The Childhood Immunization Schedule and Safety Stakeholder Concerns, Scientific Evidence, and Future Studies (2013) / Chapter Skim
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5 Review of Scientific Findings
5 Review of Scientific Findings
Pages 75-98
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From page 75... ...
One prior IOM review examined the evidence for an association between three adverse outcomes and the overall recommended childhood immunization schedule: increased susceptibility to heterologous infection; autoimmunity, as reflected in type 1 diabetes; and allergy, as reflected in asthma (IOM, 2002)
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From page 76... ...
"immunization" or "vaccines," combined with the following terms for health outcomes of interest: • "autoimmune diseases" (which captures "diabetes mellitus, type 1") , • "asthma," • "hypersensitivity," • "seizures" or "epilepsy" or "febrile seizures," • "child developmental disorders, pervasive" (which captures "autis tic disorders")
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From page 77... ...
This number was further reduced to 143 by exclusion of articles that reviewed vaccines not included in the current or recent childhood immunization schedule or included vaccines for adolescents, such as the human papillomavirus vaccine, and by elimination of references duplicated in more than one category. The number of articles reviewed was further reduced by limitation of the search to articles describing studies that examined at least one health outcome and at least one of the following elements of the schedule, including • number of vaccines, • frequency of administration, • spacing between doses, • cumulative doses, • age of the recipient, and • order of vaccine administration.
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From page 78... ...
All data, including immunizations (diphtheria and tetanus toxoids and pertussis vaccine or diphtheria and tetanus toxoids absorbed [DT] , oral poliovirus [OPV]
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From page 79... ...
Data on the three vaccines that were received before age 6 months were obtained from the pediatric record: bacillus Calmette-Guérin (BCG) , diphtheria-tetanus-poliomyelitis, and pertussis vaccines.
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From page 80... ...
Overall, the study reported a negative correlation between atopy and the cumulative number of vaccine doses received, including pertussis vaccine. The principal limitation was the self-reporting of vaccination history.
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From page 81... ...
The group analyzed data from three randomized controlled trials evaluating differences in outcomes by age 7 years after immunization with DT or DT plus pertussis vaccine in a study with four arms: a two-component experimental pertussis vaccine, a five-component pertussis vaccine, a whole-cell pertussis vaccine, or no pertussis vaccine arm. All vaccines had aluminum phosphate as an adjuvant.
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From page 82... ...
data on asthma, the timing of immunization, and the number of recommended immunizations by age 2 to determine whether increases in asthma prevalence paralleled trends in the number of immunizations recommended; however, the increase in the incidence of asthma reported in NHIS preceded the increase in the recommended number of vaccines. This information did not support a relationship between the recommended number of childhood immunizations and the increase in the prevalence of asthma and, in fact, provided evidence of no association.
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From page 83... ...
has not been extended to examine acellular pertussis vaccine. One publication (Thomson et al., 2010)
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From page 84... ...
It found no increased risk of ITP after immunization with vaccines other than MMR in young children but did find an association between ITP and immunization with HepA; tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine adsorbed; and varicella vaccine in older children. However, because of the small number of reports of ITP and potential confounders, the researchers concluded that further investigation is needed.
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From page 85... ...
In 1997, the pertussis vaccine was modified to the acellular pertussis vaccine, which was incorporated into the diphtheria, tetanus, and inactivated poliovirus vaccine. The schedule of the combined vaccine was modified to be given at 3, 5, and 12 months of age.
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From page 86... ...
The retrospective cohort study found no evidence for an increased risk of neurodevelopmental disorders, with the possible
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From page 87... ...
(2003) studied the relationship between cumulative thimerosal exposure via the whole-cell pertussis vaccine and autistic spectrum disorder.
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From page 88... ...
Other Neurodevelopmental Disorders Forty-one papers concerning a relationship among immunizations, immunization schedule, or vaccines and learning disorders, communication disorders, developmental disorders, intellectual disability, attention deficit disorder, disruptive behavior disorders, tics, and Tourette's syndrome were identified via an Ovid MEDLINE database search. This list was reduced to eight papers after use of the exclusion criteria described above, including exclusion of papers on vaccines not currently recommended for administration to children under age 6 years.
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From page 89... ...
found that children who had received their immunizations on time and also those who had received at least 10 doses did not have better neuropsychological outcomes in this study than those who had received fewer doses, and no significant differences were found between those who received the least vaccines and those with the greatest vaccine exposure during the first 7 months of life. In a cohort study conducted in Brazil, Marques et al.
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From page 90... ...
A positive association between cumulative thimerosal exposure and the development of tics was found for subjects from one MCO, whereas a positive association with language delay was found for subjects from the other MCO. In Phase 2 of the study, the most common associations seen in Phase 1 were evaluated in a third MCO, and no significant associations were demonstrated.
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From page 91... ...
-Hib on the development of both febrile seizures and the later development of epilepsy as well as the risk of these adverse events after pneumococcal vaccine was added to the combined DTaP-IPV-Hib. This was a self-controlled case series study based on children with febrile seizures during follow-up of the cohort.
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From page 92... ...
The study compared the adverse events that occurred after patients received whole-cell pertussis vaccine, acellular pertussis vaccine, or acellular pertussis vaccine along with pneumococcal vaccine. The data were
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From page 93... ...
received HepB at the same time as pertussis vaccine, but this clinical feature was not factored into the analysis. In summary, the literature associating the overall immunization schedule with seizures, febrile seizures, and epilepsy is limited and inconclusive.
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From page 94... ...
in research that is sufficiently funded to ensure the collection of a large quantity of high-quality data. Recommendation 5-1: To improve the utility of studies of the entire childhood immunization schedule, the committee recommends that the National Vaccine Program Office develop a framework that clarifies and standardizes definitions of • key elements of the schedule, • relevant health outcomes, and • populations that are potentially susceptible to adverse events.
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2004a. Neurodevelopmental disorders following thimerosal containing childhood immunizations: A follow-up analysis.
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2010. Childhood immunization and atopic disease into middle-age -- A prospective cohort study.
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2012. Signal identification and evaluation for risk of febrile seizures in children following trivalent inactivated influenza vaccine in the Vaccine Safety Datalink Project, 2010-2011.
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