Zombie viruses are a term used to describe viruses that are trapped in permafrost, which is ground that is frozen for at least two years straight. When permafrost soil samples thaw out, the viruses can revive and are still infectious, which is why they are given the name "zombie virus" because they have returned to life. These viruses are not necessarily harmful to humans, but they could infect humans, not just single-celled organisms. The study found that DNA viruses have the capacity to remain infectious for more than 48,500 years in permafrost. However, there is no such thing as a zombie virus in the scientific community. Zombie narratives are often rooted in scientific truth about how infections spread, but genetic mutations that occur as a result of viruses are far more subtle than zombie fiction will have you believe.