10 vaccination misconceptions (that don’t hold water)


In light of the recent Disneyland measles outbreak which has revived the pro- and anti-vaccination debate, it may be newsworthy to revisit a few common misconceptions about why vaccines don’t work that would have even homeopaths saying “nah, that’s just too far-fetched.”

  1. Diseases had begun to disappear before the introduction of vaccines due to improved hygiene and sanitation.
  2. Most people who get the disease have been immunized.
  3. Vaccines have many side effects – including death – and may have unknown long-term effects.
  4. The DTP vaccine causes sudden infant death syndrome.
  5. Vaccine-preventable diseases have been practically eradicated from the U.S., thereby eliminating the need to vaccinate children.
  6. More than one vaccine at a time can ‘overload’ a child’s immune system.
  7. Vaccines cause autism.
  8. Thimerosal causes autism.
  9. Whether children are immunized is their parents’ business only.
  10. Natural immunity is better than vaccination immunity.


1.      Diseases had begun to disappear before the introduction of vaccines due to improved hygiene and sanitation.

Vaccination opponent Robert Mendelsohn, M.D says that there is “no convincing scientific evidence that mass inoculations can be credited with eliminating any childhood disease.” He claims that no one really knows why polio and other diseases have been virtually eradicated, but that improved living and socioeconomic conditions, rather than vaccines, should be credited. An example of this would be that diseases decreased in the U.S. when vaccinations were widespread as well as in Europe where no mass immunizations took place. First of all, an infectious disease will either kill or immunize isolated populations with little disease immunity. Second, whether disease decrease without immunizations has no relevance to whether or not vaccines are effective. On the other hand, there are several examples that they are (Japan’s Pertussis deaths skyrocketing in the 70’s when vaccination rates fell; the success of the Hib vaccine for meningitis in the U.S.). Without going too far back, measles had been under control due to vaccination programs, but now that an increasing number of parents refuse to inoculate their children, outbreaks such as the one in California are bound to happen. 

2.      Most people who get the disease have been immunized.

In an outbreak, sometimes the number of those who have been vaccinated surpass the number of those who haven’t, even with vaccines that are almost 100% effective, like the measles shot. But if we go to the root of the problem, we’ll see that the outbreak is caused by lack of immunization. Moreover, the purpose of inoculation is not to fully protect a single individual but to immunize as many as possible so even the few who are not vaccinated will be protected as well. Consider the following two examples taken from the Skeptic Dictionary and Quackwatch.org:

Example 1

Example 2

Imagine a robust individual who is not vaccinated and gets mumps. Before his parents keep him home from school he infects half his classmates, some have been vaccinated and are not affected. Some have not been vaccinated and they get the mumps. Most recover. Maybe one of the non-vaccinated dies. There may also be a child who was vaccinated but who is not very robust and she gets infected by several people, some of whom have been vaccinated and some who have not. Both can be carriers of the virus. The weak but vaccinated girl dies. Does this mean the vaccine doesn't work? No. It means that if some people don't get vaccinated they can jeopardize those who do. On the other hand, if most people have been vaccinated, those in the population who haven't been vaccinated benefit from the actions of the others and get protection against the disease without being vaccinated. If too many people take this free-ride approach, the group suffers.

In a high school of 1,000 students, none has ever had measles. All but 5 have had two doses of measles vaccine, and so are fully immunized. The entire student body is exposed to measles, and every susceptible student becomes infected. The 5 unvaccinated students will be infected, of course. But of the 995 who have been vaccinated, we would expect several not to respond to the vaccine. The efficacy rate for two doses of measles vaccine can be as high as 99.5%. In this class, 7 students do not respond, and they, too, become infected. Therefore 7 of 12, or about 58%, of the cases occur in students who have been fully vaccinated. This doesn't prove the vaccine didn't work - only that most of the children in the class had been vaccinated, so those who were vaccinated and did not respond outnumbered those who had not been vaccinated. Looking at it another way, 100% of the children who had not been vaccinated got measles, compared with less than 1% of those who had been vaccinated. Measles vaccine protected most of the class; if nobody in the class had been vaccinated, there would probably have been 1,000 cases of measles.


3.      Vaccines have many side effects – including death – and may have unknown long-term effects

Many vaccine-opposing publications imply that vaccines have many side effects based on the number of reports received by the Vaccine Adverse Events Reporting System (VAERS). However, the vast majority of these reports concern mild and temporary side effects like a sore arm or minor fever – which can be relieved by taking acetaminophen prior to or following vaccination. More severe adverse effects, including death, occur on a ratio of 1 per thousands or millions of doses. The bottom line is that all medications have side effects, but if we weigh the benefits against the disadvantages, vaccines turn out to be one of the safest medications there are.

4.      The DTP vaccine causes sudden infant death syndrome

A small number of children have died of SIDS not soon after being vaccinated with DTP. But the mere fact that most SIDS deaths occur around the age range when three DTP shots are given reveals that these shots are bound to precede quite a share of SIDS deaths by sheer chance.

