Tamiflu, the drug which many governments have stockpiled to ward off a deadly bird flu pandemic, appears to be an effective treatment for the disease if administered early enough, its maker Roche Holding AG said.
Roche said on Friday tests on animals showed Tamiflu could work against the current virus but that more studies were needed into how much Tamiflu should be given in order to effectively combat the virus in humans.
“The results suggest that Tamiflu can prevent H5N1 mortality in animals,” Roche said in a statement on Friday.
“However, further studies are needed to identify the optimal dose of Tamiflu administered later (24 and 48 hours) after the infection with the virulent H5N1 virus,” the firm said.
The statement follows research published on Thursday in The Lancet medical journal in which doctors said they had found no evidence that Tamiflu was effective against bird flu.
Roche’s study evaluated the efficacy of Tamiflu, known generically as oseltamivir, given to ferrets four hours after infection with the current strain of the disease, H5N1.
“These initial results are encouraging as they demonstrate that early treatment with oseltamivir is effective in treating the H5N1 avian influenza virus,” said Elena Govorkova, who conducted the study at St Jude Children’s Research Hospital in the United States, in a statement.
The virus given was extracted from a person in Vietnam who became infected with bird flu, said David Reddy, the executive in charge of sales of Tamiflu to governments.
“This is animal data and in a limited number of animals,” he told reporters, stressing the drug was given very soon after infection.
Reddy said that from Roche’s experience with seasonal flu, the drug was known to be most effective when given within 48 hours of symptoms first appearing. He declined to give any timeframe for administering the drug to treat bird flu, but noted the virus was more aggressive in nature.
A study released in December in the New England Journal of Medicine suggested that the H5N1 virus could evade the drug, but Roche has said that the patient in question had been given the wrong dose.
Reddy also said the Lancet study was “irresponsible” for suggesting that doctors should not be prescribing Tamiflu for seasonal flu.
The World Health Organization said it would continue to recommend Tamiflu despite questions over efficacy as a bird flu treatment.
Asked whether the WHO was changing its recommendations, spokeswoman Christine McNab said: “Absolutely not, not at this point. There is no evidence that we should do that.
“We will, of course, be tracking ongoing studies which will be really helpful in determining for example the dosage of oseltamivir that would be necessary,” she said.
In the absence of a vaccine against the virus, the World Health Organization (WHO) recommends that governments build stockpiles of drugs such as Tamiflu, one of a class of medicines known as neuraminidase inhibitors.
Bird flu is known to have killed at least 80 people since late 2003. Victims contract the virus from close contact with infected birds, but there are fears it could mutate into a form that passes easily from person to person, sparking a pandemic.
Roche has earmarked a total of 5 million treatments of the drug as free stockpiles, part of which has been dubbed a fire blanket to be used to contain a pandemic. The remainder will be shipped to affected regions and deployed on a local level.