In general, there are 4 types of tests used to detect virus infections, 2 of which are currently relevant for COVID-19. 1. Cultures: this is the gold standard for determining what has caused a virus infection, but it is difficult to do, takes weeks to perform, is very expensive, and can only be performed in highly specialized labs. It is impractical for use in a pandemic, except as a research tool. 2. Antigen tests: these tests look for special proteins found on the surface o