Disease outbreaks partially fueled by replacement employees

When a teacher, doctor, or nurse calls in sick, someone has to take that worker’s place. The need for substitutes peaks during infectious disease outbreaks—for example, about 17% of nurses in Canada missed work at some point during the 2009 H1N1 influenza pandemic (virus pictured here). A new study by Samuel Scarpino and Laurent Hébert-Dufresne at the Santa Fe Institute in New Mexico and Antoine Allard from the University of Barcelona in Spain suggests that replacing sick workers during a disease outbreak actually accelerates the spread of the pathogen. The researchers considered a model in which some people who work in essential services were replaced shortly, though not immediately, after they got sick. By entering an environment where the disease has almost certainly spread, replacements become more susceptible to infection than an average member of the population. The total number of infected people in the model therefore increased, as...