All you need to read in the other general journalsBMJ 2012; 344 doi: https://doi.org/10.1136/bmj.e1021 (Published 16 February 2012) Cite this as: BMJ 2012;344:e1021
Transmission of pandemic flu halved during Alberta’s 2009 school holidays
A model of the H1N1 influenza pandemic in one province of Canada suggests that closing schools for summer holidays in 2009 greatly reduced the spread of infection and the incidence of confirmed cases. The end of the holidays may have kick started the second wave of the pandemic, say the authors, although falling temperatures and the arrival of autumn weather were also important factors in the upsurge of cases in late October and early November. They estimate that closing schools for the summer cut transmission of H1N1 in school children by around half and ended the first wave of the pandemic early in all age groups⇑.
The new model adds to growing evidence of a link between school closure and reduced transmission of flu viruses, says a linked editorial (p 238). Schoolchildren are high transmitters and seem to drive the trajectory of pandemics in particular. Closing schools to contain pandemics is controversial, not least because of the social and economic disruption that follows, but public health authorities now have enough evidence to at least consider it as a future strategy, says the editorial. Natural experiments in social distancing from St Louis in 1918, from Mexico in 2009, and now from Alberta all point the same way. They also share the same limitations. It is almost impossible, using observation alone, to isolate the effect of school closures from other changes that occur at the same time, including weather, vaccinations, distribution of antiviral drugs, and a rapid surge in the population’s enthusiasm for handwashing.