As researchers estimate that nearly all Americans have been exposed to SARS-CoV-2, the virus that causes COVID-19, whether through infection or vaccination, we are no longer "immunologically naive"—in other words, our immune systems are familiar with certain variants of SARS-CoV-2. This familiarity can pose a problem for vaccine development. In immunology, the phenomenon of "original antigenic sin" or OAS is a colloquial term for the body's first encounter with a virus, which can forever "bias"

Tag-uri: Coronavirus