A programming oversight allowed the Wow gold classic debuff to disperse beyond the website of the Hakkar boss fight and into the world at large. Hunter characters may summon and discount pets to fight in their side at will. Once dismissed, all of the consequences on the pets are paused until it's known as back out again. In consequence, the pets could contract Corrupted Blood through the boss fight, vanish and then display the symptoms elsewhere in the world map when they were summoned. There it would spread to other pets and players which came in contact with them.

Cities like the dwarven city Ironforge and orc town Orgrimmar were overrun in hours. Non-playable characters, who could not die as a result of particular coding, could also catch the effect, meaning any player that passed by them could get Corrupted Blood.

Once word got out, players searched frantically for news about what was happening.

"The entire world chat would burst any time a town dropped," says Nadia Heller, an ex-World of Warcraft player whose persona lived through the incident. "We kept a close eye not only on our guild conversation but on world chat as well to determine where not to proceed. We didn't need to grab it."

The spread of Corrupted Blood, and the player's behavioral changes to this, caught the interest of epidemiologist Dr. Nina Fefferman, who was a World of Warcraft player at the time of this episode. Fefferman reached out to her colleague Dr. Eric Lofgren. In 2007, the two published a paper that detailed their findings, such as complex models of individual behaviour in a pandemic. Fefferman says the episode has helped inform her current research into predictive modeling about covid-19.

"What I do is study all the elements of infectious disease outbreaks which help us prepare for pandemics," explained Fefferman, a mathematical biologist. "We really saw the full gamut of behaviors we find in the actual world reflected in the player characters during Corrupted Blood."

Dr. Dmitri Williams, an associate professor from USC who was also playing World of Warcraft during the Corrupted Blood incident, questions if Fefferman's findings are valid mirrors to real-life behaviour.

"There are matches in which you're encouraged to behave in a way which you would never behave offline," Williams said. "You must know [the sport ], play it and understand the culture so you may make these types of determinations that, yeah, this is a pretty good proxy."

Despite this, Fefferman believes that virtual worlds like World of Warcraft are ideal testing environments for cheap classic gold bulk behavioral responses to outbreaks. "It is not just that people were role-playing. People were themselves," Fefferman said.