The definition of herd immunity is as follows:
“ The resistance to the spread of a contagious disease within a population that results if a sufficiently high proportion of individuals are immune to the disease, especially through vaccination. The level of vaccination needed to achieve herd immunity varies by disease but ranges from 83 to 94 percent”.
Let me backtrack a bit. For a long time the vaccine-suspicious (I’m trying out different names for “anti-vaxxer” just because I think there’s so much of a stigma that goes with that label) have made fun of the fact that “everyone needs to be vaccinated or they won’t work” because, wasn’t that admitting that vaccines don’t work? So people scoffed, and asked, “Why do I have to vaccinate my child to make your child’s vaccine more efficacious?” The response to that mockery was a marketing campaign started by pharma and propagated by media and “herd immunity” is its title. They made it our moral obligation to protect the immunocompromised and the weaker among us. Our duty to do “do the right thing”. It sounds so noble. Altruistic. Unselfish. Beautiful, in a way. For the greater good is our new mantra. Collectivism is always so pretty on the surface isn’t it? It’s got a rotten core though. Every single time.
So where did herd immunity come from? How did it start? Turns out, it was first coined in the late 1920’s in reference to measles (getting the actual infection, not being vaccinated, since the vaccine for measles wasn’t made until the late 60s). A scientist noticed that when a large amount of children got the measles (68%) in a certain town the entire population would be immune for decades, even the susceptible would be protected because almost everyone around them was immune.  Mothers passed on immunity in breastmilk so babies were protected until weaned. The elderly were protected because they had already had it as children. Immunity was lifelong.
Dr Russel Blaylock, retired neurosurgeon puts it this way:
“In the original description of herd immunity, the protection to the population at large occurred only if people contracted the infections naturally. The reason for this is that naturally-acquired immunity lasts for a lifetime. The vaccine proponents quickly latched onto this concept and applied it to vaccine-induced immunity. But, there was one major problem – vaccine-induced immunity lasted for only a relatively short period, from 2 to 10 years at most, and then this applies only to humoral immunity. This is why they began, silently, to suggest boosters for most vaccines, even the common childhood infections such as chickenpox, measles, mumps, and rubella.
Then they discovered an even greater problem, the boosters were lasting for only 2 years or less. This is why we are now seeing mandates that youth entering colleges have multiple vaccines, even those which they insisted gave lifelong immunity, such as the MMR. The same is being suggested for full-grown adults. Ironically, no one in the media or medical field is asking what is going on. They just accept that it must be done.
That vaccine-induced herd immunity is mostly myth can be proven quite simply. When I was in medical school, we were taught that all of the childhood vaccines lasted a lifetime. This thinking existed for over 70 years. It was not until relatively recently that it was discovered that most of these vaccines lost their effectiveness 2 to 10 years after being given. What this means is that at least half the population, that is the baby boomers, have had no vaccine-induced immunity against any of these diseases for which they had been vaccinated very early in life. In essence, at least 50% or more of the population was unprotected for decades.”
It’s a mathematical theory that has never actually been tested, especially not on vaccines. The theory is propped up through mathematical models, assumptions, and mixing actual measles cases with vaccination rates (not the same thing).  The first goal for vaccine-induced herd immunity was 55%, and it’s been changed over and over since then. The fact that more children are vaccinated now than they’ve ever been before makes no difference. It’s never been enough to see herd immunity achieved by vaccination in real life.
The 95% number for herd immunity goal was based on a mathematical model done by Hethcote in 1983 and it has never been studied, proven, or expounded on since then. 
And then there’s China, where the reported coverage for the MMR vaccine is “greater than 99%” and the conclusion of the study states, “However, the incidence of measles, mumps and rubella remains high.” 
Antibodies do not tell the full tail of immunity or protection, but if they did, it would be important to note that up to 10% of the fully vaccinated fail to mount antibody levels at all.  So let that sink in. Even if every single person was up to date as children and adults, we could still never achieve 100%. Not even 95%. And we would need to know how long that antibody response lasts before it starts to wane.
If you want to read an excellent, well cited article on how unvaccinated children pose zero risk to anyone, please read this letter to legislators by my favorite Harvard Immunologist.
Herd immunity is the cornerstone of the pro-mandate people who want vaccines forced on everyone. Fear is the driving factor, of course, and I just want to disprove it as thoroughly as I can. It’s an absolute lie and a mythological hope that cannot be applied to vaccines because we haven’t figured out how to artificially stimulate the immune system in such a way that the artificial immunity lasts a lifetime.
Let me ask you a question. Are you up to date on your vaccines? When was the last time you got your DTaP or MMR? Let’s be generous and say they give 20 years of protection. Are you still protected? Do you realize that most adults (estimated at somewhere around 70%) don’t get their adult boosters? That puts our herd immunity waaaay under where it should be.
Instead of causing fear, this fact should be liberating. Smallpox hasn’t returned even though we quit vaccinating for it in the 70’s, and polio is not coming back even though most of us no longer have antibodies for it.
Allowing 2% (where “antivaxxer” numbers are as of Jan 2019) of the childhood population to choose a different path puts no one at risk. They pose no threat, and are not to be feared. Fear makes people crazy. I truly hate how the media and mainstream medicine have bought into this fear campaign. We can do better by not allowing this tide of madness to carry us into wanting to force a small minority to do something they don’t want to.