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Research Article
Journal of Translational Science
ISSN: 2059-268X
J Transl Sci, 2021 doi: 10.15761/JTS.1000459 Volume 7: 1-11
Health effects in vaccinated versus unvaccinated children,
with covariates for breastfeeding status and type of birth
Brian S. Hooker1
* and Neil Z. Miller2
1
Department of Sciences and Mathematics, Simpson University, Redding, California 96003 USA
2
Institute of Medical and Scientific Inquiry, Santa Fe, New Mexico 87506 USA
*Correspondence to: Brian S. Hooker, Department of Sciences and Mathematics,
Simpson University, Redding, California 96003 USA, E-mail: drbrianhooker@
gmail.com
Key words: vaccination, breastfeeding, cesarean section, autism, attention
deficit, asthma
Received: April 03, 2021; Accepted: May 29, 2021; Published: June 12, 2021
Introduction
Vaccination is the predominant public health practice utilized by
nations to prevent the spread of communicable illnesses. In the United
States, fully vaccinated children receive 26 vaccine doses by 15 months
of age to protect against 14 different infections [1]. By 18 years of age,
the Centers for Disease Control and Prevention (CDC) recommends
54 inoculations against 16 diseases: hepatitis A and B, Haemophilus
influenzae type B (Hib), diphtheria, tetanus, pertussis, polio, rotavirus,
influenza, pneumococcus, meningococcus, measles, mumps, rubella,
varicella, and human papillomavirus [1].
In 2011, the National Academy of Medicine (NAM), formerly called
the Institute of Medicine (IOM), published the report, Adverse Effects
of Vaccines: Evidence and Causality, where the relationships between
specific vaccines and different adverse health effects were considered
[2]. Based on the scientific literature at the time, the IOM committee
found inadequate evidence to accept or reject a causal association
between 135 of 158 relationships between vaccines and adverse events.
Among the remaining 23 adverse events, 18 were found to be associated
with vaccination and five were not. That same year, the U.S. Department
of Health and Human Services funded a health survey that estimated
54% of U.S. children have at least 1 of 22 chronic health conditions
[3], up from 12.8% in 1994 [4]. Although the causes of these persistent
health ailments are undoubtedly multifaceted, some studies have found
significant relationships between vaccines and many of these conditions,
including allergies [5,6], asthma [6,7], attention deficit disorder (ADD/
ADHD) [5,8-10], autism [5,11-13], ear infections [5,14,15], seizures
[16-18], developmental delay [5,9,19], diabetes [20-22], and more.
Several factors could contribute to whether a child will have a
vaccine-associated adverse event, including a genetic predisposition,
illness (which might be a contraindication to vaccine administration),
quality of vaccines (which can vary by manufacturing methods),
Abstract
Using survey data from respondents associated with three medical practices in the US, vaccinated children were compared to unvaccinated children for the incidence
of severe allergies, autism, gastrointestinal disorders, asthma, ADHD, and chronic ear infections. All diagnoses were based on parental reporting with chart review for
confirmation of diagnoses. Cases were stratified with non-cases based on year of birth and sex, and compared using a logistic regression model which also accounted
for breastfeeding status and type of birth (vaginal versus cesarean section). Vaccinated children were significantly more likely than unvaccinated children to be
diagnosed with severe allergies (OR = 4.31, 95% CI 1.67 – 11.1), autism (OR = 5.03, 95% CI 1.64 – 15.5), gastrointestinal disorders (OR = 13.8, 95% CI 5.85 – 32.5),
asthma (OR = 17.6, 95% CI 6.94 – 44.4), ADHD (OR = 20.8, 95% CI 4.74 – 91.2), and chronic ear infections (OR = 27.8, 95% CI 9.56 – 80.8). Vaccinated children
were less likely to be diagnosed with chickenpox (OR = 0.10, 95% CI 0.029 – 0.36). Children who were “vaccinated and not breastfed” or “vaccinated and delivered
via cesarean section” had the highest rates of adverse health outcomes. In this study, higher ORs were observed within the vaccinated versus unvaccinated groups for
several adverse health conditions. Further research is essential to understand the full scope of health effects associated with childhood vaccination.
and sensitivity to one or more vaccine components. Some infants
might be more susceptible to an adverse reaction due to biochemical
or synergistic toxicity associated with concurrent administration of
multiple vaccines. For instance, Goldman and Miller [23] found linear
relationships between the number of vaccine doses administered at
one time and rates of hospitalization and mortality; additionally, the
younger the infant at the time of vaccination, the higher the risk of
serious deleterious events.
In 2013, NAM acknowledged that studies are needed to compare
health outcomes between fully vaccinated, partially vaccinated, and
completely unvaccinated children [24]. Such research should investigate
potential short- and long-term health effects associated with modified
vaccine schedules, as occurs when children receive fewer vaccines per
well-child visit than recommended or when vaccines are received later
than recommended. Very few studies exist where health outcomes
associated with the pediatric vaccination schedule have been assessed.
This is partly due to ethical concerns of withholding vaccines from
an unvaccinated control group within such a study [24]. Indeed, this
precludes the use of double-blinded studies on vaccine health effects,
and even in clinical trials an earlier version of the same vaccine is often
used as the placebo control for the newly tested vaccine.
One study, by Mawson et al. [5], compared entirely unvaccinated
children to partially vaccinated and fully vaccinated children. The
Hooker BS (2021) Health effects in vaccinated versus unvaccinated children, with covariates for breastfeeding status and type of birth
J Transl Sci, 2021 doi: 10.15761/JTS.1000459 Volume 7: 2-11
vaccinated children showed higher odds of being diagnosed with
pneumonia, ear infections, allergies and neurodevelopmental disorders.
In another more recent study by Hooker and Miller [25], vaccinated
children were compared to unvaccinated children during the first
year of life for later incidence of health consequences. Vaccination
before 1 year of age was associated with increased odds of being
diagnosed with developmental delays, asthma, and ear infections. In
secondary analyses, higher odds ratios (ORs) were also detected for
gastrointestinal disorders. Lyons-Weiler and Thomas [26] found higher
rates of office visits and diagnoses of common chronic ailments in the
most vaccinated children as compared to children who were completely
unvaccinated.
In the study presented here, children from three pediatric medical
practices in the United States were used as a convenience sample to
compare health outcomes in fully vaccinated, partially vaccinated,
and completely unvaccinated populations. Vaccination records and
diagnoses were based on a parental survey, though in a separate analysis
diagnoses of children were confirmed with chart review from the
participating pediatricians’ electronic medical records. The evaluated
health outcomes include severe allergies, autism, gastrointestinal
disorders, asthma, attention deficit disorders (ADD/ADHD), and
chronic ear infections. A control diagnosis of chickenpox was also
evaluated. Breastfeeding status and type of birth—vaginal delivery
versus a cesarean section—were considered.
