issue of access to the results of trials from previous years on the medicines in use today.”