E-Mail The coronavirus pandemic has created a great demand for rapidly diagnosing SARS-CoV-2 infections. Reliable rapid tests are needed, for example, at airports and ports for testing travellers quickly and effortlessly before their journey. Researchers at the University of Helsinki have developed a new rapid assay principle for viral antigen detection, applying it to diagnosing SARS-CoV-2 infections. The test is based on a phenomenon known as time-resolved Förster resonance energy transfer (TR-FRET), where energy travels between two light-sensitive molecules when they are close enough to each other. TR-FRET makes it possible to measure viral particles or the body's own proteins by using what are known as 'mix and read'-type tests on complex biological samples, such as serum or even whole blood. In fact, the researchers have previously applied the procedure in the rapid detection of antibodies.