Haemophilus influenzae type b disease control using Pentacel

Abstract

IMPACT (Immunization Monitoring Program, ACTive) investigators reported a dramatic decline in the cases of invasive Haemophilus influenzae type b (Hib) at the program’s 11 (now 12) paediatric centres with the introduction of Hib conjugate vaccine programs. Between 1985 and 1995, case totals fell from 485 to 20 cases. Eight cases were seen in both 1996 and 1997. During 1997, provinces switched to Pentacel (Pasteur Merieux Connaught Canada, North York, Ontario) as the vehicle for Hib vaccination. It is reassuring that in the two subsequent years, only a single case of Hib infection was detected among children who completed a three-dose primary series, indicating that the Hib component of Pentacel is highly effective. Of the 16 cases seen from 1998 to 1999, six had not been appropriately vaccinated because their parents refused immunization. Another child had recently emigrated from a country where Hib vaccination is not routine. The remaining cases were nonpreventable, the patient being either too young to have completed primary immunization (one case) or occurring in children vaccinated before the introduction of Pentacel (seven cases). The case total in 1999 would have been four if the vaccination not been refused in three instances.