Progress in the prevention of group B Streptococcus

Group B Streptococcus (GBS) is a significant bacterial pathogen that poses substantial health risks, particularly among neonates and pregnant women. It is responsible for a range of severe infections, including sepsis, pneumonia, and meningitis, which can lead to high morbidity and mortality rates in these vulnerable populations. Therefore, the prevention of GBS and the implementation of necessary measures to prevent its progression to invasive GBS disease are of critical importance. Prior to the introduction of vaccines, intrapartum antibiotic prophylaxis (IAP) was considered the primary preventive strategy, as it effectively reduced the incidence of early-onset GBS (EOGBS) infection, defined as infection occurring within the first seven days of life. Moreover, it has notable limitations. The IAP is not only ineffective in preventing late-onset GBS (LOGBS, manifesting between the eighth day and the first three months of life) infections but also unlikely to prevent neonatal infections associated with stillbirth, preterm birth, or the early postnatal period. The widespread use of IAP may not only contribute to the emergence of antibiotic resistance due to excessive antibiotic exposure, but also exert detrimental effects on the neonatal microbiome. The development of effective GBS vaccines has therefore become a critical priority in modern medicine. This review delves into the intricate and multifaceted nature of GBS vaccines, beginning with an exploration of their antigenic targets. Antigens are fundamental components of vaccines because they stimulate the immune system to recognize and combat pathogens such as bacteria. In the case of GBS, several promising antigens have been identified, including capsular polysaccharides (CPS) and surface proteins. Among these, CPS stand out due to their critical role in enabling the bacterium to evade the host immune response. The article reviews the typical representatives of polysaccharide conjugate vaccines (the 6-valent GBS polysaccharide conjugate vaccine (GBS6)), the CPS-protein conjugate vaccine (semisynthetic carbohydrate-based vaccines), and protein-based vaccines (GBS-NN vaccine). Moreover, the article evaluates the potential impact of GBS vaccines on reducing disease burden. The ultimate objective is to support ongoing efforts in vaccine development aimed at mitigating associated health risks.