U.S. Flu Shot Policy Shields More Kids Than Canada's Program, Study Finds

MONDAY Sept. 19, 2011 -- American youngsters are much less likely to come down with the flu than their northern neighbors due to a public health policy in the United States that calls for vaccinating 2- to 4-year olds, according to a Canadian-American research team.

The United States' influenza vaccination policy for preschoolers was launched by the U.S. Advisory Committee on Immunization Practices in 2006. To date, its Canadian equivalent -- the National Advisory Committee on Immunization -- has not implemented a similar practice.

The result: since the U.S. policy took effect, the percentage of preschoolers who were rushed to an American emergency room to be treated for the flu fell by 34 percent, relative to Canadian children.

"The differences in the U.S. and Canadian policies created conditions for a natural experiment for evaluating the effects of U.S. policy change in the target age group," study co-author John Brownstein, director of the Computational Epidemiology Group at Children's Hospital Informatics Program (CHIP) in Boston, explained in a news release.

Brownstein and colleagues at McGill University in Montreal present their findings in the Sept. 19 issue of the Canadian Medical Association Journal.

To reach their findings, the authors analyzed data covering nearly 115,000 visits to the ER for influenza-like illness that took place between 2000 and 2009 at two hospitals: one in Boston and one in Montreal. Both cities are described as having similar profiles regarding the onset of seasonal flu.

The researchers noted that this timeframe covered a period during which U.S. and Canadian vaccine policies for preschoolers were the same, as well as when they deviated from one another.

Once the new American vaccine policy for preschoolers came into effect in 2006, the U.S. rates of admission to ER for flu-related complications declined by 34 percent.

The team also noted there was an 11 percent and 18 percent lower rate of visits for flu care among older children in the Boston hospital, as compared with those in the Montreal facility.

The researchers theorized that although both countries had similar vaccine policies for older children, it could be that inoculating preschoolers ended up protecting other family members from the viral spread. In addition, they said, the new U.S. policy could have increased awareness about the need for flu vaccine.

The study was funded by the Canadian Institutes of Health Research, the National Institute of Allergy and Infectious Diseases and the U.S. National Library of Medicine.

More information

For more on children and the flu, visit the U.S. Centers for Disease Control and Prevention.

Posted: September 2011


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