It can feel like the coronavirus (COVID-19) pandemic is winding down and life is almost back to normal. But people are still getting infected and testing remains an important way to prevent the spread of the virus. It’s the only way to know if a runny nose or headache is due to coronavirus, not the flu or a cold.
There are different testing options, and knowing when and why to test can get confusing. Here's a summary.
What Are the Types of Coronavirus (COVID-19) Tests?
Tests for coronavirus look for either a current infection or a past infection.
Current Infection (Viral Testing)
To check if someone is infected with coronavirus, health care providers look for pieces of the virus in a sample of mucus or saliva (spit). These tests, called viral tests, can tell if the person is infected on the day of the test. This is why viral tests are also sometimes called “diagnostic tests.”
The two main types of viral tests are:
- molecular tests (such as the PCR test), which look for the genetic material, or RNA, that's inside the virus
- antigen tests, which look for proteins on the surface of the virus
The viral test sample is usually taken from inside the nose with a swab (like a Q-tip). Most commonly the sample is taken at the start of the nostrils, but it can also be taken from the middle of the nose, or the very back of the nose. Less often, the sample comes from the throat, the inside of the cheeks, or along the gums or tongue. And rarely, it might involve collecting saliva (or spit) in a small container.
Tests can be done in a doctor's office, urgent care center, or other sites (such as pharmacies or pop-up test sites). Many people now use at-home COVID tests.
Depending on the type of test and where it was done, results can be ready within minutes to hours, or it can take a few days or longer if the test went to a lab. Results might take longer if a community does many tests at the same time.
A "positive" test means a person is infected with coronavirus, and a "negative" test means they aren't infected. But sometimes the test results aren't accurate. A test result can be negative even when someone has the virus. This is called a false negative test. And sometimes tests can be positive long after the initial infection when a person is no longer contagious. This is why it’s so important to discuss test results with a health care provider who can help interpret what the result means and what you should do about it.
Past Infection (Antibody Testing)
To see if someone had coronavirus in the past, health care providers can look for antibodies, which the body makes after an infection. It can tell if someone had an infection in the past, at least 2–3 weeks before the test. That's how long it takes the body to make antibodies after infection. This can't tell if the person is infected at the time of the test, which is why this test isn't used to diagnose COVID-19.
This is a blood test, with a sample taken either from a vein or a fingertip (called a "fingerstick"). Results can be ready on the same day, or up to a week later. There's no home kit for antibody testing yet.
The body will also produce antibodies after a person gets a COVID vaccine. Some antibody tests will detect antibodies from infection, and other tests will detect antibodies from vaccines. Some tests look for both. Health experts are still studying the best ways to use antibody tests. For now, they do not recommend using antibody testing to see whether a person is immune to the coronavirus or how well the vaccine is working.
How Can Parents Help?
Ask the testing site about the type of test they will do. Then use simple terms to explain it to your child. If the site says they will swab the front or middle of the nose, you can assure your child that this is simple to do and not uncomfortable at all. Sometimes it tickles or triggers a sneeze.
If you or your kids get tested for coronavirus, talk with your doctor about the results and what they mean for your family. Someone with a positive test is most likely infected and contagious. They will need to isolate to prevent the virus from spreading to others. Sometimes people need to stay home even if their test is negative. Your doctor can tell you what your next steps are.