The deadliest viruses in human history, from COVID to smallpox
HIV particles, in red and yellow, are budding from an infected cell in a electron micrograph. NIAID/NIH Over the first two years of the COVID-19 pandemic, the coronavirus directly or indirectly killed about 15 million people worldwide, according to estimates from the World Health Organization. In the United States, more people died in 2020 and 2021 than during the 1918 influenza pandemic, which was widely called the most deadly in recorded history. The word “deadly” certainly applies to the virus that causes COVID-19. And yet, epidemiologists hesitate to give SARS-CoV-2 the superlative of deadliest virus in human history. To them, the raw number of mortalities caused by a given virus doesn’t always paint the full picture of a pathogen’s danger—especially when comparing viral outbreaks across time. Raw mortality numbers have to be taken...