No, the COVID-19 vaccine will not cause you to have a positive viral test.

Many people have been concerned that COVID-19 vaccines themselves can cause someone to get COVID-19 and/or will cause someone to test positive on a viral test. The first issue we addressed in a previous post in February: you cannot catch the virus from the vaccine. 

So what does it mean if someone does test positive after being vaccinated? That they must have been infected w/ COVID-19 prior to or just after being vaccinated. It’s possible (no vaccine is 100% effective at blocking infection) but the good news is that all of the vaccines currently authorized do exceptionally well at preventing severe disease requiring hospitalization.

Additionally, none of the vaccines currently authorized nor those still in trials can cause someone to test positive on a test such as the viral polymerase chain reaction (PCR) test, which looks for active infection by searching for pieces of viral genetic material. However, the vaccine may contribute to a positive result on an antibody test which normally looks for a previous infection. A positive result on this type of test after being fully vaccinated can indicate that your body has had an immune response to the vaccine (a good thing!), not that you have an active infection. 

It’s important to know that a negative result on an antibody test does not necessarily mean that the vaccine didn’t work or that a person has not had an immune response to the vaccine. In fact, antibody testing following vaccine administration is not currently recommended. We are still learning that protection from COVID-19 involves more than just antibodies. 

Last update: April 6, 2021 11:30am ET

Science review: JAB