I'm not a parent so I won't guess, but I can imagine a parent wanting their children vaccinated with commonly-available vaccines. Maybe not, though.
You would be amazed at what goes into these vaccines! For example, the DPT shot is administered 4 times and spread out over several months. Before administering it, parents are given a letter explaining the possible side effects which include death. There are cases of children who died after their 3rd dose. This vaccination is mandatory as are a host of others.