How is it spread?
Contrary to popular belief, the influenza virus is not commonly spread by the direct inhalation of viral particles suspended in the air. It is spread after touching a person or a surface contaminated with the virus and then touching your own mucous membranes (i.e. eyes, nose, or mouth) or being directly exposed to a person shedding the virus (i.e. being sneezed or coughed on) \citep{cdca}. A good protection for preventing infection is frequently washing your hands, not touching your face, and (you guessed it) vaccination!
What’s in a vaccine?
The influenza vaccine is made of certain molecules that are unique to the influenza virus. The vaccine does not contain a live virus and it is not possible to get the flu from the vaccine \cite{vaccine}. After a vaccination, your immune system will recognize the infection if you come into contact with the virus and fight it off before you become unwell. Since influenza viruses change from year to year, it is important to have a flu shot yearly. For best possible protection, three or four influenza strains are included in every vaccine. The 2017-2018 vaccine included protection from two influenza A strains (H1N1 and H3N2) and an influenza B strain\cite{vaccine}. Some vaccines contained an extra influenza B strain but in general, influenza A viruses cause the most severe infections. When referring to “H” and “N” in the naming of the strains, these stand for molecules found on the surface of the virus which enable the virus to recognize and invade human cells \cite{cdcb}. They are called hemagglutinin and neuraminidase. These molecules change from year to year which is the reason the flu shot also changes year on year.