Cost-effectiveness analysis of universal maternal immunization with tetanus-diphtheria-acellular pertussis (Tdap) vaccine in Brazil.

BACKGROUND

Pertussis incidence has increased significantly in Brazil since 2011, despite high coverage of whole-cell pertussis containing vaccines in childhood. Infants <4 months are most affected. This study aimed to evaluate the cost-effectiveness of introducing universal maternal vaccination with tetanus-diphtheria-acellular pertussis vaccine (Tdap) into the National Immunization Program in Brazil.

METHODS

Economic evaluation using a decision tree model comparing two strategies: (1) universal vaccination with one dose of Tdap in the third trimester of pregnancy and (2) current practice (no pertussis maternal vaccination), from the perspective of the health system and society. An annual cohort of newborns representing the number of vaccinated pregnant women were followed for one year. Vaccine efficacy were based on literature review. Epidemiological, healthcare resource utilization and cost estimates were based on local data retrieved from Brazilian Health Information Systems. Costs of epidemiological investigation and treatment of contacts of cases were included in the analysis. No discount rate was applied to costs and benefits, as the temporal horizon was one year. Primary outcome was cost per life year saved (LYS). Univariate and best- and worst-case scenarios sensitivity analysis were performed.

RESULTS

Maternal vaccination of one annual cohort, with vaccine effectiveness of 78%, and vaccine cost of USD$12.39 per dose, would avoid 661 cases and 24 infant deaths of pertussis, save 1800 years of life and cost USD$28,942,808 and USD$29,002,947, respectively, from the health system and societal perspective. The universal immunization would result in ICERs of USD$15,608 and USD$15,590 per LYS, from the health system and societal perspective, respectively. In sensitivity analysis, the ICER was most sensitive to discounting of life years saved, variation in case-fatality, disease incidence, vaccine cost, and vaccine effectiveness.

CONCLUSION

The results indicate that universal maternal immunization with Tdap is a cost-effective intervention for preventing pertussis cases and deaths in infants in Brazil.