Why is there not a vaccination for virus?

This statement is incorrect; vaccinations are available for many viral infections. Vaccinations work by introducing a weakened or inactivated form of the virus into the body. This allows the immune system to develop antibodies against the virus without causing illness.

Many common viral infections have effective vaccines available, including measles, mumps, rubella, polio, tetanus, hepatitis A and B, and influenza. These vaccines have dramatically reduced the incidence of these diseases and have saved countless lives.