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Double dose of antiviral drug offers no added benefit in severe influenza

31 May 2013

Giving double doses of the antiviral drug oseltamivir, or Tamiflu, offers no clinical or virological advantages over a standard dose for patients admitted to hospital with severe influenza infection, according to a randomised trial published today and funded by the Wellcome Trust, the US National Institute of Allergy and Infectious Diseases, and the Singapore National Medical Research Council.

This is the first study to look at the effectiveness of higher doses of oseltamivir in cases of severe flu infection and has implications for global guidelines on clinical management and stockpiling drugs for pandemic preparedness, including the current outbreak of the H7N9 virus.

Most people who are infected with flu will recover within two weeks, but some people will develop complications (such as difficulty breathing) that can result in hospital admission and can be life-threatening.

Studies have shown that early treatment with oseltamivir is beneficial for patients with uncomplicated flu infection and improves survival in hospitalised patients with severe infection. This has led some authorities to recommend double doses of oseltamivir for the treatment of patients with severe flu infections.

The study, conducted by researchers from the South East Asia Infectious Diseases Clinical Research Network, involved 326 patients with severe flu infection at 13 hospitals in Indonesia, Singapore, Thailand and Vietnam. Most of the patients were children under the age of 15.

Patients were given either a standard dose or a double dose of oseltamivir for five days. Their virus levels were monitored for the duration of the treatment, along with other outcomes such as admission to intensive care, the need for mechanical ventilation to assist with breathing, and death.

The findings, published online today in the 'British Medical Journal', reveal no difference in virus levels at day five between the treatment groups. There were also no clinical differences in the outcome of patients including need for ventilation, time in hospital, rate of death, or rates of adverse events between the different doses.

Professor Jeremy Farrar, Director of the South East Asia Infectious Disease Clinical Research Network, said: "The recommendation to give higher doses of oseltamivir to severe cases of flu infection has major implications for clinical management, public health and planning for antiviral stockpiles but has not been grounded in evidence. Our findings do not support routine use of double doses to treat severe flu infections, which could help to conserve drug stocks in the event of a pandemic."

Image: Influenza viruses (blue) infecting cells of the trachea. Credit: R Dourmashkin, Wellcome Images.


Jen Middleton
Senior Media Officer, Wellcome Trust
020 7611 7262

Notes to editors

Effect of double dose oseltamivir on clinical and virological outcomes in children and adults admitted to hospital with severe influenza: double blind randomised controlled trial. BMJ 2013 (epub ahead of print).

The British Medical Journal has also published an editorial to accompany the paper.

About the South East Asia Infectious Disease Clinical Research Network
The South East Asia Infectious Disease Clinical Research Network (SEAICRN) is a collaborative partnership of hospitals and research institutions in Thailand, Vietnam, Indonesia and Singapore formed in September 2005. The SEAICRN focuses on clinical research on human and avian influenza and other infectious diseases of public health importance in the region. The Network develops and implements protocol-based studies following international standards.

About the Wellcome Trust
The Wellcome Trust is a global charitable foundation dedicated to achieving extraordinary improvements in human and animal health. It supports the brightest minds in biomedical research and the medical humanities. The Trust's breadth of support includes public engagement, education and the application of research to improve health. It is independent of both political and commercial interests.

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