As the number of COVID-19 cases in this country continues to surge, there has been a rush of Americans seeking to get tested for the coronavirus that causes it. If you’re considering testing but are confused about the various types of tests and what they do and when to get them, here’s a brief overview that might help.
The first thing you need to understand is that there are different types of tests that are used at different times. Certain tests are used to detect if you are currently infected with SARS-Cov-2, the virus that causes COVID-19, and there are different tests that can determine if you’ve already had the virus.
If you want to know if you are currently infected, there are two types of tests: molecular tests and antigen tests. Molecular tests are typically performed using nasal swabs or throat swabs, but some test saliva or another bodily fluid. Molecular tests look for genetic material that can only come from the virus, which will be present if you are infected.
Antigen tests, which are done using nasal or throat swabs, identify antigens from the virus. Antigens are protein fragments that initiate an allergic response in the body. Antigen tests are more likely to miss an active COVID-19 infection compared to molecular tests. It may be recommended that you get a molecular test if your antigen test is negative but you have COVID-19 symptoms, which include cough, shortness of breath and fever.
You can get these tests from your doctor or state or local health department. Most states have set up testing centers throughout the community to provide easy access for residents. Many centers offer the rapid COVID-19 test, which is an antigen test that provides results the same day as opposed to the 3-5 day wait time for most nasal swab tests. The FDA has also approved a COVID-19 home testing kit.
On the other hand, antibody tests look for antibodies to the virus in your blood, which may indicate that you’ve previously been infected by the coronavirus. Antibodies are proteins made by the immune system that help fight foreign invaders such as viruses. They may help ward off future attacks by the viruses and keep you from getting the diseases they cause a second time.
Unfortunately, researchers are uncertain about how much immunity antibodies to the coronavirus provide against getting COVID-19 again. Research suggests that coronavirus antibody levels may wane over just a few months. Confirmed and suspected cases of reinfection have been reported, but remain rare. Researchers are working to better understand this phenomenon.
Antibody tests are not a good way to determine if you are currently infected with the coronavirus because it can take 1-3 weeks after infection for your body to make antibodies. You may test negative but have an infection in its early stages. Further, you can test positive for antibodies even if you had an asymptomatic infection.
Antibody tests are available through your doctor or a verified laboratory. Typically, results are available within a few days.
The tests for COVID-19 are new and it’s unclear how accurate they really are because there are no “gold standard” tests to compare them to. In addition, these tests were made available by Emergency Use Authorization by the FDA. Under an EUA, the makers were permitted to market the tests even though they didn’t receive formal approval due to a public health emergency.
Studies show that the rate of false negative results with molecular tests vary depending on how long the infection has been present but ranged from 20 percent when testing was performed five days after symptoms began to up to 100 percent when testing was done earlier in the infection. False negatives are more common with antigen tests, which is why they are not favored by the FDA as a single-use test for active infection.
The reported rate of false negatives with antibody tests ranges from 0 to 30 percent depending on the research study and when in the course of the infection the test was done. Having an antibody test too soon after infection can lead to false negative results.
Most people who develop COVID-19 have a relatively mild form of the disease and don’t need any special treatment or hospitalization. In addition to symptoms of fever, cough and shortness of breath, they may also experience a sore throat and tiredness that may last one to two weeks. Other people who are infected may be asymptomatic.
But for some people, COVID-19 is a severe illness that requires hospitalization, sometimes in an intensive care or special COVID unit. The risk for this is higher for people who are older and have chronic health conditions such as diabetes.
Whether you test positive or negative for the coronavirus, take steps to protect yourself and others. Wash your hands often, avoid close contact with others, cover your mouth and nose with a mask when around others, cover coughs and sneezes, clean and disinfect, and monitor your health daily. And follow CDC guidelines if symptoms develop.