The measles outbreak and recent statements by politicians like Rand Paul and Chris Christie have reignited the debate on childhood vaccinations. However, there is very little to debate; vaccinations are proven to protect public health. Still, this isn’t stopping vaccination critics from spouting misinformation. Here are nine examples.

1. Vaccines cause ‘profound mental disorders.’ This wild conspiracy theory has been circulating before Sen. Rand Paul appeared on CNBC to double down on the message. Previously, it was promoted by Michele Bachmann during her quixotic quest for the White House in 2012.

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After lambasting then Gov. Rick Perry during a presidential debate for mandating vaccinations in Texas, Bachmann took to the airwaves to continue the attack. Bachmann claimed that young girls who get the human papillomavirus (HPV) vaccine could suffer from permanent brain damage.

“There’s a woman who came up crying to me tonight after the debate. She said her daughter was given that vaccine,” Bachmann said on Fox News. “She told me her daughter suffered mental retardation as a result. There are very dangerous consequences.”

Bachmann was unable to produce the name of the woman who spoke to her and nobody has since come forward. There are no known cases of women or girls who have a sudden onset of profound mental disabilities as a result of the HPV vaccination.

2. Vaccines cause autism. This crazy talk of “profound mental disorders” and “mental retardation” likely comes from the thoroughly debunked pet theory of anti-vaxxers that there is a link between immunization and autism, a neurological condition. However, this link has been thoroughly discredited by countless medical studies. In 1998, a British surgeon named Andrew Wakefield published an article about a possible link between the measles-mumps-rubella (MMR) vaccine and autism based on his observations of only 12 children. Wakefield’s study has since been debunked, and he has since lost his license to practice medicine in Great Britain over evidence of professional misconduct associated with the study.

Meanwhile, no other scientific study has been able to replicate Wakefield’s findings, and many of these studies involve millions of children, not just 12.

3. Childhood vaccinations contain mercury. A little more than a decade ago, most childhood vaccinations contained a preservative called thimerosal, which can break down to create the ethylmercury compound in the body. While science knows that methylmercury is extremely toxic, the health effects of ethylmercury weren’t as well documented, and since then numerous peer-reviewed medical studies have failed to demonstrate any association between the levels of thimerosal children used to receive in vaccines and any neurological or developmental disorder. Keep in mind that the body uses ethylmercury differently than methylmercury; ethylmercury breaks down and clears the body much more quickly than does methylmercury. Therefore, low-level exposures from vaccines are not the same as long-term environmental methylmercury exposure.

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However, after hearing concerns over parents about the presence of thimerosal in vaccines, the pharmaceutical industry voluntarily phased out thimerosal as a preservative in childhood vaccinations. Today it is only used in a limited amount of influenza vaccinations.

4. Mandating vaccines is government overreach. Another common theme in Rand Paul’s fevered delusion of American dystopia: the Kentucky Senator reinforced this theme in his CNBC interview saying that “the state doesn’t own the children. Parents own the children.” This sentiment was also echoed by Gov. Chris Christie this week.

Anti-vaxxers may claim that it is not the job of the government to mandate vaccinations, but this libertarian philosophy falls apart when it runs into public health policy.

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For starters, children aren’t chattel to be “owned” by parents and they shouldn’t be made victims of their parents’ vaccination paranoia. Yet, anti-vaxxers claim that the children should be subjected to the whims of their parents, no matter how deluded they might be. Furthermore, not vaccinating goes well beyond a parenting issue, it is a critical public health issue. When people do not vaccinate their children, it weakens the herd immunity needed to keep potentially deadly diseases like the measles and pertussis from infants too young to be vaccinated and those with compromised immune systems.

Vaccine denialism has already shown to have a negative effect on public health in some regional pockets, and it’s leaving those communities open to outbreaks. In 2013, researchers confirmed that a 2010 whooping cough outbreak in California—the worst in the U.S. in more than 50 years—was spread primarily by the children of parents who received non-medical exemptions for school vaccinations from the state. The study showed that the outbreak was found exclusively in clusters where children were not vaccinated. Many infants who were too young to be immunized were hospitalized with pertussis as a result, ten of them died.

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5. The science behind vaccines is disputable. Vaccines are roundly misunderstood. Critics claim that science doesn’t know how or if they work, and others claim that people can actually get sick from vaccinations. Others say that they are ineffective.

In reality, there’s a wealth of evidence showing that vaccines have stopped plagues and epidemics in the past. Take both smallpox and polio, which both killed and crippled substantial portions of of Western populations before vaccinations were introduced. Also, the rate of measles steadily dropped in the two decades following 1963, the year vaccination was first widely introduced.

6. Vaccines cause the diseases. Few childhood vaccinations contain a live version of a virus and it is impossible to get a disease from a dead virus. Only those immunizations made from weakened, or attenuated, live viruses may produce mild symptoms. Those include the chicken pox and measles-mumps-rubella vaccines (oral polio vaccines with a weakened virus were discontinued in 2000). It is possible, but unlikely, that a child may develop a much milder form of one of these diseases after receiving one of these vaccinations. However, children with weakened immune systems and those being treated for diseases like cancer, should still avoid vaccines that contain attenuated viruses.

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7. Doctors get paid by pharmaceutical companies to give vaccinations. Anti-vaxxers argue that the pharmaceutical industry and doctors are getting rich by giving children vaccinations. Some even claim that doctors are given bonuses for each vaccination they give. It’s hard to argue with such a cynical accusation, but many vaccines are created by research facilities and given to pharmaceutical companies to produce, which do so at low margins (MMR vaccinations cost less than $1 to produce). Furthermore, there are nearly 60,000 pediatricians in the U.S., so you would think that one of them would have a change of heart or somebody associated to one of them would have exposed such a nefarious plot by now. But it hasn’t happened.

8. Society really doesn’t need vaccinations. Most vaccine critics say that people can build up natural immunities to diseases that are just as effective as vaccinations. While it’s true that we can build up immunity, there are only two ways to be effectively immunized from a disease, either having the disease or being vaccinated, and having the disease is a risky proposition. So, yes, children who have had the measles are now immune, but a large percentage of those children will be hospitalized and many will suffer from ear infections and some from meningitis as a result.

Vaccine critics also say that many childhood diseases were being wiped out because of better sanitation, not vaccinations. And while improved health care, better nutrition, and modern socioeconomics play a positive role in public health, they really only increase the survival rate of diseases, they don’t prevent them.

The drastic drop in measles happened long after western civilizations were benefiting from better health care, nutrition and sanitation. It only happened when the vaccination was first widely given to children. Further, as sanitation has improved significantly even in the last three decades, shouldn’t we be seeing a further drop in the incidence of diseases like pertussis and the measles today instead of a marked increase? The only thing that is changed in recent years is a decrease in childhood vaccinations.

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9. Measles is a harmless disease. Measles is one of the most infectious airborne diseases known to man; a single infected person on an airplane or in a crowded room can easily spread the disease to nearly every other person present who hasn’t been vaccinated. But vaccine critics make the claim that measles is a common and benign childhood disease, but that claim is far from the truth. For every 1,000 cases, it is estimated that between one and two people will be killed by it. Only recently, as many as 750,000 people, mostly children in South Asia and sub-Saharan Africa, lost their life to measles in a single year. And unlike Ebola, which has not killed nearly as many people as measles, these deaths are entirely preventable.