So the new anti-Vax mantra is "My body, My choice"?

[jeff47]

40. Vaccines aren't like a shield.

Vaccines train your immune system to respond very quickly to a particular disease.

(Part of) The immune system works by trying random combinations to make antibodies until one of those antibodies sticks. When it stumbles upon something that sticks, it pumps out tons of that antibody, which disrupts the disease, curing the ill person.

Your immune system has "memory cells" that remember which antibodies worked in the past. Whenever a new infection occurs, your body tries these memory cells. If one of the memory cells is a match, you short-circuit the lengthy "try random combinations" step. Which means you fight off the disease extremely quickly. So fast you do not have symptoms, and are unable to spread the disease to others.

Vaccines give your body a chance to make those memory cells from a dead or weakened version of the disease. That way you are very slightly ill from the vaccine, but when the real thing shows up you have memory cells to fight it off quickly.

So a person vaccinated against measles actually catches the measles. But their immune system responds so quickly that they have no symptoms and are unable to spread the disease to others.

But vaccines have a failure rate. For reasons we can not explain, they just don't make memory cells sometimes. For the measles part of the MMR vaccine, the failure rate is 2% of the people who get both childhood doses. These people will suffer just like they were not vaccinated. What protects them? Herd immunity.

With any disease, eventually your immune system wins or you die. In either case, you quickly stop spreading the disease. So the disease needs to move on to a new host in order to survive. When enough of the population is immunized, the disease can't do that. It keeps running into vaccinated people who kill the disease off too quickly for it to spread. So the disease dies out. That is herd immunity.

Herd immunity occurs when around 90% of the population is vaccinated. The 2% failure rate + the small number of people who can't be vaccinated for medical reasons + Christian Scientists is <90%, so we used to have herd immunity against measles. Anti-vaxxers broke that by lowering the number of vaccinated people.

If you or your children are vaccinated against measles and are exposed to it, there's a 90% chance you will get infected. There's a 2% chance you will suffer the disease, thanks to the vaccination.