Pertussis vaccination in pregnancy in Canada: a cost-utility analysis

Abstract

Background: The Canadian National Advisory Committee on Immunization recommends universal vaccination against pertussis in pregnancy. We assessed the cost-effectiveness of vaccination with tetanus-diphtheria-acellular pertussis (Tdap) vaccine in pregnancy in Canada.

Methods: We conducted a cost-utility analysis comparing a vaccination program to no program corresponding with the 2017 Canadian guideline for economic evaluation from the Canadian Agency for Drugs and Technologies in Health. We developed 2 models - part decision tree, part Markov model - to estimate the long-term cost and quality-adjusted life-years (QALYs) for pregnant women and their infants. We obtained epidemiologic data from 2006 to 2015, and derived costs and utility values from relevant sources. Results were reported in 2019 Canadian dollars. We obtained expected values through probabilistic analysis, with methodologic and structural uncertainty assessed through scenario analyses. The analysis adopted an acquisition price of Tdap vaccine of $12.50, with scenario analysis conducted to identify the threshold price for vaccination to be cost-effective.

Results: In the base-case scenario, for every 1000 pregnant women vaccinated, the program would lead to a gain of 0.3 QALYs, occurring solely in infants, at an increased total cost of $12 987, or $44 301 per QALY gained. Based on a threshold of $50 000 per QALY gained, vaccination would have been cost-effective in 6 of the 10 years included in the model (range of incremental costs $20 463-$100 348 per QALY gained). The threshold cost for Tdap vaccine to be cost-effective over the 10-year horizon was $14.03.

Interpretation: Based on a threshold of $50 000 per QALY gained, vaccination against pertussis in pregnancy would be cost-effective if the acquisition cost per vaccine were $14.03 or less. Province- and territory-specific analyses should be done to inform local decision-making.

Figure 1:

Markov models to estimate the long-term cost and quality-adjusted life-years associated with vaccination with tetanus–diphtheria–acellular pertussis vaccine v. no vaccination in pregnancy. (A) Infants. (B) Women.

Figure 2:

Cost-effectiveness acceptability curve for pertussis vaccination during pregnancy in Canada. Costs are presented in 2019 Canadian dollars. Note: QALY = quality-adjusted life-year.

Figure 3:

Estimated incremental cost per quality-adjusted life-year (QALY) gained by acquisition cost of pertussis vaccine. Costs are presented in 2019 Canadian dollars.