It's Worth a Flu Shot

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The first effective flu vaccines were tested in clinical trials in the mid-1930s after a group of scientists were able to recreate the virus in hen eggs. The vaccine was developed after a group of English scientists discovered that influenza was caused by a virus and not bacteria as was originally believed. 

The race to create an effective vaccine was spurred by the devastation wrought by the Great Influenza pandemic of 1918 (also known as the Spanish flu), which killed an estimated 50 million people worldwide. Before World War II, the United States government funded a wartime program to develop vaccines as the flu accounted for roughly half of US military casualties during World War I. As a result, the first inactivated flu vaccine was developed at the University of Michigan in 1945 and was tested on United States soldiers. 

To this day, most flu vaccines are made using egg-based technology similar to the one created in the vaccine’s early days.