Experts also think another deadly virus helped to kill millions of people, which was what? Polio Smallpox Anthrax Botulism

The answer is **Smallpox**.<br /><br />Historical evidence suggests that smallpox, alongside the bubonic plague (often referred to as the Black Death), contributed significantly to the massive death tolls during periods of widespread plague. While the bubonic plague was the primary killer, smallpox outbreaks were common and often exacerbated the devastation. People weakened by the plague were more susceptible to smallpox, and vice-versa.<br />