Background: Emerging infectious diseases are a  growing threat, through population growth, increased trade and travel,  urbanization, deforestation, and climate change.  Clinical research in response to emerging infectious diseases is  challenging; selecting and contracting the appropriate study sites for a  trial is time consuming, and often too few patients can be timely  recruited to acquire high-quality evidence about the best treatment  strategies. In 2014, the EU-funded PREPARE project (Platform foR European Preparedness Against (Re-)emerging Epidemics) was initiated to rapidly respond to severe infectious diseases outbreaks. It initiated two adaptive platform trials, the REMAP-CAP and the ALIC4E trial, determining the effectiveness of multiple treatment strategies for a single disease. The REMAP-CAP trial was designed for a pandemic of severe community-acquired pneumonia and expanded globally during the COVID-19 pandemic. It has already delivered 10 important conclusions for better treatment of COVID-19...