Clinical development strategy for a candidate group A streptococcal vaccine

Group A streptococci (GAS) cause a wide spectrum of diseases ranging from benign pharyngitis and skin infections to severe invasive disease and the immune sequelae rheumatic fever and rheumatic heart disease. Pharyngitis, one of the most frequent diseases caused by GAS, is highly prevalent in school-age children in temperate climates and a major cause of antibiotic use. An efficacious vaccine would reduce disease burden associated with pharyngitis and the need of care for sick children. Importantly, GAS pharyngitis is recognised as the main precursor for acute rheumatic fever so a vaccine that is efficacious against GAS pharyngitis should also prevent acute rheumatic fever and rheumatic heart disease. It may also prevent post-streptococcal glomerulonephritis and invasive disease since GAS pharyngitis is one of the precursors for these clinical syndromes. There has been no clearly articulated pathway for clinical trial design leading to GAS vaccine registration. This review outlines a clinical development strategy detailing the phases of development required for registration of a candidate GAS vaccine for GAS pharyngitis initially, followed by impetigo and associated sequelae. The major advantages of a strategy first focused on GAS pharyngitis is an early proof of principle, that can be followed by studies for other clinical syndromes. The end goal being the availability of a preventive tool for the most prevalent GAS-associated diseases globally.