Vaccines—Who Needs 'Em?

[Lemur]

FYI, I've never gotten a shot in my life. Do you think I am endagering your kids?

Yes, you are a threat to my children. No vaccine is 100% effective, but if enough of the population gets vaccinated, the virus/bacteria can't get a proper burn going in the populace. So if an individual comes down with the disease, it fails to spread.

Even though the vaccines do not give 100% immunity, in aggregate they act as if they do if enough of the herd gets vaccinated. See herd immunity for further reading. Sample:

"Vaccines are never 100% effective. Some people are genetically unable to respond to the vaccine, some have immunodeficiencies that preclude receiving vaccines or developing a response to the vaccine, some haven’t gotten around to vaccination or are too young to receive a vaccine. If you vaccinate a large number of people, besides preventing disease in an individual, it helps protect the vulnerable in a population. Vaccines prevent disease propagation."

I always thought that immunity meant...well, that you're immune. The only way unvaccinated kids would be a threat if it were a virus that mutates quickly enough to make the vaccination obsolete.

See answer above. The whooping cough vaccine, for example, is believed to have a 64% effectiveness rate. If enough kids get the vaccine, however, the virus is effectively stopped dead. But only if enough of the population gets vaccinated.

So Vuk, the local chiropractor, and the lady in that YouTube video are all endangering my children through a willful act of premeditated stupidity.