By Dr. Mercola

When it comes to vaccine safety, a complaint that I’ve frequently expressed is the lack of credible studies comparing vaccinated and unvaccinated populations.

At best, we’ve had vaccination surveys1 based on self-reported data,2 and while that evidence strongly suggested unvaccinated children experience better health and fewer health problems, they were dismissed by most public health officials as unimportant. There are also published studies showing annual influenza vaccination takes its toll on your health, 3,4,5,6 and may do more harm than good in the long term.

Now, two pilot studies led by Anthony Mawson,7 an interdisciplinary epidemiologist and social scientist with a doctorate in public health, have helped to shed some light on the topic.

The gold standard in scientific research is replication and, while the conclusions of these studies need to be replicated using other data sources, they are another piece of evidence showing there are negative health outcomes for vaccinated children, and that unvaccinated children are actually healthier. It’s a good start, and it’s important to know these studies exist.

Vaccination Schedule May Place Preemies at Increased Risk of Neurodevelopmental Disorders

The first paper,8 published in the peer-reviewed open-access Journal of Translational Science (April 24, 2017), is a cross-sectional study of 6- to 12-year-olds exploring the association between preterm birth, vaccination and neurodevelopmental disorders, using data from both vaccinated and unvaccinated populations. Preemies receive the same vaccines and number of doses recommended by the federal childhood vaccination schedule as full-term babies, and on the same time schedule.

Data show anywhere from 8 to 27 percent of extremely preterm infants develop autism spectrum disorder (ASD). Premature birth is a known risk factor for neurodevelopmental problems of varying severity, yet prior to this study, the impact of the vaccination schedule on this risk had never been assessed. Not surprisingly, the results suggest the federally recommended childhood vaccination schedule may be inappropriate for premature infants. The abstract reads, in part:

“The possible role of vaccination in neurodevelopmental disorders (NDD) among premature infants is unknown, in part because pre-licensure clinical trials of pediatric vaccines have excluded ex-preterm infants.

This paper explores the association between preterm birth, vaccination and NDD, based on a secondary analysis of data from an anonymous survey of mothers, comparing the birth history and health outcomes of vaccinated and unvaccinated homeschool children 6 to 12 years of age.

A convenience sample of 666 children was obtained, of which 261 (39 percent) were unvaccinated, 7.5 percent had an NDD … and 7.7 percent were born preterm. No association was found between preterm birth and NDD in the absence of vaccination …

However, vaccination coupled with preterm birth was associated with increasing odds of NDD, ranging from 5.4 [percent] compared to vaccinated but non-preterm children, to 14.5 [percent] compared to children who were neither preterm nor vaccinated.

The results of this pilot study suggest clues to the epidemiology and causation of NDD but question the safety of current vaccination practices for preterm infants. Further research is needed to validate and investigate these associations in order to optimize the impact of vaccines on children’s health.”

Vaccination Linked to Higher Risk of NDD Among Full-Term Babies Too

The fact that no link was found between premature birth and NDDs among the unvaccinated raises the disturbing possibility that the vaccination schedule for premature babies could be responsible for the neurological disorders some premature babies exhibit, which have been previously assumed to be simply a result of premature birth.

This provocative possibility is further strengthened by the finding that vaccination was, in fact, linked with a higher risk of NDD among full-term children. As noted in the paper, aside from preemies being excluded from pre-licensure vaccine trials, another reason this issue has never been formally investigated is “the assumed overall safety of vaccinations.” The results reveal why assuming safety uses seriously flawed logic.

Another powerful example of why safety should never be assumed are West African studies that revealed a high titer measles vaccine interacted with the diphtheria-tetanus-pertussis (DTP) vaccine and resulted in a 33 percent increase in infant mortality.9 Those shocking findings led to the withdrawal of that measles vaccine. But what would have happened had those studies never been done? Clearly, we need more like them.

The fact is, all vaccines need to be carefully evaluated not only individually for long-term safety, but also for synergistic toxicity when the vaccine is given in combination with other vaccines and given repeatedly over a period of time. In 2013, a physician committee at the Institute of Medicine (IOM), National Academy of Sciences, pointed out that the current federally recommended childhood vaccine schedule for infants and children from birth to age 6 had not been adequately studied for safety.10

The physicians and IOM staff only were able to identify fewer than 40 studies published in the previous 10 years that addressed the 0- to 6-year-old child vaccine schedule.

The IOM committee concluded there was not enough scientific evidence to determine whether or not the numbers of doses and timing of federally recommended vaccines children receive in the first six years of life are associated with health problems in premature infants or the development of chronic brain and immune system disorders that affect a child’s intellectual development, learning, attention, communication and behavior, such as ADD/ADHD, learning disabilities and autism.

