The “Corrupted Blood incident”, as it was also called, has surprisingly important real-life lessons for dealing with pandemics.

In 2005, millions of people woke to a dystopic scenario. At first, no one really understood what was happening — but then the blood started gushing. Gouts of blood would start flowing from, first from one person, and then from almost everybody.

Trapped in the jaws of a raging pandemic, with no real refuge in sight, people panicked. The disease was merciless: once infected, everyone suffered. Weaker individuals were instantly killed, and those who could handle the disease abandoned the infected areas, leaving behind piles of corpses and biowaste. It was a full-blown disaster.

You’ve never heard about it because this wasn’t a real-life plague. It was a ‘disease’ that affected World of Warcraft characters, spreading to millions of characters. But while this may be a gaming pandemic, researchers believe there are important real-life lessons to learn from it.

Corrupted blood

Hakkar the Soulflayer was introduced as a raid boss in World of Warcraft (WoW) in September 13, 2005. Hakkar was a Blood God, a sort of uber-vampire.

As any self-respecting raid boss, Hakkar was also hard to defeat. Max-level characters would party up, go through the gauntlet, and then challenge him. Without careful planning and powerful spells and items, they would almost certainly fail. But, as it always happens, strong parties would outpower him. As Hakkar would feel that he is starting to lose, he would use his last trump card: a strong lifesteal spell.

To combat this last-resort attack, players would intentionally poison themselves — then, as Hakkar would siphon their blood, he would essentially poison himself. Job done, the boss was defeated, parties took their loot and life carried on as normal on the WoW servers.

Until someone (Patient Zero) de-summoned his pet while the poison effect was still active. Without suspecting a thing, Patient Zero went about his business in the WoW world. But later on, when they re-summoned their pet, it was still infected with Hakkar’s plague — and it started spreading like wildfire.

“Every time you’d summon that pet you’d reinfect yourself and all the players around you and it wouldn’t check if you were in a raid so you’d do it while you were in town and the entire town would get corrupted,” says Shane Dabiri, Blizzard’s then chief of staff.

“It was all unintentional, it was just a bug,” Dabiri says.

Weaker characters were killed, resurrected, and then killed again after a few seconds. Entire cities were contaminated, and only strong characters could survive — and most abandoned towns entirely, leaving behind piles and piles of infected character corpses.

The corrupted blood effect was only meant to be active in Hakkar’s realm, but due to a coding bug, it was able to spread, making the World of Warcraft servers unexpectedly mirrored a real-life epidemic.

Containment measures

Players panicked. They weren’t sure if the disease was intentional or not, and many couldn’t do anything in the game. Their characters were doomed.

Blizzard staff weren’t entirely sure what to do either. They knew it wasn’t intentional, but how do you contain the problem? The company attempted to institute a voluntary quarantine to stem the disease, but this failed spectacularly. Not only did players not respect the quarantine, but some actually used the pandemonium to wreak havoc, intentionally spreading it.

It was surprisingly similar to a real outbreak. It originated in a remote region, and both characters and animals were spreading it (just like some types of flu). It was spread by close contact, it affected urban areas the most, and some individuals were asymptomatic and virtually immune (the strongest characters). It bore all the hallmarks of a true epidemic, with one scary feature: it couldn’t be stopped.

After more than a week of desperately trying to contain the disease, Blizzard gave up. It seemed impossible, so they just pulled the plug — they purged the server with a hard reset from before the disease was spread, fixed the bug, and that was that.

But in real life, we don’t have a hard reset option.

Real-life lessons

Aside from terrorizing WoW players and making for a really cool anecdote, this story also has important lessons. At the Games For Health conference in Baltimore, in 2008, epidemiologist Nina H. Fefferman, Ph.D of Tufts University and Rutgers University spoke on the difficulties in modeling disease origins and control. Individual behavior, she explained, is rarely incorporated into disease models.

Massive Multiplayer Online games (such as WoW) could solve some of these problems inherent with more traditional models, joking that she was going to use gamers as ‘guinea pigs.’ Subsequently, she co-authored a paper in Lancet Infectious Disease discussing the epidemiological and disease modeling implications of the outbreak, mentioning that this is an exciting new step and a potentially new arena of studying outbreaks in the virtual world.

“By using these games as an untapped experimental framework, we may be able to gain deeper insight into the incredible complexity of infectious disease epidemiology in social groups,” the paper read.

She wasn’t the only one with this idea. Ran D. Balicer, an epidemiologist physician at the Ben-Gurion University of the Negev in Beersheba, Israel, published an article in the journal Epidemiology. He described the similarities between the WoW pandemic and real-life outbreaks such as avian influenza and SARS — which was also caused by a coronavirus, like the current Covid-19 outbreak. The event, he argues, is unique — and very useful in understanding the complex dynamics of a pandemic.

“The pandemic plague that resulted is unique. Unlike previous “virtual plagues” that had been officially planned, this was a local effect that went out of control—a naturally occurring virtual outbreak,” the study read.

Fefferman and Balicer both suggested collaborations between game companies and researchers to study such events.

“Expert modelers of infectious diseases might consider collaborating with the game’s administrators,” Balicer wrote. “Such collaborations could harness the immense computational power invested in these economically-driven, large-scale virtual environments, while allowing simulations more wide-ranging than any options currently available.”

But Blizzard, the company behind WoW, was reticent. When the CDC contacted Blizzard and requested statistics on this event for research on epidemics, it was told that this was all a glitch and no useful data was available. Even when Blizzard designed an intentional pandemic in 2008, medical researchers were not included, and a valuable research opportunity was lost.

But several important lessons can be drawn nonetheless.

WoW vs Covid-19

What made the World of Warcraft pandemic truly devastating was that there was no way to build immunity to it. Characters suffered and could then be reinfected immediately after convalescence.

In the case of influenza, for instance, after you get a strain, your body builds at least some immunity to it. You may get a different strain, or you may get the same strain after a while, but you have at least some degree of natural protection. If there would be no immunity to it at all, we’d just pass it between ourselves again and again, and it would be incredibly difficult to contain.

In the case of Covid-19, it’s not exactly clear how likely reinfection is. Some startling reports in China suggest a reinfection rate of over 10%, but it’s still too early to tell. For any disease, however, the reinfection rate is extremely important.

Secondly, like in WoW, urban areas tend to pose a very high risk for pandemics. Unfortunately, Covid-19 emerged in Wuhan — a large metropolis with over 11 million inhabitants. This meant that the initial containment was impossible, and the disease spread rapidly. Continuous cycles of infection (between pets and humans or purely human groups) are, thankfully, not reported with the current outbreak.

Aside from the initial outbreak, the disease has reached dozens of countries already. But the outbreak will truly surge if the disease starts to spread to urban areas.

Lastly, teleportation was a major problem (in WoW). Characters would spread the disease far and wide, making the outbreak hard to track and contain. We don’t have teleportation in the real world (yet), but we have something very similar: flying. Researchers modeling the coronavirus outbreak have highlighted that flight patterns are one of the most important parameters for understanding where the disease might strike next.

Unfortunately, we don’t have an all-powerful spell to go back and erase the virus. We have to rough our way through it.