One reason why parents can be reluctant to immunize is that vaccines have been so effective that parents do not have experience with most of the diseases we can protect against. They therefore do not know the devastation the illnesses can cause, leading to a natural tendency to not worry about them.
I have been doing pediatrics for over 40 years now, and have seen most of these diseases, and will offer my perspective here.
Flu is a major cause of death and hospitalization in the US each year. The vaccine is not perfect, but it is useful. I still hospitalize a few children each year in whom this could have been avoided if they were vaccinated.
I used to hospitalize several children each year for vomiting and diarrhea due to rotavirus; I have not had this happen since I started giving the vaccine.
I have seen a parent who had polio as a child and survived, only to develop progressive muscle weakness due to post-polio syndrome as an adult. I have seen a child with autism, due to her mother having German measles (rubella) during the pregnancy.
I have seen children with devastating brain damage following meningitis from HIB and pneumococcal bacteria, both preventable conditions nowadays.
I did part of my medical training in England during a pertussis epidemic. I have seen wards filled with children with pertussis.
I have seen a beautiful child who had measles when younger, and apparently did fine, only to develop a late complication, SSPE, many years later. She developed uncontrollable seizures, and gradually lost the ability to use her muscles.
Chicken pox is felt to be a relatively harmless condition. My daughter caught the disease before the vaccine came out; she subsequently had shingles as a late complication, in her 20’s. Before the vaccine was developed, over 100 children would die from chicken pox in the US each year. I have seen two children, previously healthy, die suddenly from this disease. In one, it went to her brain, causing encephalitis, and she literally seized to death. In the other, the child developed a condition called purpura fulminans, and bled to death within hours.
Over my career, I have seen heart-breaking outcomes from vaccine preventable diseases. I never want to see these again. Please vaccinate your children.