If you have a cough or a fever nowadays, you know exactly what to do: go to the doctor, get a COVID test, and quarantine so you can stop the spread. But we also know that plenty of people contract COVID-19 and transmit it before they know they have it — and some people never even realize that they are contagious at all. So, when it comes to asymptomatic carriers, how do you shut down the line of transmission?

According to Dr. Michael Mina, an epidemiologist and immunologist at Harvard Medical School and Brigham and Women’s Hospital in Boston, the answer is wide-scale and frequent rapid testing. The tests are cheap, effective enough to find the superspreaders, and currently exist in large numbers in some countries. However, in the U.S. there is no easy access to at-home, instant-result rapid tests yet.