Can smallpox return from 500-year-old virus fragments?

Smallpox is the only human infectious disease to have been eradicated worldwide. Researchers have now recovered fragments of ancient DNA belonging to variola virus, the virus that causes smallpox, from the naturally mummified remains of two Indigenous people buried in northern Chile.

For centuries, smallpox caused devastating epidemics. Its severe form, variola major, killed around 30% of those infected, although the rate varied between outbreaks and populations.

The first documented outbreak in the Americas occurred on the island of Hispaniola in 1518. During the 16th century, successive epidemics became a major contributor to the catastrophic loss of Indigenous life, amid the wider violence and disruption of European colonisation.

In 1967, the World Health Organization (WHO) launched an intensified eradication programme, combining vaccination with surveillance and containment. The last-known naturally acquired case occurred in Somalia in 1977, and the WHO declared smallpox eradicated in 1980.

Live variola virus is officially retained at two high-security WHO-designated laboratories for approved research. The material found in Chile consists only of damaged genetic fragments preserved for centuries.

These remains date from approximately 1492 to 1631, spanning the transition from Inca rule to the Spanish colonial period. They are the first ancient smallpox genomes recovered...

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