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 Prevention, Randomized, Open Label, Active Control, Parallel Assignment, Safety/Efficacy Study (NCT00381615), a randomized phase 2 study. The primary outcome is Percentage of Subjects With Bactericidal Titers, BCA ≥1:4, 30 Days After the Third Immunization.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00381615 |
| Phase | Phase 2 |
| Condition | Healthy |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 147 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Novartis Vaccines |
| Results posted | Yes |
2. Clinical Question
Population
The study enrolled healthy infants. The primary endpoint analysis was defined for a per-protocol population: enrolled participants who received the relevant vaccine doses correctly, provided evaluable serum samples at the relevant times, and had no major protocol violation as defined before analysis. The registry record does not report the number of participants included in that endpoint analysis or the number excluded from it.
Intervention
The central immunogenicity question concerned recombinant meningococcal serogroup B vaccine, rMenB, administered with or without outer membrane vesicle, OMV-NZ. The infant-series endpoint description concerns vaccination through the third dose, with assessment one month after that dose. Arm descriptions also refer to schedules involving routine vaccines, although the registry record does not provide complete descriptions for every schedule.
Comparator
The randomized parallel-group study included four named groups: rMenB, rMenB+OMV, Routine, and Routine+OMV. The record describes routine vaccines in the groups and indicates that the two rMenB formulations were under study. It does not provide primary-endpoint estimates by group or a reported statistical contrast between any particular pair of groups.
Primary question
The primary endpoint was the percentage of participants with bactericidal antibody titers of at least 1:4 against meningococcal strains 44/76-SL, 5/99, and NZ98/254, assessed at baseline and one month after the third immunization in the infant series. The registry record describes the endpoint but does not report the percentages, confidence intervals, or a comparison result. Thus, the clinical question can be stated from the endpoint definition, but its answer cannot be determined from the posted primary outcome data.
3. Trial Design
This was a Phase 2, randomized, open-label, multicenter, controlled study with parallel assignment. The registry lists enrollment of 147 and describes the participants as healthy infants. The record status is completed. The study explored safety and immunogenicity of two formulations of a meningococcal B vaccine when given to healthy infants.
The four named groups were rMenB, rMenB+OMV, Routine, and Routine+OMV. The two vaccine formulations differ in whether OMV-NZ was included. The arm descriptions indicate that infants in the rMenB and rMenB+OMV groups received an infant series at 2, 4, 6, and 12 months of age. They also describe routine vaccines in these groups. The descriptions for the Routine and Routine+OMV groups refer to routine vaccinations and a single dose of the relevant rMenB formulation at 12 months. Some arm-description text is incomplete in the registry record, so the full schedule details cannot be established for every group.
Random allocation and a parallel-group structure support comparisons between assigned groups, while open-label masking means treatment assignment was not concealed from participants or study personnel as a blinded intervention. The registry does not report allocation ratios, the method used to generate or conceal the random sequence, or procedures for blinded laboratory assessment. It also does not report a protocol-based sample-size justification. The registered enrollment is not itself evidence of how many participants contributed to each immunogenicity analysis.
The study dates in the record are start 2006-09 and primary completion 2007-07. These dates describe the registry fields and do not establish when all analyses were finalized. The sponsor is listed as Novartis Vaccines. The study's stated focus was safety and immunogenicity; the primary endpoint was an antibody response measure rather than a clinical disease outcome.
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: All enrolled subjects were included in the trial.
Overall Study
| Stage | rMenB | rMenB+OMV | Routine | Routine+OMV |
|---|---|---|---|---|
| STARTED | 48 | 50 | 25 | 24 |
| COMPLETED | 44 | 45 | 24 | 22 |
| NOT COMPLETED | 4 | 5 | 1 | 2 |
Reasons for not completing this period:
| Reason | rMenB | rMenB+OMV | Routine | Routine+OMV |
|---|---|---|---|---|
| Withdrawal by Subject | 1 | 3 | 0 | 1 |
| Lost to Follow-up | 3 | 2 | 0 | 1 |
| Protocol Violation | 0 | 0 | 1 | 0 |
Analysis population for the primary outcome, as defined in the registry: Analysis was performed on the per protocol (PP) set, i.e. all subjects in the enrolled population who received all the relevant doses of vaccine correctly; provided evaluable serum samples at the relevant time points, and had no major protocol violation as defined prior to analysis.
