Counteracting disease spread over city commuter networks

Public transport networks in large cities are the perfect way for a disease to spread. The confined spaces, the high numbers of people passing through—especially during the daily commute—mean that a virulent disease could make its way across the city in even a few hours.

To face this challenge, health officials need to design countermeasures that fight disease spread while remaining cost effective. A promising strategy, research shows, is to target the hubs of the transport network, such as particularly busy stations. A study by the IIASA Evolution and Ecology Program uses innovative network analysis to show how such hubs can best be identified.

Using Tokyo as a test case, the team developed a new type of “network centrality measure,” which quantifies the relative importance—in terms of disease spread—of each location in the network.

The results show that the impact of taking countermeasures at the largest station is more than 1,000 times more effective in stopping disease spread than at the second largest station, even though the number of people passing through is only around 1.5 times larger. On top of this, the effect of countermeasures at other stations is strongly dependent on the number of commuters at the largest station.

Providing vital information to city health officials around the world, this study is among the first to show that only the largest hubs play such an extraordinary role.

The researchers also found the stations that are important for preventing an outbreak of infection in the population are not necessarily the same as those that are important for reducing the number of people infected.