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For those who live in New Zealand, or on smaller Pacific or Caribbean islands, it is an important question.
Nations that share borders - particularly porous borders - with other nations, or that have multiple points of entry or see large numbers of incoming arrivals, would have a much harder time preventing (or even delaying) the entry of a pandemic virus to their shores.
But for island nations, the prospects are somewhat brighter.
During the 1918 Spanish flu, a few Pacific islands managed to prevent, or at least delay, entry of the virus by enforcing strict quarantines.
A dispatch printed in the March, 2008 edition of the CDC's Journal of Emerging Infectious Diseases provides some historical perspective.
Protective Effect of Maritime Quarantine in South Pacific Jurisdictions, 1918–19 Influenza Pandemic
Melissa A. McLeod,* Michael Baker,* Nick Wilson,*
Heath Kelly,† Tom Kiedrzynski,‡ and Jacob L. Kool§
*University of Otago, Wellington, New Zealand; †Victorian Infectious Diseases Reference Laboratory, Melbourne, Australia; ‡Secretariat of the Pacific Community, Noumea, New Caledonia; and §World Health Organization Office for the South Pacific, Suva, Fiji
Abstract
We reviewed mortality data of the 1918–19 influenza pandemic for 11 South Pacific Island jurisdictions. Four of these appear to have successfully delayed or excluded the arrival of pandemic influenza by imposing strict maritime quarantine. They also experienced lower excess death rates than the other jurisdictions that did not apply quarantine measures.
The four successful quarantines were in American Samoa (5 days' quarantine) and Continental Australia, Tasmania, and New Caledonia (all 7 days' quarantine).
- The Spanish Flu did not reach American Samoa until 1920, and had apparently weakened, as no deaths were reported.
- Australia's quarantine kept the influenza away until January of 1919, a full 3 months after the flu has swept New Zealand with disastrous effects.
- Tasmania kept the flu at bay until August of 1919, and health officials believed they received an milder version, as their mortality rate was one of the lowest in the world.
- By strictly enforcing a 7-day quarantine, New Caledonia managed to avoid introduction of the virus until 1921.
Today we get a new study that models the efficiency of quarantining arrivals on unaffected island nations during an influenza pandemic.
This research is based on having the ability to enforce strict quarantines, and a modest number of arrivals (8,000). As the number of arrivals goes up, the chances of someone harboring the virus getting through increases.
By instituting a 9 day quarantine on arriving visitors, or a 6-day quarantine along with using rapid influenza testing, the authors believe that such a quarantine might `contribute substantially to preventing the arrival of pandemic influenza (or at least delaying the arrival date).'
Quarantine for pandemic influenza control at the borders of small island nations
Hiroshi Nishiura , Nick Wilson and Michael G Baker
BMC Infectious Diseases 2009, 9:27doi:10.1186/1471-2334-9-27
Published:
11 March 2009
Abstract (provisional)
Background
Although border quarantine is included in many influenza pandemic plans, detailed guidelines have yet to be formulated, including considerations for the optimal quarantine length. Motivated by the situation of small island nations, which will probably experience the introduction of pandemic influenza via just one airport, we examined the potential effectiveness of quarantine as a border control measure.
Methods
Analysing the detailed epidemiologic characteristics of influenza, the effectiveness of quarantine at the borders of islands was modelled as the relative reduction of the risk of releasing infectious individuals into the community, explicitly accounting for the presence of asymptomatic infected individuals. The potential benefit of adding the use of rapid diagnostic testing to the quarantine process was also considered.
Results
We predict that 95% and 99% effectiveness in preventing the release of infectious individuals into the community could be achieved with quarantine periods of longer than 4.7 and 8.6 days, respectively. If rapid diagnostic testing is combined with quarantine, the lengths of quarantine to achieve 95% and 99% effectiveness could be shortened to 2.6 and 5.7 days, respectively. Sensitivity analysis revealed that quarantine alone for 8.7 days or quarantine for 5.7 days combined with using rapid diagnostic testing could prevent secondary transmissions caused by the released infectious individuals for a plausible range of prevalence at the source country (up to 10%) and for a modest number of incoming travellers (up to 8000 individuals).
Conclusions
Quarantine at the borders of island nations could contribute substantially to preventing the arrival of pandemic influenza (or at least delaying the arrival date). For small island nations we recommend consideration of quarantine alone for 9 days or quarantine for 6 days combined with using rapid diagnostic testing (if available).
