Status of group B streptococcal vaccine development

Lancefield group B streptococci (GBS), also referred to as Streptococcus agalactiae, is a gram-positive, opportunistic pathogen that colonizes the gastrointestinal and genitourinary tracts of up to 50% of healthy adults In 1938, it was first identified as a human pathogen, causing human fatal puerperal sepsis By the 1970s, GBS had emerged as the predominant pathogen causing septicemia and meningitis in neonates and infants living in diverse regions GBS infection in newborns is usually classified as an early-onset disease (EOD) and late-onset disease (LOD), respectively) depending on the age of the infant at the time of disease manifestation Recent advances in the diagnosis and treatment of GBS infections and global hygiene standards have significantly reduced the development of neonatal infections and mortality, particularly due to EOD. However, recent estimates also show 0.5-2 cases of neonatal GBS infections per 1,000 births with a mortality rate of 9.6%-22% In addition, recent reports have revealed that an increasing number of those infections occurred in pregnant women and non-pregnant adults who typically had an underlying medical condition. The incidence of GBS infection among those adults increased from 3.6 cases/100,000 persons in 1990 to 7.3 cases/100,000 persons in 2007, with significantly higher case fatality rate at 15% Although vaccination is the most promising strategy for preventing GBS infection, currently no licensed GBS vaccine is avail-