Below is an instruction from Human. Write a response.
    ### Instruction:
    how vaccines prevent disease
    ### Response:
    Why Are Childhood Vaccines So Important? It is always better to prevent a disease than to treat it after it occurs. Diseases that used to be common in this country and around the world, including polio, measles, diphtheria, pertussis (whooping cough), rubella (German measles), mumps, tetanus, rotavirus and Haemophilus influenzae type b (Hib) can now be prevented by vaccination.
    