Warning: this article contains some spoilers for The Last of Us show and game.HBO's acclaimed series The Last of Us's cast is led by Pedro Pascal as Joel and Bella Ramsey as Ellie, the two main characters who develop a familial bond.

As they venture across the US, the Cordyceps virus. The duo's travels see them encounter various types of infected in season 1, and the first episodes of season 2 have already proven that the infected are more dangerous than ever.

The Origins Of The Last Of Us' Infection Explained

The Fungal Infection Started From Tainted Food

The origins of the Cordyceps virus vary slightly between the games and the series, but in both cases, the virus initially emerges from the fungus growing unknowingly on food. In The Last of Us game, the outbreak is explained in a news clipping as having come from crops in South America that had mold growth on them. Because the crops and their products were then sold and shipped to other locations, the Cordyceps spread rapidly. The show changes this slightly, with Joel telling Ellie that it could have come from products like bread or cereals.

What's more, the series does include a scene set in the 1960s of an expert expressing his fear over the possibility that a fungal infection of the sort could occur thanks to rising global temperatures and fungus evolving to exist in temperatures similar to that of the human body. Thus, while the Cordyceps outbreak first occurred because of mold growth on plants, the reason it was able to spread to humans is that the fungus evolved to withstand conditions within the human brain.

How The Infection Spreads From Infected To Other People & Why The Infected Really Attack

Characters Have To Avoid Being Bitten

The Last of Us's infected are terrifying, as is the process of being infected and transitioning into one of them. The primary infection method that is seen throughout both the games and the series is being bitten by one of the infected. Those whose bodies have become overrun by the Cordyceps virus are driven insane, and the fungus makes them aggressive toward living people. Upon sensing a potential human who could become an incubator for the virus, the infected will attack, hoping to transfer Cordyceps.

While spores have not been introduced yet at the start of season 2, The Last of Us' creators have hinted that this form of infection may appear later.

Because the virus is spread through bodily fluids from an infected person, beyond biting, victims can be infected from a scratch, though that has not always been true in the show so far. Likewise, the show has yet to introduce the other major source of infection from the game: spores. Spores are released from the bodies of the infected and can often be found in warm, moist areas, similar to how normal mold grows. To combat being infected by spores, the game's characters are often seen wearing gas masks.

The Different Stages & Variants Of Infected Explained

The Show Has Already Introduced Several Variants Of Infected

The Last of Us introduces several different types of infected to create fear and showcase how the Cordyceps virus takes hold of its victims. The first stage, and the most commonly seen in the game and show, is runners. Runners are people who have been more recently infected, who will violently attack any human in sight. Beyond runners, the type of infected that is seen fairly early in the HBO series is clickers. Clickers have been infected for longer and are blind due to fungal growth over their eyes, but they are able to navigate using clicking noises.

The stalkers are smarter and able to analyze their prey to attack more effectively.

After runners and clickers, Joel and Ellie also encounter a bloater in season 1 of the series. Bloaters are massive infected that are much more resistant to being killed. They are not as fast or erratic as runners, but their size makes them terrifying. At the beginning of The Last of Us season 2, the show introduces yet another kind of infected that presents a new danger to humans, which are known as stalkers. The stalkers are smarter and able to analyze their prey to attack more effectively.

The games also include each of the same types of infected as the series, but they also have two other kinds that have the potential to be introduced in the future. One of those is shamblers, which are somewhat similar to bloaters but have developed acid-filled spores that explode when they are injured. The game also includes the rat king, which is a much more rare variant that is made up of multiple different types of infected that have melded together.

How Infected Can Be Killed In The Last Of Us

There Are Multiple Methods That Can Kill An Infected

There are several ways that infected can be killed in The Last of Us. The most commonly seen way in the series is by shooting them, but characters can also kill them with other weapons like knives or bats. Additionally, a common way to kill the infected is with fire. However, some types of infecteds are more difficult to kill than others. For example, while it is possible to kill a runner with one headshot, bloaters are much more difficult to kill.

What Happens To The Body After An Infected Person Is Killed

The Fungus Can Continue To Grow

While The Last of Us makes it clear that an uninfected person cannot become infected after dying, what happens to the infected corpses after they are killed is much more sinister. Killing an infected kills the body, but it does not necessarily kill the fungus inside it or stop the fungus from growing even more. Instead, after an infected person dies, the fungus will overtake their body, spreading out to look for another host.

This is confirmed by the dead infected that Ellie and Joel encounter, which are stuck to walls or floors by the web of fungus spreading out around them. In addition to the infected being controlled by the Cordyceps long after they are killed, The Last of Us season 2 has also shown that the more advanced infected use their dead counterparts as shields to protect them from harsh weather and lull humans into a false sense of security.

The Cordyceps Network In The Last Of Us Explained

The Infected Are All Connected

One of the most interesting additions to The Last of Us that the creators, Neil Druckmann and Craig Mazin, changed in the TV series is the Cordyceps Network. In the game, there is much more focus given to the spores and how they can infect people, but Druckmann shared with Polygon that they opted against that to avoid having their characters' faces covered a lot of the time. Instead, they used the Cordyceps Network to allow the fungus to travel widely and send messages quickly.

The Cordyceps Network in The Last of Us functions very similarly to how fungus grows in real life. While people are used to seeing mushrooms as a result of the fungi's growth, like many organisms, there is actually an incredibly vast and complex root system below. This is part of the "mycorrhizal network," and it allows the fungus to connect to other plants. This system benefits the entire network by communicating information about the health of the organisms and sending necessary nutrients, which provides a real-world explanation for how the infected sense each other in The Last of Us.

How Ellie Is Immune To The Last Of Us' Infection

Her Unique Birth Has Made Her Immune

Understandably, the majority of the characters in The Last of Us are concerned about the prospect of being bitten by an infected person and turning, but Ellie is the one character who will never have this problem. She hides her condition throughout the game and show, but Ellie is the only confirmed character to have immunity. While it is initially unclear how exactly she manages to avoid being infected after sustaining a bite from an infected person, The Last of Us' season 1 finale clarifies that Ellie's mother was bitten while giving birth.

This amount of the virus remaining inside Ellie throughout her life essentially worked as a vaccine, preventing her from getting sick after being bitten.

Because Ellie's mother received a bite before being able to cut her umbilical cord, Ellie was born with a small amount of the Cordyceps virus already present in her body. This amount of the virus remaining inside Ellie throughout her life essentially worked as a vaccine, preventing her from getting sick after being bitten. Ellie keeps her immunity a secret in The Last of Us to protect herself, with the question of whether she could have been used in creating a Cordyceps cure ultimately remaining unanswered.

Source: Polygon