COVID-19 Update

a lab worker performing a coronavirus test
a lab worker performing a coronavirus test
a lab worker performing a coronavirus test

Coronavirus Test FAQs

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As communities begin to reopen, continued testing for COVID-19 is needed to help control its spread. Lisa Maragakis, senior director of infection prevention, answers common questions about testing.

What are the types of coronavirus tests?

There are two basic types of tests for COVID-19.

Viral or diagnostic test: A viral test can tell you if you are currently infected with the coronavirus that causes COVID-19. This is the test you will receive if your doctor refers you for a COVID-19 test based on your symptoms and other factors.

Early in the pandemic, researchers at Johns Hopkins Medicine developed a screening test that we use, along with other types of viral detection tests, to check for the virus.

Antibody test: An antibody test can show if you were previously exposed to or infected with the virus that causes COVID-19, and if your body has created antibodies in an attempt to defend itself. It takes at least 12 days after exposure for your body to make enough antibodies to show up on a test.

This test helps scientists gather data about how the immune system fights off COVID-19 in recovered patients. We do not yet know if a person with a positive antibody test is protected from getting re-infected with the virus or, if so, how long that protection might last.

Doctor taking a swab sample.

Johns Hopkins Ramps Up COVID-19 Testing to 1,500 a Day

A team of about 90 people work around the clock in the microbiology lab to process as many as 1,500 tests each day — a number that could double as the lab continues to add processing platforms.

Who should get a coronavirus test?

The answer varies based on many factors including a person’s symptoms, exposure history and underlying risk factors for severe disease.

People Who Have COVID-19 Symptoms:

Not everyone with symptoms requires a test. Many people have mild symptoms and can self-isolate at home — they may not need a test. Tests can be helpful, however, to find out if symptoms are due to COVID-19 so you can take precautions to avoid passing the virus that causes COVID-19 to others.

Talk to your health care provider to find out what he or she recommends. Remember, unless you have life-threatening circumstances that require calling 911 or going to an emergency department, stay home and call your doctor’s office to discuss your symptoms before going to a health care facility or testing site. This helps prevent the spread of the virus.

It’s also important to know that the availability of testing varies by state and local health department. Johns Hopkins Medicine provides tests with a doctor’s referral and, in some cases, for Maryland and Washington residents who do not have a referral.

According to the U.S. Centers for Disease Control and Prevention (CDC), priority to be tested for COVID-19 should be given to:

  • Hospitalized patients with COVID-19 symptoms
  • People who work in health care facilities and group residences such as nursing homes
  • First responders (emergency medicine technicians, police officers, firefighters and others) who have COVID-19 symptoms
  • People with COVID-19 symptoms who live in long-term care facilities or other group living settings, including prisons and shelters

Priority next goes to those who:

  • Have COVID-19 symptoms such as cough, fever or chills, shortness of breath or difficulty breathing, muscle or body aches, sore throat, new loss of taste or smell, diarrhea, headache, new fatigue, nausea or vomiting, or congestion or runny nose.
  • Are recommended for testing by their doctor or local health department for public health monitoring or other reasons

People Who Don’t Have COVID-19 Symptoms:

Many health experts believe that more people — including those with no symptoms of the virus — need to be tested to help prevent the virus’s spread. Since availability of testing supplies varies across the country, this is being discussed by federal, state and local agencies.

People Who Have Recovered from COVID-19:

After you have recovered, your doctor may refer you for a viral test to see your progress in getting over the virus.  This is not required, however, and in general, people can stop isolating themselves once enough time has passed and they have started to feel much better. Please talk with your health care provider or see the CDC website for guidance about how long to self-isolate after having COVID-19.

Your doctor may recommend an antibody test if you had COVID-19 and have recovered. If you want to participate in a research study, having an antibody test sometimes can be helpful for scientists to gather data about how the virus affects people differently.

Scientists are still trying to understand if antibodies to the virus that causes COVID-19 prevent people from becoming infected again and, if so, how long a person may be immune once they’ve recovered. More data is needed in order to know when a person should be re-tested if he or she develops symptoms again after recovering from COVID-19.

How is testing done for COVID-19?

Be sure to follow all information from your health care provider before getting a test. Many testing facilities, including Johns Hopkins Medicine, schedule tests by appointment. It’s also important to follow social distancing and wear a mask until the test is administered, and again afterward.

For the test, the health care professional will wear protective clothes, mask and a face shield, and then collect samples of your saliva or respiratory fluids.

The test to diagnose COVID-19 is simple and similar to a flu test. A care team member takes samples of saliva or fluids from deep inside your nose and the back of your throat with a swab. It is mildly uncomfortable but only takes a few seconds. The samples are then packaged according to CDC guidelines and sent to a laboratory for analysis.

The laboratory tests these samples for the presence of the new coronavirus (SARS-CoV-2), which causes COVID-19. Results will be shared with you by either your care provider or the lab.

Illustrated tablet with multiple choice answer selections

Coronavirus (COVID-19) Self-Checker

Check symptoms. Protect yourself. Get information.

Where can I get a coronavirus test?

In most cases, COVID-19 tests must be ordered by a doctor. The doctor might test you or refer you to a commercial testing center or a testing location set up by your city or town. Johns Hopkins Medicine provides tests at several locations with a doctor’s referral.

As noted above, testing varies by state, so talk to your doctor if you feel you need one.

The Food and Drug Administration has approved in-home test kits for use under certain circumstances. The samples still need to be sent to a lab for results.

How long does it take to get COVID-19 test results?

The time to process the test varies. Presently, it takes anywhere from an hour to several days to get results. Some hospitals, such as Johns Hopkins, have testing labs on-site. The specimens are tested for the presence of the new coronavirus, which causes COVID-19. The doctor reports the results to the patient and to the public health authorities if it is positive.

If your test shows you’ve been infected, your doctor will advise on next steps. Most cases of the illness are mild and can be managed at home, but here is more information about what to expect if you have COVID-19.

If I’ve been tested once, do I need to get tested again?

Getting a negative test result means it is unlikely you were infected with the new coronavirus when your test sample was taken. But you could still be infected if you got your test when you were in the earliest stages of infection, before the virus was detectable. Also, you could catch the coronavirus later and need to be tested again. Let your health care provider know if your symptoms persist or worsen, and you might need another test.

If you get sick and your coronavirus test is positive, once you are better, your doctor may order another test to gauge your recovery and determine if you might still be contagious to others. This is not required, though — most people can stop isolating themselves once enough time has passed and they have started to feel much better. Please talk with your health care provider or see the CDC website for guidance about how long to self-isolate after having COVID-19.

Scientist carefully insets a pipette into a test tube.

Coronavirus (COVID-19)

What you need to know from Johns Hopkins Medicine.

Updated June 26, 2020