Studies reveal key clues about COVID-19 immunity, immune recall

How does the immune system remember and recognize viral invaders it has encountered in the past? A trio of newly published studies of people infected with SARS-CoV-2, vaccinated against the virus, or both are providing tantalizing new clues about the factors that influence the speed and magnitude of the immune system's response to subsequent infection with variants of SARS-CoV-2.
How does the immune system remember and recognize viral invaders it has encountered in the past? A trio of newly published studies of people infected with SARS-CoV-2, vaccinated against the virus, or both are providing tantalizing new clues about the factors that influence the speed and magnitude of the immune system’s response to subsequent infection with variants of SARS-CoV-2.