There is no need for a second test to determine whether or not someone who tested positive for COVID-19 but who has since recovered from their illness should be released from isolation.

If you can't be homebound for ten days, retesting is an option (though it might not be necessary if you've been fever-free for 24 hours and are still using a face mask, as the CDC suggests) (CDC).

This page describes the circumstances under which a second test following a positive COVID result would be warranted and why the CDC advises against such a test for persons who have fully recovered. It also details how long a person who tests positive for COVID is infectious, how long a positive result can last, and when it could be safe to end isolation if the person is symptom-free.

If I get a positive result for COVID, what should I do?

If you test positive for COVID, current CDC recommendations say that you should stay home for at least five days and take measures for at least ten days.

Suppose a person has been isolated for five days and has shown no signs of COVID. In that case, they may return to their routine if they can continue wearing a properly fitting mask when interacting with others.

Isolation for five days should be practiced by those with mild symptoms, beginning when the symptoms first appeared. For this reason, we recommend waiting 24 hours after the last sign of illness (such as a fever) to remove the patient from isolation.

They should keep wearing a tight-fitting mask around other people for at least another five days after their symptoms have improved, just in case.

Can I Avoid Testing If I Get COVID?

After five days, anyone who has access to a COVID test and wishes to do so may do so. However, individuals are not required to take the test, and the outcome will not affect whether they must continue to wear a mask among other people for another five days.

The Centers for Disease Control and Prevention (CDC) advises waiting 24 hours after the last symptom and the absence of fever to take a test.

If the test returns negative, you can stop staying in isolation after five days. However, you should still be careful and wear a mask until day 10.

After a positive test, isolation should be maintained until day 10.

If you tested positive on day 5, you shouldn't get any more tests. After ten days of isolation, further testing is unnecessary for those who have successfully recovered from COVID.

If a person cannot or chooses not to undergo repeat COVID testing after five days of isolation, the CDC advises that they continue to take measures until day 10.

In what time frame could I expect a positive COVID test?

Even if they feel better, people may get retested for COVID out of concern that they are still spreading the virus if they have a positive result the first time around.

While this progress, many people continue to test positive for COVID despite not having any symptoms and being asymptomatic carriers. As a result, people may continue to show positive for COVID for several weeks or months after recovering from their illness.

Scientific studies have revealed that PCR tests can detect virus particles in most patients as early as six days before COVID symptoms begin and continue to show up for another two weeks afterward.

While tests can still detect viral RNA after nine days, researchers have been unable to develop the live virus from collected specimens.

In other words, a person can continue to test positive for COVID even after the infectious period has ended (after eight days)

Someone with a positive COVID test might not be contagious.

Nucleic acid reverse transcriptase-polymerase chain reaction (RT-PCR) assays are the gold standard for diagnosing COVID-19. Respiratory samples are used to replicate viral genetic material. One copy of viral RNA is needed for a positive result, and the assays can multiply that copy.

These tests can detect even trace levels of the virus with great accuracy. Despite this, the presence of viral fragments does not prove the presence of a viable virus.

Not all viral fragments generate symptoms or can be transmitted to others, even if they have been found. There is a three-month window during which the viral pieces can be discovered.

Serum Antibody Testing

Blood tests called "antibody" or "serology" checks for anti-COVID-19 antibodies. Antibodies are proteins the immune system produces in response to an infection or vaccination. For a time afterward, they can reduce your risk of infection and the severity of any disease you could get. The duration of this protection varies depending on the condition and the individual.

An antibody test would have to be performed to rule out a current infection with the COVID-19 virus. Because antibodies are not produced until 1–3 weeks after infection, they may not be detectable in an antibody test if you are currently infected.

Retesting After a Positive COVID-19 Test According to CDC Recommendations

If your symptoms improve after five days of quarantine, the CDC recommends but does not require that you retest.

The CDC recommends that anyone with access to antigen tests should consider using them. If you have two negative tests within 48 hours of each other, you can take off your mask before day 10.

Even if your symptoms have subsided and you are no longer in isolation, you should continue to wear a mask until day ten unless you have access to an antigen test or retest after finishing your isolation.