GENEVA, Sept. 11 (Xinhua) -- School closure, if adopted timely and properly, can effectively slow down the spread of the A/H1N1 flu virus, the World Health Organization (WHO) said on Friday.

    "School closure can operate as a proactive measure, aimed at reducing transmission in the school and spread into the wider community," the UN agency said in a news briefing posted on its official website.

File photo shows a health official at the entrance of a middle school in Lanzhou, capital of northwest China's Gansu Province, Aug. 31, 2009. A/H1N1 flu cases broked out in the middle school there since Aug. 28, and the confirmed infected patients grew to 26 till 3 pm Aug. 30. (Xinhua File Photo/Han Chuanhao) Photo Gallery>>>

    According to the agency, the main health benefit of proactive school closure comes from slowing down the spread of an outbreak within a given area and thus flattening the peak of infections.

    "This benefit becomes especially important when the number of people requiring medical care at the peak of the pandemic threatens to saturate or overwhelm health care capacity," it said.

    By slowing the speed of spread, school closure can also buy some time as countries intensify preparedness measures or build up supplies of vaccines, antiviral drugs, and other interventions, it added.

File photo shows students of Beijing No. 2 Experiment Primary School queue for temperature check at the school gate in Beijing, China, on Sep. 1, 2009. Middle schools and primary schools started the new semester in China on Tuesday. (Xinhua File Photo/Li Qingshan) Photo Gallery>>>

    But the timing of school closure is critically important. Modeling studies suggest that school closure has its greatest benefits when schools are closed very early in an outbreak, ideally before one percent of the population falls ill.

    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.

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) Photo Gallery>>>

    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.

Special Report:  World Tackles A/H1N1 Flu