A weaponized smallpox virus could have a devastating effect on the world’s major cities, infecting thousands because of the growing numbers of people with suppressed immunity, researchers have warned.

Smallpox, which was eradicated globally in 1980, is classed by the United States government as a category A bioterrorism agent because of its potential to spread rapidly, infect swathes of the population and incite widespread fear and panic.

Researchers at the University of South Wales have used a mathematical model to predict how many people would become infected and how many would die in bioterrorism attacks on New York and Sydney. READ MORE