Our Last Cordyceps Zombie Virus and Stages Explained
The Cordyceps infestation in The Last of Us brings a terrifying new twist to zombies, and it has several terrifying stages that require some explaining.

Making the leap from video games to TV, The Last of Us features a nightmarish Cordyceps infection that turns its hosts into zombies through several gruesome stages. Unlike classic depictions of the undead, the infected in The Last of Us aren't looking for brains, but malevolent and bestial creatures that see all uninfected as dangerous threats. From almost human to completely unrecognizable beasts, Cordyceps has many more stages than the weary old zombie virus of yesteryear.
The various stages of Cordyceps represent the complete loss of humanity within the host, with each new iteration bringing dangers not apparent from the previous stage. As with any zombie-like creature, infection is a big problem, and infected cordyceps are even more dangerous because they can spread the infection through spores and bites. Even though HBO's The Last of Us show changed the in-game storyline, the different stages of the Infected still appear in the episodes as viewers get a chance to see how Cordyceps works.
What Is Cordyceps?

The most important difference between The Last of Us' iconic infection and the zombies in shows like The Walking What died was that Cordyceps is not a virus at all. Instead, the infection is caused by a fungus that inhabits the host, eventually taking over the brain and dehumanizing the host. The infection continues to spread throughout the host, which in effect creates stages in the life cycle of the infected person. Instead of reanimated corpses like the zombies in The Walking Dead, the infected are actually hosts where the fungal infection ravages.
This distinction actually makes them more dangerous, as the destruction of the body does not necessarily mean the end of the infected creature itself. Since Cordyceps is a fungus, it reproduces via spores and can infect humans without the zombie needing to bite or directly attack its prey. Furthermore, when infected hosts are neutralized, the fungi in them can continue to grow and infect long after their original host has been killed. This makes the infection harder to detect, and it is only a matter of days before the unfortunate soul starts showing symptoms and begins the first stage.
Runner

Like something ripped straight from an unmade George Romero zombie movie, Runners maybe The most well-known phase of all the phases of The Last of Us infected groups. The runners, who still maintain a human appearance, are named for their speed and unpredictable motivation. Due to the recent infection, the fungus has not yet fully taken over their brains, leaving them with only the most animalistic attack and flight instincts left. Runners aren't particularly dangerous individually, but they tend to form large groups and can be extremely deadly when packed together. Runners are a common enemy in the game, and they're certainly a regular in the series.
Stalker

The HBO version of The Last of Us avoids adaptation issues by focusing on horror, and few things in the game are more terrifying than the many stages of the Infected. Weeks after infection, the stalker mutates into a second stage, becoming a dangerous stalker. On stalkers, the fungal infection becomes more pronounced, and the infected even begin to grow fungi outside their bodies, giving them additional senses. Unlike runners, who attack with impunity, stalkers literally stalk their prey, and their attacks are more The strenuous movements of the infected in the first stage.
Clicker

While zombies are a cliché, The Last of Us managed to create an iconic creature that represented the horror of the entire series, and the HBO show got hits. Clickers are Infected who have survived for a year or more and have lost most of their humanity from the previous two stages. As the hideous fungal growth completely covers their faces, the clickers develop an echolocation ability that allows them to perceive their surroundings while being completely blind. The origin of their name is the tingling sound, an early warning of their coming.
Clickers are much stronger than Runners or Stalkers due to fungal growth, and their attacks are more dynamic than their predecessors. In addition to their attacking abilities, the clickers' fungal growth provides protection, allowing them to withstand brutal assaults without flinching or incapacitating. Despite further infestation, clickers are a very smart enemy that cannot be easily dodged and will constantly seek out enemies once spotted. , a chilling highlight of the series, HBO's adaptation of The Last of Us surprised clickers It looks scarier than in the game.
Bloater

In the world of The Last of Us, the fourth and final stage of the Infected's evolution is represented by the massive and imposing Bloat. Bloating is a natural progression of clickers after years of being infected and has grown to become covered in the fungal growth that makes stage three such a deadly enemy. Bloaters are huge, lumbering creatures that move slowly. However, they are virtually impervious to attack, and their superhuman strength allows them to tear apart unsuspecting victims with their own hands. Even fire weapons that are useful for other stages are useless when inflated.
HBO's Last of Us trailer reveals a major change in the life cycle of the Infected in the series, but in terms of established lore, the Bloat is the dangerous pinnacle of the Infected. In addition to their unfathomable strength, bloatworms are capable of producing poisonous growths that can be hurled at uninfected individuals as an additional ranged weapon. Due to their rarity and overwhelming danger, bloats are unlikely to appear very often in The Last of Us series, but they're certainly just as scary on the show as they are in the game.
Season 1 of The Last of Us premieres January 15 on HBO.