Methods
Source of data: Patient data were obtained from a voluntary survey
instrument (see Supplemental Appendix) given online primarily
to participants in three pediatric practices in the United States. All
questionnaire data including patient identification were kept on a
separate, secure drive and all data files were de-identified, such that
specific patient identification could not be made, prior to statistical
analysis, in accordance with IRB guidelines. The Institutional Review
Board at Simpson University for research with human subjects reviewed
and authorized this analysis independent of the researchers.
A total of 1929 surveys were completed for the analysis. This was
limited to children born between January 1, 1998 and December 31,
2016. In addition, children with congenital conditions leading to
diagnoses (based on limited chart review) were omitted from the study.
This left 1565 children in the cohort (Figure 1).
Parents who completed the survey rated their children’s vaccination
status as “no vaccines,” “partially vaccinated” or “vaccines up-to-date.”
Parents then selected from the following health conditions/disorders
that their child either had or had not been diagnosed with: severe allergy
(requiring prescription epi-pen), autism, chronic gastrointestinal issues
(recurrent or chronic constipation or diarrhea), asthma (moderate to
severe), ADD/ADHD (requiring medication), and chronic ear infections
(3 or more per 12 months). Seizures (requiring medication) and type
Total patients completing first
online survey (n = 1929)
Remaining patients
born between Jan. 1, 1998
and Dec. 31, 2016 with no
congenital defects (n = 1565)
Excluded patients with
congenital defects and not born
between Jan. 1, 1998
and Dec. 31, 2016 (n = 364)
Analysis – n = 1208 within the
participating practices,
n = 337 not within participating
practices, and n = 20 unknown
Total patients completing
second online survey
(n = 935) Excluded patients with
congenital defects and not born
between Jan. 1, 1998
and Dec. 31, 2016 (n = 104) Remaining patients
born between Jan. 1, 1998
and Dec. 31, 2016 with no
congenital defects (n = 831)
Figure 1. Creation of study cohorts for each analysis
Hooker BS (2021) Health effects in vaccinated versus unvaccinated children, with covariates for breastfeeding status and type of birth
J Transl Sci, 2021 doi: 10.15761/JTS.1000459 Volume 7: 3-11
1 diabetes were considered for assessment, but there were insufficient
numbers of cases to complete a statistical analysis. Additionally, parents
were asked about the type of birth (vaginal or cesarean), if the child
was exclusively breastfed for a 6 month duration or longer, and current
education status of the child (public/private school or home educated).
In a second, follow-up survey, parents were asked if their children
ever had chickenpox (as a positive control diagnosis). There were 935
responses to the second survey (among those who also completed the
first survey) and of those, 831 were carried forward to the main analysis,
based on previously discussed exclusion criteria (Figure 1). Parents
who completed the initial survey also indicated whether their children
were patients in one of the three pediatric practices participating in the
study. Of the 1565 children in the cohort, 77.2% were in a participating
medical practice, 21.5% were not (typically, they were friends or
relatives of families who were associated with one of the participating
medical practices), and 1.3% did not respond to the question. Parents of
children who were patients in the participating medical practices selfidentified, which enabled diagnoses of children to be confirmed with
chart review from the participating pediatricians’ electronic medical
records.
Analysis method: Data were analyzed for relationships between
vaccination status and the different conditions considered using a
cohort design in a logistic regression model. SAS® University Edition
was used for statistical analyses with relationships deemed significant
at p < 0.05 without correction for the number of statistical tests
performed. For fully vaccinated versus unvaccinated, the study was
designed to have a power of 80% to detect an odds ratio of 2.4 with a
95% probability and 90% to detect an odds ratio of 2.7. For partially
vaccinated versus unvaccinated, the study was designed to have a power
of 80% to detect an odds ratio of 1.8 with a 95% probability and 90%
to detect an odds ratio of 1.96. Given that different diagnoses may
be more or less likely depending on the age of patient and sex, cases
and non-cases were stratified based on year of birth and sex. Each
condition was evaluated with and without covariates, which included
breastfeeding status and type of birth. In the first analysis, outcomes for
children with “vaccines up-to-date” were compared directly to those for
“unvaccinated” children. This analysis was completed with and without
covariates. In the second analysis, outcomes for “partially vaccinated
children” were compared directly to those for “unvaccinated children”
which was also completed with and without covariates. In analyses
based on children from participating medical practices only, and chart
review to confirm diagnoses, unvaccinated children were compared
to children who received any vaccine (where “partially vaccinated
children” and children with “vaccines up-to-date” were combined into
one cohort). In further analyses, odds ratios were assessed for separate
categories of patients based on vaccination and breastfeeding status as
well as vaccination and birth delivery status. Odds ratios and p-values
were calculated using a simple 2×2 design with Fisher’s exact test.
Results
Demographic data: Demographic data for the study sample are
shown in table 1. After removing responses for children not within the
specified age range, the cohort size was 1565, of which, 945 (60.4%)
were completely unvaccinated, 484 (30.9%) were partially vaccinated
and 136 (8.7%) had vaccines up-to-date. Within the cohort, 81.7%
of the children were delivered vaginally and 18.3% were delivered
via cesarean section. Also, 80.9% were breastfed for at least 6 months
and 19.1% were not. In addition, 54.5% of the children were currently
enrolled in a public or private school, 34.9% were home educated, and
10.6% were either too young or too old for school. The evaluated health
conditions include allergies (4.3%), autism (2.9%), gastrointestinal
disorders (6.2%), asthma (3.7%), ADD/ADHD (2.0%), and chronic ear
infections (4.0%). Demographic data for the second survey are listed in
table 2 which included 831 children among the first survey respondents.
The proportions within this cohort were generally consistent with the
first group listed in table 1. Chickenpox was reported in 15.6% of the
children. Age data for the cohorts are listed in tables 3 and 4, where
the mean age of the children is generally between 9 and 11 years and
relatively consistent among the different subgroups.
