BBC Science Focus

CAN I GET THE CORONAVIRU­S TWICE?

JR

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There have been a few stories of people apparently being re-infected by the coronaviru­s SARS-CoV-2. These people reportedly became infected and hospitalis­ed, and then were sent home once they’d tested negative for the virus. Then, days or weeks later, they tested positive again. But this doesn’t necessaril­y mean that they caught the coronaviru­s twice.

First, during recovery from infection, a person may have such low amounts of the virus in their body that our tests can’t accurately detect it. However, their body may still be fighting the virus, and a resurgence of the virus (and symptoms) can occur, resulting in a positive test. In this case, it would just be one protracted infection, not a re-infection.

Second, we know that in most people, the SARS-CoV-2 virus generates a strong immune response. With the related coronaviru­s SARS-CoV, this response creates an immune memory of the virus that prevents reinfectio­n for one to two years, and it’s likely that this is also the case for the new virus. SARS-CoV-2 also has a fairly low mutation rate, which means that it (hopefully) won’t change enough that our immune system no longer remembers it (this is what the flu virus does and why we need a new jab every year).

If this all turns out to be true, then it would suggest that re-infections are unlikely. However, SARS-CoV-2 is so new that we won’t know for sure until we’ve found out just how protective our immune response to the virus is, and how long it lasts.

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