Travel-related measures in the early stage of the epidemic. (A) Probability distribution of the arrival time (date of arrival of the first symptomatic case) in Germany for different values of traffic reduction, ϕ. The vertical dotted line indicates the observed arrival time in the country, as obtained from official reports, and the vertical solid line indicates the starting date of the travel restrictions (25 April, 2009), which was the day after the international alert. The probability distributions were obtained from 2,000 stochastic realizations, and data were binned over 7 days. (B) Cumulative probability distributions of the first seeding event from Mexico to Germany for different values of traffic reduction ϕ. We considered any source of infection in the seeding event, including symptomatic cases and non-detectable infected cases, such as latent and asymptomatic. (C) Delay in the case importation from Mexico to a given country compared with the reference stochastic forecast output (SFO) as a function of the travel reduction ϕ. The delay was measured in terms of the date at which the cumulative distribution of the seeding from Mexico (B) reached 90%.
Tizzoni et al. BMC Medicine 2012 10:165 doi:10.1186/1741-7015-10-165