Vaccination is absolutely important. As the son of a physician AND a nurse, the brother of a medical student, and a science teacher myself, I feel I can state that with knowing quite a bit about how vaccines work. Of course, the crazier anti-vaccination speakers out there would probably say that that just makes me complicit in the conspiracy.
The idea behind a vaccine is simple: you take a very small sample of a deactivated (IE: dead) virus and inject it into the body of a human being. While the virus itself poses no threat to the person (it being dead and incapable of replication), the body recognizes the presence of the virus and produces antibodies against that specific virus, so that if you do catch it in the future, then you already have a pre-prepared first line of defense to help you fight it. When had, this vaccination ranges from being helpful when the time comes around (such as for chicken pox) to highly necessary for survival (see smallpox).
Jon Stewart was actually talking about the anti-vaccination movement this week, and how it's seemingly brought elements of both sides of the political spectrum together in their stand against the practice. And that's because the rhetoric against vaccination has components that can appeal to both sides.
For the right, you've got the 'I Hate You, Big Government' angle. The government tells us to vaccinate our kids, to do this and do that, well I'm not gonna do it because it's Big Brother and all of that.
For the left, it's more the 'I Hate You, Big Business' angle. One of the more common things you hear in the anti-vaccination movement is about how Big Pharma is making money hand over fist over all these vaccinations that we don't need anymore because we wiped out the diseases and they're not around anymore so why are we still putting money in their pockets?
Both sides ignore one simple fact. When you stop vaccinating your kids, and you do it on a large scale, you lose herd immunity - which is the thing that prevents big-scale outbreaks from pulling a Black Plague. One of the major concerns by the Continental Army during the Revolution was the presence of smallpox - Jenner hadn't invented his cowpox vaccine yet (and wouldn't for a full decade until after it was over) - so all that was available was inoculation, which still incapacitated people. It just had the more generous benefit of them mostly not dying. Washington himself had the pox (pre-Revolution), and he was looking for the right opportunity to inoculate his army because he knew that one errant smallpox outbreak could wreck the colonials.
The British regulars, on the other hand, had no such problems, their armies were largely immune to the pox - most people who needed inoculation were Loyalists who had grown up in the colonies rather than the UK proper. During the siege of Boston, for example, the citizens were wracked with smallpox, but the British dismissed it because most of their troops weren't susceptible to the disease. Herd immunity.
In medicine today you hear a lot about 'preventative medicine' - ounce of prevention worth a pound of cure and stuff like that. Herd immunity, and vaccination, are probably the ultimate examples of that - stop a disease before it starts, before it becomes a full-blown outbreak like at Disney.
And as for Jenny McCarthy and her stupid idea about how a vaccine caused her kid's autism? Autism is a neurological disorder. While the exact cause remains unknown, research shows that there is a strong component of genetics involved, and there might be a handful of environmental factors involved. Some of the environmental factors claimed to cause autism include chemicals like phthalates and phenols, which are used in the manufacture of plastic water bottles; diesel exhaust; and alcohol.
But I'm not hearing Jenny McCarthy campaigning against disposable water bottles, the use of diesel fuel, and drinking.