On this day 40 years ago, smallpox was made history. It's the only human disease to be eradicated so far. A lesson we must take is: when the world unites behind science and public health measures we can defeat diseases and protect lives and livelihoods. | World Health Organization (WHO)

Eradication of smallpox has not eliminated the risk of accidental or intentional reintroduction of the variola virus, and although smallpox vaccination was highly successful, traditional vaccines had toxic effects that could be severe. New research findings are summarized in a short video. See all Quick Take videos: http://nej.md/quick-take | The New England Journal of Medicine