Division of Pediatric Infectious and Immunologic Diseases, University of British Columbia, Vancouver, British Columbia. dscheifele@cw.bc.ca
The uniform use in Canada of a single Haemophilus influenzae type b conjugate vaccine in combination with diphtheria, tetanus, acellular pertussis, and inactivated poliovirus vaccines (DTaP.IPV/Hib) facilitates ongoing assessment of vaccine effectiveness, including any effects of recently added concurrent vaccinations and increasing time since vaccination. Surveillance at 12 pediatric centers in 2004-2007 indicates that vaccine failures remain rare and case totals approach an irreducible minimum, with no age shift.