Why get the flu shot?

herd immunity

Photo credit: http://www.vaccines.gov

Imagine that you’re at the mall and you see someone you don’t like – maybe an ex or that annoying kid from high school – but the mall is crowded that day and you can easily blend into the crowd and escape. Now imagine that the mall isn’t crowded. This unsavory person sees you and walks over. Because there aren’t a lot of people around for you to hide among, now you have to talk to someone you’d really rather avoid. In the case of infectious diseases, what actually happens is your body becomes the feeding ground of an organism whose numbers have been so long controlled by preventative medicine that they have all but faded from cultural memory.

Vaccination programs work on the principle of herd immunity; that is, once a certain percentage of people have been vaccinated, then the disease can’t continue in the population because it doesn’t have enough chances to spread to new people and thus the whole “herd” is effectively immune. The flu has a herd-immunity threshold of over 60%, which means that in order to minimize the effects of flu season, more than half of us┬áneed to get vaccinated.

Also, if you get the flu shot, then you probably won’t get the flu.


The equation for calculating how many people need to be vaccinated, for those who are interested.