There is no evidence to support claims that Tamiflu and Relenza, two flu medications, reduce hospital admissions or complications related to flu, according to research.
Roche’s Tamiflu (oseltamivir) and GlaxoSmithKline’s Relenza (zanamivir) are two drugs normally prescribed for the prevention and treatment of flu in adults and children, preventing further complications and admissions to hospital. But researchers claim there is no substantial evidence to make these claims.
The new study, jointly published by The Cochrane Collaboration and The BMJ, said that when used as a preventative treatment, the drug can reduce the risk of people suffering symptomatic influenza, but it is unproven that it can stop people carrying the flu virus and spreading it to others.
The latest updated Cochrane Review: Neuraminidase inhibitors for preventing and treating influenza in healthy adults and children, is based on full internal reports of 20 Tamiflu (oseltamivir) and 26 Relenza (zanamivir) trials.
These trials involved more than 24,000 people and the 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 influenza. This raises further questions about the most effective way to support drug regulation and public health policy decision-making.
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 US has spent more than $1.3 billion buying a strategic reserve of antivirals, while in the UK 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 the Cochrane researchers to verify the safety and effectiveness of Tamiflu – and led to questions over decisions to stockpile the drug while the risks and benefits remained uncertain.
The worldwide use of Tamiflu, has increased dramatically since the outbreak of H1N1 virus (Swine Flu) in April 2009. It was initially believed that it would reduce hospital admissions and complications of influenza, such as pneumonia, during influenza pandemics. However, the original evidence presented to government agencies around the world was incomplete. The Cochrane Review has benefited from access to more complete reports of the original research, now made available by the manufacturers, Roche and GlaxoSmithKline.
Although the review has confirmed small benefits on symptom relief, there is little to justify any belief that it reduces hospital admission or the risk of developing confirmed pneumonia. 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.