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We regularly answer frequently asked questions about life during the coronavirus crisis. If you have a question you’d like us to consider for a future post, email us at goatsandsoda@npr.org with the subject line: “Weekly Coronavirus Questions.” See an archive of our FAQs here.
Ah, the start of a new school year. Maybe you’re one of millions of Americans who have started mingling with peers in the dorms and suddenly find yourself sniffling and wondering if you have COVID-19.
Or you’re just getting back from your summer vacation and the back of your throat has a worrisome itch.
You consider taking an at-home rapid test, but you have lots of questions. With new FDA recommendations on testing, how many times should you test for a definitive result? And, how infectious are you if the positive line is faint? And what if the test turns positive — but only after an hour?
We posed your questions to the experts: Dr. Abraar Karan, infectious disease researcher at Stanford; Meriem Bekliz, virologist at the University of Geneva; and Dr. Preeti Malani, professor of medicine at the University of Michigan. Here’s the scoop:
So I caught COVID-19 and after 10 days I’m still testing positive. But the line on my rapid test is really faint now compared to a week ago. What’s the deal? Exactly how contagious am I?
“The faintness or darkness of the line probably has some correlation to degree of infectiousness especially early on [during the infection],” says Karan.
So if the line is faint, that could mean your risk of accidentally passing the virus on to others is low.
“Some people may not be infectious because the tests could be picking up viral debris from a waning infection,” says Bekliz.
But don’t rip off your mask just yet: There could be other reasons for a faint line.
There is “some room for error” with those rapid tests, Karan says. You’re sticking a cotton swab up your nose and hoping to snare some virus. A faint line could mean you’ve collected less virus this time around. Maybe you swabbed for less time or in only one nostril when your test instructions say to swab both.
“In general, a darker line is a result of more virus [on the swab],” says Malani. “But antigen tests are not especially sensitive, so even with a negative test, you can be contagious.”
So the bottom line, say our experts: If you’re testing positive – even with a faint line — you should behave as if you are contagious.
If there’s any hint of a positive line, Bekliz recommends you continue to wear a mask, work from home if possible and generally limit contact with other people.
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Read More: Are there false negatives? What does a faint line mean? : Goats and Soda : NPR