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March 18, 2025 11 mins

The widespread infection of roughly four million virtual characters all started with a giant snake demon. In 2005, the massively multiplayer online video game World Of Warcraft introduced a special event raid, where groups of players could team up to fight a giant snake demon named Hakkar the Soulflayer. Hakkar would cast a spell called “Corrupted Blood” on players, which would slowly whittle down their health.

The effect of the spell was only supposed to last inside the raid arena—when players returned to the main world of the game, the spell would dissipate. But thanks to a software glitch, that wasn’t the case if the player had a pet companion. When the pets returned to the main world, they started infecting players and non-playable characters with the Corrupted Blood spell. If the player wasn’t powerful enough to heal themselves, they would die and erupt in a fountain of blood before turning into a skeleton.

What followed was a virtual pandemic that startlingly resembled today’s COVID-19 pandemic, from the spread, human behavior, and cultural response. Blizzard, the developer of the game, wanted players to social distance. Some players listened, but others flouted the rules, traveling freely and spreading the disease with them. Conspiracy theories formed about how the virus was engineered by Blizzard on purpose, and others placed blame on players with pets as the cause of the outbreak, mirroring the racist anti-Asian attacks and rhetoric surrounding COVID-19 today. 

Coincidentally, two epidemiologists, Nina Fefferman and Eric Lofgren, were there to witness the World Of Warcraft outbreak unfold. They studied and used the incident to model human behavior in response to a pandemic. Their findings were published in The Lancet in 2007. Many of their observations came to pass in 2020 when COVID-19 appeared. 

Today, we're revisiting a 2021 conversation that SciFri producer Dee Peterschmidt had with Eric Molinsky, host of the podcast Imaginary Worlds, who reported this story for his show. He talks about the epidemiologists who studied the outbreak and how it prepared them for the public responses to COVID-19.

Universe of Art is hosted and produced by Dee Peterschmidt, who also wrote the music. Our show art is illustrated by Abelle Hayford. And support for Science Friday’s science and arts coverage comes from the Alfred P. Sloan Foundation.

Do you have science-inspired art you’d like to share with us for a future episode? Send us an email or a voice memo touniverse@sciencefriday.com.

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