PCR Tests. PCR tests detect viral RNA and are primarily processed in a lab. They are good at detecting COVID in the days after you are first exposed, sometimes even before you feel sick - for this reason they are referred to as the "Gold Standard" of COVID tests. PCR tests are usually done at a doctor's office or a testing center, though there are (expensive) home options. PCR tests can stay positive even after you are no longer contagious. RATs Rapid Antigen Tests. RATs are also called "at-home" tests. They are less sensitive than PCR tests, and so they might be more likely to miss the virus - especially at the very beginning of an infection. RATs are good at detecting COVID once you've been sick for a few days, because they detect pieces of virus when your "viral load" is high. Viral load goes down when you are no longer contagious; for this reason, RATs are helpful tools for deciding when it is safe to leave quarantine.
