For many adults, especially those who grew up in an era when measles, chickenpox or the flu were simply “childhood illnesses,” it can feel natural to believe that getting sick is how the body builds strong immunity.
While…

For many adults, especially those who grew up in an era when measles, chickenpox or the flu were simply “childhood illnesses,” it can feel natural to believe that getting sick is how the body builds strong immunity.
While…