Fully vaccinated versus unvaccinated children, with covariates:
Results from the logistic regression analysis of fully vaccinated children
(“vaccines up-to-date”) versus unvaccinated children are shown in
table 5. This model included covariates for breastfeeding status and
type of delivery as well as strata for year of birth and sex. A consistent
association was seen for all health conditions studied. Children up-todate with their vaccines were significantly more likely than unvaccinated
children to be diagnosed with severe allergies (OR = 4.31, 95% CI 1.67 –
11.1), autism (OR = 5.03, 95% CI 1.64 – 15.5), gastrointestinal disorders
(OR = 13.8, 95% CI 5.85 – 32.5), asthma (OR = 17.6, 95% CI 6.94 –
Category Male Female Total
Total Sample 808 757 1565
Unvaccinated 482 463 945 (60.4%)
Partially Vaccinated 255 229 484 (30.9%)
Vaccines up-to-date 71 65 136 (8.7%)
Vaginal Delivery 643 636 1279 (81.7%)
Cesarean Section 172 114 286 (18.3%)
Breastfed 642 624 1266 (80.9%)
Not Breastfed 166 133 299 (19.1%)
Public/Private School 439 414 853 (54.5%)
Home Educated 288 258 546 (34.9%)
Not in School 81 85 166 (10.6%)
Allergies (severe) 43 25 68 (4.3%)
Autism 38 12 50 (3.2%)
Gastrointestinal Disorders 51 46 97 (6.2%)
Asthma 41 17 58 (3.7%)
ADD/ADHD 18 14 32 (2.0%)
Ear Infections (chronic) 40 23 63 (4.0%)
Table 1. Demographic Data (First Questionnaire)
Hooker BS (2021) Health effects in vaccinated versus unvaccinated children, with covariates for breastfeeding status and type of birth
J Transl Sci, 2021 doi: 10.15761/JTS.1000459 Volume 7: 4-11
Category Male Female Total
Total Sample 444 387 831
Unvaccinated 253 213 466 (56.1%)
Partially Vaccinated 150 140 290 (34.9%)
Vaccines up-to-date 41 34 75 (9.0%)
Vaginal Delivery 339 325 664 (79.9%)
Cesarean Section 105 62 167 (20.1%)
Breastfed 349 317 666 (80.1%)
Not Breastfed 95 70 165 (19.9%)
Public/Private School 259 217 476 (57.3%)
Home Educated 143 121 264 (31.8%)
Not in School 42 49 91 (10.9%)
Chickenpox 70 60 130 (15.6%)
Table 2. Demographic Data (Second Questionnaire/Control Diagnosis)
Age in Years Mean Standard Deviation Minimum Maximum
Total cohort 9.79 5.13 2.5 21.47
Unvaccinated 9.05 4.95 2.5 21.47
Partially vaccinated 10.89 5.15 2.52 21.33
Vaccines up-to-date 11.03 5.36 2.79 21.14
Vaginal Delivery 10.00 5.25 2.5 21.47
Cesarean Section 8.85 4.46 2.55 21.22
Breastfed 9.62 5.15 2.5 21.47
Not Breastfed 10.50 4.98 2.52 21.34
Table 3. Additional Demographic Data (First Questionnaire)
Age in Years Mean Standard Deviation Minimum Maximum
Total cohort 9.99 5.17 2.5 21.34
Unvaccinated 8.88 4.93 2.5 21.34
Partially vaccinated 11.38 5.13 2.56 21.34
Vaccines up-to-date 11.56 5.19 3.26 20.75
Vaginal Delivery 10.32 5.30 2.5 21.34
Cesarean Section 8.69 4.40 2.56 21.23
Breastfed 9.81 5.24 2.5 21.34
Not Breastfed 10.73 4.84 2.56 21.34
Table 4. Additional Demographic Data (Second Questionnaire)
44.4), ADD/ADHD (OR = 20.8, 95% CI 4.74 – 91.2), and chronic ear
infections (OR = 27.8, 95% CI 9.56 – 80.8). The OR for chickenpox,
our positive control, reflected the protective effect of vaccination with a
significant relationship (OR = 0.10, 95% CI 0.029 – 0.36).
Partially vaccinated versus unvaccinated children, with
covariates: Results from the logistic regression analysis of partially
vaccinated children versus unvaccinated children are shown in table 6.
This model also included covariates for breastfeeding status and type of
delivery as well as strata for year of birth and sex. Again, a consistent
association was seen for all conditions studied with ORs ranging from
4.45 (95% CI 2.36 – 8.38) for allergies to 13.1 (95% CI 4.89 – 34.8) for
ear infections. All associations were statistically significant, and again
vaccination was protective against chickenpox (OR = 0.31, 95% CI
0.085 – 0.53).
Vaccinated versus unvaccinated children, no covariates: Results
from the logistic regression analysis with no covariates (but with strata
for year of birth and sex) are shown in Supplemental tables S1 and
S2 for fully vaccinated versus unvaccinated and partially vaccinated
versus unvaccinated, respectively. These results are consistent with
those obtained with covariates where all relationships are statistically
significant and vaccination is protective against chickenpox.
Table 5. Fully vaccinated children (“vaccines up-to-date”) versus unvaccinated children. Logistic regression model, stratified based on year of birth and sex, with covariates for breastfeeding
status and type of birth.
Diagnosis Vaccinated
Cases/Non-cases
Unvaccinated
Cases/Non-cases
Odds Ratio
(95% CI) p-value
Allergies (severe) 8/128 15/930 4.31 (1.67 – 11.1) 0.0025
Autism 7/129 9/936 5.03 (1.64 – 15.5) 0.0048
Gastrointestinal Disorders 22/114 12/933 13.8 (5.85 – 32.5) <0.0001
Asthma 23/113 8/937 17.6 (6.94 – 44.4) <0.0001
ADD/ADHD 10/126 3/942 20.8 (4.74 – 91.2) <0.0001
Ear Infections (chronic) 23/113 5/940 27.8 (9.56 – 80.8) <0.0001
Chickenpox 4/71 90/376 0.10 (0.029 – 0.36) 0.0004
Hooker BS (2021) Health effects in vaccinated versus unvaccinated children, with covariates for breastfeeding status and type of birth
J Transl Sci, 2021 doi: 10.15761/JTS.1000459 Volume 7: 5-11
Any vaccine versus unvaccinated children, participating medical
practices only: In table 7, only children from participating medical
practices (79.5% of the total cohort) were included in a logistic
regression analysis of children who received “any vaccine” (fully and
partially vaccinated children are counted together) versus unvaccinated
children. This model included covariates for breastfeeding status and
type of delivery as well as strata for year of birth and sex. Results
were consistent with the main analyses (Tables 5 and 6). Vaccinated
children were significantly more likely than unvaccinated children
to be diagnosed with all health conditions under consideration, and
vaccination was protective against chickenpox.
Any vaccine versus unvaccinated children, confirmed diagnoses
only: In table 8, only children with diagnoses confirmed from electronic
medical records (80.8% of the cohort of children who were patients
in one of the three participating medical practices) were included in
a logistic regression analysis of children who received “any vaccine”
(fully and partially vaccinated children are counted together) versus
unvaccinated children. This model included covariates for breastfeeding
status and type of delivery as well as strata for year of birth and sex.
