Preventing the Spread of Bird Flu

cockerelIn the week that the H7 variant of avian influenza has led to the culling of 35000 chickens in England, scientists at Imperial College London have simulated the spread of a “human” bird flu epidemic and say that rapid treatment and isolation of infected individuals not only from the public but their household contacts will be essential to prevent thousands of deaths. They also suggest that vaccine stockpiles should be gathered together in readiness for a pandemic, even if the vaccine is not very potent. However, it is strict border controls and travel restrictions that will be needed to slow an outbreak and prevent a global pandemic.

Neil Ferguson and colleagues used computer modelling to evaluate the influence of a range of anti-pandemic measures, such as treatment and prophylaxis with antiviral drugs, household quarantine, vaccination and restrictions on travel. They found that with a policy of giving antiviral drugs both as treatment to infected cases and prophylactically to the patient’s families coupled with early closure of schools hit by the outbreak, rates of disease could be cut by almost a half.

However, for this policy to be feasible, antiviral stockpiles would need to be sufficient to treat 50% of the population – twice what many countries are planning. Combining such a policy with targeted immunization of children with a stockpiled trial vaccine might reduce illness rates by two-thirds, even if the vaccine was not particularly effective in its protection. Even greater drug coverage would have a correspondingly larger protective impact. Ferguson provides more details in this week’s Nature.