Beginning in early March, there have been cases reported in which a patient who had recovered from COVID-19 later tested positive for the disease. This raised the important question of whether a person can get re-infected after recovering from the illness. But before we answer that question, let’s quickly learn about the science here.
When a person becomes infected by a virus, the body creates antibodies against the infection. These antibodies help fight off the original infection, and are ready to fight off the infection if the body is exposed to it a second time. In fact, this is the basis for vaccines. By exposing a healthy person to a small amount of virus, the healthy person can develop the protective antibodies without getting the full blown illness.
Unfortunately, not all viruses can be vaccinated against easily. For instance, each year there are different strains of the flu. Although scientists do their best to predict which ones are most likely to cause yearly flu outbreaks, they are not always right, which is why the flu vaccine is never 100% effective. In the case of COVID-19, we do not know enough about the virus to know how significantly it may change over time, nor do we know if the antibodies that our body generates are protective against future infections.
At this time, virology experts tend to agree that COVID-19 ‘reinfection’ reports probably are not true re-infection. A more likely explanation is that people who recovered from COVID-19 never actually got rid of the virus in the first place. Imagine one of these cases had a positive COVID-19 test in early March, but then recovered from illness and had a negative test in late March. If a test in early April showed the virus once again, one explanation is that the person got a new infection. But a more likely explanation is that the test in late March was a false negative, and simply did not detect the fact that the person still had the virus in his/her body. Yet another possibility is that the positive test in early April does not represent true “infection”, but rather shows remnants of the virus that are no longer active, cannot cause symptoms, and cannot infect other people.
Regardless of the explanation, re-infection does not seem to be a primary concern at this time. We hope this remains the case, as re-infection could pose a big challenge to developing a vaccine for COVID-19 that is protective against future infections.