We all now are able to take the rapid at-home COVID-19 test.   But few know when to do this . Say you suddenly appear to have symptoms like fever, cough, congestion or sore throat, and immediately take a fast antigen test, where you can see your result in 15 minutes.  If negative, feel assured. However, when symptoms begin, you won't test positive until three to five days later . Thus you MUST take a second test in this time frame to ascertain that you are negative. The problem is exactly when?  Second day?  Third?  Fourth?  Fifth?  Many say fifth?  Very confusing.  No consensus. False negatives occur all the time.  False positives are rare. The safest measure is to take both the fast test and a PCR test, which needs to be sent to a lab and can take a couple of days for the result. Thus, the safest strategy is to: Quickly rapid test yourself if you have any kind of condition that suggests you might have COVID. If negative, feel good, but isolate yourself. 3-5 days later take a seco