Delta variant on path to become dominant strain worldwide as surge in the highly transmissible variant increases urgency for vaccinating large numbers of vulnerable peopleRising infection rates resulting in increased hospitalizations are overwhelming health systems and leaving many countries in urgent need of life-saving oxygenTesting rates in much of the world is too low, especially low- and lower-middle-income countries [1] – leaving much of the world blind to how the disease is evolving and vulnerable to new variantsFunding the Rapid ACT-Accelerator Delta Response (RADAR) urgent appeal for US $7.7 billion would enable: significantly increased testing and better surveillance to detect and protect against new variants; more oxygen to treat.