You Can Test Positive for COVID-19 Long After Being Infected

How long you will test positive for COVID-19 depends on several factors. You may continue to test positive for a while after your first positive test, but you may test negative after nine days. PCR tests may continue to show a positive result for up to 90 days after your first diagnosis. Additionally, reinfections are possible within 90 days, which can make it hard to know if you have a new infection or are still testing positive from a previous infection.

The discrepancies between tests and the lengths of their positive results boil down to what each test looks for and how sensitive it is. PCR tests are highly sensitive and are good at detecting whether the virus is still in your body. Rapid antigen, or at-home, tests are generally less sensitive than PCR tests.

Read on to learn how long you can test positive for COVID-19 and what to do if your test is positive.

Will Different Tests Show Different Results? 

There are two types of COVID-19 tests: Rapid antigen and polymerase chain reaction (PCR). Sometimes, those tests produce different results. 

Research has found that PCR is the "gold standard" for detecting COVID-19. PCR tests usually take a long time to produce results. In contrast, rapid antigen tests are low-cost, quick measures for diagnosing COVID-19.

PCR tests are highly sensitive and can easily detect COVID-19, even if you do not have symptoms. Rapid antigen tests are usually less sensitive and likelier to produce false negative results if you do not have symptoms than PCR tests. 

You only need to take one PCR test to confirm a COVID-19 diagnosis. The CDC advises taking another rapid antigen test 48 hours after receiving a negative result if you have symptoms. Three consecutive negative rapid antigen test results, taken 48 apart, are necessary if you do not have symptoms.

PCR and rapid antigen tests may show different results, even after fully recovering from COVID-19. After your symptoms subside, you may test negative with a rapid antigen test, but a PCR test may still detect the virus. 

Research has found that PCR tests may yield positive results for up to three months. That's because SARS-CoV-2, the virus that causes COVID-19, can linger in your upper airways after your symptoms subside. The viral particles are weakened and cannot replicate.

Am I Still Contagious If I Test Positive?

The CDC says you may still be infectious if you test positive with a rapid antigen test.

In that case, continue wearing a high-quality mask around others. After 48 hours, take another rapid antigen test to confirm. You are not infectious and may end isolation if you have two consecutive negative rapid antigen test results.

A positive rapid antigen test is more likely to signal the presence of infectious SARS-CoV-2 particles than a positive PCR test, especially if you have no symptoms.

The CDC has found that PCR tests detect non-infectious SARS-CoV-2 particles for three months or longer after recovery. Some evidence suggests that the live virus is not present in your upper airways after nine days. In other words, you are likely not contagious after that point.

When Should I Retest? 

You do not need to retest after testing positive. Instead, you may end your isolation after five days if you feel better and are fever-free for 24 hours without using a fever-reducing medicine. You are most infectious during those five days, but the CDC advises wearing a high-quality mask through day 10.

Still, if you decide to retest, a rapid antigen test will likely yield the most accurate results for ending your isolation.

You may need to test again within three months of a positive COVID-19 test, such as for travel. The CDC advises using a rapid antigen test instead of a PCR test if it's been less than three months since you had COVID-19.

"Because of the chance of persistent positive results by a molecular test, infected individuals should not use a [PCR] to determine if they are no longer infectious," said Binnicker.

Check your destination's entry requirements, which vary from country to country. Simply being up-to-date on your COVID-19 vaccines may sometimes supersede the need for a negative test result.

A Quick Review 

Some people may test positive after recovering from COVID-19. How long you test positive is determined, in part, by what test you use. PCR tests may show a positive result up to three months later. In contrast, rapid antigen tests may not detect COVID-19 after nine days.

The severity of your illness and your immune system may affect how long you might test positive. People with severe COVID-19 or a weak immune system often have a harder time getting rid of the virus than others.

If you get COVID-19, take the necessary precautions, including isolating and wearing a mask around others. Talk to a healthcare provider if you develop moderate-to-severe symptoms or are not improving.

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.