This pin is based off the public health anti-spitting posters that were posted on lamp posts and streetcars during the 1918 H1N1 influenza pandemic.
"The 1918 influenza pandemic was the most severe pandemic in recent history. It was caused by an H1N1 virus with genes of avian origin. It is estimated that about 500 million people or one-third of the world’s population became infected with this virus. The number of deaths was estimated to be at least 50 million worldwide with about 675,000 occurring in the United States." (CDC)
