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 or can reduce their population to sustainable levels. Others maintain that, whatever the merits of the idea, the human reproductive drive will prevent humankind from ever voluntarily seeking extinction. The Voluntary Human Extinction Movement was founded by Les U. Knight, a high school substitute teacher living in Portland, Oregon. After becoming involved in the environmental movement as a college student in the 1970s, Knight attributed most of the dangers faced by the planet to human overpopulation. He joined the Zero Population Growth organization, and chose to be vasectomised at age 25. He later concluded that the extinction of humanity would