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When to Retest After Having COVID

By: Christine Zink, MD

Tens of millions of people in the United States have been infected with COVID-19, resulting in hundreds of thousands of deaths. After being infected with COVID-19, there is curiosity about how often people should test themselves when they should test, and whether they should continue to retest after having the illness.

This article reviews why the Centers for Disease Control and Prevention (CDC) does not recommend repeat testing for people who have recovered from COVID-19.

Do I Need to Obtain Post-COVID-19 Testing?

The short answer is no.

Currently, the CDC guidelines indicate that if a person tests positive for COVID-19—regardless of vaccination status—they need to isolate at home for at least five days and take precautions for at least 10 days.

This means that after five days, a person who does not have symptoms can end isolation if they can still wear a well-fitted mask around other people for an additional five days.

People with mild symptoms should isolate for five days from symptom onset and ensure that their symptoms are improving and they are fever-free for 24 hours before ending isolation. If symptoms have improved at day five, then they should continue wearing a well-fitted mask around other people for another five days.

At the end of five days, if a person has access to a COVID-19 test and wants to test, they can. But, a person does not need to test, and the test result does not change whether a person still needs to wear a well-fitted mask for an additional five days.

The CDC recommends that you only test if you have been fever-free for 24 hours without the use of fever-reducing medication and your other symptoms have improved. If the test result is negative, the person can end isolation after day five and wear a well-fitted mask around others until day 10. If the test result is positive, the person should continue to isolate until day 10.

After that time, no further testing is recommended, even if a person tested positive on day five. Repeat testing after recovery from COVID-19 is not required after 10 days of isolation.

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Sick and Immunocompromised People

These guidelines do not apply to moderately or severely ill people with COVID-19 or people with weakened immune systems. Immunocompromised people should always isolate for at least 10 days and up to 20 days for people who were severely sick with COVID-19.

If a person does not have access to repeat COVID-19 testing after five days in isolation or does not want to retest, the CDC recommends that people take precautions until day 10 by continuing to wear a well-fitted mask around others at home and in public.

At-Home Testing

People with mild to moderate symptoms often obtain COVID-19 testing on their own and care for themselves at home. With the rise in cases, testing options are becoming harder to find. There are several at-home testing kits available, but they’re scarce. The government has launched a program to help ease the testing hurdle by providing free at-home rapid COVID-19 testing kits, but only four per household are allowed.

How Long After Having COVID-19 Will Someone Still Test Positive?

People might obtain repeat COVID-19 testing because they are under the impression that another positive COVID-19 test result—even if symptoms are improving—means that they are still contagious. These people may feel a duty to limit the spread of the disease further.

However, many people can continue to test positive for the virus even though they are not symptomatic or contagious, sometimes for weeks or even months.

For PCR tests, evidence shows that in most people, viral particles can be detected as early as six days before symptom onset and up until two weeks later.

However, although viral RNA can continue to be detected, scientists have not been able to grow live viruses from collected specimens nine days after symptom onset. This suggests that even though a person can continue to test positive, they are no longer contagious eight days after symptom onset.

How Can Someone Test Positive for COVID-19 and Not Be Infectious?

The best COVID-19 tests are the nucleic acid reverse transcriptase-polymerase chain reaction (RT-PCR) tests. These tests work by creating copies of viral genetic material in respiratory samples. The tests can take a single copy of viral RNA and amplify it to show a positive result.

Essentially, these tests are very good at detecting small amounts of viral material. However, these viral fragments do not indicate a live virus. Their existence does not mean that the viral fragments can lead to symptoms or be passed to others. These viral fragments can be detected for up to three months.

If Someone Continues to Test Positive for COVID-19, Will They Become Contagious Again?

The question to retest becomes more confusing when we add the element of repeat infection.

People who have recovered from COVID-19 develop protective antibodies that help prevent the virus from replicating and infecting new cells. However, scientists do not fully understand the effectiveness of this antibody protection or how long it lasts.

Some research has suggested that neutralizing antibodies are present for at least six months. Therefore, the risk of reinfection is low but not impossible, and reinfection is more likely in unvaccinated people.

