11th September 2015. Also known as the day the world fell apart. The origin of the virus is currently unknown to anyone outside the scientific field, all we know is the name.

Virus Z.

The deadly airborne parasite travelled quickly across the world, infecting anyone who wasn't strong enough to withstand it.

The neocortex and limbic systems were damaged in the brain, affecting hunger, intelligence, memory and rationality, leaving only the Reptilian complex, the part of the brain responsible for instincts. This is why those infected have only the knowledge required for survival and show no emotion, creating dangerous creatures with no memory of their past life and only one goal in their minds- to feed.

All we know is that the virus was released eighteen years ago across the planet, but there were no machines that could to detect it and no symptoms were being shown by those who were infected. Anyone born after this event had a natural immunity to the virus.

The fact that the horror struck on the fourteenth anniversary of 9/11 aroused suspicion from remaining members of various governments, but these accusations were quickly forgotten as the virus travelled to every corner of the earth and infected everyone without an immunity.

The symptoms were shown too late, there wasn't enough time for doctors and scientists to create a cure or conduct enough experiments to determine the cause. People in their fifties and onwards were the first to change, soon followed by the younger adults. Teenagers and children panicked, certain that they'd be the next to change, unaware of their immunity. When they realised that the disease had no effect on them, most went out in search of other people, no idea of the danger that lay ahead of them. Those left untouched have to learn how to survive among these creatures, desperate to try and outlive them. They have to fight for survival in a world controlled by hunger, scavenging for supplies anywhere they can get them.

I am one of those people. My name is Hazel Brooke and somehow I've managed to survive this far, along with my small group of four. Their names are Harry Rose, Lucy Green, Malik Singh, and William Dailey. Harry is fifteen, Lucy fourteen, Malik sixteen, William seventeen and I'm sixteen. Between us we elected roles for ourselves in the group, to make us feel safer and more organised. Malik is the 'medic', as his aim was to graduate university and become a doctor. Lucy decides where we go and through which route, Harry and me are the best fighters, and William makes all the tactical decisions to make sure we stay alive.

It's been almost a year since everything starting, and somehow we've managed to survive, moving from building to building and collecting anything useful that we can find. William, Harry and I each carry a kitchen knife, I carry a compound bow that I got from eBay and Harry has a small axe he found in a garden shed when we were scavenging for supplies.

Unlike what you'd expect, we have no plan for the future. All we have left is the hope that one day it'll be over and that we'll find somewhere safe where they can't get us- where we can be happy again.

When I first saw one of the infected I was in a Physics lesson. It threw itself at the window, growling at everyone inside, too weak to break it. Instead, it was just pressed up against it, covering the glass in blood and pus. No one knew what to do, some even started laughing and mocking it, assuming that it was someone who'd got into a fight while drunk.

The teacher went outside to tell him to go away and offered to call him an ambulance, but he never got the chance. His intestines were ripped out of his body before he had a chance to run. That's when it started getting serious. Everyone started screaming like lunatics, pushing people over to get past them and get as far away from it as possible.

That's when the school was surrounded. Every window was blocked by an infected body, with pure grey skin and mad yellow eyes, darting around like a wild animal. Eventually the windows gave way, and one by one the infected people streamed through into the building. People around me were dropping like flies, a river of blood quickly filling the corridors. They were unlike anything we'd ever seen or heard about, they could run.

And by run, I mean sprint. Usain Bolt speed.

With every hour that passed, their speed would slow as their brains deteriorated, constricting them to jogging speed after a day. I hid in my locker until I was sure that I was safe, silently having many separate breakdowns. I could see all of the people being murdered only a few feet away from me from the slits in the metal, their organs ripped from them in front of their own eyes.

I lost count of how many times I vomited within those few hours. I stood in the locker until I collapsed from exhaustion. And the world that I woke up to was very different to the world I left. Corpses littered the corridors and classrooms, friends, students and teachers were left dead with the same horrific expression on their faces.

Eleven. That's how many people managed to stay alive on that day. Eleven students out of over a thousand. After four months only five of the eleven were still alive. Some let the fear control them and drive them insane, while the others were too weak and scared to fight, and ended up becoming meals. Now, just like those who were infected, we only have one goal in our minds, only one goal that keeps us breathing day after day.

Survival.