Restricting travel could help reduce the spread of infections like SARS by more than 50%. In a study published today in the open access journal BMC Medicine, Swedish researchers simulated infection scenarios and tested the impact of travel restrictions on the spread of infection. They show that banning trips longer than 50 km would greatly reduce the spread of infection, even if 30% of the population did not comply.
Martin Camitz, from the Swedish Institute for Infectious Diseases Control and Fredrik Liljeros, from Stockholm University simulated the spread of an infection in Sweden, using data about all inter-city trips carried out by 17,000 individuals during two assigned months. All single, inter-city trips were included, regardless of the destination, aim of the trip and the mode of transport. The authors then tested scenarios where the infection outbreak started in Stockholm and where travel between towns and cities was subsequently restricted.
The results of the simulations show that restricting travel so that all trips further than 50 km are banned would reduce the number of infected individuals by 50% and the number of affected municipalities by over 80%. A ban on trips longer than 20 km would reduce the spread of the infection even more. The impact of a travel ban on the spread of infection would be significant even if compliance were as low as 70%.
The authors conclude: "The model and results are robust and there is no reason to believe that the results are not generally applicable to any country or region."
The effect of travel restrictions on the spread of a moderately contagious disease
Martin Camitz and Fredrik Liljeros
BMC Medicine 2006, in press (14 December 2006)