Again, results were consistent with the main analyses. Vaccinated
children were significantly more likely than unvaccinated children to
be diagnosed with all health conditions under consideration.
Relationships between vaccination and breastfeeding status:
Relationships between vaccination and breastfeeding status, and
vaccination and birth delivery status, are shown in tables 9 and 10,
respectively. In these tables, fully and partially vaccinated children are
counted together. In table 9, children were placed into four groups:
1) unvaccinated and breastfed, 2) unvaccinated and not breastfed,
3) vaccinated and breastfed, 4) vaccinated and not breastfed. The
proportion of children affected by each adverse health condition
increases nearly consistently from one category to the next, with
the lowest percentages observed mainly among the “unvaccinated
and breastfed” children while the highest are observed among the
“vaccinated and non-breastfed” children. A consistent increase was
observed for allergies (1.5%, 2.1%, 6.0%, 13.9%), autism (0.8%, 2.1%,
5.3%, 9.4%), asthma (0.6%, 3.1%, 6.0%, 12.4%), and chronic ear
infections (0.5%, 1.0%, 7.4%, 13.4%). Additionally, odds ratios (and
p-values) were calculated utilizing “unvaccinated and breastfed” as the
Diagnosis Vaccinated
Cases/ Non-cases
Unvaccinated
Cases/ Non-cases
Odds Ratio
(95% CI) p-value
Allergies (severe) 45/439 15/930 4.45 (2.36 – 8.38) <0.0001
Autism 34/450 9/936 5.13 (2.32 – 11.3) <0.0001
Gastrointestinal Disorders 63/421 12/933 10.4 (5.39 – 20.0) <0.0001
Asthma 27/457 8/937 5.30 (2.29 – 12.3) 0.0001
ADD/ADHD 19/465 3/942 8.25 (2.31 – 29.5) 0.0012
Ear Infections (chronic) 35/449 5/940 13.1 (4.89 – 34.8) <0.0001
Chickenpox 36/254 90/376 0.31 (0.085 – 0.53) <0.0001
Table 6. Partially vaccinated children versus unvaccinated children. Logistic regression model, stratified based on year of birth and sex, with covariates for breastfeeding status and type of
birth
Diagnosis Vaccinated
Cases/ Non-cases
Unvaccinated
Cases/ Non-cases
Odds Ratio
(95% CI) p-value
Allergies (severe) 38/415 8/747 6.04 (2.67 – 13.7) <0.0001
Autism 29/424 7/748 5.29 (2.17 – 12.9) 0.0003
Gastrointestinal Disorders 41/412 8/747 8.43 (3.76 – 18.9) <0.0001
Asthma 22/431 5/750 5.95 (2.14 – 16.5) 0.0006
ADD/ADHD 17/436 3/752 5.97 (1.60 – 22.3) 0.0079
Ear Infections (chronic) 38/415 3/752 19.7 (5.83 – 66.2) <0.0001
Chickenpox 33/239 70/340 0.32 (0.18 – 0.57) <0.0001
Table 7. Children from participating medical practices only. Logistic regression model, “any vaccine received”* versus unvaccinated, stratified based on year of birth and sex, with covariates
for breastfeeding status and type of birth.
*The vaccinated cohort includes children who received any vaccine (fully and partially vaccinated children are counted together).
Diagnosis Vaccinated
Cases/ Non-cases
Unvaccinated
Cases/ Non-cases
Odds Ratio
(95% CI) p-value
Allergies (severe) 36/394 6/734 7.75 (3.11 – 19.3) <0.0001
Autism 27/403 3/737 13.0 (3.73 – 45.0) 0.0001
Gastrointestinal Disorders 36/394 4/736 14.4 (4.94 – 41.7) <0.0001
Asthma 18/412 4/736 6.06 (1.96 – 18.8) 0.0018
ADD/ADHD 12/418 1/739 12.7 (1.50 – 107) 0.020
Ear Infections (chronic) 28/402 2/738 22.6 (5.18 – 99.1) <0.0001
Table 8. Children with diagnoses confirmed from electronic medical records.† Logistic regression model, “any vaccine received”* versus unvaccinated, stratified based on year of birth and
sex, with covariates for breastfeeding status and type of birth.
* The vaccinated cohort includes children who received any vaccine (fully and partially vaccinated children are counted together). † Chickenpox diagnoses could not be confirmed via chart
review because many families did not visit the physician for such a diagnosis.
Hooker BS (2021) Health effects in vaccinated versus unvaccinated children, with covariates for breastfeeding status and type of birth
J Transl Sci, 2021 doi: 10.15761/JTS.1000459 Volume 7: 6-11
Unvaccinated + Breastfed
Reference
diagnoses/total
Unvaccinated + Not Breastfed
OR (p-value)
diagnoses/total
Vaccinated + Breastfed
OR (p-value)
diagnoses/total
Vaccinated + Not Breastfed
OR (p-value)
diagnoses/total
Allergies (severe) Ref.
13/848 (1.5%)
1.35 (0.66)
2/97 (2.1%)
4.09 (<0.0001)
25/418 (6.0%)
10.3 (<0.0001)
28/202 (13.9%)
Autism Ref.
7/848 (0.8%)
2.53 (0.23)
2/97 (2.1%)
6.67 (<0.0001)
22/418 (5.3%)
12.5 (<0.0001)
19/202 (9.4%)
Gastrointestinal Disorders Ref.
11/848 (1.3%)
0.79 (1.0)
1/97 (1.0%)
9.87 (<0.0001)
48/418 (11.5%)
17.1 (<0.0001)
37/202 (18.3%)
Asthma Ref.
5/848 (0.6%)
5.38 (0.040)
3/97 (3.1%)
10.7 (<0.0001)
25/418 (6.0%)
23.8 (<0.0001)
25/202 (12.4%)
ADD/ADHD Ref.
3/848 (0.4%)

0/97 (0%)
9.04 (<0.0001)
13/418 (3.1%)
24.2 (<0.0001)
16/202 (7.9%)
Ear Infections
(chronic)
Ref.
4/848 (0.5%)
2.20 (0.42)
1/97 (1.0%)
16.9 (<0.0001)
31/418 (7.4%)
32.6 (<0.0001)
27/202 (13.4%)
Table 9. Relationships between vaccination* and breastfeeding status,† with odds ratios (and p-values) based on “unvaccinated and breastfed” as the reference group.
*The vaccinated cohort includes children who received any vaccine (fully and partially vaccinated children are counted together). † Exclusively breastfed for ≥ 6 months versus not
exclusively breastfed for ≥ 6 months.
Unvaccinated + Vaginal Delivery
Reference
diagnoses/total
Unvaccinated + C-section
OR (p-value)
diagnoses/total
Vaccinated + Vaginal Delivery
OR (p-value)
diagnoses/total
Vaccinated + C-section
OR (p-value)
diagnoses/total
Allergies (severe) Ref.
