This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Healthy, Immunized Communities Study (NCT03854734), a randomized na study. The primary outcome is Percentage of Participants With Intent to Vaccinate Adolescent Child (Tdap, MCV, HPV).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03854734 |
| Phase | NA |
| Condition | Vaccine Hesitancy, Communicable Diseases in Children |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 148 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Milton S. Hershey Medical Center |
| Results posted | Yes |
2. Clinical Question
Population
Parents of children attending 4 middle schools. The registry reports enrollment of 148 participants. Participants were assigned to a study arm according to their associated school. The study focused on parents’ responses concerning adolescent children and age-appropriate Tdap, MCV, and HPV vaccination.
Intervention
A multi-component approach combining a community event intended to raise parental awareness of vaccination importance with social marketing in the form of educational material targeting parents’ attitudes and knowledge.
Comparator
Usual care, described as educational emails about broad health topics intended to keep the control group engaged.
Primary question
How did parents’ reported intent to vaccinate, or report that their child was up-to-date, change from baseline to 6-month follow-up, and how did those responses compare between the usual-care and multi-component intervention arms for Tdap, MCV, and HPV?
The question concerns a reported intention and vaccination-status measure, not a direct comparison of completed vaccinations alone. Tdap and MCV responses classified participants as intending to vaccinate or already up-to-date versus having no intention or planning an exemption. For HPV, the exemption response was excluded because HPV vaccination is not required for school entry. The registry describes comparisons within and between arms over time. It does not report the numerical results of those comparisons, so the direction or size of any change cannot be established from the registry record.
3. Trial Design
The Healthy, Immunized Communities Study is listed as a completed randomized study with a parallel design. The registry classifies it as single-masked, but does not identify which participants, investigators, or other parties were masked. The study involved 4 middle schools, randomized to usual care or a multi-component intervention. Parents were assigned to an arm based on their associated school, making the school the level at which allocation was organized. The registry reports enrollment of 148 participants.
The intervention combined a community event to increase parental awareness of vaccination importance and educational material using social marketing to address parents’ attitudes and knowledge. The usual-care arm received educational emails on broad health topics to keep the control group engaged. Both arms were assessed using surveys at baseline and at follow-up at 6 months. The registry describes parental intent for Tdap, MCV, and HPV separately.
The study is listed as phase NA. The record identifies Milton S. Hershey Medical Center as sponsor and gives the status as completed. The listed study start was 2019-02-14 and primary completion was 2020-02-28. The registry record does not report details such as the randomization procedure, how the schools were allocated, the number of participants in each arm, or the identity of the masked party. Those design details should not be inferred from the labels alone.
Because participants followed their school’s allocation, responses from parents attending the same school may share features. The registry does not explain whether or how the analysis accounted for this school-level grouping. It does specify generalized estimating equations for the outcome analysis, but the stated description does not identify all correlation assumptions or model settings.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: Four schools were randomized to two arms (intervention vs. control). 502 individuals were assessed for eligibility and 354 were excluded for not meeting inclusion criteria (n=265) or declining to participate (n=89).
Overall Study
| Stage | Usual Care | Multi-Component Intervention |
|---|---|---|
| STARTED | 70 | 78 |
| COMPLETED | 70 | 78 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: 4 middle schools were randomized to either a usual care or multi-component intervention arm. Participants (parents) were assigned to a study arm based on their associated middle school. 30 participants either did not complete the follow up survey (n=27) or did not answer all questions (n=3), as questions were not required. Discrepancies in percentage reporting in the outcomes table below results from inconsistent rates of missingess (range 0-4) across variables (Tdap, MCV, HPV).
