An anonymised dataset of 2,797 adult in and outpatient (≥15 years) with a fever ((≥37.5°C) who gave informed consent to participate in a clinical observational study conducted in four countries (Lao PDR, Malawi, Mozambique and Zimbabwe) between June 2018-March 2021. Dataset contains variables on clinical history of illness, signs and symptoms for creating severity scores, treatment history and socio-demographic information, and outcomes (alive or dead) by day 28 follow-up. Study staff collected demographic data, took a standardised clinical history, and performed a physical examination which included measuring the clinical signs for calculating the adult severity scores; MEWS, qSOFA, and UVA. All data were collected Open Data Kit where data were validated during the point of entry and outliers for clinical observations were detected using statistical methods.