Can a Virus wipe out humanity

Is it possible for a virus to wipe out all of humanity? If its not how come?

In a simple answer no. A virus needs a balance between killing the host and ensuring survival. Viruses don't want to kill their host as than they won't be able to replicate itself. Viruses are molecular parasites. They need to ensure they don't kill the host to fast.

Technically, No. Hypothetically, in science, anything is possible. But probability says no. Virus's are only alive when they have inserted their genetic information into a cell, so they are dependent on our survival. Now, eventually, the virus will kill the human if no precautions have been taken. But here's the catch: Genetic variation.

The saying "Survival of the Fittest" is due to Genetic Variation. There will always be resistance to a virus that is carried by at least one person, probably more than one. The Genetic Variation causes adaptation and, in effect, evolution. The Fittest will survive the virus, while to less Fit will die. In the next generation, more and more will carry the resistant gene from the Virus.

In essence, No. One single Virus will not destroy humanity. There will always be some people who are resistant to the virus.

If, and ONLY if, the virus could survive for decades in the soil, air, or other environment or IF it had a lot of animal vectors that it didn't kill. This means that even if humans isolated themselves for a century, they'd come out and be immediately exposed again.

It would also have to incredibly contagious to humans, for statistically there are always a few people that just don't encounter the virus particles or encounter very few. So, very, very, very easy to spread.

And then, it would have to be a virus that is not only deadly, and highly contagious, and have many many animal hosts (too many kinds and hosts for us to kill them), it would also have to be one that it's totally impossible for a human to carry a mutation to be immune to.