Around the turn of the century a massive plague swept across the Americas and spread to most of the world rather quickly. Survivors have manged to maintain small communities all over the world, and infection rates seem to be dropping (albeit slowly) after 26 years. Thermotactile Aggressive Gabriel's Virus (TAG) was named after the first victim Adam Gabriel - a mass murderer who was on death row and volunteered as a Guinea pig for a scientific experiment that lead to the accidental creation and evolution of the virus.

What We Know: AKA - the rules of TAG

1: If you're tagged, you become IT
Those who are infected are used by the parasitic virus (passed by skin to skin contact) as Intermediary Terminals, leaching nutrients from them. Symptoms are nearly invisible for the 2-8 hours, followed by a headache, and eventually hallucinations, and high fever. Throughout this time, the develop dark-brownish splotches on their skin. Sometimes, small and unnoticeable and only in one location of the body, however some get it all over their bodies and it ranges in size from unnoticeable to unmissable. This veries from person to person. These symptoms get progressively worse until the 22-24 hour mark, when the body temp. sky rockets to 200 degrees, killing them nearly instantly.

2: If you tag someone, they will become IT, and you will no longer be IT
By engaging in skin to skin contact with another person for 3 seconds or more one can pass the infection onto the other person and stop the infection from fully taking hold in themselves. However, a former carrier is still contagious for that 24 hour period, anyone they make skin to skin contact with will likely become infected.

3:There are no (immediate) No Tag Backs
The way the infection works is by acclimating to your specific body once it's attached to you. The only reason you body doesn't develop antibodies to get rid of it immediately is that the infection works faster than your body can keep up. Those who have had contact with a certain strain and survived can effectively develop antibodies against it if they were to encounter that strain again. However, after traveling through two or more hosts, the strain will have mutated enough to no longer be recognized by those antibodies.

In short, if an IT tags someone, and they try and tag the original IT back, nothing will happen, the virus won't even try to spread back to them from the host the IT has infected. The original IT's antibodies are too strong for the virus to thrive. But if that newly infected IT tags someone else, and they can tag the original IT, and that person would likely become reinfected.

4: Home Bases
There are small gated communities that are the homes specifically for uninfected people. It costs a lot to live in one of these places, and in order to ensure no none brings in the virus, everyone inside is not allowed to leave unless fully covered in special armor, which is disinfected upon reentry - followed by a followup strip search and 25 hour quarantine of all individuals who left.
As an added precaution, anyone attempting to seek asylum in the community must either go through 25 hour quarantine or be shot on spot.

Those who do leave on missions for their Home Base are given orders to treat any person not part of their group as infected and are trained to use deadly force if any suspected IT gets within 5 feet of them.

5: Ollie Ollie Oxen Free
Ollie is a survivor in North America who puts out a monthly report broadcast via FM radio detailing where all the least infected areas in the US and Canada are located so that uninfected survivors can follow the trail and possibly make a new start there.

6: Hot Potato Colonies
There are small camps of people who survive by passing the infection around a small community of people, determined not to die, but not to spread the infection outside of their group. Rules and regulations in such a community differ from place to place. These places are often very discreet about their whereabouts and existence because:

7: Red Rovers
What's left of the government is still trying to manage this situation. Their solution is to capture ITs or recently uninfected but still contagious people and transport them in massive red buses to quarantine sites (concentration camps) where they are cataloged into a database, forced to give details about whom they have interacted with before and after their infection, and then essentially wait to die. Every so often misinformation leads to individuals who were previously uninfected being taken by the government to these quarantine sites and exposed to ITs.