The COVID-19 pandemic is no longer considered a global public health emergency, but people are still getting infected, and some will get very sick.
Should We Still Test for COVID-19?
Testing is still 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 COVID-19.
This can be extra important for people who have a higher risk for severe illness if they get COVID-19. If they test positive, taking antiviral medicines can keep them from getting very sick and needing hospital care.
Someone who tests positive might choose to stay away from family members or friends to protect them from infection (especially those at risk for severe illness) or wear a mask around them. And testing negative after being sick can reassure someone that they're no longer contagious and won't infect others.
What Are the Types of COVID-19 Tests?
Tests look for either a current infection or a past infection.
Current Infection (Viral Testing)
To check if someone is infected, 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. These usually are done in doctor's offices, urgent care centers, or pharmacies.
- antigen tests, which look for proteins on the surface of the virus. These are the quick tests that people can do at home.
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.
A "positive" test means a person is infected and a "negative" test means they are not 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. That's why it’s important to discuss test results with a health care provider. They can explain what the result means and what to do next.
Past Infection (Antibody Testing)
To see if someone was infected 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.
The body will also produce antibodies after a person gets a COVID-19 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.
What Else Should I Know?
If you or your kids get tested, 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. The quick antigen tests sometimes come out negative even when a person is infected, but this is more likely to happen at the beginning of the illness.
Repeating a negative test can be helpful if it’s important to confirm that symptoms are due to COVID-19. A couple of days later, a quick antigen test will probably have a positive result. A negative test at the end of the illness (following a positive one at the beginning) can be a sign that a person is no longer contagious.
