Why are vaccinations necessary components of the healthcare programs?

• Why are vaccinations necessary components of the healthcare programs?
• Are there reasons for people not being vaccinated despite of such elaborate healthcare programs? Explain.
• What are the consequences of people not being vaccinated?
• What is the impact of religious, cultural, legal, and ethical issues that parents need to consider before vaccination?
• What type of information will help the parents make an informed decision about vaccinating their children?