While The Walking Dead is very clear about the direct threat caused by its zombies (aka Walkers), there’s an underlying danger to the franchise’s specific zombie plague that isn’t addressed by the series’ flash-forward conclusion. In fact, the issue remains such a problem by the comic series’ ending, it basically guarantees humanity will once again be overrun by zombies.

Walking Dead‘s zombie can kill with a single bite, but the franchise makes it very clear that every human is already infected with whatever causes them to rise again. A zombie bite does not directly turn a victim into a walker. Rather, a zombie bite will kill a person, and once the person is dead, they rise again, ready to bite and turn the humans around them. This is proved throughout the series, right up until the penultimate issue 192, when Rick himself is shot and subsequently turns, surprising Carl when he comes home to see his father. However, in the next issue’s flash-forward to the future, the obvious implications of this fact remain unaddressed.

When a grown Carl Grimes cuts down a stray zombie in Robert Kirkman and Charlie Adlard’s The Walking Dead #193, he immediately checks to see if it has bitten someone else. His obvious concern is that if it has bitten another person, they need to be tracked down before they can turn others and create a group of zombies too large to be dealt with easily. As he would surely understand, a failure to do so would lead to another zombie outbreak, just when the world is recovering from ‘the Trials,’ as the prior chaos is now known. The zombie is an outlier in a society which has now established a huge safe zone which is reliably protected from the remaining dead, and yet this new civilization has a problem right at its heart.

Even with its ending, The Walking Dead doesn’t explain how people cope with the fact that if someone dies in their sleep, they’ll instantly become a zombie and attack society from within the safe zone – now populated by many people who didn’t live through the first outbreak and have no experience in staying alive. A person suffering from an illness who dies at home while their family are asleep could create a mini-outbreak that suddenly snowballs into a new outbreak, and likewise any kind of fatal accident could immediately create a zombie. Even the paranoid Carl shares a tent with a fellow survivor while out on errands.

There’s no perfect way to avoid people dying and becoming a threat, but for a story that digs deep into the practical and psychological measures survivors adopt during a zombie apocalypse, it’s strange that the comics never address how people deal with the possibility of random death (for example, by making all doors self-locking or having people sleep in separate rooms to prevent unexpected zombies wandering free), which is a certainty over a long enough time frame. Carl Grimes seems to recognize the complacency creeping into the world and suggests that it be checked before it’s too late, but even he ignores society’s biggest internal threat. Sooner or later, someone will die unexpectedly in their own home, at which point the horrors of The Walking Dead are likely to be repeated.