Proportionally fewer US young children are hospitalized due to flu than in Canada, because the USA expanded its recommendations for seasonal flu shots to include 24 to 59 month-old kids during the 2006/2007 flu season, while Canada did not do so until 2010, researchers reported in CMAJ (Canadian Medical Association Journal).

The difference between the timing of the US Advisory Committee on Immunization Practices and its sister organization, the National Advisory Committee on Immunization (Canada), “created a natural experiment to evaluate the effect of the policy of the USA”, the authors wrote.

John S. Brownstein, an assistant professor of pediatrics at Boston Children’s Hospital, and team gathered data from 2000 through 2009 and estimated what the relative changes in visits to emergency departments for flu-like illnesses occurred at two pediatric hospitals, one in Montreal, Quebec, Canada, and the other in Boston, Massachusetts, USA - they were especially interested in any changes that occurred after the US policy change.

They found:

  * There were 1,043,989 emergency department visits at the two hospitals.
  * 114,657 visits were related to flu-like illnesses.
  * There was a 34% drop in rates of flu-like illness among 2 to 4 year old kids in the American hospital compared to the Canadian one after the 2006 US policy change.
  * There was an 11% to 18% drop in rates among other age groups

The authors concluded that the earlier change in policy in the USA resulted in lower influenza-related morbidity among two to four year-old American children compared to their peers in Canada.

They added:

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Written by Christian Nordqvist