The present invention provides a method for rapid, highly specific and sensitive detection and quantification of a virus by observing viral substrate binding to its host receptor protein. The invention also provides a method for rapid, highly specific and sensitive detection and quantification of a virus in an individual suspected of being infected with a virus. The invention further provides a test kit for rapid, highly specific and sensitive point-of-care detection of a virus in an individual. The viruses and their host receptor proteins that can rapidly be detected include SARS-CoV-2 and its host receptor protein ACE2. The surprisingly rapid, specific and sensitive method and kit of the invention provide a point-of care test capable of diagnosing individuals suffering from COVID-19 by observation of a color change in the assay, which color change occurs in about five minutes, and which test can be completed by a user in about 60 minutes.