(NEXSTAR) - Sore throat, runny nose and headache - the symptoms may mean that your body is struggling through a cold, flu or a COVID infection. You may not have had access to a COVID-19 test, or your symptoms may have disappeared before you had the chance. There is also the possibility that you tested too early in the infection so you got a false negative.
Is there a way to know if the illness you had a month ago, or even last year, was COVID or something else?
The short answer is yes. In practice, however, the answer is more complicated.
The way to find out if you have had COVID-19 before is by using antibody or serology tests. When your body is exposed to the virus, it forms antibodies to fight it. These tests look for these antibodies to confirm previous infection.
Your body also produces antibodies when you receive the COVID-19 vaccine, but these tests can actually tell the difference between the two types of antibodies.
There are two types of antibodies that your body produces: antibodies to the tip protein (S), which are formed by vaccination, and antibodies to the nucleocapsid (N), which are formed by prior infection.
If a test shows you have the N-type antibodies, it indicates a previous infection, a spokesman for the Centers for Disease Control explained to Nexstar. If the test shows that you have S-type antibodies and do not have N-type antibodies, then it indicates that you have been vaccinated but have not been infected.
It can take weeks for someone to develop antibodies after infection, the CDC said. If you think you have been exposed to the virus recently, you should seek out a viral test, such as an antigen or a PCR test.
Someone can test positive for antibodies, even if they have never had COVID symptoms.
Both the CDC and the Food and Drug Administration have said they do not recommend antibody testing as a way to determine if you are protected against the virus.
"The CDC is evaluating antibody protection and how long antibody protection can last," the agency said. "Cases of re-infection and post-vaccination infection have been reported but remain rare. However, getting vaccinated even if you have already had COVID-19 can help your body make more of these antibodies."
Antibody testing cannot distinguish between COVID-19 variants, the CDC said, so they cannot be used to tell which variant a person was infected with.
If you would like to have antibody testing performed, the CDC suggests that you contact your local health department or doctor's office for a referral to a laboratory.