5.      Vaccine-preventable diseases have been practically eradicated from the U.S., thereby eliminating the need to vaccinate children

Infectious diseases are like Lord Dunsany’s deity Mana-Yood-Sushai, who must be eternally lulled to sleep, and vaccines are like the lesser deity that must drum forever “for if he cease for an instant then Mana-Yood-Sushai will start awake, and there will be worlds nor gods no more.” If children were no longer vaccinated the protection there is now could easily vanish, and few cases of disease could multiply by the thousands. Moreover, some of the diseases that have been eliminated in the U.S. still exist in other countries, and may be brought back by travelers – which is why the CDC recommends travelers to get their shots before visiting certain countries.

6.      More than one vaccine at a time can ‘overload’ a child’s immune system.

Some people believe that multiple shots can overload a child’s immune system and weaken it so that they are more susceptible to asthma or respiratory problems in the future. The truth is that the number of antigens –substances that trigger immune responses – is nowhere near the number of antigens that babies are exposed since the moment they are born, and thus not likely to “represent an appreciable added burden on the immune system that would be immunosuppressive,” according to Institute of Medicine’s Adverse Events Associated with Childhood Vaccines report. There is not only no risk related to giving a child several shots during the same visit – and as early as possible – but multiple simultaneous vaccinations can save parents time and money and spare the child the trauma of delayed inoculations or a spaced-out schedule.

7.      Vaccines cause autism.

The cause of autism has not been clearly established yet, but the scientific consensus is that it is a genetic disorder that starts before the autistic person is born – and, obviously, before they have even been vaccinated. The person who manufactured the non-existent link between the between measles, mumps, rubella (MMR) vaccine and autism was Dr. Andrew Wakefield in a study published in The Lancet in 1998. The study has been long-debunked and retracted and Wakefield lost his medical license – which was hopefully worth the £400,000 he was paid by lawyers to falsify data to prove the MMR vaccine to be unsafe. Unfortunately, the damage was done and the following year the Cable News Network aired a program on which the parents of three-year-old Liam Reynolds claimed he had developed autism two weeks after receiving measles, mumps and rubella (MMR) vaccine – the first of many parents who have latched on to Wakefield’s fabrications.

Many of these very same parents have created anti-vaccination websites that perpetuate the autism myth by posting inaccurate and anecdotal information about the alleged cause-and-effect relationship between immunization and autism. But there is no scientific evidence or reason to believe that MMR or any other vaccine causes autism or any sort of behavioral condition. And even if they did, it would have to be a very rare occurrence – kind of like a Bigfoot sighting – given the millions and millions of children who have been vaccinated and lead perfectly healthy lives. If a child develops autism symptoms after being inoculated, and their parents see a link between the two events, it really is nothing more than an example of a logical fallacy called post hoc ergo propter hoc, or “after this, therefore because of this” (B followed A so A must have caused B). A big part of the problem is that, as MMR and Autism author Dr. Michael Fitzpatrick puts it, parents of autistic children think their personal experience makes them experts on the subject, when actually their research has only had one goal: to prove something that they already believe in.

8.      Thimerosal causes autism

Another reason for the vaccination-autism panic is that they contain thimerosal, a mercury compound used as a preservative to prevent microbial contamination. Thimerosal is no longer in use in most childhood vaccines, and has never been used in the MMR, varicella (chickenpox), inactivated polio (IPV), or pneumococcal conjugate vaccines. Furthermore, the substance is more than likely not harmful and only though so because anti-vaxxers probably confuse ethyl mercury – which humans metabolize thimerosal as – with methyl mercury, which is indeed noxious. Additionally, the amounts of thimerosal used were very small, there is no link between mercury and autism, autistic children do not present movement disorders and peripheral nerve damage common in mercury poisoning, and there is no evidence or reason to assign a toxic cause to autism.

9.      Whether children are immunized is their parents’ business only

As Sanjay Gupta wrote on CNN.com, “it’s not just because I love my kids that I vaccinated them – it's because I love your kids as well.” Parents who refuse vaccination endangered their own children – which already makes it somebody else’s business – as well as those children who are too young to be immunized, and even those who have been inoculated (see examples above). It’s not called ‘herd immunity’ for nothing. 

10.  Natural immunity is better than vaccination immunity

Natural immunity develops from contracting and overcoming an infectious disease. Studies show, however, that the immune response of people who have been immunized against several diseases is just as good as that of people whose immunity stems from an infection – if not better, because it forgoes the actual infection.


Although all of these misconceptions are based on pseudo-science, there is no denying the negative influence that religion has on the issue of vaccination – as it does on most issues. It’s no coincidence that all anti-vaxxers are in a way creationists and deniers of evolution, as Michael Shermer points out to Bill Maher. In any case, as Shermer also indicates, “one of the most remarkable features of science is that it often leads its practitioners to change their minds and to say "I was wrong,"” a feature that “happens a lot more in science than it does in religion or politics.” If you are against vaccination, it’s time to look at the hard evidence and say, “I was wrong.”