The Cost-Effectiveness of Varicella Vaccination In Peru

OBJECTIVES: Sentinel surveillance in Peru reports 29,132 outpatient (average 2009-14) and 9,124 hospitalized (2016) varicella cases, likely an underestimate of true burden. The objective of this study was to quantify the burden of varicella in Peru, and estimate potential impact and cost-effectiveness of universal varicella vaccination (UW). METHODS: A dynamic transmission model of varicella infection was calibrated to reported age-specific varicella incidence data, adjusted for underreporting and care-seeking patterns. Results from a recent chart review study provided data on unit costs and health-care resource utilization. Vaccination strategies based on the current Peruvian vaccination calendar and coverage were considered (A: 1st dose 12m/90% coverage; B: 1st dose 18m/60%; C: 1st dose 12m/90% + 2nd dose 18m/60%; D: 1st dose 12m/90% + 2nddose 4y/50%). Scenario analyses focused on varicella vaccine qualities (effectiveness, duration) and costs. RESULTS: More than 500,000 varicella cases per year at a cost of over S/50M (Peruvian S/1=0.31USD) were estimated, and all vaccination strategies were cost-saving (payer perspective). The most cost-effective strategy for a vaccine with long duration of protection was D, followed by C, A, and B, but for vaccines with shorter duration of protection C was preferred to D. Notably, two-dose strategies based on high-quality vaccines, even at higher prices, were more effective and cost-effective than strategies (one or two dose) using low-quality vaccines at lower prices. The least expensive strategy is A with a high-quality vaccine; this is estimated to prevent 3.4M cases and 557 deaths over ten years. CONCLUSIONS: Both one and two dose UW are cost-effective/cost saving. Due to low coverage of other vaccines administered at potential time points for 2nddose (18m or 4y), the incremental value of this dose is dependent on ability to raise coverage at that visit. UW in Peru has the potential to bring immediate and sustainable health gains.