Joint Statement on Contact Tracing: Date 19th April 2020 https://drive.google.com/file/d/1OQg2dxPu-x-RZzETlpV3lFa259Nrpk1J/view Open letter from 300+ scientists from 25+ countries laying out 4 principles for open, transparent and private-by-design COVID-19 contact tracing systems, focusing on decentralised approaches to limit surveillance repurposing.