The feasibility of age-specific travel restrictions during XXXX pandemics.

@entity1 @entity683 @entity3082
BACKGROUND: Epidemiological studies have shown that imposing travel restrictions to prevent or delay an @entity683 pandemic may not be feasible. To delay an @entity3082 substantially, an extremely high proportion of trips (~99%) would have to be restricted in a homogeneously mixing population. Influenza is, however, strongly influenced by age-dependent transmission dynamics, and the effectiveness of age-specific travel restrictions, such as the selective restriction of travel by @entity1 , has yet to be examined. METHODS: A simple stochastic model was developed to describe the importation of infectious cases into a population and to model local chains of transmission seeded by imported cases. The probability of a local @entity3082 , and the time period until a major @entity3082 takes off, were used as outcome measures, and travel restriction policies in which @entity1 or adults were preferentially restricted were compared to age-blind restriction policies using an age-dependent next generation matrix parameterized for @entity683 H1N1-2009. RESULTS: Restricting @entity1 from travelling would yield greater reductions to the short-term risk of the @entity3082 being established locally than other policy options considered, and potentially could delay an @entity3082 for a few weeks. However, given a scenario with a total of 500 imported cases over a period of a few months, a substantial reduction in the probability of an @entity3082 in this time period is possible only if the transmission potential were low and assortativity (i.e. the proportion of contacts within-group) were unrealistically high. In all other scenarios considered, age-structured travel restrictions would not prevent an @entity3082 and would not delay the @entity3082 for longer than a few weeks. CONCLUSIONS: Selectively restricting @entity1 from traveling overseas during a pandemic may potentially delay its arrival for a few weeks, depending on the characteristics of the pandemic strain, but could have less of an impact on the economy compared to restricting adult travelers. However, as long as adults have at least a moderate potential to trigger an @entity3082 , selectively restricting the higher risk group ( @entity1 ) may not be a practical option to delay the arrival of an @entity3082 substantially.
