Vanesa Martinez of The Irish Times reports that the common policy of replacing a teacher or a health worker with a substitute when they are sick could help to increase the spread of disease, a new study found.

This result may be counterintuitive but the authors back up their analysis of mathematical models of the spread of disease with actual recorded data from past outbreaks.

Infectious diseases would spread faster due to placing a healthy person in a situation where he or she could become infected as well.

“Findings show that a common-sense response during outbreaks could in fact be adding to the problem,” says Prof Lina Zgaga, Associate Professor of Epidemiology at Trinity College Dublin Centre for Health Sciences.

The results could help develop better public health policies during outbreaks, the authors say. For example, vaccinating key workers could significantly decrease the danger of faster disease spreading.

Yes, vaccines work.

The results are published this week in the scientific journal Nature Physics.