Innovative treatment regimens for possible severe infections. The Simplified Antibiotic Therapy Trial (SATT) and African Neonatal Sepsis Trial (AFRINEST) study groups. 1In a young infant (0-59 days old), at least one sign of severe infection (i.e. movement only when stimulated, not feeding well on observation, temperature greater than or equal to 38°C or less than 35.5°C or severe chest in-drawing. 2In a sick young infant, presence of any of the following signs - unconscious, convulsions, unable to feed at all, apnoea, unable to cry, cyanosis, bulging fontanelle, major congenital malformations inhibiting oral antibiotic intake, active bleeding requiring transfusion, surgical conditions needing hospital referral, persistent vomiting defined as vomiting following three attempts to feed the baby within 30 minutes. AFRINEST: African Neonatal Sepsis Trial; PSBI: possible serious infection; SATT: Simplified Antibiotic Therapy Trial; WHO: World Health Organization.