School Closures (May Cut Infection Rate By 40%)

By Naomi Kresge

July 20 (Bloomberg) -- Closing schools during a severe flu pandemic may cut infection rates as much as 40 percent at the peak of the outbreak because of children’s role in spreading the disease, U.K. researchers said.

School closures might be even more effective against swine flu than against seasonal flu, according to a study published today in The Lancet. The research weighed the pros and cons of such a move and stopped short of endorsing it.

“The H1N1 pandemic could become more severe, and the current cautious approach of not necessarily recommending school closure in Europe and North America might need reappraisal in the autumn,” the Imperial College London researchers wrote.

Governments worldwide are battling the virus, which has taken root across the globe faster than any previous flu pandemic, according to the World Health Organization. Britain’s chief medical officer last week said the National Health Service is bracing for as many as 65,000 deaths from the disease.

“Children are thought to be important vectors of transmission, more infectious and susceptible to most influenza strains than adults, and high contact rates in schools favor transmission,” wrote Simon Cauchemez and Neil Ferguson from the college’s department of infectious disease epidemiology.

Impact on Economy

So far, 60 percent of the world’s reported 39,620 swine flu cases occurred in those aged 18 or younger, according to the study. The researchers used data from intentional or coincidental school closures during past influenza outbreaks, including a study of French school holidays over a 21-year period that found school holidays prevented one in six flu cases and a study of U.S. cities during the 1918 pandemic.

Cauchemez, Ferguson and their colleagues also weighed the social and economic impact of closing schools. A 12-week closure could cost as much as 6 percent of the U.S. gross domestic product and up to 1 percent of U.K. GDP, the study said, and could disproportionately affect poor families.

“In a severe pandemic, countries might be ready to pay those high social and economic costs,” they wrote.

The research will be published in the August edition of the Lancet Infectious Diseases, which focuses on flu.

Swine flu has killed 29 people so far in the U.K., health officials said last week.

To contact the reporter on this story: Naomi Kresge in Zurich at nkresge@bloomberg.net

Is thimerosal still in the vaccines that children receive?

Thimerosal is a compound that is 49.6% mercury by weight

Currently, all pediatric vaccines in the routine infant immunization schedule are manufactured without thimerosal as a preservative. As of January 14, 2003, the final lots of vaccines containing thimerosal as a preservative expired.

Other vaccines for example, influenza vaccine; tetanus and diphtheria vaccine for older children and adults continue to be manufactured with thimerosal as a preservative although influenza vaccine without thimerosal preservative is also available.