Cost-effectiveness analysis of maternal vaccination against Group B streptococcus in Japan

Background: Group B Streptococcus (GBS) is a leading pathogen causing life-threatening bacterial infections in neonates (early- or late-onset) and infants, and is associated with preterm and stillbirth. Japan introduced national guidelines to reduce early-onset neonatal GBS disease, with universal prenatal screening and intrapartum antimicrobial prophylaxis (IAP). However, screening/IAP does not prevent GBS associated late-onset disease, preterm or stillbirth. Maternal GBS vaccines in development are targeted at infant GBS disease but may provide benefit across perinatal outcomes. We aimed to assess cost-effectiveness of a future maternal GBS vaccine, for a base case prevention of infant GBS disease in combination with screening/IAP compared to screening/IAP alone.Methods: We used a decision tree model to estimate cases of infant GBS disease, deaths, and neurodevelopmental impairment (NDI), GBS-related stillbirths, and the associated costs and loss in QualityAdjusted Life Years (QALYs). We calculate the threshold price at which a vaccine would be costeffective assuming a cost-effectiveness threshold of yen 5 million/QALY. We explored the potential benefit of a maternal GBS vaccine that also prevents preterm birth in a scenario analysis.Results: Maternal GBS vaccination in Japan could prevent an additional 142 infant GBS cases annually, including 5 deaths and 21 cases of NDI, and 13 stillbirths compared to screening/IAP alone. The incremental cost-effectiveness ratio (ICER) was yen 3.78 million/QALY with a vaccine cost of yen 5,000/dose. If the QALY lost for stillbirth is included, the ICER is reduced to yen 1.78 million/QALY. Median threshold vaccine price was yen 6,900 per dose (95 % uncertainty interval yen 5,100 to yen 9,200 per dose). If maternal GBS vaccination also prevented half of GBS-associated preterm, the ICER would be reduced to yen 1.88 million/QALY.Conclusions: An effective maternal GBS vaccine is likely to be considered cost-effective in Japan at a price of yen 5,000/dose. Effectiveness against other adverse perinatal outcomes would increase health benefits and cost-effectiveness.& COPY; 2023 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).