Using what you have: A low-cost method for assessing the epidemiological importance of individuals

Early detection of infectious disease outbreaks and prevention measures such as vaccination are important means of controlling such outbreaks. Under resource constraints, it is often not possible to survey every member of a community for early outbreak detection, or provide every person with a dose of vaccine. In such situations, sentinels should be defined to detect outbreaks with maximum likelihood, and prevention measures should targetindividuals who are most likely to be affected. CIDD researchers Timo Smieszek and Marcel Salathé developed a low-cost method- called collocation ranking- for identifying members of a community that are particularly suited for early detection and targeted-intervention strategies.

Usually, individuals of high epidemiological importance are determined by analyzing close-contact network data. Collecting such data typically involves contact surveys, in which people are asked to report all of their contacts that are close enough to transmit infection. Another approach is to equip a community with wireless sensors that are worn by the study participants and record all of their close encounters. Both data collection methods are very resource-intensive and cannot be done for every potential outbreak setting. Instead, the collocation ranking method developed by Smieszek and Salathé is based on data that is readily available, like class rosters at a school. The researchers found that the collocation rank, which relates to the cumulative time a member of a community spends with other individuals at a specific venue, predicts the likelihood and timing of infection very well when compared to other, more costly and data-intensive measures. Their results indicate that collocation ranking is a promising method for providing critical low-cost information that is needed to set up sentinel surveillance systems and to target prevention measures effectively.


This research has been published in BMC Medicine and selected as “Editor’s Pick.” Gerardo Chowell, a professor at Arizona State University, and Cécile Viboud, a scientist at the US National Institutes of Health, discussed the potentials and implications of this research in a commentary for BMC Medicine. To follow this discussion:


Synopsis by Timo Smieszek

Written By: Smieszek T& Salathe M

Paper Url:

Journal: 11:35

Journal Reference: 11:35

Paper Id: 10.1186/1741-7015-11-35