“More like:
but it might cause your downstairs neighbor a lot of water damage.”
No one claims one unvaccinated child will significantly affect “herd immunity”.
You should better make an analogy like: sure your leaky faucet won’t impact our planet, but if everyone refused to fix their faucets. Then there would be a real problem.
And that’s certainly true. If enough people refuse vaccination we are seriously risking deadly outbreaks.
And I’m all for public policy strongly educating and pressuring people to vaccinate. As far as mandating it, I don’t know. Big philosophical, ethical, and constitutional questions there.