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Short-term school closings not an effective way to block influenza outbreaks

December 30, 2009 | 11:51 am

Pig Short-term school closings are not an effective way to block the spread of influenza viruses, and may even be counterproductive, Pennsylvania researchers have found. To be fully effective, the closures must last at least eight weeks, they reported in the Journal of Public Health Management and Practice.

School closures were common last spring during the first wave of pandemic H1N1 influenza. Such closures are based on the idea that such institutions are fertile places for viruses to spread and that children then carry the viruses into the community, but their use has been controversial. The closings place additional burdens on parents, cause loss of income to school staff, and interfere with children's educational progress, nutritional status (through school lunch and breakfast programs) and other activities. Parents forced to stay at home to care for their children lose income or even their jobs, a scenario that is more likely among low-income families. The Centers for Disease Control and Prevention now recommends that school closings occur only in limited circumstances.

Dr. Bruce Lee, an epidemiologist at the University of Pittsburgh, and his colleagues used computer modeling based on Allegheny County, Penn. to simulate various scenarios. The county has 1,242,755 residents, 537,405 households and 35,333 workplaces employing 563,874 adults.

The researchers concluded that closing schools for up to two weeks might delay the peak of an outbreak slightly but that, at worst, it might increase transmission by dumping susceptible children back into schools in the middle of an epidemic when they are most vulnerable to infection. To be effective, the closures had to last for at least eight weeks, they concluded. They also found that isolating sick kids individually and keeping them from attending school also had little impact on the course of the epidemic.

Results from an Australian study published in the online journal Emerging Infectious Diseasessupport this conclusion, although for different reasons. Dr. Paul V. Effler and his colleagues from the Department of Health in Perth, Australia, studied the activity of 233 kids during a school closing prompted by a swine flu outbreak and concluded that the closing did little to keep the kids out of contact with each other. At least 74% of the children reported at least one outing with other children away from home during the closing, with an average of almost four such outings per student. The authors thus concluded that the primary objective of the school closings--keeping children isolated in order to prevent spread of the virus--was a failure.

-- Thomas H. Maugh II