What I meant is we know what happens if we have working vaccine. Meaning that working vaccine leads to less people being sick and that leads to less deaths from

What I meant is we know what happens if we have working vaccine. Meaning that working vaccine leads to less people being sick and that leads to less deaths from virus. As to the vaccine itself it is usually easy to come up with a formula that can disrupt the virus (any potent poison or lava flow can do that). The difficult part is that the formula must also not disrupt anything important. No amount of knowledge about virology can help with the second part, human body is vastly more complex than the virus.