1. We can't trust the researchers or the doctors because they're all part of a vast "Big Pharma" conspiracy to make money off of vaccines.
There are at least five good and obvious reasons why this is clearly not true, but I'll make room here for just one: The "naive" parent who didn't "do her homework" by running a google search or listening to her friends is not, in fact, the one paying for her child's vaccines. Vaccinations are paid for largely by private health insurance companies and, for uninsured children, the government. Hopefully we can all agree that health insurance companies are not an innocent, naive, duped party in this or any other equation. Not only is the health insurance industry a major political powerhouse, but health insurance companies employ hundreds of physicians whose sole jobs are to find ways to deny coverage for any medical care that is even arguably not "medically necessary." If you must have a conspiracy theory, and you really don't believe vaccines work, maybe you should consider the idea that the "Big Health Insura" put out all the anti-vaxx internet quackery so that fewer people would vaccinate. *I* know that's not true, because *I* know that health insurance companies don't want to pay for babies hospitalized with pertussis. But if you're a vaccine-denier, then I have to tell you that my conspiracy theory is far more likely than yours.
2. They've never done a study of vaccinated versus unvaccinated children and autism rates.
They have, in fact, and it was done in Denmark - here it is. It studied all children born in Denmark from 1991-1998. Update: Here's another one, this one a massive study new this year, out of the U.S.! What they haven't done is a double-blind study. And that's not because Big Pharma is preventing one - it's because it would be considered unethical to randomly assign babies to not be vaccinated.
3. It's actually the vaccinated children who are dangerous - they are the ones most commonly infecting other people.
One good argument against that is that it's factually not true. See also this, this, and this: ("The second [CDC] report provided additional data on the 159 measles cases reported in 16 states and New York City this year, through August. ... Most of the measles cases occurred in people who were unvaccinated (131) or had unknown vaccination status (15). Among unvaccinated U.S. residents in the group, 79% remained unvaccinated because of 'philosophical objections' to the practice.")
But let's imagine it were true, and vaccines were only ("only"), say, 85% effective. Now imagine a town of 100 people. Ninety of them are vaccinated and ten are not. Everyone is exposed. If this were to happen, in theory, 10 unvaccinated people would contract the illness, but thirteen vaccinated people would. It's simple math.
Oh yeah, the pertussis vaccine. That one has its own ironic twist. In 1997 we switched over to an acellular vaccine formula in order to appease vaccination fears. The cellular formula was more effective but it had more side-effects - more fevers, and thus more febrile seizures. But febrile seizures are not actually dangerous and if you're prone to them, you're not going to avoid them by not getting vaccinated. My 13-month old inherited them from her father and while she never experienced one after a vaccination, she had one anyway when she caught a simple passing illness that spiked her fever. She's perfectly fine and was never in any danger. So now to avoid a false danger we've increased the real danger: a less effective vaccine where vaccination rates are declining.
**Even at that, though, studies show that even in populations including non-infants (so people far removed from their infant pertussis vaccines), the unvaccinated are 2.5 times as likely to catch (and potentially spread) the disease.
4. If vaccines are actually effective, vaccinated people shouldn't care whether some people don't vaccinate.
Is this how you feel about hand-washing?
5. It's better to be "naturally" infected than to receive a vaccine.
This reasoning is so circular it makes my head hurt: It's better to risk death, brain damage, paralysis, birth defects, and various kinds of cancer by getting a full-blown "natural" case of one or more of these diseases because... because it's a more effective way of making sure you don't ever get the disease you already had.
And if you do subscribe to this theory, I certainly hope you're formula-feeding. Antibodies passed to your infant through your breast milk won't be quite as effective or long-term as the antibodies your baby's own body would produce in response to full-on "natural" infections of various illnesses. You wouldn't want to jeopardize his developing immune system by nursing, would you? (Disclaimer: This is sarcasm; I'm nursing my 13 month old through this winter JUST to give her any antibodies I happen to acquire).
6. We shouldn't blindly trust our doctors.
Agreed. Physicians make mistakes, and we as patients can optimize our medical care by staying informed and by self-advocating where appropriate. Thankfully, though, we have very little such work to do when it comes to vaccination. Contrary to what anti-vaxxers would have you believe, vaccines are some of the most thoroughly studied medications out there and there is not just a national but a global consensus on their safety and efficacy. Really, people, you might find my vaccination posts a little too snarky for your tastes. But at least admit that it's not exactly humble to ignore the consensus of every legitimate medical and public health group in the world.