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.
Population: Analysis was performed on all enrolled subjects.
| Characteristic | Unit | rMenB | rMenB+OMV | Routine | Routine+OMV | Total |
|---|---|---|---|---|---|---|
| Participants analysed | 48 | 50 | 25 | 24 | 147 | |
| Age, Continuous | Days | 59.0 (SD 3.4) | 60.9 (SD 5.9) | 60.4 (SD 5.9) | 60.9 (SD 6.1) | 60.2 (SD 5.3) |
| Sex: Female, Male: Female | Participants | 24 | 22 | 9 | 7 | 62 |
| Sex: Female, Male: Male | Participants | 24 | 28 | 16 | 17 | 85 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Subjects With Bactericidal Titers, BCA ≥1:4, 30 Days After the Third Immunization, measured over Baseline and one month after third-dose of infants series.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | Percentage of subjects |
| Endpoint classification | Binary Endpoint |
The primary endpoint measures the percentage of participants whose serum bactericidal antibody titer reached at least 1:4 against each of three meningococcal strains: 44/76-SL, 5/99, and NZ98/254. Titers were to be evaluated before vaccination and one month after the third dose of the infant series. The registry specifies a serum bactericidal assay and a per-protocol analysis population.
This kind of percentage is a binary response summary: each participant either meets the stated titer threshold or does not, for a given strain and assessment time. It can communicate how often a prespecified immune-response criterion was met. The accompanying 95% confidence interval is intended to express uncertainty around an estimated percentage. It does not by itself show whether a difference between groups is statistically or clinically important; that depends on the estimates, their uncertainty, and the comparison being considered.
The endpoint is an immunogenicity measure, not a direct count of meningococcal disease cases. The registry record does not report the endpoint percentages or confidence intervals, and it does not identify a single combined result across the three strains. Therefore, the endpoint's definition is available, but its observed values and comparative interpretation are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted record establishes the study question and design, but not the numerical primary outcome. It defines the primary measure as the percentage with bactericidal titers of at least 1:4 against three specified strains at baseline and one month after the third immunization. However, no observed percentages, confidence intervals, or group-specific primary outcome estimates are reported in the registry record. The registry also lists zero analyses. As a result, the primary endpoint cannot be interpreted as showing a particular response level or a difference between formulations from this record.
The endpoint description names a per-protocol population, defined by receipt of relevant doses, evaluable serum samples at relevant time points, and absence of major protocol violations. That definition matters because the analyzed participants may differ from the full enrolled population. The record does not state how many participants met the definition, how many had missing serum samples, or whether a separate analysis included all randomized participants. These omissions limit assessment of how representative the endpoint analysis may have been.
There are four named groups and the overall enrollment is 147, but group-specific enrollment and primary-outcome denominators are not reported. The overall enrollment should not be treated as the denominator for each endpoint estimate. Nor can the arm-specific serious adverse event counts be used to infer the immunogenicity results: they concern a different outcome and population accounting.
The record lists secondary immunogenicity outcomes, including fourfold rises, geometric mean titers and ratios, and proportions meeting a titer threshold at other times. The outcomes describe several measures and time points, but their numerical results are not included. The primary outcome is also explicitly not reduced to one comparison because it has several categories or time points. Without the group estimates, analysis contrasts, and uncertainty measures, a reader cannot establish the direction, magnitude, or precision of any immunogenicity difference.
General statistical interpretation: an estimate describes the observed data, while a confidence interval gives a range of values compatible with those data under the method's assumptions. A broad interval indicates imprecision; a narrow interval indicates greater precision, though neither alone determines practical importance. No such interval values are reported for the primary endpoint, so no precision judgment about its observed response percentages is possible from the registry record.
Safety information is listed separately. The serious adverse event figures report affected participants and participants at risk by group, while several serious-event terms have listed percentages. Those entries can be read descriptively, but the registry record does not provide a complete account of event timing, causal attribution, or comparative statistical analysis. The figures should not be treated as evidence of a causal difference between groups.
9. Statistical Methods Explained
The trial used random allocation and parallel assignment. In general, randomization is intended to make assigned groups comparable on average with respect to both measured and unmeasured characteristics. It does not guarantee identical groups in a particular study, and interpretation still depends on how allocation was generated, maintained, and analyzed. The registry record does not report the random-sequence method, allocation concealment, or allocation ratio.
