To my knowledge, the tests that are carried out in Munich use a so-called ELISA device. My vague understanding is that this tests reacts with a specific protein of SARS-Cov2 and has no known cross-reaction with other harmless corona viruses. Disadvantage of the test is probably that it is quite complex and not much capacity is available. Here in Munich, however, about 3000 households are now randomly selected and tested in order to estimate the real number of infected persons. This is the press release of the munich university. DeepL.com works great to translate german texts to english: https://www.lmu-klinikum.de/aktuelles/pressemitteilungen/mun...