And there's no vaccine for viruses, right

Not zactly, WW. There are vaccines for some viruses, just not for all viruses. In fact, vaccines are made from viruses. IIR, there are live-virus vaccines, which use a weakened strain of the virus to cause the body to produce antibodies, and killed-virus vaccines, which use dead viruses to do the same. You may be thinking of the fact that there are no antibiotics for viruses. None of the so-called wonder drugs are effective against viruses, which is why we shouldn't insist the doctor give us something for a bad cold - doesn't do any good and contributes to the development of antibiotic-resistant organisms. [/my medical knowledge]