COVID-19 is a new disease and there's still a lot to learn.

When someone tests positive, their first thought might be that they would need to be re-tested and receive a negative result to be completely cleared, whether they're showing symptoms or not.

But doctors say that's not really the case and the tests don't always tell the whole story.

"Being infectious and having a positive test are almost two different things at this point," said Dr. Alex Benjamin, chief of infection control and hospital epidemiology at Lehigh Valley Health Network.

That means if you test positive for the virus, you don't necessarily need to wait for a negative result to safely return to work or interact with other people.

"If you're symptomatic and you test positive then it's usually just confirmation your symptoms are related to COVID. However the test is not good at determining whether you've been cured of COVID or not," said Dr. Benjamin.

Rather, Dr. Benjamin agrees with CDC guidance, which says if you test positive, you should isolate for at least 10 days, and remain quarantined until symptoms stop.

"If your symptoms have resolved and you don't have any fevers, then it's okay for you to go back out of isolation, return to work, and you're not contagious at that point," said Dr. Benjamin.

It gets tricky because patients can test positive for COVID up to 90 days after developing symptoms, even if they aren't infectious. That's because the swab can pick up proteins which may not actually be part of the living virus.

"The test can't tell you if the virus it picks up is just particles that are residual from your initial infection or if they're just particles that are not transmissible to other people," said Dr. Benjamin.

That's why the CDC says re-testing a patient in the three months following initial infection isn't necessary unless they continue to show symptoms.

The CDC also says while re-testing may not be needed in those three months, this doesn't mean recovered patients are immune to reinfection during that time. Doctors also say immunity cannot be totally determined through antibody testing because COVID-19 antibodies can disappear after a few months.