Sally Furniss
Well-known member
From the International Conference on Emerging Infectious Diseases 2008 pg 95 http://www.cdc.gov/eid/content/14/3/ICEID2008.pdf
Board 31. Potential Value of Multiple Border Control Interventions to Prevent Pandemic Influenza in Island Settings
N. Wilson1, H. Kelly2, M. Baker1, G. Sertsou 1; 1University of Otago, Wellington, Wellington, NEW ZEALAND, 2 Victorian Infectious Diseases Reference Laboratory, Melbourne, AUSTRALIA.
Background:
There have been historical successes with influenza pandemic control by island nations using maritime quarantine. Some islands have also recently included border control in their pandemic plans. We aimed to quantify potential border control measures for preventing or delaying pandemic influenza in island settings.
Methods:
We used a published method to model the proportion of cases developing symptomatic pandemic influenza on airline flights. We applied this method to air travel from Hong Kong, the assumed source area, to six island nations in the South Pacific: American Samoa, Fiji New Caledonia, New Zealand (NZ), Samoa, and Tuvalu. We then performed a threshold analysis using parameters from the epidemiological, modeling and historical literature and the deterministic modeling software InfluSim to determine the likely outcome of the implementation of incoming and outgoing travel restrictions, routine six-day facility-based quarantine, entry screening and tracing of contacts at risk from in-flight transmission.
Results:
NZ, the largest island population considered and Tuvalu, the smallest, were at the extremes. We found that 57% (NZ) to 93% (Tuvalu) of cases with a median time of infection 24 hours before commencing travel would have developed symptoms of pandemic influenza by the time of arrival in the capital city. During early WHO pandemic phase 6, it was estimated that all six countries could prevent cases being released into the community at the threshold of <1 case per 20 weeks. At the peak of phase 6, Tuvalu would require 99% travel reduction by citizens and 100% reduction by non-citizens, but no other interventions, to meet the threshold of <1 case in 20 weeks. However, even with all plausible border control interventions detailed above, it was likely that NZ would still release 1.3 undetected cases per week into the community. This would be sufficient to initiate and sustain a pandemic in the absence of additional interventions.
Conclusion:
The threshold analysis suggests that, for these island nations, border control interventions would probably be successful in the early stages of an influenza pandemic. But at the peak of phase 6, very rigorous measures would be required for island nations with substantail travel volumes if the release of cases into the community was to be prevented.
Board 31. Potential Value of Multiple Border Control Interventions to Prevent Pandemic Influenza in Island Settings
N. Wilson1, H. Kelly2, M. Baker1, G. Sertsou 1; 1University of Otago, Wellington, Wellington, NEW ZEALAND, 2 Victorian Infectious Diseases Reference Laboratory, Melbourne, AUSTRALIA.
Background:
There have been historical successes with influenza pandemic control by island nations using maritime quarantine. Some islands have also recently included border control in their pandemic plans. We aimed to quantify potential border control measures for preventing or delaying pandemic influenza in island settings.
Methods:
We used a published method to model the proportion of cases developing symptomatic pandemic influenza on airline flights. We applied this method to air travel from Hong Kong, the assumed source area, to six island nations in the South Pacific: American Samoa, Fiji New Caledonia, New Zealand (NZ), Samoa, and Tuvalu. We then performed a threshold analysis using parameters from the epidemiological, modeling and historical literature and the deterministic modeling software InfluSim to determine the likely outcome of the implementation of incoming and outgoing travel restrictions, routine six-day facility-based quarantine, entry screening and tracing of contacts at risk from in-flight transmission.
Results:
NZ, the largest island population considered and Tuvalu, the smallest, were at the extremes. We found that 57% (NZ) to 93% (Tuvalu) of cases with a median time of infection 24 hours before commencing travel would have developed symptoms of pandemic influenza by the time of arrival in the capital city. During early WHO pandemic phase 6, it was estimated that all six countries could prevent cases being released into the community at the threshold of <1 case per 20 weeks. At the peak of phase 6, Tuvalu would require 99% travel reduction by citizens and 100% reduction by non-citizens, but no other interventions, to meet the threshold of <1 case in 20 weeks. However, even with all plausible border control interventions detailed above, it was likely that NZ would still release 1.3 undetected cases per week into the community. This would be sufficient to initiate and sustain a pandemic in the absence of additional interventions.
Conclusion:
The threshold analysis suggests that, for these island nations, border control interventions would probably be successful in the early stages of an influenza pandemic. But at the peak of phase 6, very rigorous measures would be required for island nations with substantail travel volumes if the release of cases into the community was to be prevented.