The Booster Shot is a small glass vial of medicine and a needle. It is the most valuable thing a survivor can carry. It is the only medicine that can stop the Z-Virus.
Given within 5 minutes of exposure, the Booster Shot stops the infection.
Given later than 5 minutes, it cannot stop the infection. It only gives advantage on the Turn save.
Five minutes is not long. A Booster in a pack back at camp is no help. Survivors who can afford one keep it on their belt.
Lifeline makes the Booster Shot at its campus in Atlanta. It is made from the blood of Mutated donors. The Z-Virus in their blood did not kill them, and that blood holds what stops the virus early. One donor gives enough blood for about 3 doses a month. Lifeline made the first Booster Shot in 2048.
A Booster Shot costs 100 Credits. That is more than a year of hard work pays. Most of the time it is not for sale at all. Strongholds keep their Boosters for guards, doctors and leaders.
Some Mutated donors are paid for their blood. Many more are held in Lifeline donor camps and are not paid. They cannot leave. Camp Seven, outside Atlanta, is one of the biggest. Most people in the strongholds do not ask where their Boosters come from.
The Marked, a group of Mutated outcasts, smuggle Booster Shots out of the donor camps. They sell them for less than Lifeline does, or give them to people who cannot pay. Lifeline calls this theft.
The Booster Shot is for Humans. Mutated and Undead cannot be infected, so they never need one.