January 14, 2025 • The COVID19 mRNA vaccine generates enough of an antibody response to protect against severe disease for six months. But other vaccines offer yearslong — even lifelong — immunity, such as the measles or yellow fever vaccines. Is there a way for scientists to tell how long a person's immunity will last? A team at Stanford Medicine might have found a way to do just that — with the help of some of the cells found in our bone marrow.