The adage that “the older you are, the wiser you get” doesn’t always apply to our immune systems. Despite being exposed to a lifetime’s worth of illnesses, immune systems in the elderly are worse at fighting stealthy, shape-shifting viruses like the flu.

Why aging decreases our immune system’s abilities has been a mystery to researchers. But a new study published in Cell Host & Microbe finds that our infection-battling B-cells become blunted with age, making us less equipped to fight