Some people are unable to get vaccinated, due to medical complications. Those people rely on others being vaccinated so that they don't contract some disease.
How would you endanger others if you weren't? Well you could potentially contact the disease and then spread it to those others, right?
If you're asking how you would endanger someone in a society where 100% of all other people were vaccinated, well I guess you don't but that's not the world we live in.
Right, like I figured. So it is a matter of probabilities. If one lives in a country where a super majority is vaccinated, particularly if that same person does not travel, the likelihood of him both contracting such a disease, interacting with a person not vaccinated against that disease, and then that person contracting the disease is vanishingly small. That is not remotely comparable to blowing through red lights, such as you suggested in your example. So my follow up question, is then, why the vitriol? The comments here are incredibly aggressive, particularly considering the usual behavior of the community. It seems to me the average commenter here is more likely to get in a head-on collision due to daydreaming about the rust borrow checker while driving home than the scenario presented earlier is to happen.
All vaccines have primary and secondary failure rates. Primary failure occurs if you get vaccinated but you do not develop antibodies (This is rather crude description of immunological memory but let just stick with it). Secondary one occurs when you get vaccinated, you develop antibodies but once you contract the disease you still get it (e.g. you immunological memory does not kick it). Both of these are well known effects and are subject of research to develop more effective vaccines.
So even in population where 100% people get vaccinated there is insignificant percentage of those who are still susceptible to given disease.
How would you endanger others if you weren't? Well you could potentially contact the disease and then spread it to those others, right?
If you're asking how you would endanger someone in a society where 100% of all other people were vaccinated, well I guess you don't but that's not the world we live in.