Flu

Police in Seattle, Washington, wear masks to protect themselves during the 1918 flu pandemic that killed nearly 50 million people. (National Archives/Time Life/Getty)

The ghosts of influenza past Your immune system’s response to flu is shaped by its very first exposure to influenza in childhood: the more similar a circulating virus is to that first-experienced strain, the stronger your natural defences against it. Understanding how this immunologic ‘imprinting’ works could help to improve our relatively ineffective vaccines against flu. Nature | 11 min read See also: Nature editorial: “Signs of hope emerge against influenza”