Avian flu pandemic could be brought under control in three weeks
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《英国医生杂志》
An avian influenza pandemic could be prevented but only with swift and targeted intervention at an early stage, say two research papers published online on 3 August in the journals Nature and Science (www.nature.com, doi: 10.1038/nature04017 and www.sciencemag.org, doi: 10.1126/science.1115717).
Both studies assumed that each person infected would transmit the disease to fewer than two people. Although H5N1 avian flu has very low virulence, no one can predict the reproduction number of any future flu pandemic strain as it could recombine with an existing highly virulent human flu strain. Assuming a reproduction number of less than two, however, both models predict that an outbreak could be brought under control in the first three weeks.
The studies used computer simulations to assess the effectiveness of early intervention in pandemic outbreaks in Thailand, which was chosen for its rich supply of research on social networks rather than because of its likelihood as the origin for an outbreak.
The two computer simulations are part of the Models of Infectious Disease Agent Study research network, which is funded by the US National Institute of General Medical Sciences. "These new models illustrate how the fundamental features of infectious disease spread and can be captured to predict possible outcomes and the potential impact of interventions," said Jeremy Berg, director of the institute.
The studies both evaluated the potential effectiveness of targeted mass prophylaxis with antiviral drugs and quarantine measures. Research led by Neil Ferguson, professor of mathematical biology at Imperial College, London, and lead author of the paper published in Nature, modelled the potential spread of avian flu across the whole population of 85 million people and concluded that if the basic reproduction number of the virus was below 1.8, geographically targeted prophylaxis and social distancing could bring an outbreak under control, and that a stockpile of three million doses of antiviral drugs would be sufficient.
"Policy effectiveness depends critically on how quickly clinical cases are diagnosed and the speed with which antiviral drugs can be distributed," he wrote.
In the paper published in Science, Ira Longini, a biostatistician at the Rollins School of Public Health, Emory University, Atlanta, modelled an outbreak in Thailand's Nang Rong region with a population of 500 000 and estimated that, with a reproductive number below 1.6, an antiviral stockpile of 100 000 to 1 million doses would be sufficient. "If prevaccination occurs, then targeted antiviral prophylaxis could be effective for containing strains with a reproductive number as high as 2.1," he wrote.
The World Health Organization welcomed the research papers and highlighted the need to work with countries currently affected by the outbreak of H5N1 avian flu. "The real question is how do we strengthen surveillance and reporting so that the very brief window out-lined in these reports can be utilised? We would work with countries where there have been outbreaks of avian influenza to strengthen their surveillance systems," said Dick Thompson, WHO's spokesman in Geneva.
To date, WHO has only 120 000 doses stockpiled. Roche, the manufacturer of the antiviral drug Tamiflu, announced on 3 August that it is in discussions with WHO to donate a substantial amount of the drug to the organisation.(Jane Parry)
Both studies assumed that each person infected would transmit the disease to fewer than two people. Although H5N1 avian flu has very low virulence, no one can predict the reproduction number of any future flu pandemic strain as it could recombine with an existing highly virulent human flu strain. Assuming a reproduction number of less than two, however, both models predict that an outbreak could be brought under control in the first three weeks.
The studies used computer simulations to assess the effectiveness of early intervention in pandemic outbreaks in Thailand, which was chosen for its rich supply of research on social networks rather than because of its likelihood as the origin for an outbreak.
The two computer simulations are part of the Models of Infectious Disease Agent Study research network, which is funded by the US National Institute of General Medical Sciences. "These new models illustrate how the fundamental features of infectious disease spread and can be captured to predict possible outcomes and the potential impact of interventions," said Jeremy Berg, director of the institute.
The studies both evaluated the potential effectiveness of targeted mass prophylaxis with antiviral drugs and quarantine measures. Research led by Neil Ferguson, professor of mathematical biology at Imperial College, London, and lead author of the paper published in Nature, modelled the potential spread of avian flu across the whole population of 85 million people and concluded that if the basic reproduction number of the virus was below 1.8, geographically targeted prophylaxis and social distancing could bring an outbreak under control, and that a stockpile of three million doses of antiviral drugs would be sufficient.
"Policy effectiveness depends critically on how quickly clinical cases are diagnosed and the speed with which antiviral drugs can be distributed," he wrote.
In the paper published in Science, Ira Longini, a biostatistician at the Rollins School of Public Health, Emory University, Atlanta, modelled an outbreak in Thailand's Nang Rong region with a population of 500 000 and estimated that, with a reproductive number below 1.6, an antiviral stockpile of 100 000 to 1 million doses would be sufficient. "If prevaccination occurs, then targeted antiviral prophylaxis could be effective for containing strains with a reproductive number as high as 2.1," he wrote.
The World Health Organization welcomed the research papers and highlighted the need to work with countries currently affected by the outbreak of H5N1 avian flu. "The real question is how do we strengthen surveillance and reporting so that the very brief window out-lined in these reports can be utilised? We would work with countries where there have been outbreaks of avian influenza to strengthen their surveillance systems," said Dick Thompson, WHO's spokesman in Geneva.
To date, WHO has only 120 000 doses stockpiled. Roche, the manufacturer of the antiviral drug Tamiflu, announced on 3 August that it is in discussions with WHO to donate a substantial amount of the drug to the organisation.(Jane Parry)