Most of us have never heard of herd immunity – it’s likely you searched the term because you saw it on the news or in a thread debating vaccinations.
People on the “v
This argument is ironic – force more people to be vaccinated to protect the people who choose not to vaccinate?
Many in the anti-vax movement argue there is no proof herd immunity exists and the theory is wrongfully applied to vaccination programs. Let’s get this straight: the people who need protection by herd immunity are the people who discredit the merits of it, and the people shouting about it are protected by the vaccine and don’t need herd immunity. It’s enough to make your head spin.
What is Herd Immunity, Anyway?
At the scientific and epidemiological level, herd immunity is statistically sound. Let’s take Joe, a person infected with the measles.
Measles is very contagious, it has about a 90% infectious rate. This means if no one has immunity, 9 of the 10 people Joe has contact with will come down with the measles.
Then for each of those 9 people, they infect 9 out of 10 more people. It is easy to see why measles was such a big deal before the vaccine in the US in 1963. Before the vaccine, 3 – 4 million people in the US were infected each year.
This graphic shows Joe, infected in green, spreading his green to 9 of 10 people, then those 10 people spread it to 81/100 people.
Let’s see how this would be different if 50% of the population were immune to the measles:
Joe infects 5/10 people, those 10 infect 25/100 people.
What if 90% were immune?
Joe infects 1/10 people, those 10 infect 1/100 people.
This is the basic idea of herd immunity and why there is a push for high rates of vaccinations. For those who don’t believe herd immunity is real, isn’t 6.5 million unvaccinated children with no measles proof enough?
The Bottom Line of Herd Immunity
One case of the measles in an area where the vaccine rate is high is like a flame with no accelerant – it runs it’s course and dies out.
A community of unvaccinated individuals is like an apartment full of gas – think Fight Club. Tyler Durden can leave the gas on and fill the apartment, but it won’t ignite into a fire until there is a spark. In the same way, a community full of unvaccinated people won’t get the measles – until Joe comes to town. At a 90% infection rate, they can’t help but be consumed by the fire of the disease.
I’d rather just turn off the gas.