Piecemeal closures don’t ease epidemics

U. WARWICK (UK) — Widespread school closures are the only way to significantly curtail the spread of an epidemic, according to a new study that finds limited closures are ineffective at reducing strain placed on hospitals.

“Influenza potentially places an extreme burden on local health services. This was observed in both the 2009-10 swine-flu pandemic and this year’s seasonal flu outbreak,” says Thomas House, of the University of Warwick.

“Our work uses mathematical models to assess how school closures reduce the burden on particular hospitals. Although sustained national closures of schools can be very effective, they are costly and disruptive, and can even prevent parents in the health service from responding to any epidemic.

“We find in the worst cases, that short duration, localized closures cannot fully prevent some hospitals exceeding capacity. This means, when facing the threat of a severe pandemic, a coordinated and possibly extended period of school closures may be necessary.”

Details of the study are reported in the journal Proceedings of the Royal Society B.

Even with broadly optimistic assumptions about school closures, the proportion of hospitals above capacity in their intensive care units  cannot be brought to zero and only achieves its lowest value of 12 percent when there is a coordinated closure of at least 30 percent of all schools.

In fact if less optimistic (but more realistic) assumptions are made about the timing and selection of closures there is no significant difference on the strain put on intensive care units until at least 50 percent of all schools are closed.

“Our work supports the decision not to close schools as a control measure during the 2009/10 swine ‘flu pandemic,” House says. “If a pandemic is serious enough to require measures like school closures, then they need to be well timed and large scale to have much effect.”

The Warwick research team is asking for more public help to create even bigger data sets to help future modeling of these problems that could help inform decision making in future epidemics.

“The results in this work rely on existing information about local schools and hospitals, and yet tell us a lot about our ability to control pandemics, says Matt Keeling, professor of life sciences.

“Yet, if we wish to devise more refined control methods, we need far more information about people’s contact patterns and the behavior of ‘flu in the UK.”

More news from University of Warwick: http://www2.warwick.ac.uk/newsandevents/