Vaccines have saved more lives than probably any other medical intervention.
If we roll the clock back more than 200 years in Europe many of your children would not reach adulthood because they succumbed to diseases we now protect them from with vaccines such as measles, diphtheria, polio, typhoid, meningitis etc.
Take a flight to developing nations and see children in wheelchairs or hobbling from polio. Visit refugee camps devastated by measles.
You will understand better why we say YEHS to vaccines.