File photo shows school children hold a banner as they take part in a H1N1 flu, formerly known as the swine flu, awareness run in the southern Indian city of Hyderabad August 17, 2009. (Xinhua/Reuters File Photo)

Under ideal conditions, school closure can reduce the demand for health care by an estimated 3050 percent at the peak of the pandemic. However, if schools close too late in the course of a community-wide outbreak, the resulting reduction in transmission is likely to be very limited.

Policies for school closure also need to include measures that limit contact among students when not in school. If students congregate in a setting other than a school, they will continue to spread the virus, and the benefits of school closure will be greatly reduced, if not negated.

Governments should also take into consideration the economic and social costs of school closure when dealing with an outbreak, the WHO said.

The main economic cost arises from absenteeism of working parents or guardians who have to stay home to take care of their children.

In addition, school closure may also disrupt the provision of essential health care, as many doctors and nurses are parents of school-age children.