Disease burden due to Group B Streptococcus in the Indian population and the need for a vaccine - a narrative review.

Streptococcus agalactiae, a Gram-positive bacterium, causes invasive infection known as Group B streptococcal disease (GBS). It is a leading cause of neonatal death and complications prior to delivery. The burden of GBS is unknown in India despite the high incidence of preterm and stillbirths. In this study, we performed a narrative review of the available literature (published in the last 10 years) on the epidemiology of GBS, using PubMed and Google Scholar, to understand its impact in India and evaluate potential strategies to prevent the disease in the high-risk population, that is, neonates. The review showed that the incidence of early- and late-onset GBS in neonates (per 1000 live births) was in the ranges of 0.090-0.68 and 0.0-0.07 respectively. The overall case fatality rate reported in only one study was 0.63. In pregnant women, the prevalence of GBS colonization was 2-62% and its transmission to their newborns varied from 6.7% to 11.1%. The serotype distribution of GBS is unclear, but some studies reported the distribution of types Ia, Ib, II, III, V, VII among pregnant women in India. The associated risk factors for GBS colonization in pregnant women are unclear but a few studies suggest the role of age and multigravida, while the risk factors in neonates include preterm birth, prolonged rupture of membrane (⩾18 h), maternal fever, obstetric complications, and prolonged labor >18 h. Screening of GBS is not a routine practice in India and intrapartum antibiotics prophylaxis is limited to only in risk conditions to prevent neonatal disease transmission. A few studies also suggest that high birth rate, poor detection methods, and financial constraints limit routine GBS screening in a developing country such as India. Hence, maternal vaccination is the most promising strategy to prevent neonatal GBS and Pfizer's hexavalent GBS conjugate vaccine (GBS6) is being developed for GBS neonatal disease.