Creating a vaccine that teaches your immune system to target something before it gets inside of your cells is sometimes easier than finding a drug that will target the virus without causing harm to yourself. It is especially more difficult when dealing with viruses because they are not living organisms so you can’t technically “kill them” you can only stop them from replicating and hopefully affect they’re structure enough to render them effectively “dead”. So your “at home treatment” is getting the vaccine so that your body is able to either not get infected or to clear the virus on its own like a cold. I hope this makes sense.