Thanks to advances in vaccine medicine, we live in a world where our immune systems can be taught to fight off a disease before we fall ill. As adults age, however, their immune systems begin to weaken, limiting the response to infectious bacteria and viruses in their bodies.

Influenza, better known as the flu, is a highly contagious virus that attacks the respiratory system. The virus is passed from person to person though respiratory droplets emitted when an infected person talks, sneezes, or coughs. People find themselves at risk for contracting the flu when inhaling the infected droplets or touching their eyes, mouth or nose after touching something that has been infected.