Essay question: why would parents withold vaccines from their children?

To answer this essay question effectively, a candidate would have to demonstrate the basic understanding of the principles and significance of vaccination including the "herd effect." This could be followed by discussion of vaccine side effects and poorly conducted clinical trials (e.g. the later disproved link between autism and the MMR vaccine) as well as protective measures that ensure that vaccines are effective and safe. Another important point to address is the education of the public about vaccination and the ethical dilemma as to whether it is right for a country to make childhood vaccinations mandatory by law.