How Long Can You Test Positive for COVID Following Infection?

After contracting COVID-19, how long will you test positive? There's no way to know for sure.

The answers vary, according to health officials.

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, however, 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 previously stated.

"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."

Here's what else to know about COVID testing:

How long after COVID exposure could you test positive?

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."

When is the best time to get tested after exposure?

The CDC states that anyone who may have been exposed to someone with COVID should test five days after their exposure, or as soon as symptoms occur.

"If symptoms occur, individuals should immediately quarantine until a negative test confirms symptoms are not attributable to COVID-19," the guidance states.

Former Illinois Department of Public Health Director Dr. Ngozi Ezike previously said that incubation times could be changing, but those who test early should continue testing even if they get negative results.

"We might be learning that the time of incubation might be a little shorter. So maybe you'd be testing at two days," Ezike said. "Obviously if you're symptomatic, you test right away. But you know, if you want to test at two days, but that negative test... the two days should not make you think, 'Oh good, I'm clear,' you know? You might want to test again and of course symptoms you cannot ignore - scratchy throat, headaches, all kinds of symptoms - anything new can be a symptom of this new illness."

How soon might COVID symptoms appear?

According to earlier CDC guidance, COVID symptoms can appear anywhere from two to 14 days after someone is exposed to the virus.

Anyone exhibiting symptoms should get tested for COVID-19.

Some people may never experience symptoms, though they can still spread the virus.

A person is also considered contagious before symptoms appear.

When are people with COVID most contagious?

The CDC says that its guidelines were updated to reflect growing evidence that suggests transmission of COVID-19 often occurs one to two days before the onset of symptoms and during the two to three days afterward. 

"This has to do with data from the CDC that really showed after seven days there's virtually no risk of transmission at this point," Arwady said. "And in that five-to-seven-day window, you know, there's some depending on whether people have been vaccinated, underlying conditions, etc., but the risk drops a lot and the feeling is that in the general population, combined with masking, etc. the risk really is very low."

For those without symptoms, CDC guidance states they are considered contagious at least two days before their positive test.