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.
From the *Division of Pediatric Infectious and Immunologic Diseases, University of British Columbia, Vancouver, British Columbia; †Division of Pediatric Infectious Diseases, Dalhousie University, Halifax, Nova Scotia; ‡Centre for Immunization and Respiratory Infectious Diseases, Public Health Agency of Canada; and §Canadian Paediatric Society, Ottawa, ON.
Accepted for publication February 21, 2008.
Address for correspondence: David Scheifele, MD, Vaccine Evaluation Center L427–4500 Oak Street, Vancouver, B.C., Canada V6H 3N1. E-mail: email@example.com.