Protection against COVID-19: What do antibody levels mean?

January 31, 2024

After over three years of the COVID-19 pandemic, it’s likely that you’ve had at least one COVID infection or been vaccinated against the virus. Either way, you might be wondering what your COVID-19 antibody levels are or what they can tell you about your protection against the virus.


In case you don’t know, a COVID-19 antibody test looks for antibodies to SARS-CoV-2, the virus that causes COVID-19. These antibodies are proteins your immune system makes to fight the infection.


But what do your COVID-19 antibody levels mean? Here’s what you need to know about COVID-19 antibody testing.


First, what is a COVID antibody test?

An antibody test, also called a serology test, is done on a blood sample. When testing for COVID-19 antibodies, an antibody test looks for antibodies made against the spike protein of the COVID-19 virus. There are two main types of antibodies tested that are reported together as a total number of antibodies in your body:

  • IgM antibodies appear sooner and fade more quickly. They indicate a more recent infection
  • IgG antibodies appear later and remain in the body after infection. They indicate you had a previous infection


When should you get a COVID antibody test?

It takes time for your body to produce measurable antibodies after an infection or vaccination. Most people will have measurable antibodies three weeks after onset of COVID-19 symptoms or after receiving a vaccine dose.


Antibody levels can change over time and can provide helpful information at different points after an active infection or vaccination:

  • Early on, results indicate if you may have had a recent infection
  • Weeks later, results provide information about your immune response
  • Months later, results may show possibility of longer-lasting immunity


It is important to know that even though the presence of antibodies likely means that you have some level of protection against COVID-19, how much protection and how long it will last is still uncertain.


What do antibody test results mean?

With Labcorp's COVID-19 semi-quantitative antibody test, you don't just get a positive or negative result. You get an actual numerical value that indicates your level of antibodies. Talk to your healthcare provider to understand what your specific antibody levels may mean for you.


While COVID-19 antibody testing can provide some helpful information and inform conversations with your healthcare team, it cannot diagnose a current infection or determine your immunity to the virus. Research is underway to determine how much protection antibodies provide, what levels are needed for protection and how long antibodies can last.


Take charge of your health

Labcorp's COVID-19 Antibody Test empowers you to check if you have antibodies after exposure or vaccination. Talk to your healthcare provider about what your test results may mean for you. Knowledge about your antibody levels is power when it comes to your health.