9/802 (1.1%)
3.86 (0.017)
6/143 (4.2%)
7.41 (<0.0001)
37/477 (7.8%)
11.1 (<0.0001)
16/143 (11.2%)
Autism Ref.
5/802 (0.6%)
4.59 (0.034)
4/143 (2.8%)
9.19 (<0.0001)
26/477 (5.5%)
18.7 (<0.0001)
15/143 (10.5%)
Gastrointestinal Disorders Ref.
8/802 (1.0%)
2.86 (0.093)
4/143 (2.8%)
13.7 (<0.0001)
58/477 (12.2%)
23.1 (<0.0001)
27/143 (18.9%)
Asthma Ref.
3/802 (0.4%)
9.65 (0.0028)
5/143 (3.5%)
25.0 (<0.0001)
41/477 (8.6%)
17.9 (<0.0001)
9/143 (6.3%)
ADD/ADHD Ref.
3/802 (0.4%)

0/143 (0%)
11.7 (<0.0001)
20/477 (4.2%)
17.9 (<0.0001)
9/143 (6.3%)
Ear Infections (chronic) Ref.
4/802 (0.5%)
1.40 (0.56)
1/143 (0.7%)
22.3 (<0.0001)
48/477 (10.1%)
15.0 (<0.0001)
10/143 (7.0%)
Table 10. Relationships between vaccination* and birth delivery status, with odds ratios (and p-values) based on “unvaccinated and vaginal delivery” as the reference group.
* The vaccinated cohort includes children who received any vaccine (fully and partially vaccinated children are counted together).
reference group. Children who were “vaccinated and not breastfed”
were significantly more likely than children who were “unvaccinated
and breastfed” to be diagnosed with all health conditions studied.
Relationships between vaccination and birth delivery status: In
table 10, children were also placed into four groups: 1) unvaccinated
and vaginal delivery, 2) unvaccinated and C-section, 3) vaccinated and
vaginal delivery, 4) vaccinated and C-section. Again, the proportion
of children affected by each adverse health condition increases nearly
consistently from one category to the next, with the lowest percentages
observed mainly among the unvaccinated children delivered vaginally
while the highest are observed mainly among the vaccinated children
delivered via C-section. A consistent increase was observed for allergies
(1.1%, 4.2%, 7.8%, 11.2%), autism (0.6%, 2.8%, 5.5%, 10.5%), and
gastrointestinal disorders (1.0%, 2.8%, 12.2%, 18.9%). Additionally,
odds ratios (and p-values) were calculated utilizing “unvaccinated and
vaginal delivery” as the reference group. Children who were vaccinated
and delivered via C-section were significantly more likely than children
who were unvaccinated and delivered vaginally to be diagnosed with all
health conditions studied.
Relationships between covariates and all health conditions
under consideration: Relationships between covariates and all
health conditions under consideration were analyzed as well (shown
in Supplemental tables S3 and S4). Results were significant for
breastfeeding in cases of allergies (p=0.0076), asthma (p=0.0016), ear
infections (p=0.017) and chickenpox (p=0.0098). Breastfed children
were less likely to be diagnosed with allergies, asthma and ear infections,
but more likely to have had chickenpox. A significant relationship was
seen between delivery status in the case of gastrointestinal disorders
(p=0.011); this diagnosis was more common in children delivered via
C-section.
Discussion
The National Academy of Medicine recently acknowledged
that studies are needed to compare health outcomes between fully
vaccinated, partially vaccinated, and completely unvaccinated children
[26]. Thus far, this has not been undertaken by the institutions most
capable of conducting such studies (e.g., the CDC and World Health
Organization). Instead, more vigorous strategies are being employed
to achieve the highest possible vaccine coverage rates, resulting in the
loss of unvaccinated populations which are vital as control groups to
scientifically monitor true rates of adverse events associated with
vaccination.
In the study presented here, several acute and chronic adverse
health outcomes were found to be more likely in fully and partially
vaccinated children as compared to an unvaccinated child population.
Within the logistic regression models that included covariates for
breastfeeding status and type of delivery as well as strata for year of
birth and sex (Tables 5 and 6), all health conditions under consideration
showed highly significant relationships, with ORs ranging from 4.31
(95% CI 1.67 – 11.1) for allergies to 27.8 (95% CI 9.56 – 80.8) for chronic
ear infections in fully vaccinated children. Although partially and fully
vaccinated children were significantly more likely than unvaccinated
children to have adverse health diagnoses, ORs were considerable more
elevated in the fully vaccinated cohort, suggestive of a dose-response
Hooker BS (2021)

Health effects in vaccinated versus unvaccinated children, with covariates for breastfeeding status and type of birth
J Transl Sci, 2021 doi: 10.15761/JTS.1000459 Volume 7: 7-11
relationship or synergisitic toxicity. In partially vaccinated versus fully
vaccinated children, ORs increased from 10.4 to 13.8 for gastrointestinal
disorders, 5.30 to 17.6 for asthma, 8.25 to 20.8 for attention deficit
disorder, and 13.1 to 27.8 for chronic ear infections. For allergies and
autism, the ORs declined slightly but remained highly significant.

For chickenpox, the OR decreased from 0.31 to 0.10, confirming a protective
benefit of vaccination. According to the CDC, two doses of the varicella
vaccine are more than 90% effective at preventing this disease [27].
Data were available regarding each child’s current education status
(public/private school versus home educated). However, some of the
children were not school-aged which decreased the cohort size and
reduced statistical power, so covariates in this paper reflect breastfeeding
status and birth type only. Also, it was not possible to distinguish
between children who went to a public versus private school. Still, for
comparative purposes Tables 5 and 6 were recalculated (in unpublished
analyses) with current education status included as a covariant. Type of
education correlated with vaccination status indicating that children in
public/private schools were more likely than home educated children
to be vaccinated. In addition, all ORs were within the 95% confidence
interval of previous runs without the education variable, that is,
they were consistent with findings in the main analyses. Vaccinated
children were significantly more likely than unvaccinated children
to be diagnosed with all health conditions under consideration, and
vaccination was protective against chickenpox.
Within the logistic regression model that only considered children
from participating medical practices (Table 7), all health conditions
under consideration showed highly significant relationships, with ORs
ranging from 5.29 (95% CI 2.17 – 12.9) for autism to 19.7 (95% CI
5.83 – 66.2) for chronic ear infections. Within the logistic regression
model that only considered children with diagnoses confirmed from
electronic medical records (Table 8), again, all health conditions
under consideration showed highly significant relationships, with ORs
ranging from 6.06 (95% CI 1.96 – 18.8) for asthma to 22.6 (95% CI 5.18
– 99.1) for chronic ear infections. (Chickenpox diagnoses could not
be confirmed via chart review because many families did not visit the
physician for such a diagnosis.)
