Photo by Jean Roy, CDC
Following a WHO-led immunization campaign that spanned the globe, smallpox was declared eradicated 30 years ago, in 1980. A symposium in Rio de Janeiro was organized to focus on the lessons from smallpox eradication, considered one of the greatest achievements in modern medicine.
The acute, contagious disease killed up to 30 percent of those who were infected. The virus was transmitted through droplets projected during sneezing and coughing by symptomatic people. Its symptoms include a dense rash that turned into lifelong scars.
Smallpox had plagued humanity for at least 3,000 years. Although it no longer occurs naturally, a stockpile of the vaccine is still kept in two very secure laboratories.