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August 3, 2005

Computer Simulation Analyzes Strategies for Stopping Flu Pandemic

Prompt Public Health Action Could Contain Outbreak

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Many scientists and public health experts believe that a global pandemic caused by a deadly and highly contagious flu virus is likely one day, if not inevitable. However, computer simulations of an influenza outbreak in Southeast Asia show that a global pandemic might be averted with a prompt public health response, such as targeted geographic use of prophylactic anti-viral drugs and policies to reduce social contact, such as quarantines or temporarily closing schools and businesses. The analysis is published in the August 3, 2005, edition of Nature. The computer simulation is part of the MIDAS (Models of Infectious Disease Agent Study) project of the National Institute of General Medical Sciences (NIGMS), and involves researchers at the Johns Hopkins Bloomberg School of Public Health; the Imperial College London; INSERM of Paris, France; the Department of Community Medicine in Hong Kong and the Thailand Ministry of Public Health.

Southeast Asia is currently the focus of the ongoing avian H5N1 epidemic that has infected some humans. The virus is a potential candidate for developing into a human-to-human transmissible pathogen. Using demographic data for 85 million people living in Thailand and information from previous flu pandemics, researchers developed a computer model to test various strategies for containing an outbreak.

In the simulations, uncontrolled disease spread from a localized community outbreak to a multi-country epidemic within 60 to 90 days. The most effective containment strategy used in the simulations involved providing antiviral drugs to everyone in regions where outbreaks occurred in conjunction with measures to “increase social distance” such as closing schools and establishing quarantines. The researchers estimated that, at most, 3 million doses of antiviral drug would be needed for the strategy to be effective. Limiting prophylactic drugs to only those who come in direct contact with infected persons was less effective according to the analysis. Nationwide prophylactic drug distribution was considered impractical. Vaccines were not considered in the current analysis, because none is currently available against avian influenza and too much time would be needed to develop and manufacture one in an emergency.

“Simulations of epidemics provide decision-makers with a powerful new tool. Now it is possible to test and select strategies ‘in silicon’ before a crisis,” said Derek Cummings, a study co-author and research associate at the Bloomberg School. Cummings is also co-author of a study published in the August 5, 2005, edition of Science. Like the article in Nature, it shows that it might be possible to contain a pandemic at its source, but containment would require a carefully planned intervention.

“Our computer simulations show that it may just be possible to head off a global disaster,” said Donald S. Burke, MD, senior author of the study and professor in the Department of International Health at the Bloomberg School. “To be successful, it will require genuine international cooperation, as well as some good luck.”

“Strategies for containing an emerging influenza pandemic in SE Asia,” was written by Neil M. Ferguson, Derek Cummings, Simon Cauchemez, Christopher Fraser, Steven Riley, Aronrag Meeyai, Sopon Iamsirithaworn and Donald Burke.

Funding was provided by the National Institute of General Medical Sciences MIDAS Program, the Medical Research Council, the Royal Society, the Howard Hughes Medical Institute, the Research Fund for the Control of Infectious Diseases of the Hong Kong SAR government and INSERM.

Public Affairs media contacts for the Johns Hopkins Bloomberg School of Public Health: Tim Parsons or Kenna Lowe at 410-955-6878 or

Supplementary Video
(Requires Free Quicktime player)

Supplementary Video 1 simulates a pandemic emergence in Thailand. Red represents areas with infected individuals and green represents areas that have recovered from infection. The video shows 300 days of spread. (3MB)

Supplementary Video 2 is an example of a controlled outbreak of transmissible pandemic flu. Red indicates areas of infection while blue indicates areas where a combination of control measures has been implemented. The video shows 100 days of spread. (710KB)

Supplementary Video 3 is an example of containment failure. The colors are the as in Supplementary Video 2. The video shows 300 days of spread. (3MB)

More information on supplementary video material