Travel measures imposing a reduction of

and

are compared to the reference scenario where the observed drop in air travel to/from Mexico is taken into account.

**A**,

**B**, Probability distributions of the arrival time (defined as the date of arrival of the first symptomatic case) in the United Kingdom (

**A**) and Germany (

**B**) for different values of

. Here we consider the importation from any possible source country, not only Mexico. 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, April 25, 2009, the day after the international alert. The probability distributions are obtained from 2,000 stochastic realizations and data are binned over 7 days. Even when imposing

, the peak of the probability distribution is not delayed with respect to the real scenario.

**C**,

**D**, Cumulative probability distributions of the first seeding event from Mexico to the United Kingdom (

**C**) and Germany (

**D**) for different values of

. Here we consider any source of infection in the seeding event, including symptomatic cases and non-detectable infected cases, such as latent and asymptomatic, as allowed by the computational approach. The distributions are computed over 2,000 stochastic realizations. The effect of travel restrictions is very limited in delaying the time at which the cumulative distribution reaches the unit.

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