It's difficult to vote on this, I want to say "yes" but then I consider that some percentage of children do have an allergic reaction to immunization. One of my Uncles received the MMR shot at age 5, same as most American kids in the 1960s, but he had a reaction to it and the entire left side of his body was paralyzed.
So, if we area aware that a certain percentage of children will be injured or killed by immunization, it seems more sensible to allow the parent to decide about taking that risk, and weighing the risks and benefits.
Further, vaccinations have been used in the past as a vehicle for testing drugs on humans without their knowledge. This sort of abuse leads to widespread mistrust in immunizations that can persist for decades. Those who do such unethical testing cause irrevocable damage to human trust in medical institutions.
For this reason I would NOT make it illegal to avoid vaccinations, but rather work hard to inform and educate the public about the benefits of immunization. And, punish those who use vaccination as a cover for unethical human drug testing.