Closing schools during a deadly flu pandemic could cut the overall number of infections by 15 percent, saving tens of thousands of lives, according to a study released Wednesday.
Health officials worldwide have been on high alert in recent years, concerned that the highly virulent H5N1 bird flu virus will evolve into a form easily spread among humans, unleashing a major pandemic.
Scientists have scrambled to develop vaccines and antiviral treatments in anticipation, but stockpiling these drugs is expensive, and no one can be sure how effective they will be against a future mutation of the virus.
A team of scientists led by Simon Cauchemez at the Centre for Outbreak Analysis and Modelling at Imperial College London looked at another oft-vetted measure for coping with such a scenario: keeping kids out of school.
"There is little consensus on the probable effectiveness of school closure in reducing the impact of a pandemic," noted Cauchemez and his colleagues.
To find out what that impact might be, the researchers correlated health data from France on seasonal flu outbreaks from 1985 to 2006 with two-week periods of school holiday.
They found that shutting down classrooms led to a 20-to-29 percent reduction in the rate at which influenza was trasmitted among children.
Extrapolating from this data, they concluded that a prolonged school closure during a serious pandemic could reduce the total number of cases by 13 to 17 percent, and by 18 to 23 percent among children.
The main effect would be to spread out the impact of the outbreak. With kids not in school, the number of infections during the worst week of the pandemic could be reduced by up to 40 percent, helping prevent an overwhelming rush on health care facilities.
Cauchemez cautioned that is would be difficult to maintain low contact rates among children for prolonged periods.
He also said that any positive health effects would need to be weighed against the financial and social costs of the disruption caused by keeping classrooms shuttered for more than a month.
And while he was confident that his projections would hold for European countries, which all have similar school holiday patterns, extrapolations to developing countries were more difficult, he said.
There were three major flu pandemics in the 20th century. The so-called "Spanish flu" of 1918 killed between 20 and 40 million, while the worldwide epidemics of 1957 and 1968 each left more than a million dead.