How Long Are You Immune After Coronavirus? Studies Say It Might Be Longer Than We Thought
Since the COVID-19 pandemic began, people have been wondering the same thing: Am I immune to the virus after I am infected? And if enough people are exposed and develop antibodies, is that enough to slow or stop spread?
At first, answers to those questions were discouraging. Some sources have said that we only have immunity for a short time after infection, which isn’t enough to change the spread pattern of the pandemic.
As the body of research and knowledge around COVID-19 builds, new developments offer different perspectives. Two recent studies show that coronavirus antibodies may stick with us longer than we thought.
In one study, newly infected individuals’ antibodies were measured at the time of infection and periodically thereafter. Researchers showed that antibody titers had little to no decrease after 75 days.
In another study, patients’ antibodies were again measured at the first signs of illness and periodically thereafter. This study showed that antibodies were present for at least three months after the first symptom onset.
This differs from a study from the summer, which measured a steep drop in antibody levels after 2 ½ months.
This shows that the spread of the virus could potentially slow down if enough people are infected. The possibility of herd immunity, which is a situation where enough people are exposed and immune to slow or stop spread, is still uncertain, but longer-living antibodies than we previously thought is a good sign. The longer antibodies are in your system protecting you, the more the spread can slow.
Accuracy of antibody testing
Antibody testing isn’t perfect. Some experts say that the peak antibody response falls between 10-21 days after exposure, which would mean that testing too soon will miss antibodies that might develop, and testing too long after might skew results, also.
However, the tests for these studies occurred in a controlled setting, which may help with accuracy.
If I have antibodies, am I immune to COVID-19?
Positive antibody tests do not necessarily mean you’re immune to COVID-19.
You could have inactive antibodies – antibodies that do not fight infection. Or, you could have been exposed months prior, and your antibodies are at the end of their functional life. If that’s the case, a positive antibody test could make you underestimate your risk and become lax with guidelines.
A positive antibody test means you were exposed at some point. It’s probably not a good idea to change your precautionary behaviors because you have antibodies.
Can an antibody test tell me when I was exposed?
If you were exposed to the novel coronavirus and had no symptoms, or you had mild symptoms that could be mistaken for something else (like a bad headache), there’s no real way to tell when you were infected with COVID-19. A test will tell you whether antibodies are present or not, but they cannot tell you how long they’ve been in your system.
If you had definite symptoms or a medical diagnosis, you might have a better idea of how long ago you were infected. Still, symptoms might not appear immediately after infection. Typically, symptoms show up within 5 days, but realistically a couple of weeks could pass before you experience the first signs of infection.
Unless you are testing every day with timestamped results, you don’t know when you’ve been infected, so you cannot know how long you have had antibodies.
If you’ve tested for antibodies, there is no way to estimate the age of your antibodies on a test alone. Even if you feel sure, you don’t know whether your antibodies are capable of fighting off a new exposure.