Eight sites will be involved, including three hospitals in Kenya (Kilifi County, Migori County and Mbagathi District), two in Bangladesh (Matlab and the icddr,b Dhaka), and one in each of Uganda (Mulago), Malawi (Queen Elizabeth Community Hospital), Pakistan (Civil Hospital Karachi) and in West Africa (TBA). Site will enroll children at admission to hospital, and assess their clinical, social and economic status at admission, during hospitalisation, at discharge and during follow up for 180 days after discharge. The sites will also enrol children from the community to determine community norms (where ill and undernourished children would be expected to typically recover to). Protocols and procedures will be carefully harmonised across sites.