This is why Mawson’s pilot studies have great value and why many more studies comparing the health of vaccinated and unvaccinated children must be conducted. As noted by the IOM’s11 2013 “Childhood Immunization Schedule and Safety” report, studies are needed to examine the:

  • Long-term cumulative effects of vaccines
  • Timing of vaccination in relation to the age and health of the child
  • Effects of the total load or number of vaccines given at one time
  • Effect of vaccine ingredients in relation to health outcomes
  • Biological mechanisms of vaccine-associated injury

It’s also important for people to understand that the Vaccine Safety Datalink (VSD) database, which the U.S. Centers for Disease Control and Prevention (CDC) uses to publish studies concluding that vaccine risks are negligible or nonexistent, is a closed database.12

The patient medical records data in the VSD is obtained from HMOs that are paid by the CDC to participate. VSD medical records data is not readily available to researchers, if at all, making the CDC’s conclusions virtually impossible to replicate and verify. This simply isn’t right because it prevents independent confirmation of the CDC’s conclusions that vaccine risks are minimal and the government’s early childhood vaccine schedule is safe, thereby contributing to the poor evidence base for or against vaccine safety.

Summary of Findings

The authors of the recently published study on premature birth, vaccination and neurodevelopmental disorders summarize their findings as follows:

  • Preterm birth without vaccination was not associated with NDD
  • Term birth with vaccination was associated with a 2.7-fold (270 percent) increase in the odds of NDD
  • Preterm birth with vaccination was associated with a 5.4-fold increase in the odds of NDD compared to the odds of NDD given term birth and vaccination
  • Preterm birth with vaccination was associated with a 12.3-fold increased odds of NDD compared to preterm birth without vaccination (not technically significant because no child in the sample with an NDD was both preterm and unvaccinated)
  • Preterm birth with vaccination was associated with a 14.5-fold increased odds of NDD compared to being neither preterm nor vaccinated

In adjusted regression analyses, the association between vaccination and NDD remained even after taking other contributing factors into account. In the final adjusted model, the combination of preterm birth with vaccination was associated with a 660 percent increased odds of NDD, “suggesting a synergistic effect.” How do the authors explain these findings? A “tentative hypothesis” for why preemies are at increased risk for NDD was associated with receipt of one or more vaccines. The authors concluded:

“Receipt of one or more vaccines could precipitate NDD in some preterm infants by exacerbating a preexisting inflammatory state associated with prematurity, leading to hepatic encephalopathy and hypoxic-ischemic brain damage. Impaired liver function is a predisposing factor for preterm birth and the latter is associated with increased risks of hypoxic-ischemic brain injury …

Consistent with this hypothesis, liver dysfunction is reported as an adverse effect of vaccination and as a feature of children with autism. Furthermore, hyperbilirubinemia is associated with hypoxic-ischemic brain damage and is a feature of the preterm infant as well as children with later-onset cognitive disorders and ASD.”

Pilot Study Compares Health of Vaccinated and Unvaccinated Children

The second paper,13 published on the same issue of the journal, was a pilot study “designed as a cross-sectional survey of homeschooling mothers on their vaccinated and unvaccinated biological children ages 6 to 12,” in which a wider range of health outcomes was evaluated. The results showed vaccinated children were:

“[S]ignificantly more likely to have been diagnosed with pneumonia, otitis media, allergies and NDD (that is, ASD, ADHD and/or a learning disability). The vaccinated were also more likely to use allergy medication, to have had myringotomies with tube placement, visited a doctor for a health problem in the previous year, and been hospitalized at some time in the past.”

More specifically, the results showed vaccinated children (whether partially or fully vaccinated) were significantly more likely than the unvaccinated to have been diagnosed with:

  • Otitis media (19.8 percent versus 5.8 percent)
  • Pneumonia (6.4 percent versus 1.2 percent
  • Allergic rhinitis (10.4 percent versus 0.4 percent) as well as other allergies (22.2 percent versus 6.9 percent)
  • Eczema/atopic dermatitis (9.5 percent versus 3.6 percent)
  • Any chronic illness (44 percent versus 25 percent)

IOM’s Vaccine Safety Review Is Still of Massive Importance

This is a perfect time to mention the IOM’s vaccine safety review, “Adverse Effects of Vaccines: Evidence and Causality,”14 published in August 2011. Along with other reports the IOM has published on vaccine safety issues beginning in 1991, it is one of the most important scientific reviews of evidence in the medical literature that vaccines can cause injury and death.

The National Academy of Sciences (NAS) through the IOM (recently renamed Health and Medicine Division) historically has analyzed health policies and issued reports at the request of the U.S. government. Considered worldwide to be a prestigious scientific body, the NAS is funded not just by federal agencies, but also by pharmaceutical companies and independent philanthropic organizations and individuals.

Although vaccine safety advocates have criticized the IOM’s reports as being too conservative and minimizing the full extent of vaccine risks, no other recognized scientific authority has so clearly acknowledged that vaccines do cause harm, especially for susceptible individuals, and that there are large vaccine science knowledge gaps about safety that need to be addressed.

The first IOM reports on vaccine safety came out in 1991 (pertussis and rubella vaccines)15 and 1994 (DPT, polio, tetanus, diphtheria, measles, mumps, HIB and hepatitis B vaccines).16,17

However, the IOM’s 2011 review of recent medical literature was significant because it was quite comprehensive. Over a period of three years, a physician committee reviewed over 1,000 vaccine studies related to safety issues. Interestingly, and importantly, they excluded studies funded by the pharmaceutical industry. The IOM review focused on eight vaccines:

Hepatitis A-hepatitis B Measles, mumps and rubella vaccine Meningococcal vaccine Pneumococcal vaccine
Diphtheria, tetanus and acellular pertussis, also known as DTaP or Tdap Varicella zoster (chickenpox) HPV vaccine Influenza vaccine

Shocking Conclusion: IOM Unable to Make Causation Conclusions for Most Vaccine-Related Adverse Health Outcomes

Perhaps the most important thing the IOM did in this review was that they looked at two categories of science:

  1. Epidemiological research (large studies comparing the health outcomes of different groups of people)
  2. Bench science (basic science research into the biological mechanisms at work in the body at the cellular and molecular level)

This is important because many of the studies the CDC relies on as evidence that vaccines don’t cause any problems are epidemiological studies and, if poor methodology is used, the conclusions of epidemiological studies can be fatally flawed. In the 2011 review, the IOM committee reviewed both kinds of science.

The most shocking conclusion of this report is that, for more than 100 adverse health outcomes reported after the eight vaccines were given, the IOM committee was unable to determine whether or not the vaccines caused a commonly reported brain or immune system disorder.

In short: The scientific evidence was insufficient to make a conclusion in most cases. So the committee was unable to confirm or deny causation for most reported poor health outcomes following receipt of certain vaccines, such as multiple sclerosis, lupus and autism.

IOM Did Not Exonerate Vaccines as Being Safe for Everyone

Why was the IOM unable to determine whether there was a direct causative link between vaccines and the many serious health outcomes evaluated in these studies? Barbara Loe Fisher, founder of the National Vaccine Information Center,, which is, unquestionably, the best resource for accessing referenced information on U.S. vaccine policy and law and the safety and effectiveness of vaccines, suggested four possible explanations:

  1. The studies were not available in the published literature
  2. There were too few studies showing the same link
  3. The available studies were methodologically unsound
  4. The available studies were conflicting (i.e., there was evidence both for and against)

In the video above, I interview Fisher about this important IOM report. At the time, Fisher stated:

“What I call this category is the ‘We Don’t Know’ category. When you think about it, these vaccines are mandated for children, and yet in most instances the scientific evidence [of safety] is so poor, they don’t know!

When the report came out, there were a lot of organizations like the American Academy of Pediatrics that came forth and said, ‘They didn’t find causation … so vaccines are safe.’ That’s NOT what that report said at all. I think people need to understand the significance of it … [T]he category of ‘We Don’t Know’ is a very important category.”

IOM Proposed Individual Susceptibility May Be a Cofactor

Importantly, the IOM report also discussed individual susceptibility: the fact that some people are more vulnerable to suffering vaccine reactions and injury for biological, genetic and environmental reasons.

According to the report, both epidemiologic and biological mechanism research suggests that many individuals who experience an adverse reaction to vaccines have a preexisting susceptibility. However, the report also states that in most cases physicians DO NOT KNOW what those individual susceptibilities are and cannot predict ahead of time who will be harmed by vaccination.

That said, the physician committee conducting the 2011 IOM medical literature review listed some individual susceptibilities they believe may be important, including:

  • Genetic variation
  • Age
  • Coinciding illness
  • Environmental factors

It’s a 600-page report, so it’s not light reading by any means. Still, every physician who administers vaccines really should read it. It’s part of their responsibility to be informed about what’s in the published medical literature. This report makes it clear that when a patient’s health deteriorates after vaccination, you cannot simply brush it off as a coincidence.

Doctors have a responsibility to take each instance of a health problem that follows vaccination seriously, especially emergency room visits, hospitalizations, injuries and deaths, and file a report with the federal Vaccine Adverse Event Reporting System (VAERS).

When an individual experiences a deterioration in health after vaccination, doctors also need to understand the danger of giving more vaccinations until or unless the vaccine can be conclusively exonerated as a causative or contributing factor to that health deterioration. And guess what? For over 100 adverse events, science says they do not know whether the vaccine might be a causative factor.

What this tells us is that physicians — or anyone — recommending and administering vaccines to people, particularly to vulnerable infants and children, need to apply the precautionary principle of “first do no harm.” This is critically important when the foundation of science supporting the safety of any given vaccine, alone or in combination, for any given individual is so weak.