Flu shots given in the arm are good at preventing severe illness and much less reliable at stopping the virus from taking hold in the nose and lungs in the first place. New research points to an unexpected reason and a possible way around it.
Scientists at the University of Rochester have identified a population of immune cells in the lung that persists for more than four months after influenza infection, when the textbook says those cells should be gone within days. The cells are monocytes, part of the innate immune system, and the study finds they do not simply linger. Deleting them selectively reduced the formation of the lung's frontline memory T cells and compromised protection against a second, different strain of flu.
