Imagine you have 50 people in a room at a convention or something. Everybody’s greeting and shaking hands and whatnot.

1 of them has the flu and an aversion to covering his mouth when he sneezes ‘cause he’s gross like that.

For simplicity in this thought experiment, we’re gonna assume that this flu transmits instantly, and has zero incubation period. You’re instantly contagious as soon as the sneeze hits you.

Patient 0 sneezes, catching 5 people in his blast zone. Those people each shake hands and or otherwise infect 5 more people. And then they also infect 5 people.

5x5x5 = 125. But we only have 50 people in that room, so it’s pretty safe to say that everybody in the room gets exposed. By the end of the meeting, everybody’s sniffling and sneezing and the whole room is covered in a fine layer of snot.

Now, next meeting. Let’s say that 80% of the people in this meeting have had a flu shot, or have had this particular strain of flu before and are immune.

Our gross patient zero sneezes again, again catching 5 people in his plague spray. But on average, 80% of those people are immune and don’t pass it on like the first room did. Only ONE person gets infected. He sneezes, again catching 5 people. But again, 80% are immune, so only one person gets sick. That person sneezes and catches 5 more. One more sick.

Over the course of the same 1 hour meeting, the unvaccinated room resulted in every single person getting sick. In the 80% vaccinated room, only THREE people got sick. Even though only 80% of people were vaccinated, which is 40 people if there are 50 in the room, only 3 people, which is 6% of our room population, got sick.

20% of 50 people is 10 people. Even though 10 people were unvaccinated, only 3 actually got sick.

That’s the effect of herd immunity. Yes, three still got sick, but because of the level of immunity, some people who are at risk never even get exposed in the first place. As infections go up, even more people become immune, eventually strangling the spread of the sickness off to the point where it can more or less die out completely.

Granted, this is a simplistic example, but that’s basically how it works. If all of the people who CAN get vaccinated do so, then that protects the people who CAN’T get vaccinated for whatever reason, because the sickness never even gets to them thanks to all the other members of the “herd” who are immune.

It's mostly meant for people who are immunocompromised and cannot get the vaccine, not dumbasses with their heads buried in the sand.

I think that answers your question, but I'm not completely sure what you were asking.