Cost-effectiveness of maternal GBS immunization in low-income sub-Saharan Africa.

Louise B Russell,Sri Ram Pentakota,Stephanie J Schrag,Ajoke Sobanjo-Ter Meulen,Ben Cosgriff,Sun-Young Kim,Anushua Sinha,Jennifer R Verani

doi:10.1016/j.vaccine.2017.07.108

Abstract

A maternal group B streptococcal (GBS) vaccine could prevent neonatal sepsis and meningitis. Its cost-effectiveness in low-income sub-Saharan Africa, a high burden region, is unknown. We used a decision tree model, with Markov nodes to project infants' lifetimes, to compare maternal immunization delivered through routine antenatal care with no immunization. 37 countries were clustered on the basis of economic and health resources and past public health performance. Vaccine efficacy for covered serotypes was ranged from 50% to 90%. The model projected EOGBS (early-onset) and LOGBS (late-onset) cases and deaths, disability-adjusted life years (DALYs), healthcare costs (2014 US$), and cost-effectiveness for a representative country in each of the four clusters: Guinea-Bissau, Uganda, Nigeria, and Ghana. Maximum vaccination costs/dose were estimated to meet two cost-effectiveness benchmarks, 0.5 GDP and GDP per capita/DALY, for ranges of disease incidence (reported and adjusted for under-reporting) and vaccine efficacy. At coverage equal to the proportion of pregnant women with≥4 antenatal visits (ANC4) and serotype-specific vaccine efficacy of 70%, maternal GBS immunization would prevent one-third of GBS cases and deaths in Uganda and Nigeria, where ANC4 is 50%, 42-43% in Guinea-Bissau (ANC4=65%), and 55-57% in Ghana (ANC4=87%). At a vaccination cost of $7/dose, maternal immunization would cost $320-$350/DALY averted in Guinea-Bissau, Nigeria, and Ghana, less than half these countries' GDP per capita. In Uganda, which has the lowest case fatality ratios, the cost would be $573/DALY. If the vaccine prevents a small proportion of stillbirths, it would be even more cost-effective. Vaccination cost/dose, disease incidence, and case fatality were key drivers of cost/DALY in sensitivity analyses. Maternal GBS immunization could be a cost-effective intervention in low-income sub-Saharan Africa, with cost-effectiveness ratios similar to other recently introduced vaccines. The vaccination cost at which introduction is cost-effective depends on disease incidence and vaccine efficacy. Clinical Trial registry name and registration number: Not applicable.

Highlights

Group B streptococcus (GBS) is a leading neonatal sepsis pathogen globally, a major contributor to neonatal deaths in the world’s poorest countries, and has a high burden of disease in sub-Saharan Africa, where half of Global Alliance for Vaccines and Immunization (GAVI)-eligible countries are located [1]
We focused on a central policy question – affordable vaccination cost per dose – and present the highest per-dose costs that would meet two possible cost-effectiveness benchmarks, 0.5 gross domestic product (GDP) per capita and GDP per capita per disability-adjusted life-year (DALY) averted
We reduced vaccine efficacy against early-onset GBS (EOGBS)/late-onset GBS disease (LOGBS) in preterm infants to 0.835 of the efficacy in term infants, using data on the distribution of infants by gestational age and maternal-fetal transfer of antibody; preterm infants were subdivided into those < 34 weeks (6.6% of births) and 34–36 weeks (10.9%), with infants born at 37 weeks or more (82.5%) considered full term (Technical Appendix A4)

Summary

Introduction

Group B streptococcus (GBS) is a leading neonatal sepsis pathogen globally, a major contributor to neonatal deaths in the world’s poorest countries, and has a high burden of disease in sub-Saharan Africa, where half of GAVI-eligible countries are located [1]. In higher-income countries where it has been introduced, intrapartum antibiotic prophylaxis for GBS-colonized women has greatly reduced early-onset GBS (EOGBS) disease, which develops during the first week of life [2]. The model projected EOGBS (early-onset) and LOGBS (late-onset) cases and deaths, disability-adjusted life years (DALYs), healthcare costs (2014 US$), and cost-effectiveness for a representative country in each of the four clusters: GuineaBissau, Uganda, Nigeria, and Ghana. 4 antenatal visits (ANC4) and serotype-specific vaccine efficacy of 70%, maternal GBS immunization would prevent one-third of GBS cases and deaths in Uganda and Nigeria, where ANC4 is 50%, 42–43% in Guinea-Bissau (ANC4 = 65%), and 55–57% in Ghana (ANC4 = 87%). Conclusion: Maternal GBS immunization could be a cost-effective intervention in low-income sub-Saharan Africa, with cost-effectiveness ratios similar to other recently introduced vaccines.

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Discussion

Conclusion