Early-onset group B streptococcal disease in African countries and maternal vaccination strategies

Abstract

Invasive group B streptococcal (GBS) disease is the commonest perinatally-acquired bacterial infection in newborns; the burden is higher in African countries where intrapartum antibiotic prophylaxis strategies are not feasible. In sub-Saharan Africa, almost one in four newborns with GBS early-onset disease will demise, and one in ten survivors have moderate or severe neurodevelopmental impairment. A maternal GBS vaccine to prevent invasive GBS disease in infancy is a pragmatic and cost-effective preventative strategy for Africa. Hexavalent polysaccharide protein conjugate and Alpha family surface protein vaccines are undergoing phase II clinical trials. Vaccine licensure may be facilitated by demonstrating safety and immunological correlates/thresholds suggestive of protection against invasive GBS disease. This will then be followed by phase IV effectiveness studies to assess the burden of GBS vaccine preventable disease, including the effect on all-cause neonatal infections, neonatal deaths and stillbirths.

Keywords: Group B Streptococcus; Streptococcus agalactiae; early-onset disease; neonatal sepsis; perinatal infections.

Figure 1

Perinatal and birth outcomes of newborns with invasive group B streptococcal (GBS) disease. GBS colonisation can lead to invasive early-onset neonatal disease (pneumonia, sepsis, meningitis, neonatal encephalopathy), and can also result in maternal infection (chorioamnionitis and invasive maternal disease), preterm birth and stillbirth. In sub-Saharan Africa, 23% will demise and 38% of survivors from low- and middle-income countries have neurodevelopmental impairment.