Most people who contract COVID-19 likely won’t experience symptoms for more than two weeks at most, but could test positive even after that.
According to the Centers for Disease Control and Prevention, some people who contract COVID-19 can have detectable virus for up to three months, but that doesn’t mean they are contagious.
When it comes to testing, the PCR tests are more likely to continue picking up the virus following infection.
“PCR test can stay positive for a long time,” Chicago Department of Public Health Commissioner Dr. Allison Arwady said in March.
“Those PCR tests are very sensitive,” she added. “They keep picking up dead virus in your nose for sometimes for weeks, but you can’t grow that virus in the lab. You can’t spread it but it can be positive.”
The CDC notes that tests “are best used early in the course of illness to diagnose COVID-19 and are not authorized by the U.S. Food and Drug Administration to evaluate duration of infectiousness.”
For those isolating due to a COVID infection, there is no testing requirement to end isolation, however, the CDC recommends using a rapid antigen test for those who choose to take one.
Arwady said that guidance is likely related to determining whether or not someone has an “active” virus.
“If you did want to get a test on please don’t get a PCR. Use a rapid antigen test,” she said. “Why? Because the rapid antigen test is the one that will look to see…do you have a high enough COVID level that you are potentially infectious? Now, a PCR test, remember, can pick up up sort of traces of the virus for a long time, even if that virus is bad and even if it’s not potentially transmitting.”
So what else do you need to know about testing for COVID?
According to the CDC, the incubation period for COVID is between two and 14 days, though the newest guidance from the agency suggests a quarantine of five days for those who are not boosted, but eligible or unvaccinated. Those looking to get tested after exposure should do so five days after the exposure or if they begin experiencing symptoms, the CDC recommends.
Those who are boosted and vaccinated, or those who are fully vaccinated and not yet eligible for a booster shot, do not need to quarantine, but should wear masks for 10 days and also get tested five days after the exposure, unless they are experiencing symptoms.
Still, for those who are vaccinated and boosted but are still looking to be cautious, Arwady said an additional test at seven days could help.
“If you’re taking multiple at home tests, you know, the recommendation is five days later take a test. But if you have taken one at five and it’s negative and you’re feeling good, chances are very good that you’re not going to have any more issues there,” she said. “I think if you’re being extra careful there, if you wanted to test again, you know, at seven even, sometimes people look at three to get an earlier sense of things. But if you’re gonna do it once do it in five and I feel good about that.”
Arwady said testing is likely not necessary after seven days following exposure for those who are vaccinated and boosted.
“If you had an exposure, you’re vaccinated and boosted, I don’t think that there is any need to be testing, frankly, past about seven days,” she said. “If you want to be extra careful, you can do it at 10, but just with what we’re seeing, I would consider you really in the clear. If you’re not vaccinated or boosted, I certainly have a much higher concern that you could get infected. Definitely, ideally, you’d be seeking out that test at five and I would do it again, you know, at the seven, potentially at that 10.”
If you had symptoms, the CDC says you can be around others after you isolate five days and stop exhibiting symptoms. However, you should continue to wear masks for the five days following the end of symptoms to minimize the risk to others.