“We know that the incubation period for Covid-19 is up to 14 days. And before that, you can be testing negative, and have no symptoms,” emergency medicine physician Dr. Leana Wen said.

“But you could actually be harboring the virus and be able to transmit it to others.”

So if you want to get tested before seeing friends or family, here’s what you need to know:

If I got infected yesterday, would a test today pick that up?

Probably not. A study in the medical journal Annals of Internal Medicine examined false-negative test results of people who actually had Covid-19.