Some to be used with informed consent, because we are not all the same.
The first vaccine was crude but effective. Cowpox lesion fluid was scratched onto human skin. It protected a young boy. 1857 Edward Jenner produced a Smallpox vaccine from the cow virus. Vaccinae means pertaining to cows. The two virus were just similar enough. Today the Smallpox vaccine is a living modified human virus but not a disease producing (attenuated). Smallpox was declared eradicated, by vaccination in 1980.
The MMR vaccine, Mumps, Measles and Rubella is a modified living virus aka attenuated. Adverse reactions may occur in one in 20,000 doses. (CDC 2016) Vaccination is not always protective.
The first Polio Vaccine (J. Salk) was a killed polio virus. Immunity was modest, requiring booster injections, but no chance of disease. The second Polio Vaccine (A. Sabin) was alive but attenuated and administered in a single oral dose.
Subunit vaccines are nonliving components of the microbe, to stimulate antibodies made to neutralize those structures. Some flu vaccines are subunit types and may require boosters to keep immunity up. The Booster Effect is seen in the top left. A common subunit vaccine is for Hepatitis B.
The controversy about vaccines and children's health is emotive and conflicting. At question is the rights of the individual versus the need to protect the masses, aka the herd.