Although some studies were unable to find correlations between
vaccines and asthma [28,29], a relationship between vaccination and
allergies, including asthma, has been reported. Hooker and Miller [25]
found that vaccination before 1 year of age was associated with increased
odds of asthma (OR = 4.49, 95% CI 2.04 – 9.88). McDonald et al. [7]
analyzed the health records of 11,531 Canadian children and found
that delayed administration of the first dose of a diphtheria, tetanus and
pertussis vaccine was associated with a 50% reduced risk of childhood
asthma. Hurwitz and Morgenstern [30] reported an association between
DTP and tetanus toxoid vaccination and allergy symptoms and could
not rule out a relationship with asthma. Klugman et al. [31] found
that children who received a pneumococcal vaccine were nearly twice
as likely as non-vaccine recipients to be diagnosed with hyperactiveairway disease and asthma treated with bronchodilator agents (relative
risk = 1.91, CI 1.1 – 3.4). The authors suggest that an increase in asthma
following vaccination may be expected, due to the hygiene hypothesis
of decreased childhood infections.

In a study of Korean children
vaccinated against hepatitis B [32], a significantly higher asthma
incidence was seen among children who had seroconverted to produce
anti-hepatitis B (p = 0.009). In China, mice vaccinated according to the
Chinese infant vaccine schedule showed airway hyper-responsiveness
at a significantly higher rate than unvaccinated mice (p < 0.01) [33].
Mawson et al. [5] found a relationship between vaccination status
and neurodevelopmental disorders, including autism (OR = 3.7, 95%
CI 1.7 – 7.9). Delong [34] also reported a significant relationship to
neurodevelopmental disorders—autism and speech and language
delay—when looking at proportions of vaccine uptake in U.S.
children. In a recent study by Eidi et al. [35], some neurobehavioral
abnormalities, such as decreased sociability, increased anxiety-like
behaviors, and alteration of visual-spatial learning and memory, were
observed in baby mice treated with childhood vaccines. Geier et al.
[12] found that children diagnosed with atypical autism—pervasive
developmental disorder or Asperger syndrome—were more likely than
controls to have received greater mercury exposure during infancy
from thimerosal-containing hepatitis B vaccines (OR = 4.87, 95% CI
3.57 – 6.66). Although thimerosal has been phased out of most vaccines
administered in the United States, it still remains in multi-dose vials
of the influenza vaccine given to pregnant women and infants. The
IOM Immunization Safety Review Committee [36] conducted an
evaluation regarding thimerosal-containing vaccines and concluded
that “the hypothesis that exposure to thimerosal-containing vaccines
could be associated with neurodevelopment disorders” was biologically
plausible.
Hooker and Miller [25] reported an association between receipt
of vaccines before 1 year of age and gastrointestinal disorders, most
notably when time permitted for a diagnosis was extended from ≥ 3
years of age to ≥ 5 years of age (OR = 2.48, 95% CI 1.02 – 6.02). Although
Wilson et al. [37] found an association between 12-month vaccinations
and emergency room visits for non-infective gastroenteritis, there
is a dearth of research elsewhere regarding gastroenteritis following
vaccination, with the majority focused on intussusception following the
rotavirus vaccine [38-41]. Other reports have attributed gastrointestinal
disorders as adverse events following the oral polio vaccine [42] and the
human papillomavirus vaccine [43].
The CDC’s Vaccine Safety Datalink (VSD) database was recently
evaluated to identify children with and without an attention deficit
hyperactivity disorder (ADHD) diagnosis [9]. Children diagnosed with
ADHD were significantly more likely than controls to have received
greater mercury exposure from thimerosal-containing vaccines within
the first 15 months of life (OR = 2.5, 95% CI 2.27 – 2.75). In a study
of children 6-15 years of age [8], subjects diagnosed with ADHD were
more likely than controls to have received any vaccination within the
previous 6- and 12-month periods (p = 0.05). Mawson et al. [5] found
a highly significant relationship between vaccines and ADHD as well.
Hooker and Miller [25] found that vaccination before 6, 12, 18, and
24 months of life was associated with increased odds of ear infections
(p < 0.05). Mawson et al. [5] reported a significant relationship between
vaccination status and ear infections. Wilson et al. [14] found that for
both males and females, top reasons for emergency room visits and/
or hospital admissions after their 12-month vaccinations included
ear infections and non-infective gastroenteritis or colitis. Prior to the
RotaTeq rotavirus vaccine achieving FDA approval, 71,725 infants
were evaluated in three placebo-controlled clinical trials. Otitis media
(middle ear infection) occurred at a statistically higher incidence (p
< 0.05) within six weeks of any dose among recipients of RotaTeq as
compared with recipients of placebo [15].
Within the logistic regression models that excluded covariates for
breastfeeding status and type of delivery (Tables S1 and S2), all health
conditions under consideration showed elevated ORs consistent with
those obtained with covariates, and vaccination remained protective
Hooker BS (2021) Health effects in vaccinated versus unvaccinated children, with covariates for breastfeeding status and type of birth
J Transl Sci, 2021 doi: 10.15761/JTS.1000459 Volume 7: 8-11
against chickenpox. In a separate analysis (unpublished) we found a
strong inverse relationship between breastfeeding status and vaccination
status (p < 0.0001) as well as a direct relationship between type of birth
and vaccination status (p = 0.0037). Given these relationships, it is not
surprising that results with these covariates reinforce those obtained
when considering vaccination status alone.
Vaccination and breastfeeding status: Results from the analysis
of relationships when considering vaccination and breastfeeding
status (Table 9) show that the lowest percentages of adverse diagnoses
occurred in the two unvaccinated cohorts, most notably within the
“unvaccinated and breastfed” group of children; the highest percentages
of adverse diagnoses were observed for “vaccinated and not breastfed”
children. A consistent linear increase was observed for allergies (1.5%,
2.1%, 6.0%, 13.9%), autism (0.8%, 2.1%, 5.3%, 9.4%), asthma (0.6%,
3.1%, 6.0%, 12.4%), and chronic ear infections (0.5%, 1.0%, 7.4%,
13.4%). Additionally, ORs in the two vaccinated cohorts, as compared
to the “unvaccinated and breastfed” reference group, were significant for
all health conditions under consideration. These findings suggest that
breastfeeding has a protective effect against deleterious health outcomes
associated with vaccination. Furthermore, vaccination appears to
decrease the beneficial effects of breastfeeding, as indicated by the
higher proportions of diagnoses in the “vaccinated and breastfed” group
of children as compared to the “unvaccinated and breastfed” group.
