Wikipedia defines common sense as “knowledge, judgement, and taste which is more or less universal and which is held more or less without reflection or argument”
Try to avoid using this topic to express niche or unpopular opinions (they’re a dime a dozen) but instead consider provable intuitive facts.
This is actually good common sense. It works much more than 50% of the time. You’re responding to the very specific instance of anti-vaxxers, whose claims of relying on the immune system instead of vaccines are not considered common sense by most people.
No, I’m responding to regular people. Your immune system is way less effective than you think, hence the wrong common sense part.