You are infectious about 1-2 days before the onset of symptoms. Actually, at the onset of symptoms many are already getting less infectious. That’s why this on

You are infectious about 1-2 days before the onset of symptoms. Actually, at the onset of symptoms many are already getting less infectious. That’s why this one’s hard to catch up with. You need to be very quick when contact tracing. So, yeah, absolutely, you should quarantine after contact with a known infected person, no matter whether you have symptoms or not.