Pertussis is a drawn-out and troublesome respiratory disease. Infants have a greater burden of disease than older children and adults, and are more likely to suffer complications. New vaccination strategies need to be considered to reduce pertussis among infants. The aim of the study was to evaluate cost-effectiveness of three alternative vaccination strategies, in comparison with current vaccination schedule.
A decision-analytic model was developed to estimate the effect of different vaccination strategies on an average birth cohort in Sweden, with a time-horizon of one year. The following strategies were evaluated: 1) Cocooning, 2) Maternal vaccination, and 3) On-schedule vaccination. The main outcome was cost per gained quality-adjusted life year (QALY), i.e. the incremental cost-effectiveness ratio (ICER). Sensitivity analyses were performed on key assumptions in the model; including annual incidence of pertussis among infants and the cost of vaccination.
Cocooning and maternal vaccination result in an ICER of 240,000 euro and 66,000 euro respectively, whilst on-schedule vaccination is a dominant strategy in comparison with current vaccination schedule, i.e. have a better effect at a lower cost. The results from the three analyses are sensitive to assumptions on annual incidence. The results for cocooning and maternal vaccination are sensitive to the price of the vaccine and vaccination coverage among parents.
On-schedule vaccination would be a cost-effective and even cost-saving strategy compared to current vaccination schedule. The cocooning and maternal vaccination strategies would not be cost-effective assuming a willingness-to-pay of 50,000 euro. However, sensitivity analyses showed that a marginally increased incidence would make the maternal strategy cost-effective, and a three-folded increase would make the cocooning strategy cost-effective. Alternatively, a vaccine price reduction of 20% would make the maternal strategy cost-effective, while the required reduction for the cocooning strategy would be 80%.