Desirable characteristics of a schistosomiasis vaccine: some implications of a cost-effectiveness analysis.

This paper investigates some of the characteristics which a vaccine for schistosomiasis would require to be more cost-effective than chemotherapy. The impact of a variety of possible vaccination scenarios are assessed in terms of the discounted years of heavy infection prevented in children, and the cost-effectiveness of these approaches are compared with annual mass treatment. The analyses demonstrate that the three critical parameters determining whether a vaccine would ever be more cost-effective than mass chemotherapy are price, duration of protection and efficacy. If the vaccine had sufficient duration of protection to be delivered through the regular childhood immunization programmes (EPI), it could be more cost-effective than annual chemotherapy. The necessary condition is that adding the vaccine to EPI must not cost more than $4.30 per person in excess of one round of chemotherapy. For a shorter duration of vaccine protection, the schistosomiasis vaccine could not exceed the cost (including delivery costs) of one round of annual chemotherapy by more than approximately $3.50.