How long is COVID – 19 going to be contagious?

Recently President Trump held his first in-person rally after he tested positive for COVID -19 days ago.

Meanwhile, Senator Mike Lee, who also tested positive for COVID -19, spoke without a mask for several minutes at Supreme Court nominee Amy Coney Barrett’s nomination hearing.


“Adaija, an infectious disease physician and senior scholar for Johns Hopkins University Center for Health Security, says there are two ways to determine when it’s safe for someone recently diagnosed with COVID-19 to be around others again.

The first and preferred method is to evaluate your symptoms.”

“The simplest way is to wait a period of 10 days from symptom onset in mild to moderate cases (up to 20 days in severe cases) and then you can discontinue that person from self-isolation,” Adalja told Healthline.

“This is in line with the CDC’s guidelinesTrusted Source, which state people with COVID-19 can be around others when:

  • it’s been 10 days since their symptoms first appeared
  • they haven’t had a fever in 24 hours (without using a fever reducer)
  • other symptoms — like cough or fatigue — are improving

Those who are immunocompromised or had a severe case of COVID-19 should isolate for at least 20 days after the onset of symptoms.”

“I think it’s important to look at their clinical picture: How are they doing, how are they feeling, what are their symptoms?” Dr. Matthew Heinz, a hospitalist and internist in Tucson, Arizona, said.

“If they’re having fevers, there’s likely some degree of active infection and it’s important to continue self-isolating, Heinz added.

The second method is to administer a PCR until a patient tests negative for COVID-19 at least two times.”

“We think that a patient with a negative PCR or with a very low positive PCR is probably not infectious,” says Dr. Sheldon Campbell, a pathologist in Yale Medicine’s Department of Laboratory Medicine.

“A negative PCR is a pretty good sign someone isn’t infectious,” Campbell added.

But there’s a caveat to using a PCR test to determine a person’s ability to transmit the virus.

“There are going to be individuals that shed nonviable viral debris (and will test positive) for some period of time but not be contagious,” Adalja said, noting that he prefers the time-based symptoms approach rather than a PCR test.

Though some people may potentially shed small amounts of virus weeks after being diagnosed, others who continue to test positive may be carrying noninfectious viral remains in their body, according to Heinz.

A PCR test is not yet approved by the Food and Drug Administration (FDA) for quantitative reporting, or reporting whether a person has a high or low level test result, according to Campbell.

“We’re not quite at the point of being able to use a PCR test quantitatively,” Campbell said.


Heinz says measuring a person’s ability to transmit the virus is not an exact science.

“It’s not the easiest thing to determine,” Heinz said.

Because there are so many unknowns, Heinz suggests playing it safe if you were recently diagnosed with COVID-19.

If it’s been 14 days since the onset of symptoms and someone is still testing positive, it’s safe to assume they’re still potentially able to transmit the virus, at least to some degree.

“I would still say don’t risk it. At a minimum, [the CDC is] saying 10 days, but I still say 14 to most of my patients to be extra cautious,” Heinz said.


Scroll to Top