The study was open label, meaning masking was listed as none. This is relevant when considering outcomes that involve judgment or participant reporting. The primary immunogenicity endpoint is based on serum assay results, but the registry record does not state whether laboratory personnel were blinded to group assignment. General explanation: objective measurement can reduce some forms of assessment subjectivity, but it does not remove all possible sources of bias, such as differences in follow-up or missing samples.
The primary measure is a percentage with a binary threshold. For a specified strain and assessment time, participants are classified according to whether their bactericidal titer reaches at least 1:4. Such a percentage is straightforward to describe, but it discards information about how far individual titers lie above or below the threshold. The record also lists continuous-style immunogenicity summaries, including geometric mean titers and geometric mean ratios, among secondary outcomes. Their numerical results are not reported.
A 95% confidence interval is listed as the dispersion measure for the primary endpoint. General explanation: a confidence interval communicates the uncertainty associated with an estimate, under the statistical method and assumptions used. It should be read together with the estimate and the analysis denominator. The registry record does not include the primary percentages or their confidence intervals, so the precision of the endpoint estimates cannot be assessed.
What does the per-protocol definition imply?
The primary analysis population was defined as participants who received all relevant vaccine doses correctly, had evaluable serum samples at relevant time points, and had no major protocol violation as defined before analysis. A per-protocol analysis focuses on participants meeting those conditions. General explanation: excluding participants after randomization can weaken the balance created by random assignment, particularly if exclusions are related to treatment group or outcome. The registry record does not report counts for the per-protocol set, reasons for exclusions, or a complementary intention-to-treat analysis.
How should the binary endpoint be considered?
General explanation: a binary percentage depends both on the underlying response and on the selected threshold. A change in the threshold could change the percentage even if the distribution of measured titers did not otherwise change. The registered threshold was at least 1:4. The endpoint was assessed for three distinct strains, so results could vary by strain. The registry record does not report whether a combined summary was planned or how strain-specific results were to be compared.
What can be said about multiple outcomes?
The registry lists 17 outcome measures, including multiple immune-response measures and assessment times. Considering many outcomes can create a multiplicity issue: general explanation, the more statistical comparisons made, the greater the chance that some findings appear notable by chance if no adjustment or prespecified hierarchy is used. The registry record does not report a multiplicity adjustment, a testing hierarchy, or which secondary outcomes were confirmatory. It also reports zero analyses, so no analysis results are available to evaluate.
The record's sample-size assumptions describe a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a fraction of the observed effect. Such an illustration is not the trial's original design justification and is not observed power. No calculated participant-per-arm values are included in the record. The original sample-size rationale is not reported in the registry record.
General explanation: power is a design concept describing the chance of detecting a specified effect under chosen assumptions. It is not a measure of whether an observed result is true, and a retrospective calculation based on an observed effect can be misleading. The planning assumptions listed in the record should therefore be understood only as an illustration, not as proof that the trial was adequately powered for its primary question.
For binary outcomes, the analysis generally needs the number meeting the response definition and the number assessed in each group, as well as the chosen comparison method. Those outcome counts and analysis denominators are absent for the primary endpoint. The record gives a confidence-interval type but does not report the specific interval method, any model, covariate adjustment, or handling of participants with missing endpoint data. These methods are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 17 outcome measures, spanning bactericidal titer percentages, fourfold rises, geometric mean titers, geometric mean ratios, strains, and assessment times. Multiple outcomes and time points can create multiplicity: general explanation, when many statistical tests are conducted, some may appear unusual by chance even if there is no underlying effect. A prespecified outcome hierarchy or adjustment can help address this issue. Neither a hierarchy nor a multiplicity adjustment is reported in the registry record.
The record does not report numerical results for the primary or secondary immunogenicity outcomes, and it lists zero analyses. Consequently, there are no posted estimates or tests from which to judge how multiplicity was handled in practice. It is also not reported whether analyses were prespecified in a protocol or statistical analysis plan, whether any analyses were exploratory, or whether interim analyses were conducted.
The primary population was per protocol. The definition requires correct receipt of relevant doses, evaluable serum samples at relevant time points, and no major protocol violation. The registry record does not report the number of participants in that set, participant flow by group, missing serum-sample counts, reasons for missingness, or how missing outcome data were treated. It also does not report a separate intention-to-treat analysis or sensitivity analyses.
