Cost-effectiveness of a potential group B streptococcal vaccine program for pregnant women in South Africa

Background: In low- and middle-income countries neonatal infections are important causes of infant mortality. Group B streptococcus (CBS) is a major pathogen. A GBS polysaccharide-protein conjugate vaccine, the only option that has the potential to prevent both early- and late-onset CBS disease, has completed Phase II trials. Screening-based intrapartum antibiotic prophylaxis (LAP) for pregnant women, an effective strategy in high-income countries, is often not practical in these settings. Risk factor-based IAP (RFB-IAP) for women with risk factors at delivery has had limited success in preventing neonatal infection. We evaluated the cost and health impacts of maternal CBS vaccination in South Africa. Methods and findings: We developed a decision-analytic model for an annual cohort of pregnant women that simulates the natural history of GBS disease in their infants. We compared four strategies: doing nothing, maternal GBS vaccination, RFB-LAP, and vaccination plus RFB-IAP. Assuming vaccine efficacy varies from 50% to 90% against covered serotypes and 75% of pregnant women are vaccinated, CBS vaccination alone prevents 30-54% of infant CBS cases compared to doing nothing. For vaccine prices between $10 and $30, and mid-range efficacy, its cost ranges from $676 to $2390 per disability-adjusted life-year (DALY) averted ($US 2010), compared to doing nothing. RFB-IAP alone, compared to doing nothing, prevents 10% of infant CBS cases at a cost of $240/DALY. Vaccine plus RFB-LAP prevents 48% of cases at a cost of $664-2128/DALY. Conclusions: Vaccination would substantially reduce the burden of infant CBS disease in South Africa and would be very cost-effective by WHO guidelines. RFB-IAP is also very cost-effective, but prevents only 10% of cases. Vaccination plus RFB-IAP is more effective and more costly than vaccination alone, and consistently very cost-effective. (C) 2014 Elsevier Ltd. All rights reserved.