Breastfeeding benefits a baby’s immune system and has been found to
be protective against gastrointestinal issues (vomiting and diarrhea),
allergies and ear infections [44]. Klopp et al. [45] reported that infants
who were exclusively breastfed at 3 months of age were significantly
protected against developing asthma by 3 years of age.
Vaccination and birth delivery status: Results from the analysis
of relationships when considering vaccination and birth delivery
status (Table 10) show that the lowest percentages of adverse diagnoses
occurred in the two unvaccinated cohorts, most notably within the
group of children who were unvaccinated and born vaginally; the
highest percentages of adverse diagnoses occurred most notably in the
children who were vaccinated and delivered via C-section. A consistent
increase was observed for allergies (1.1%, 4.2%, 7.8%, 11.2%), autism
(0.6%, 2.8%, 5.5%, 10.5%), and gastrointestinal disorders (1.0%, 2.8%,
12.2%, 18.9%). Additionally, ORs in the two vaccinated cohorts, as
compared to the “unvaccinated and vaginal delivery” reference group,
were significant for all health conditions under consideration. Cesarean
births have been associated with a significantly increased rate of
allergies [46], asthma [47], and hospitalizations for gastroenteritis [48],
possibly linked to suboptimal intestinal flora from loss of contact with
the mother’s immune-stimulating vaginal and intestinal bacteria [49].
Cesarean births have also been linked to breastfeeding complications,
including delayed onset of lactation [49]. Thus, many babies lack early
immune support of breast milk, which has been shown to have a
protective effect against several adverse health conditions.
Extended breastfeeding: Within the logistic regression model that
compared infants who were breastfed for at least 6 months versus not
(Table S3), breastfed children were 52%, 61%, and 49% less likely to
have been diagnosed with allergies (OR = 0.48, 95% CI 0.28 – 0.82),
asthma (OR = 0.39, 95% CI 0.22 – 0.70), or ear infections (OR = 0.51,
95% CI 0.29 – 0.88), respectively. They were more than twice as likely as
non-breastfed children to have contracted chickenpox (OR = 2.66, 95%
CI 1.27 – 5.60). Since some of the infants stratified as “not breastfed”
actually did breastfeed for less than 6 months, this could be a factor
as to why significance was not achieved for autism, gastrointestinal
disorders and chronic ear infections. The mothers who breastfed their
babies for at least 6 months might have also been less likely than nonbreastfeeding mothers to vaccinate their children, which could explain
why chickenpox was more common in this group, or perhaps there is
an interactive effect between breastfeeding and chickenpox vaccine
immune responses, as one study found with the rotavirus vaccine [50].
Vaginal birth versus cesarean: Within the logistic regression
model that compared infants who were delivered via C-section versus
a vaginal delivery (Table S4), cesarean babies were twice as likely to
have been diagnosed with gastrointestinal disorders (OR = 1.92, 95%
CI 1.16 – 3.18). Vaginally delivered babies receive most of their gut
bacteria from their mother, while cesarean babies acquire much of
their gut composition in the hospital [51]. Transmission of maternal
gastrointestinal bacteria to the newborn is disrupted through delivery
by cesarean section, predisposing newborns to opportunistic pathogens
[51]. Healthy gut microbiota promotes development and maturation of
the immune system [52] while an aberrant gut microbiome can increase
the risk of disease [53], and has been linked to allergies [51,54], asthma
[51,54], and severe gastrointestinal infections [52].
Study strengths: One of the main strengths of this study is the ability
to complete chart review from the participating pediatricians’ electronic
medical records to confirm diagnoses indicated from parental surveys.
This was possible because respondents voluntarily included contact
information and a substantial majority of patients (79.5%) were from
one of the participating medical practices. Diagnoses confirmed from
electronic medical records are more reliable than survey responses, and
findings associated with such analyses are more credible. In table 8, only
children with diagnoses confirmed from electronic medical records
were included in the analysis. This mitigated recall bias associated with
studies that are based solely on parental surveys.
The survey included questions regarding breastfeeding status and
type of birth, which allowed these covariates to be accounted for within
all of the analyses except for supplementary tables S1 and S2 (where
they were excluded for comparative purposes). The inclusion of these
covariates within this study revealed several important relationships
between vaccination status, breastfeeding status, type of birth, and
health outcomes.
Some of the children were just 2.5 years of age when the survey was
taken, limiting the time for additional diagnoses, especially those made
later in development including autism and ADD/ADHD. Thus, the
calculated ORs could be conservative estimates of the true relationship
between vaccines and adverse health consequences as younger children
would bias the results toward the null hypothesis. Hooker and Miller
[25] found that when the time permitted for a diagnosis was extended
from children ≥ 3 years of age to children ≥ 5 years of age, slightly higher
ORs were detected for all four of the adverse health conditions under
consideration. This is discussed further in Geier et al. [55] as length of
follow-up period (i.e., patient age) allows additional opportunities to
affirm diagnoses.
Some of the infants evaluated as “not breastfed” did actually
breastfeed for less than 6 months. If the infants listed as “not breastfed”
had truly never been breastfed, the findings in table 9 indicating that
breastfeeding provides a protective benefit against adverse health
consequences would likely show even stronger effect estimates.
Additionally, in tables 7 thru 10, fully and partially vaccinated children
are counted together. This was necessary to attain sufficient cohort
size to complete the analyses. If all of the children in the analyses were
fully vaccinated, rather than a mix of fully and partially vaccinated, the
findings in these tables would likely be even more pronounced.
Hooker BS (2021) Health effects in vaccinated versus unvaccinated children, with covariates for breastfeeding status and type of birth
J Transl Sci, 2021 doi: 10.15761/JTS.1000459 Volume 7: 9-11
The addition of chickenpox as a positive control diagnosis also
lends credibility to the study as a higher incidence of chickenpox would
be expected—and was found—in the unvaccinated group. This is
similar to the results of Mawson et al. [5] where unvaccinated children
showed higher incidence of “vaccine-preventable” diseases including
chickenpox and whooping cough.
Finally, effect estimates in this paper were above 4.0. Thus, for some
confounder to explain this association it would need to be four times as
frequent in vaccinated children [56].
Potential limitations: The main weakness of this study is the use
of a convenience sample of three different pediatric practices. Also,
this study was based on responses from parental surveys which can
introduce both recall bias and selection bias. Recall bias was mitigated
by providing survey questions that were closed-ended with yes/no and
multiple choice options, and by requiring that each health condition
affirmed by the parent had been diagnosed by a medical professional.