General explanation: missing data matter because an analysis based only on participants with observed measurements may be biased if the likelihood of missingness is related to treatment assignment or the unobserved response. Without counts and a stated handling method, readers cannot assess whether missingness may affect the interpretation of the endpoint. The registry record does not report the protocol, full statistical analysis plan, or details needed to evaluate these issues.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| rMenB | 3 | 48 | 6.2% |
| rMenB+OMV | 9 | 50 | 18.0% |
| Routine | 4 | 25 | 16.0% |
| Routine+OMV | 2 | 24 | 8.3% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| rMenB | 48 of 48 |
| rMenB+OMV | 50 of 50 |
| Routine | 25 of 25 |
| Routine+OMV | 24 of 24 |
Most frequent serious adverse event terms
| Event term | Organ system | rMenB | rMenB+OMV | Routine | Routine+OMV |
|---|---|---|---|---|---|
| Bronchiolitis | Infections and infestations | 2 of 48 | 1 of 50 | 1 of 25 | 0 of 24 |
| Gastroenteritis | Infections and infestations | 0 of 48 | 2 of 50 | 0 of 25 | 0 of 24 |
| Lower respiratory tract infection | Infections and infestations | 0 of 48 | 2 of 50 | 0 of 25 | 0 of 24 |
| Hydrocele | Congenital, familial and genetic disorders | 0 of 48 | 0 of 50 | 1 of 25 | 0 of 24 |
| Deafness | Ear and labyrinth disorders | 0 of 48 | 1 of 50 | 0 of 25 | 0 of 24 |
| Pyrexia | General disorders | 0 of 48 | 1 of 50 | 0 of 25 | 0 of 24 |
| Bronchitis | Infections and infestations | 0 of 48 | 1 of 50 | 0 of 25 | 0 of 24 |
| Croup infectious | Infections and infestations | 0 of 48 | 0 of 50 | 1 of 25 | 0 of 24 |
| Gastroenteritis viral | Infections and infestations | 0 of 48 | 0 of 50 | 1 of 25 | 0 of 24 |
| Pneumonia | Infections and infestations | 0 of 48 | 1 of 50 | 0 of 25 | 0 of 24 |
Most frequent non-serious adverse event terms
| Event term | Organ system | rMenB | rMenB+OMV | Routine | Routine+OMV |
|---|---|---|---|---|---|
| Injection Site Erythema | General disorders | 47 of 48 | 49 of 50 | 25 of 25 | 24 of 24 |
| Irritability | Psychiatric disorders | 42 of 48 | 48 of 50 | 23 of 25 | 24 of 24 |
| Injection site induration | General disorders | 41 of 48 | 45 of 50 | 22 of 25 | 24 of 24 |
| Somnolence | Nervous system disorders | 37 of 48 | 40 of 50 | 22 of 25 | 20 of 24 |
| Injection Site pain | General disorders | 36 of 48 | 37 of 50 | 13 of 25 | 18 of 24 |
| Eating disorder | Psychiatric disorders | 27 of 48 | 32 of 50 | 15 of 25 | 12 of 24 |
| Crying | General disorders | 26 of 48 | 24 of 50 | 15 of 25 | 12 of 24 |
| Diarrhoea | Gastrointestinal disorders | 26 of 48 | 22 of 50 | 13 of 25 | 12 of 24 |
| Vomiting | Gastrointestinal disorders | 22 of 48 | 16 of 50 | 12 of 25 | 12 of 24 |
| Rash | Skin and subcutaneous tissue disorders | 20 of 48 | 19 of 50 | 10 of 25 | 7 of 24 |
Serious events with the highest arm-level rate: bronchiolitis (4.2%), viral infection (4.2%), purpura (4.2%), hydrocele (4.0%), croup infectious (4.0%).
The registry lists serious adverse event figures by group. For rMenB, 3 of 48 participants at risk were listed as affected; for rMenB+OMV, 9 of 50; for Routine, 4 of 25; and for Routine+OMV, 2 of 24. These are descriptive group entries, not a reported statistical comparison. The record does not state whether events were considered related to vaccination, how they were distributed over time, or whether one participant could contribute more than one event.
The listed serious-event terms and percentages are Bronchiolitis, 4.2%; Viral infection, 4.2%; Purpura, 4.2%; Hydrocele, 4.0%; Croup infectious, 4.0%; and Gastroenteritis, 4.0%. The registry record does not provide the denominators or group-specific distribution for each term in this list, so these percentages should not be interpreted as group-specific rates or used to calculate comparisons.
