Closing schools for less than a fortnight during a flu pandemic may actually increase infection rates and prolong an epidemic.
These findings by University of Pittsburgh researchers, based on a series of computer simulations, indicate that schools may need to be closed for at least eight weeks in order to cut down the spread of infection.
The value of school closures has been debated as a possible strategy to stem or slow the current H1N1 influenza pandemic.
Hundreds of schools across the US and elsewhere in the world have been closed at different periods in 2009 for fear the virus would spread more quickly if they stayed open.
"Although closing schools may seem like a reasonable way to slow the spread of flu, we found that it was not effective unless sustained for at least eight weeks after implementation," said Bruce Lee, the university's assistant professor of medicine, epidemiology and biomedical informatics who led the study.
Closing schools quickly at the start of an outbreak was much less important than keeping them closed continually throughout the epidemic, he added.
Short-duration school closures can increase transmission rates by returning susceptible students back to school in the middle of an epidemic when they are most vulnerable to infection, the study said.
{{/usCountry}}Short-duration school closures can increase transmission rates by returning susceptible students back to school in the middle of an epidemic when they are most vulnerable to infection, the study said.
{{/usCountry}}The study also found that identifying sick students individually and keeping them from attending school had minimal impact on an epidemic.
In addition, there were no significant differences between individual school closures and system-wide closures in mitigating an epidemic.
These findings were published in the Journal of Public Health Management and Practice.