This concept also applies to people who are fully vaccinated, as breakthrough infections can occur in fully vaccinated people.

Continue to Wear a Mask

Even if you have recovered from COVID-19 or are fully vaccinated, it’s still important to wear a mask indoors in a public setting and in close contact areas.

According to the CDC guidelines, in people who have recovered from COVID-19, testing is not recommended as part of a contact tracing program or new exposures within three months of a positive COVID-19 test. During these three months, a positive test result could be associated with the previous infection rather than a new infection.

However, this recommendation differs if a person experiences symptoms consistent with COVID-19 within three months. In that case, repeat testing is recommended. If the test is positive, patients should undergo a repeat five-day isolation period, according to recommended guidelines.

Can My Employer Require a Negative COVID-19 Test Result to Return to Work?

Several workplaces have implemented COVID-19 screening to help prevent the spread of SARS-CoV-2. The CDC guides workplaces in implementing these testing strategies in non-healthcare settings. They do not recommend requiring a negative COVID-19 test result before returning to work.

According to the Americans with Disabilities Act (ADA), employers who implement mandatory COVID-19 testing of employees must ensure that the testing is job-related and consistent with a business necessity. The purpose of the program should be to identify current infections.

Based on the evidence of continued positive results for months after illness, the CDC recommends a time-based and symptom-based strategy for determining when a person can return to work. This strategy means that people should follow the CDC guidelines for five days of isolation and should not return to work unless their symptoms improve or resolve.

According to the ADA, employers can require a healthcare provider’s note certifying fitness for duty after a COVID-19 infection. Public health organizations stress that this requirement could be burdensome, since healthcare professionals may be too busy to provide fitness for duty documentation.

The CDC recommends that employers should consider not requiring a healthcare provider’s note for employees to return to work. However, some employers require it anyway.

Guidelines for Employers

Employers who have implemented regular COVID-19 screening will likely require repeat testing when employees return to work. However, the ADA requires that employers follow current CDC guidelines regarding repeat testing and returning to work.

If I Continue to Test Positive for COVID-19, Does That Mean I Have Long COVID?

The World Health Organization (WHO) has developed a clinical definition for post-COVID syndromes known as long COVID. This condition occurs in people:

  • With a history of probable or confirmed SARS-CoV-2 infection
  • Who continue to have symptoms three months after the onset of initial symptoms or test positive for COVID-19
  • Who have chronic symptoms lasting for at least two months
  • Whose symptoms cannot be explained by an alternative diagnosis

Common symptoms of long COVID include:

  • Fatigue
  • Shortness of breath
  • Cough
  • Chest pain
  • Joint or muscle pain
  • Headache
  • Cognitive dysfunction or difficulty concentrating
  • Sleep problems
  • Mood changes
  • Changes in smell or taste
  • Changes in the menstrual cycle

Post-COVID-19 conditions like long COVID are a clinical diagnosis, so there is no testing method available.

Long COVID is not more common in people who continue to test positive for the virus. Research is still ongoing into understanding this constellation of symptoms.

Thus far, the CDC indicates that the people most at risk for long COVID are:

  • People hospitalized for the illness
  • Women
  • Black people
  • People aged 40 and older
  • Those with preexisting health conditions

However, this initial risk analysis was performed on a small group of people, and scientists continue to analyze the risks.

COVID-19 Treatments: What You Need to Know


Millions of people in the United States have been infected with the COVID-19 virus, and most people have recovered from the illness. Over the last few months, infections have risen, prompting people to seek COVID-19 testing and repeat testing to ensure they have recovered.

However, the CDC does not recommend repeat COVID-19 testing for people who have recovered from the illness, especially since many can continue to test positive for months and not be contagious. The CDC only says that people with mild diseases can repeat tests to end isolation early on day five. However, people still need to wear a well-fitted mask until day 10.

Additionally, the CDC does not recommend repeat testing for returning to work. Instead, workplaces should follow the CDC guidelines and use a time-based and symptom-based strategy for returning to work.

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