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Usual Care | Multi-Component Intervention | Total |
|---|---|---|---|---|
| Participants analysed | 70 | 78 | 148 | |
| Age, Continuous | years | 38.00 (SD 9.79) | 40.46 (SD 8.59) | 39.32 (SD 9.21) |
| Sex/Gender, Customized: Gender – Male | Participants | 11 | 7 | 18 |
| Sex/Gender, Customized: Gender – Female | Participants | 57 | 68 | 125 |
| Sex/Gender, Customized: Gender – No response | Participants | 2 | 3 | 5 |
| Race/Ethnicity, Customized: Race/Ethnicity – White | Participants | 32 | 43 | 75 |
| Race/Ethnicity, Customized: Race/Ethnicity – Black/African American | Participants | 6 | 7 | 13 |
| Race/Ethnicity, Customized: Race/Ethnicity – Hispanic or Latino | Participants | 22 | 20 | 42 |
| Race/Ethnicity, Customized: Race/Ethnicity – Other | Participants | 10 | 7 | 17 |
| Race/Ethnicity, Customized: Race/Ethnicity – No response | Participants | 0 | 1 | 1 |
| Relationship Status: Single OR separated OR divorced OR widowed | Participants | 26 | 30 | 56 |
| Relationship Status: Married OR living with partner | Participants | 43 | 46 | 89 |
| Relationship Status: No response | Participants | 1 | 2 | 3 |
| Annual household income: ≤$40,000 | Participants | 31 | 27 | 58 |
| Annual household income: $40,001 - $80,000 | Participants | 26 | 25 | 51 |
| Annual household income: >$80,000 | Participants | 12 | 23 | 35 |
| Annual household income: No Response | Participants | 1 | 3 | 4 |
| Education: High School or Less | Participants | 35 | 29 | 64 |
| Education: Some College | Participants | 15 | 12 | 27 |
| Education: College Graduate | Participants | 20 | 37 | 57 |
| Education: No response | Participants | 0 | 0 | 0 |
| Relationship to child: Mother | Participants | 56 | 66 | 122 |
| Relationship to child: Father | Participants | 9 | 8 | 17 |
| Relationship to child: Guardian/Grandparent | Participants | 5 | 4 | 9 |
| Grade of child: 6th | Participants | 37 | 33 | 70 |
| Grade of child: 7th | Participants | 22 | 29 | 51 |
| Grade of child: 8th | Participants | 11 | 16 | 27 |
| Gender of child: Male | Participants | 40 | 44 | 84 |
| Gender of child: Female | Participants | 30 | 34 | 64 |
| Parent participation in school events per year: ≤1 | Participants | 41 | 37 | 78 |
| Parent participation in school events per year: 2-5 | Participants | 25 | 24 | 49 |
| Parent participation in school events per year: ≥6 | Participants | 4 | 16 | 20 |
| Parent participation in school events per year: No response | Participants | 0 | 1 | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants With Intent to Vaccinate Adolescent Child (Tdap, MCV, HPV), measured over Participants were assessed at baseline and follow-up at 6 months..
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage of participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the percentage of participants with intent to vaccinate an adolescent child against Tdap, MCV, and HPV. The survey classified each vaccine response into a binary outcome. For Tdap and MCV, intention to vaccinate included either planning to obtain the shot before the first day of 7th grade or reporting that the child was up-to-date. The other category included no plans to obtain the shot or having or planning to submit an exemption. For HPV, the exemption response was excluded because HPV vaccination is not required for school entry.
This measure captures stated intention alongside reported up-to-date status. It can therefore describe parents’ survey responses about both planned vaccination and existing status, but it is not equivalent to a record of vaccination received during follow-up. The endpoint is relevant to the study’s stated aim of examining whether education and awareness relate to parents’ vaccination intentions. Separate vaccine-specific outcomes also preserve distinctions among Tdap, MCV, and HPV rather than combining them into one undifferentiated response.
Participants were assessed at baseline and at 6 months. The registry says the vaccine variables were compared within and between treatment groups from baseline to follow-up. It does not report the resulting percentages, changes, risk ratios, confidence intervals, or significance tests. Consequently, the endpoint’s observed pattern and precision are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies the intended comparison and analysis approach, but it does not provide numerical outcome results. It names parental intent for Tdap, MCV, and HPV as the primary measure and describes assessment at baseline and follow-up at 6 months. It also says that comparisons were made within and between treatment groups. However, the registry does not report arm-specific percentages, participant counts for each response, estimated changes, risk ratios, confidence intervals, or p-values. Without those results, the magnitude, direction, and statistical precision of the observed differences cannot be described.
The record lists 3 analyses and describes vaccine-specific variables for Tdap, MCV, and HPV. The presence of analyses does not itself establish that any difference was statistically significant. The endpoint description says risk ratios were used to quantify the magnitude and direction of significant differences, but no such estimates or significance results are reported in the registry record. It would therefore be inappropriate to conclude that the intervention increased, decreased, or had no effect on reported intent from the information recorded.
The stated model is a generalized estimating equations model using a log-binomial logistic regression framework. In general, a risk ratio expresses the relative frequency of an outcome between groups or conditions; its interpretation depends on the comparison and reference category. A confidence interval, if reported, would show the range of estimates compatible with the analysis under its assumptions and would help convey precision. Neither estimates nor confidence intervals are available in the registry record.
The school-based assignment is important when interpreting any eventual estimate. Parents assigned through the same school may have correlated responses, and repeated surveys from the same parent can also be correlated. Generalized estimating equations are commonly used to estimate population-average associations when observations are correlated, but the registry description does not specify how the model handled school-level grouping, repeated measures, or both. It also does not identify the working correlation structure or variance estimator. Those details affect how uncertainty should be understood.
