How long could I be contagious before a positive virus test?
Studies have shown that people can be contagious for about two days before developing symptoms of COVID-1
In fact, right before symptoms develop is when people are probably the most contagious, said Dr. Werner Bischoff, an infectious disease specialist at Wake Forest University.
Even people who never develop symptoms can spread the infection. This is a problem because many people would never resort to testing unless they develop symptoms or know they have been exposed.
But there’s a trickier part to this question: What if someone knows they’ve been exposed but the virus test comes back negative – could they still be contagious?
A negative test within less than seven days of exposure “is a very, very poor indicator of the presence of viruses on board,” said Dr Alan Wells of the University of Pittsburgh Medical Center.
Some tests are less accurate than others, and you have to account for the incubation period, he said.
A negative test between seven and 10 days of exposure is a better indicator, Wells said, but even then some people may not test positive until later.
“This is why if you’ve had credible exposure, you should wear a mask and you should quarantine yourself if you have any questions,” he said.