Here's How Long It Takes to Test Positive for Coronavirus After Exposure
An infectious diseases specialist explains why your coronavirus test results may not be accurate.
A recent report from the Centers for Disease Control and Prevention (CDC) estimated that 40 percent of all coronavirus transmissions happen from people who show no symptoms. That's either because they're asymptomatic or because they're pre-symptomatic (meaning their symptoms have not yet surfaced). So, that begs a couple of very complicated questions when it comes to COVID-19 testing: How do you know when to tested for coronavirus? And can you trust the results?
Emily Landon, MD, an epidemiologist and infectious diseases specialist at the University of Chicago Medicine, told NPR that the COVID-19 contagion takes at least three to five days after exposure to test positive. Given the lack of reliability for results, "a negative test shouldn't be seen as your ticket to stop being cautious," the outlet reports.
"We don't know how good these tests are in individuals who don't have symptoms," Landon explained. "We know they're pretty good at picking up COVID when it's present in people who have symptoms. But we have no idea what a negative test means in an individual that doesn't have symptoms."
Further, some people can test positive, then negative, then positive again. "Hospitals often test people with symptoms twice to try to be more certain about the finding," NPR reports.
Early in the spread of the coronavirus, the serious lack of tests became a challenge in trying to stop the spread of COVID-19 and learn about who was most susceptible. And now that tests are more ubiquitous and widely available, the number of cases has shot up, simply due to the sharp increase in administrated tests. (To be clear, these tests are tests for the presence of the virus and not the antibody tests that reveal the ability to fend off COVID-19, though those tests are also not entirely reliable either.)
If you feel sick or have been in contact with someone with COVID-19, then by all means, get tested. But, as Landon notes, even if the test comes back negative, that is no reason to not continue to be cautious since you could very well be carrying the virus. And for more on those without symptoms, check out This Is Why Some People Have Coronavirus Symptoms and Others Don't.