The registry reports that 30 participants either did not complete the follow-up survey (n=27) or did not answer all questions (n=3). This is relevant because the outcome depends on survey responses at baseline and follow-up, but the record does not describe how missing responses were treated in the analysis. The absence of that detail, together with the absence of outcome estimates, means the posted information supports a description of the trial question and method, not a conclusion about the intervention’s observed results.
The record also lists zero serious adverse events, other adverse events, and deaths in both groups. These entries describe the adverse-event fields in the registry; they do not substitute for the missing primary-outcome estimates or explain how event collection was conducted.
9. Statistical Methods Explained
Why use a binary outcome?
The registry describes each vaccine response as dichotomized: responses are placed into one of two categories rather than analyzed as a multi-level scale. For Tdap and MCV, one category combines an intention to obtain the shot with reporting that the child is already up-to-date. The other combines no intention with having or planning an exemption. The HPV definition excludes the exemption response. This approach creates a clearly defined outcome for each vaccine, but combines responses that may represent different situations: an existing vaccination status and a future intention are not identical. The reported percentage therefore refers to the study’s classification, not solely to future vaccination completed after enrollment.
What does a generalized estimating equation do?
In general, generalized estimating equations estimate population-average relationships while allowing observations to be correlated within a defined group. Correlation can arise when the same participant answers surveys at multiple times, or when participants share a school context. Treating correlated observations as if they were wholly independent can make uncertainty estimates inappropriate. A generalized estimating equations approach can address correlation when the grouping structure and variance estimation are specified suitably. The registry names this method but does not report its working correlation structure, variance estimator, or whether school-level clustering was explicitly included.
What is the log-binomial framework?
For a binary outcome, a log-binomial model uses a logarithmic link to model the probability of the outcome. Under this framework, exponentiated model contrasts can be expressed as risk ratios. A risk ratio compares the probability of the defined response between two conditions; a value’s direction and interpretation depend on which group and response category are used as the reference. The registry says risk ratios were used to quantify the magnitude and direction of significant differences, but does not report estimates or specify the exact contrasts. No direction or size of an effect can therefore be stated.
How do baseline and follow-up enter the question?
The endpoint was assessed at baseline and at follow-up at 6 months. The registry says Tdap, MCV, and HPV variables were compared within and between treatment groups from baseline to follow-up. A within-group comparison concerns how responses in one arm vary over time; a between-group comparison concerns how the arms differ. A model can account for the relationship between repeated responses when its structure is specified for that purpose. The record does not provide coefficients, a full model equation, covariates, or enough detail to reconstruct the exact contrasts.
How should uncertainty and planning be understood?
In general, a confidence interval communicates uncertainty around an estimated effect, while a p-value assesses compatibility of the observed data with a specified null model and assumptions. Neither replaces the estimate itself, and neither is reported for the primary endpoint in the registry record. The record also does not report a sample-size justification or an original power calculation. Any sample-size planning illustration based on an observed effect is distinct from the trial’s design rationale and is not observed power. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between arms, a normal approximation, and an effect to detect expressed as a fraction of the observed effect. The registry record does not give a numerical planning result for this primary outcome, and its description notes that the several outcome categories or time points were not reduced to one comparison.
These methods explain how the endpoint could be compared, not what the study found. In particular, general properties of generalized estimating equations or risk ratios cannot fill in missing model settings or missing outcome estimates. The registry description does not report adjustment variables, a detailed analysis population, model diagnostics, or a strategy for handling incomplete survey data. Those omissions limit independent assessment of the analysis as recorded.
10. Multiplicity, Missing Data and Analysis Populations
The primary outcome involves three vaccine-specific responses: Tdap, MCV, and HPV. Each was assessed at baseline and follow-up at 6 months, and the registry describes within-arm and between-arm comparisons. Considering multiple vaccines and comparisons can create a multiplicity issue: when many hypotheses are examined, the chance of at least one apparently unusual result can increase. The registry record does not report whether a multiplicity adjustment, hierarchy, or single prespecified contrast was used. It also does not state how the 3 analyses relate to a formal testing strategy.
Missing survey information is documented. The registry says 30 participants either did not complete the follow-up survey (n=27) or did not answer all questions (n=3). It does not report how many missing responses applied to each vaccine, arm, or time point, or whether the stated counts refer to the analysis population for every outcome. The approach to missing data, including any imputation, complete-case analysis, or sensitivity analysis, is not reported in the registry record.
The record does not identify an intention-to-treat, per-protocol, or other named analysis population. It also does not report exclusions after randomization or how participants with incomplete responses were handled. These details matter because survey completion can affect which responses contribute to a comparison, especially when the endpoint is evaluated at more than one time point. No particular missing-data mechanism should be assumed from the recorded counts alone.
