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

Getting a positive result on a COVID-19 test typically means that it's time to isolate. According to the Centers for Disease Control and Prevention (CDC), the length of time you'll need to isolate will depend on several factors, like whether or not you had symptoms and, if you did, how severe they were (more on this below).

But knowing when to stop isolating and resume your normal activities isn't always so clear-cut. That's because it's also possible to test positive for COVID-19 for weeks or even months after your initial infection despite being symptom-free.

Much of this has to do with the type of COVID-19 test used since some tests can detect the virus in your body longer than others. Here's what to know about how long you can test positive for COVID-19 and what to do if your test comes back positive.

How Long Do People Usually Test Positive for COVID-19?

Exactly how long you test positive for COVID-19 after your symptoms start improving depends on the test you take. With an antigen test or rapid test, you can test positive for a few weeks after your initial test. With a nucleic acid amplification test (like PCR), your results may be positive for up to 90 days.

The discrepancies between tests and the lengths of their positive results boil down to what each test looks for and how sensitive it is. (Tests that have high sensitivity produce few false-negative results. That's why highly sensitive PCR tests, for example, are really good at detecting whether or not the virus is still in your body.)

PCR tests are designed to pick up viral RNA, or the virus' genetic material, David Dowdy, MD, an Epidemiologist with the Johns Hopkins Bloomberg School of Public Health, told Health.

"Even if the virus is dead, the RNA can still be hanging around, so you can get a false-positive [PCR test result] up to two months or so after the infection," said Dr. Dowdy. "It's not super, super common, but it certainly does happen."

Meanwhile, antigen tests—more often known as rapid or at-home tests—detect antigens, which are specific proteins from the virus. Antigen tests are generally less sensitive than PCR tests, and both tests work best in people who have symptoms.

The type of test used is not the only reason why someone would continue to keep testing positive for COVID-19 for a while. Your immune system is also an important factor. It determines how well equipped you are to fight foreign invaders like viruses.

"In some people…especially those with a compromised immune system, they may continue to be contagious for a longer period of time, especially if they continue to have symptoms," Matt Binnicker, PhD, director of clinical virology at the Mayo Clinic, told Health. Accordingly, the CDC recommends longer isolation periods for people who will have a harder time fighting off the virus.

There is a simple reason why people with compromised immune systems stay contagious longer. As Dr. Dowdy explained, their "immune system is not getting rid of the virus" as effectively as it should—which would also result in testing positive for COVID-19 for a longer period of time than someone who doesn't have a compromised immune system.

What Are the Masking Guidelines?

As a barrier, masks can help stop the spread of diseases transported on respiratory droplets. They help reduce the chance of you catching the virus from someone else who has it or spreading it to another person if you have it. Find a mask that fits well, offers good protection, and is comfortable to wear for extended periods of time.

The CDC recommends wearing masks based on how high COVID-19 levels are in your community:

• Low COVID-19 levels in the community: While you can mask up anytime you want, wearing a mask on public transportation is advised.
• Medium or high levels: If you're at high risk of getting sick, wearing a mask offers an additional layer of protection. If you live with or are often around someone who is at high risk, you may also want to wear a mask when indoors with that person (and get tested before you see them).
• High levels: Everyone should be wearing a mask if a high number of COVID-19 cases are being reported in your community. People who are at high risk of getting sick and those who are around at-risk people should also consider avoiding non-essential activities in public that take place indoors.

These groups may also want to take more precaution:

• Children
• People who are older
• People with some medical conditions
• People who are pregnant or recently were
• People with disabilities who have difficulties wearing a mask
• People who are traveling

When To Isolate

Everyone who has COVID-19 needs to isolate. This includes people who think they may have COVID-19 but don't have the test results yet. Here's what the CDC recommends if you do test positive for COVID-19:

• You test positive and have no symptoms: In this case, isolate for five full days. The first day will be the day after you got tested. If you don't have symptoms, you can end isolation after those five days.

If you have symptoms, isolation will be a little bit different.

• You test positive and have mild symptoms, even if symptoms start after a few days: The CDC also recommends isolating for five days. However, these five days start from the first day after you noticed symptoms (not the first day after your test).
• You test positive and have moderate symptoms: This includes shortness of breath or difficulty breathing. You'll need to isolate for 10 days.
• You test positive and have severe symptoms: This would mean you needed to be hospitalized. Isolation is recommended for at least 10 days, but you can be infectious for longer.
• You test positive and are moderately or severely immunocompromised: It is recommended to isolate for at least 20 days. You'll also want to talk to your healthcare provider about what's best in your situation, which may include serial testing (getting multiple tests done).

When you reach the end of the recommended isolation period, your symptoms will determine whether you can end isolation:

• If your symptoms are improving and you haven't had a fever in the last 24 hours (or taken any fever-reducing medication), you're done isolating.
• If you still have a fever or other symptoms are not improving, continue isolating and see a healthcare provider if necessary.
• When you end isolation, continue wearing a high-quality mask around others indoors, whether at home or in public, until at least day 11. (If two antigen tests taken 48 hours apart show you are negative, you can stop wearing your mask sooner. More on this below.)

Retesting After a Positive COVID-19 Test

It is not necessary to retest after recovering from COVID-19, but it is recommended to take further precaution and mask up through day 10. However, if you want to stop masking before day 10, you may decide to take an antigen test. You will need two negative antigen test results in a row, 48 hours apart, to stop masking before day 10.

However, if you test positive after your symptoms start improving, you may still be infectious. The CDC says to continue masking. If symptoms return after you have recovered or worsen after the isolation period, the CDC recommends restarting isolation at day 0. (If you think it could be a false-positive, you can retest.)

Even after you're done masking, you may still need to test again within three months of a positive COVID-19 test, such as for travel. If it's been less than three months since you had COVID-19, the CDC advises using an antigen test instead of a PCR test.

"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.

If you are getting ready to travel, make sure to check your destination's entry requirements, as they can vary from country to country. According to Dr. Dowdy, simply being up to date on your COVID-19 vaccines may supersede the need for a negative test result in some instances.

A Quick Review

People can continue to test positive after recovering from COVID-19. How long someone continues to test positive is determined, in part, by which test they are using. Highly sensitive tests, like PCR, will show a positive result for up to three months later. In contrast, less sensitive antigen and rapid tests may show a positive result for a few weeks.

A severe case of COVID-19 or weakened immune system can also affect how long you might test positive. In these cases, your body will have a harder time fighting off and getting rid of the virus, and isolation for you will last a while longer than five days.

If you get COVID-19, take the necessary precautions, which include isolating and wearing a mask when around others. Talk to a healthcare provider if you develop moderate or severe symptoms, or your symptoms 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.