Valutazione economica dell’attivazione in Italia della schedula sequenziale per la vaccinazione antipoliomielitica

Summary

Objective: A sequential schedule based on two doses of inactivated poliovaccine (IPV) followed by two doses of oral poliovaccine (OPV), which has replaced the OPV-only schedule adopted in Italy up to 1999, reduces the incidence of vaccine-associated polioparalysis (VAPP), the most dangerous adverse event of OPV. The aim of this study was to assess whether the expected benefits derived from fewer cases of VAPP (and, consequently, reduced treatment costs) would offset the increase in national spending associated with the new vaccination programme (because of the use of the more expensive IPV).

Design: Data concerning VAPP cases in Italy until 1999 were requested to the Ministry of Health. However, the extremely limited amount of data (which did not allow individual cases to be traced) and the wide variation in VAPP clinical picture and evolution over the years, made the assumption necessary — on the basis of available data — of an hypothetical typical case of VAPP, with a life-expectancy fixed at 75 years, for which both medical and non medical direct costs were estimated. The annual costs of the two schedules were calculated considering a 95% national coverage for the first three doses of poliovaccine within the first 24 months of life.

Results: Until 1999 the frequency of VAPP in Italy was 0.9 cases/year. The sequential schedule would avoid 0.768 cases/year; thus the expected benefits would be € 548,721.0. With the new immunisation schedule, an increase in annual spending of € 2,782,350.0 is estimated, with a net cost of € 2,233,629.0/year; thus, in Italy, for each case of VAPP avoided, a national spending of € 2,908,371.10/year is estimated.

Conclusions: The study results show that the costs of the sequential schedule outweigh the expected economic benefits associated with a decreased incidence of VAPP. Therefore, the necessary epidemiological target of reducing the risk of VAPP has an economic burden, which will further increase when Italian policy-makers decide to abandon the sequential schedule in favour of the exclusive use of IPV, the only way to eliminate the risk of VAPP.