11. What the Result Does, and Does Not, Mean
The study addresses whether a community- and school-based package of vaccination education and awareness activities was associated with changes in parents’ reported vaccination intent or up-to-date status. Its endpoint is a survey classification for Tdap, MCV, and HPV, with responses assessed at baseline and follow-up at 6 months. That definition is the basis for interpreting any estimate reported from the study.
The registry record does not include the primary-outcome results. It therefore does not establish whether reported intent differed between arms, changed over time, or was similar across groups. It also does not provide estimates of precision. The absence of a reported result is not evidence that the groups were the same, and it cannot be interpreted as evidence for or against an intervention effect.
Even with estimates, the endpoint would need to be read as a combined survey measure of intention and, for some responses, existing up-to-date status. Intentions are not the same as vaccination completion. The HPV definition also differs from Tdap and MCV because the exemption response was excluded. Comparisons across vaccine outcomes would need to account for those distinct classifications.
More broadly, the study’s school-based allocation, incomplete follow-up, and unspecified missing-data and correlation procedures are relevant to assessing precision and interpretation. The registry record describes a randomized design and an analysis framework, but does not provide sufficient outcome detail to evaluate the results. No medical conclusion about vaccination or treatment should be drawn from the recorded information alone.
12. Why This Trial Matters Statistically
Statistically, this study illustrates how an intervention question can combine a cluster-based allocation structure with repeated survey measurements. Parents were assigned according to their associated middle school, while outcomes were assessed at baseline and follow-up at 6 months. Both features can create correlated observations: participants may share a school context, and repeated responses from an individual are not necessarily independent. A generalized estimating equations approach is named, but the record does not specify how these sources of correlation were modeled.
The endpoint also demonstrates why operational definitions matter. The study classified intent and reported up-to-date status together for Tdap and MCV, while excluding exemption responses for HPV. These choices define what the reported percentage would represent and shape comparisons between vaccines. A statistical estimate is only interpretable in relation to the exact response categories that generated it.
Several vaccines and time comparisons can raise questions about multiplicity, and incomplete follow-up raises questions about missing-data handling. The registry record documents these areas but does not describe a correction strategy, a missing-data method, or a named analysis population. Those are important elements for understanding how robust an estimate may be.
Finally, the record provides a useful distinction between a registered analysis plan description and reported results. It states a model family and intended use of risk ratios, yet it does not report numerical endpoint estimates. A clear statistical account should separate what the design and methods specify from what the posted results establish. In this case, the record supports discussion of the analytic question and its limitations, but not a quantitative conclusion about the intervention.
13. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The registry record does not report the primary outcome estimates, arm-specific response percentages, confidence intervals, or p-values. This prevents assessment of the observed direction, magnitude, and precision of the comparisons. The record identifies 3 analyses and vaccine-specific outcomes but does not explain whether or how multiplicity was addressed.
Only 4 middle schools were randomized, and parents were assigned by their associated school. The record does not report the number of schools in each arm or the number of participants by arm. It also does not explain whether the analysis accounted for school-level clustering. With few allocated schools, the handling of cluster-level variation is particularly important for uncertainty, but the relevant model details are not reported.
Thirty participants either did not complete the follow-up survey (n=27) or did not answer all questions (n=3). The registry does not describe missing-data methods, outcome-specific completeness, or the analysis population. It also does not report whether any sensitivity analyses were conducted. The extent to which incomplete responses could affect comparisons cannot be determined from the record.
The endpoint combines intention with reported up-to-date status for Tdap and MCV, while applying a different exemption rule for HPV. It measures survey responses rather than vaccination completion as an outcome. The registry does not report survey validation details, participant characteristics, or other information that would help assess generalizability. Masking is listed as single, but the masked party is not identified. The record also does not provide model covariates, correlation structure, or variance-estimation details.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Healthy, Immunized Communities Study — NCT03854734.
- Registry record last updated 2024-07-12; status last verified 2024-01.
- Results first posted 2024-07-12.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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17. Record Summary
The Healthy, Immunized Communities Study is listed as a completed randomized, parallel study sponsored by Milton S. Hershey Medical Center. Four middle schools were randomized to usual care or a multi-component intervention, with parents assigned according to their school. Enrollment was 148. The intervention combined a community event and educational material; usual care involved educational emails on broad health topics.
The primary endpoint was the percentage of participants classified as intending to vaccinate, or reporting that the child was up-to-date, for Tdap, MCV, and HPV. Assessments were at baseline and follow-up at 6 months. The registry describes generalized estimating equations using a log-binomial framework and says risk ratios were used to quantify significant differences.
The record reports that 30 participants either missed follow-up or did not answer all questions. It does not report primary-outcome estimates, confidence intervals, p-values, missing-data methods, or detailed model settings. Adverse-event entries list zero serious events, other events, and deaths in both groups.