I want to separately pull out this graphic from the @ASMicrobiology #COVID19 #testing paper since I think it’s *super* helpful. #RNA tests tell us if you’re infected right now (mostly, see next tweet). #Serology tells us if you were recently(ish) infected. 
1st important point. RNA tests can pick up any viral RNA, whether that’s live infectious virus or garbage RNA still in your body. Also the sample might not capture RNA (say the virus is in your GI not your nose & we sample your nose). This can give false negatives.
2nd point. Serology doesn’t typically make for good rapid tests, since your body needs time to make antibodies. You don’t magically make them as soon as you see a pathogen, it takes a few days for the machinery to get warmed up and going (think like a factory).
Serology CAN tell us who had the infection at some point. We don’t know how quickly we make antibodies to #COVID19 (5ish days?) & we don’t know how long we keep those antibodies (months? Years?). But both tests together will give us a complete picture of COVID in the pop.
Here’s the paper since apparently y’all missed that tweet:
