Pilot comparative study on the health of vaccinated and unvaccinated 6- to 12- year old U.S. children

Abstract

Vaccinations have prevented millions of infectious illnesses, hospitalizations and deaths among U.S. children, yet the long-term health outcomes of the vaccination schedule remain uncertain. Studies have been recommended by the U.S. Institute of Medicine to address this question. This study aimed 1) to compare vaccinated and unvaccinated children on a broad range of health outcomes, and 2) to determine whether an association found between vaccination and neurodevelopmental disorders (NDD), if any, remained significant after adjustment for other measured factors. A cross-sectional study of mothers of children educated at home was carried out in collaboration with homeschool organizations in four U.S. states: Florida, Louisiana, Mississippi and Oregon. Mothers were asked to complete an anonymous online questionnaire on their 6-to 12-year-old biological children with respect to pregnancy-related factors, birth history, vaccinations, physician-diagnosed illnesses, medications used, and health services. NDD, a derived diagnostic measure, was defined as having one or more of the following three closely-related diagnoses: a learning disability, Attention Deficient Hyperactivity Disorder, and Autism Spectrum Disorder. A convenience sample of 666 children was obtained, of which 261 (39%) were unvaccinated. The vaccinated were less likely than the unvaccinated to have been diagnosed with chickenpox and pertussis, but more likely to have been diagnosed with pneumonia, otitis media, allergies and NDD. After adjustment, vaccination, male gender, and preterm birth remained significantly associated with NDD. However, in a final adjusted model with interaction, vaccination but not preterm birth remained associated with NDD, while the interaction of preterm birth and vaccination was associated with a 6.6-fold increased odds of NDD (95% CI: 2.8, 15.5). In conclusion, vaccinated homeschool children were found to have a higher rate of allergies and NDD than unvaccinated homeschool children. While vaccination remained significantly associated with NDD after controlling for other factors, preterm birth coupled with vaccination was associated with an apparent synergistic increase in the odds of NDD. Further research involving larger, independent samples and stronger research designs is needed to verify and understand these unexpected findings in order to optimize the impact of vaccines on children's health.

Beliefs about Vaccinations: Comparing a Sample from a Medical School to That from the General Population

“…It is possible that the focus on differing views on vaccinations in the social media may contribute to individuals’ varied opinions regarding the factual and mythical vaccination information. Further research evaluating the long-term efficacy and safety of present childhood vaccinations by comparing the health outcomes of vaccinated and unvaccinated children would provide greater support for the development of individuals’ perceptions of vaccinations [ 41 ]. Additional studies should be conducted to further examine reasons why there is a lack of consensus among those with expertise knowledge in a given field.…”

Non-specific effects of vaccinations in high-income settings: How to address the issue?

“…In this way, the control groups should not be afraid of the transmissible diseases prevented by the vaccines in evaluation, because the participants would not be concentrated in a confined territory, and the herd immunity effect of the vast majority of vaccinees would protect them. Probably, they will contract anyway a higher number of the infectious diseases targeted by the specific vaccines evaluated in the RCT, as it is already well documented in cross-sectional studies 25 or in population cohorts 24 . Nevertheless, having they voluntarily done the informed choice to adhere to a blinded RCT, the risk of incurring in some more vaccine-preventable infectious diseases should not be a great personal or ethical problem.…”

“…To partially overcome the systematic differences between the two different populations of vaccinated and unvaccinated, a researcher has conceived an innovative, pilot comparative study, on the health of vaccinated and unvaccinated 6-12year-old U.S. children educated at home 25 .…”

“…Homeschool families have somewhat more years of formal education and a higher average family size (just over three children) compared to the national average of just over two children. The main reasons for homeschooling was an aim to a moral environment, better family relationships, or for more contact with their children 25 . These families are more homogeneous than those compared in KIGGS 24 , and this might theoretically limit the structural environmental differences that bias other similar observational comparisons.…”

“…The two studies 25,26 have generated many interesting hypotheses, but they suffer by a major weakness, that can bias the results. Indeed, the incipit of the letter to parents likely induce the response of those mothers who believe that their children have had a damage from vaccination, and not of those whose children have not had any harm.…”