Pandemic smallpox was responsible for 300–500 million deaths. As recently as the early 1950s, an estimated 50 million cases of smallpox occurred in the world each year. After successful vaccination campaigns throughout the 19th and 20th centuries, the WHO certified the eradication of smallpox in December 1979. To this day, smallpox is the only human infectious disease to have been completely eradicated, and one of two infectious viruses ever to be eradicated. Historically, measles was prevalent throughout the world, as it is highly contagious. According to the U.S. National Immunization Program, 90% of people were infected with measles by age 15.
Voluntary Human Extinction Movement has, however, primarily been spread through coverage by media outlets, rather than events and its newsletter. VHEMT sells buttons and T-shirts, as well as bumper stickers that read "Thank you for not breeding". Knight argues that the human population is far greater than the Earth can handle, and that the best thing for Earth's biosphere is for humans to voluntarily cease reproducing. He says that humans are "incompatible with the biosphere" and that human existence is causing environmental damage which will eventually bring about the extinction of humans (as well as other organisms). According to Knight, the vast majority of