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Imagine your immune system is a military and every time it encounters a new attack, it builds a defense customized for the virus at hand. That defense is called antibodies. While these protective proteins can provide us some information about what our immune system has encountered, such as the SARS-CoV-2 type of the coronavirus, it doesn't give us a full picture.
What antibodies can tell you
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If you’ve been infected with the virus – If you get a COVID-19 antibody test and the results show that your body has COVID-19 antibodies, it is presumed that you were infected with COVID-19 in the past.
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If you received a COVID-19 vaccine – A COVID-19 vaccine (which cannot infect you with the virus) will also cause you to test positive for antibodies.
What antibodies may not tell you
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If you are currently infected with COVID-19 – Antibodies generally start developing one to three weeks after infection. If you are currently sick with COVID, your antibody test may be negative, because your immune system may not have had time to create antibodies. If you have been exposed to someone with COVID-19 or you are experiencing symptoms, speak with a provider virtually. Visit LVHN.org/virtual to find the virtual care option that works best for you.
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If you had the virus a while ago – Following an infection, your body will build up antibodies, and over time those antibodies will begin to diminish. If you had COVID-19 more than six months ago, an antibody test may not detect antibodies to the virus. The length of time antibodies are detectable in your system depends on the response of your personal immune system. Antibody levels normally decrease over time after infection, and a negative antibody test does not necessarily mean you are no longer immune.
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If you have protection against the virus – Different levels of antibodies are needed to provide protection against different viruses. Unfortunately, we don’t know the exact level of antibodies that are needed to provide protection against COVID-19. Let’s assume again that you had COVID-19 six months ago, you received an antibody test today and the results were negative – no COVID-19 antibodies were detected. If you were to be re-exposed to the same virus, your immune system will still respond by creating antibodies, this time more swiftly than it did to your first infection. On the other hand, your friend may have had the virus two months ago, had a COVID-19 antibody test that detected antibodies, and still be susceptible to the virus. Detectable antibodies in your blood can give you a clue as to what happened in the past and what’s to come, but it cannot tell the whole story.
Whether or not you have had COVID-19 or received a vaccination, you still need to practice social distancing, hand-washing and mask-wearing. It is unclear at this point if the vaccine prevents people from becoming infected with COVID-19 or if it prevents feeling sick when infected. That means you could still transmit the virus after you’ve received your shot.