سود و زیان ایمن سازی کودکان با واکسن کونژوگه پنوموکوک در کانادا

To estimate cost-effectiveness of routine and catch-up vaccination of Canadian children with seven-valent pneumococcal conjugate vaccine, a simulation model was constructed. In base scenario (vaccination coverage: 80%, and vaccine price: $58 per dose), pneumococcal disease incidence reduction would be superior to 60% for invasive infections, and to 30% for non-invasive infections, but the number of deaths prevented would be small. Annual costs of routine immunization would be $71 million (98% borne by the health system). Societal benefit to cost ratio would be 0.57. Net societal costs per averted pneumococcal disease would be $389 and 125,000 per life-year gained (LYG). Vaccine purchase cost is the most important variable in sensitivity analyses, and program costs would be superior to societal benefits in all likely scenarios. Vaccination would result in net savings for society, if vaccine cost is less than $30 per dose. Economic indicators of catch-up programs are less favorable than for routine infant immunization.

Streptococcus pneumoniae remains an important cause of serious illness in children [1]. In Canada, the highest incidence of invasive pneumococcal infection is observed in those aged less than 2 years, and the case-fatality rate is 7% in children with pneumococcal meningitis and 44% in those presenting with septic shock [2]. Total costs of otitis media in Canadian children were estimated at $428 million in 1994 [3]. Antibiotic resistance is a matter of concern. In Quebec, only 3% of S. pneumoniae invasive strains were moderately susceptible or resistant to one or more of eight usual antimicrobial agents in 1984–1986 [4], and the proportion was 25% in the period 1996–1998 [5]. A seven-valent pneumococcal conjugate vaccine (Prevnar®) has been recently licensed for paediatric use [6]. The serotypes included in PCV-7 (4, 9V, 14, 19F, 23F, 18C, 6B) account for the large majority of invasive infections in children less than 5 years of age [7]. The safety and clinical efficacy of PCV-7 have been studied in randomized trials in the US [8] and [9] and Finland [10]. Decisions regarding inclusion of this new vaccine in routine immunization schedules for infants will have to be made by provincial/territorial health authorities, and economic evaluation is an important factor in these decisions. Results of economic analyses in the US [11] cannot be extrapolated validly to the Canadian context, due to differences in the composition of families, natural caregivers, employment rates, incomes, and costs of health services. In Canada, there is a comprehensive health insurance program in every juridiction offering gratuitousness of most medical and rehabilitation services. Publicly funded immunization programs are a provincial/territorial responsibility and free access to vaccines varies across the country [12]. The goal of this study is to estimate the effectiveness, cost and utility of a publicly funded immunization program against pneumococcal infections in Canadian children, using four doses of PCV-7 for routine vaccination of young infants, and 1, 2 or 3 doses for catch-up programs for older children.

The introduction of PCV-7 in Canada has the possibility of significantly reducing morbidity and societal costs associated with pneumococcal disease in children. With a unitary purchase cost of $58 per dose, our analysis indicates that overall program costs to society would be superior to financial benefits in all likely scenarios. However, at a unitary vaccine purchase cost of $30 or lower, this potential program would actually save money for society. Catch-up immunization programs for older children would be associated with a lower reduction in morbidity and cost-effectiveness ratios would be less favorable than with routine immunization of infants.