I'm having some trouble thinking of argumentation lines for the affirmative, insofar as a minority refusing a vaccine shouldn't affect the majority, because the majority has been vaccinated and is (of course, to a limited extent) immune. This is frustrating every brainstorm I have on affirmative argumentation lines. Some ideas?Let me see if I can help you out of this self-imposed jam.
First, the "to a limited extent" is important. Vaccines don't provide 100% immunity. For some unlucky recipients, they provide no immunity at all; for others (and this number is most likely much larger), they merely reduce the severity of symptoms. So unimmunized persons are a danger even to the immunized.
Second, unimmunized persons are a danger to those who, for health reasons, simply cannot be immunized. (Of course, this also presents a dilemma for the affirmative; does "compulsory" allow any exceptions?)
Third, a minority refusing a vaccine can influence others to avoid the vaccine, decreasing "herd immunity" (which often requires a high threshold--90% or more). That's why, in recent years, outbreaks of dangerous contagious diseases have increased in areas where they were nearly a non-factor. Polio. Diphtheria. Whooping cough. All over the world, missed vaccinations are putting lives at risk.
Fourth, the risk of bioterrorism or a pandemic that might justify quarantine would probably also justify compulsory immunization in the interest of national security.
Fifth, children who would otherwise receive safe vaccinations risk dying due to their parents' unnecessary or even irrational concern.
Sixth, people who refuse vaccination are a danger to themselves; in a paternalistic political philosophy, this is grounds for intervention.
Seventh, unimmunized persons who lack insurance are a drain on public coffers.
Eighth... well, that's all I've got in ten minutes.
Readers: other ideas?