Vickers and colleagues analyzed the incidence of pertussis reported to the Saskatoon Regional Health Authority in Saskatchewan between Jan.1, 1995, and Sept. 30, 2005.They found that children aged less than 1 year or aged between 1 and 4 years who had only received whole-cell pertussis (wP), or a combination of wP and acellular pertussis (aP), had a lower incidence of pertussis than children who had received only aP, whereas a reverse trend was seen in children aged 5-9 years. [click link for full article]
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