Additionally, the electronic medical records of children in the three
participating medical practices were reviewed for confirmation
of diagnoses. Although the findings in this paper were based on a
convenience sample and survey, a recent study [25] utilizing data
taken directly from patient chart records and diagnosis codes reported
results similar to those found in this paper, including increased rates
of gastrointestinal disorders, asthma and ear infections in vaccinated
children as compared to unvaccinated children.
Regarding selection bias, adults who took the survey may have
been more likely than adults in the general population to have had a
child who, after receiving vaccines, was diagnosed with one or more
of the adverse health conditions investigated in this paper. It’s also
possible that parents of unvaccinated children without adverse health
conditions were more motivated than other parents to participate
and be represented in the survey. Either of these possibilities could
have influenced the study results. Another consideration is that the
proportions of unvaccinated and home educated children in the sample
population, 60.4% and 34.9% respectively, are greater than proportions
found in the general population. Also, mothers who breastfed for
a minimum duration of 6 months could have been more “vaccine
hesitant” than those who did not. And 21.5% of children included in
the main analyses were not patients in one of the three participating
medical practices. However, to overcome the effect of combining
distinct populations, Table 7 included children from participating
medical practices only. Results were consistent with the main analyses,
lending credibility to the overall findings.
Differences in healthcare-seeking behavior among non-vaccinating,
partially-vaccinating and fully-vaccinating families could also introduce
selection bias. Glanz et al. [57] reported that undervaccinated children
showed lower rates of outpatient medical provider visits (incidence risk
ratio = 0.89, 95% CI 0.89-0.90) within a large retrospectively matched
cohort study involving the CDC’s Vaccine Safety Datalink. However,
this difference would be insufficient to fully account for effect estimates
observed in this paper that were greater than 4.0.
Ascertainment of vaccination status was limited to three broad
categories that do not reflect the different numbers, types and timing
of the various vaccinations received. Partially vaccinated children
received at least one vaccine but less than the recommended quantity
which represents a highly variable range. Also, younger children in the
study who were up to date on their vaccines received fewer vaccines
than older children who were up to date, representing again a variable
range. This precluded the specificity that would have provided more
options for analyses.
Several studies have shown that some vaccines have non-specific
effects that either increase or decrease susceptibility to infectious
diseases not targeted by the vaccine. The most recent vaccine
administered exerts the greatest effect. Live vaccines such as measles,
MMR and BCG tend to lower risk (providing a beneficial influence)
while non-live vaccines such as hepatitis B [58], DTP (diphtheriatetanus-pertussis) and IPV (inactivated polio) tend to increase risk.
For example, Bardenheier et al. [59] found a lower risk of non-targeted
infectious disease hospitalizations among children whose last vaccine
received was live compared with inactivated vaccine (hazard ratio =
0.50, 95% CI 0.43 – 0.57). In a recent meta-analysis conducted by Aaby
et al. [60], girls who received an inactivated vaccine after receiving
a measles vaccine were significantly more likely to die from other
causes compared with girls who received an inactivated vaccine before
receiving a measles vaccine (mortality rate ratio = 1.89, 95% CI 1.27 –
2.80). Although this current study did not consider non-specific effects
(due to the lack of specific vaccine data) it is possible that the most
recent vaccine administered could have influenced the results.
The only demographic data available were breastfeeding status,
type of birth (vaginal versus cesarean), and current education status.
Other factors that may influence health outcomes, such as vaccinations
during pregnancy and gestational age at birth, were not included on the
questionnaire. There are undoubtedly demographic differences within
the two groups studied (vaccinated versus unvaccinated), especially
regarding socioeconomic status and maternal education. According to
Smith et al. [61] mothers in families where vaccines were delayed and
declined tended to have higher levels of college education and families
were more affluent. Although there are no direct studies on gestational
age at birth in vaccinating versus non-vaccinating families, Zerbo et
al. [62] indicated that children born to women receiving the influenza
vaccine during pregnancy had significantly higher gestational age.
Dueker et al. [63] showed that each week of gestational age beyond 35
weeks through 41 weeks significantly decreased developmental delays
in infants. Also, children born prematurely (34 to 37 weeks) showed a
higher rate of hospitalizations for asthma [64].
Conclusion
In the study presented here, children from three pediatric medical
practices in the United States were used as a convenience sample to
compare health outcomes in fully vaccinated, partially vaccinated, and
completely unvaccinated populations. Within the logistic regression
models, higher ORs were observed within the fully and partially
vaccinated groups versus the unvaccinated group for severe allergies,
autism, gastrointestinal disorders, asthma, attention deficit disorder
(ADD/ADHD), and chronic ear infections. The OR for chickenpox,
our positive control, was significantly low, affirming the protective
effect of vaccination. Similar results have been observed in earlier
studies. Results from the analysis of relationships between vaccination
and breastfeeding status showed that the lowest percentages of adverse
diagnoses were observed for “unvaccinated and breastfed” children;
the highest were observed for “vaccinated and not breastfed” children.
Results from the analysis of relationships between vaccination and birth
delivery status showed that the lowest percentages of adverse diagnoses
were observed for unvaccinated children delivered vaginally and the
highest were observed for vaccinated children delivered via cesarean
section. These particular analyses, and results, appear to be unique in
the medical literature.
Hooker BS (2021) Health effects in vaccinated versus unvaccinated children, with covariates for breastfeeding status and type of birth
J Transl Sci, 2021 doi: 10.15761/JTS.1000459 Volume 7: 10-11
The findings in this study must be weighed against the strengths
and limitations of the available data and study design. Additional
research utilizing a larger sample from diverse medical practices will
yield greater certainty in results, essential to understanding the full
scope of health effects associated with childhood vaccination.
Author contributions
BSH incepted the study design and analyzed the data. BSH also
helped draft the manuscript and interpret the data. NZM contributed
to the drafting of the manuscript, design of the study, analysis and
interpretation of the data, and critical revisions of the work. All authors
have read and agreed to the published version of the manuscript.
Funding
This research received no external funding.
Acknowledgements
The authors thank Dr. Jacob Puliyel (Head of Pediatrics, St.
Stephens Hospital, Delhi, India) and Dr. Chris Shaw (Neuroscientist
and Professor of Ophthalmology, University of British Columbia,
Vancouver, Canada) for their critical review of the manuscript.
Conflict of interest
Dr. Hooker is a paid scientific advisor and serves on the advisory
board for Focus for Health (formerly Focus Autism). He also serves on
the Board of Trustees for Children’s Health Defense (formerly World
Mercury Project) and is a paid independent contractor of Children’s
Health Defense as well. Dr. Hooker is the father of a 23 year old male
who has been diagnosed with autism and developmental delays. Mr.
Miller has written and lectured on vaccine safety and was a paid
consultant to Physicians for Informed Consent.
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