Abstract
Background: This paper uses a straightforward method of quantifying the benefits and risks of immunization, illustrated by universal immunization programs in British Columbia against invasive Haemophilus influenzae type b disease (Hib), measles, rubella, and paralytic poliomyelitis.
Methods: Data were extracted from provincial communicable disease and vaccine adverse event surveillance systems. Average disease incidence was compared before and after implementing universal immunization programs. Estimates of prevented deaths and serious disease complications were calculated and compared with expected numbers of serious vaccine-associated adverse events (VAAEs).
Results: Average incidence of reported cases decreased 90 to 100% over a 5-year period after implementing universal programs. These benefits were sustained or strengthened over time. Rates of reported serious VAAEs were low.
Discussion: The remarkable success of immunization has created a paradox. Despite a low absolute risk of serious VAAEs, the relative risk of some VAAEs can exceed risk of disease in the province.
Résumé
Contexte: L’étude emploie une méthode simple pour quantifier les avantages et les risques de l’immunisation, tels qu’illustrés par les programmes de vaccination systématiques de la Colombie-Britannique contre l’infection invasive à HiB (hémophilus influenzae B), la rougeole, la rubéole et la poliomyélite paralytique.
Méthode: Nous avons extrait des données des systèmes provinciaux de surveillance des maladies transmissibles et des réactions adverses aux vaccins, puis comparé l’incidence moyenne des maladies avant et après la mise en oeuvre de programmes de vaccination systématiques. Nous avons ensuite estimé les décès et les complications graves évités, que nous avons comparés avec le nombre attendu de réactions adverses vaccinales (RAV) graves.
Résultats: L’incidence moyenne de cas déclarés a diminué dans une proportion de 90 à 100 % sur cinq ans après la mise en oeuvre des programmes systématiques. Ces avantages se sont maintenus ou renforcés avec le temps. Les taux déclarés de RAV graves étaient faibles.
Question à débattre: Le succès remarquable de la vaccination entraîne un paradoxe: bien que le risque absolu de RAV grave soit faible, le risque relatif de certaines RAV peut dépasser le risque de la maladie dans la province.
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