Canadian researchers have found compelling evidence that closing schools is an effective way to control flu epidemics. Scientists at McMaster University in Ontario and elsewhere compared patterns of flu transmission with weather and school calendars in Alberta from April to December 2009. The study, published in Annals of Internal Medicine, found that transmission rates were linked to weather, but even more strongly to the closing of schools in the spring and their reopening in the fall.
What did the study show? The ending and restarting of school terms had a major effect in attenuating the first wave and starting the second wave of pandemic influenza cases. Mathematical models suggested that school closure reduced transmission among school-age children by more than 50% and that this was a key factor in interrupting transmission. The models also indicated that seasonal changes in weather had a significant effect on the temporal pattern of the epidemic.
The researchers acknowledge that their model cannot include all possibly relevant factors, but the significant effect of school closings persisted even when their analyses included weather, geographical factors and variations in consistency of reporting. Pupils are important drivers of flu transmission, they conclude. In addition to closing schools, targeting children for vaccination and hygiene could substantially reduce an epidemic’s severity.
The conclusion? Analysis of data from unrestricted virologic testing during an influenza pandemic provides compelling evidence that closing schools can have dramatic effects on transmission of pandemic influenza. School closure seems to be an effective strategy for slowing the spread of pandemic influenza in countries with social contact networks similar to those in Canada.