Assessing Adolescent Immunization Options for Pertussis in Canada: a Cost-Utility Analysis
Objective: In Canada, adolescent pertussis vaccination helps prevent transmission. Trade-offs with respect to disease prevention and effectiveness can be associated with immunization timing. The objective of this study is to assess the cost-utility of different adolescent pertussis immunization strategies. Methods: A cost-utility analysis was conducted using a Markov model, with adolescents (beginning at age 10 years) as the cohort of interest. The model assessed three vaccination strategies: 1) immunization of 10 year olds, 2) removal of adolescent vaccination, or 3) immunization of 14 year olds (status quo comparator). The analysis was conducted from a healthcare payer perspective and used a lifetime time horizon. Primary outcomes included life years, quality-adjusted life years (QALYs), health system costs, and incremental cost-effectiveness ratio (ICER). Costs and outcomes were discounted at 1.5% annually. Deterministic and probabilistic sensitivity analysis was conducted to assess parameter uncertainty. Results: The current recommended adolescent immunization strategy (at 14 years old) resulted in an average of 40.4432 expected QALYs at a cost of $34.36 per individual. This strategy was dominated by immunization at 10 years and no immunization. Compared to no immunization, immunizing at 10 years of age had an ICER of $108,703.01 per QALY. Results were robust across a series of deterministic and probabilistic sensitivity analyses; findings were most sensitive to infection probability, vaccine cost, vaccine effectiveness, probability of mortality, and cost of inpatient care. At a cost-effectiveness threshold of $50,000/QALY, removal of the adolescent vaccine represented the most cost-effective strategy in 97% of simulations. However, at a threshold of $100,000/QALY, immunization at 10 years of age is marginally cost-effective relative to no immunization, with a 58% probability of being cost-effective. Conclusion: Findings suggest that alternatives to the current Canadian adolescent pertussis vaccine schedule – especially no immunization – are more cost-effective relative to current immunization of 14 year olds.