4 August 2005: Drug stockpiles needed in preparation for flu pandemic
Creating a massive stockpile of antiviral drugs - and the means to distribute them quickly - will be key to preventing millions of deaths from influenza, according to researchers studying the likely spread of the virus.
Public health experts fear that a global flu pandemic may emerge soon with potential effects similar to the 1918-19 Spanish flu outbreak that killed an estimated 20 million people. More than 50 people have died in south east Asia over the past two years from avian influenza virus contracted from domestic poultry. Although there is little evidence so far of disease spread through human to human contact, experts believe it is only a matter of time before a mutation emerges to allow direct transmission.
Data released today by two separate research groups suggest there is the knowledge and technology available to control the next epidemic. Both groups have produced computer models for the spread of outbreak originating in Thailand and reach the same conclusions about the strategies needed to contain the virus.
Both recommend the immediate introduction of 'social distancing measures' - the closure of schools and workplaces in the area around the outbreak. Vaccination may also be useful. There is no effective vaccine against any newly emerged viral strain, but existing vaccines might provide some degree of immunity. More importantly, those people at risk should receive prophylactic treatment with a neuraminidase inhibitor antiviral drug, Tamiflu.
'This drug has been used successfully to treat patients with avian flu and when used in healthy people it acts like a temporary vaccine,' said one of the lead researchers, Neil Ferguson, a computational biologist at Imperial College, London, UK.
Ferguson's team estimates that a stockpile of three million doses would be enough to contain the pandemic. The company that manufactures Tamiflu, Roche, is discussing establishing a stockpile with the World Health Organisation. If it is needed, the drug would need to be available within three days of the first reports of an outbreak. But given the high state of readiness to tackle the disease in those states most at risk, Ferguson says it is realistic to expect an outbreak to be declared early, with fewer than 50 people affected.
Jenny Mumford of the Contagious Diseases Consortium at the University of Cambridge, UK, cautioned that the two parallel studies were 'interesting but theoretical'. The success of the computer simulations depends crucially on the accuracy of assumptions made about a component called Ro - the reproduction number, which measures the number of people infected by each original case, she said. John Bonner
N M Ferguson et al, Nature (DOI: 10.1038/nature04017)
I M Longini et al, Science (DOI:10.1126/science.1115717)