Deaths are not reported in the registry record. The other adverse event figures list all participants at risk as affected in each group, but the event definition and details are not given in the information recorded. Serious and other adverse event entries describe different categories and should not be conflated. These safety counts alone do not establish causation or a comparative safety conclusion.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a randomized, open-label, parallel-group Phase 2 study of rMenB formulations was conducted in healthy infants, with safety and immunogenicity as its focus. It specifies a primary immunogenicity endpoint based on the proportion meeting a bactericidal titer threshold against three meningococcal strains, measured at baseline and one month after the third infant-series dose. This is useful information about what the study set out to measure.
The record does not report the primary outcome percentages, confidence intervals, group-specific denominators, or comparative estimates. It therefore does not establish from the posted primary results how many participants met the threshold, how results differed by strain or group, or how precise any estimate was. The secondary outcome names likewise indicate planned or registered measures, not findings.
General explanation: an immune-response marker is not the same as a clinical disease outcome. The endpoint concerns serum bactericidal titers; it is not a count of meningococcal disease cases. The record does not provide clinical disease results, nor does it report enough numerical immunogenicity data to assess the endpoint's magnitude or uncertainty.
The safety entries are counts of participants affected by serious adverse events, alongside group denominators, and a list of serious-event terms with percentages. They are descriptive and do not include a comparative analysis or an account of causal attribution. They should not be used by themselves to infer that a formulation caused or prevented an event. Deaths are not reported in the registry record.
The enrollment figure of 147 describes the overall study enrollment, not the number assessed for every endpoint. The primary analysis population was per protocol, and its size and missing-data details are not reported. Thus, the enrolled total cannot substitute for endpoint-specific denominators or resolve concerns about exclusions and missing samples. Overall, the registry record supports a description of the research question and selected safety entries, but not a conclusion about comparative immunogenicity or safety.
13. Why This Trial Matters Statistically
Statistically, this study illustrates the distinction between a registered endpoint and a reported result. The registry describes a threshold-based antibody percentage, the strains assessed, the timing of measurement, and the per-protocol population. Those details identify what an analysis would need to summarize. Yet the actual percentages and confidence intervals are not reported, so the endpoint's observed magnitude and precision remain unavailable.
The design also raises common interpretation questions. Randomization is relevant to between-group comparisons, while open-label conduct and a per-protocol analysis make details of measurement, exclusions, and missing samples important. The registry record does not provide enough information to evaluate allocation procedures, laboratory masking, participant flow, or missing-data handling. These are not merely formal reporting details: they affect how confidently readers can interpret a group comparison.
Multiple strains, time points, and immunogenicity measures make prespecification and multiplicity handling important. The record lists 17 outcomes but does not report a testing hierarchy or adjustment method. Without numerical analyses, readers cannot determine which findings were primary, how uncertainty was quantified across outcomes, or whether any observed pattern was consistent across strains and time points.
The record also distinguishes the trial's enrolled population from its per-protocol endpoint population. Reporting both the size and composition of those populations would help readers judge how the analysis relates to random assignment. Since the endpoint counts and analysis denominators are not reported, that assessment is not possible. These limitations underscore why complete outcome reporting is essential for statistical interpretation, even when a study's design and endpoint definitions are recorded.
14. 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 most consequential trial-specific limitation in the registry record is the absence of numerical primary immunogenicity results. Although the endpoint definition identifies the threshold, strains, timing, confidence-interval type, and per-protocol population, the record does not give group-level response percentages, confidence intervals, or analysis denominators. There is no basis in the posted results for estimating the size or precision of a group difference.
The study had four named groups and overall enrollment of 147, but participant counts by group and endpoint-specific counts are not reported. The primary analysis required evaluable serum samples and compliance with relevant dosing and protocol requirements. Without participant flow or exclusion counts, the relationship between enrollment, randomization, and the analyzed population cannot be assessed.
The registry identifies the study as open label, but does not report whether laboratory assessors were masked to assignment. It does not state the randomization method or allocation concealment. The available arm descriptions are incomplete, limiting assessment of the full vaccination schedules and the exact contrasts represented by the groups.
Although 17 outcome measures are listed, the record does not report which analyses were conducted, any multiplicity strategy, or a statistical analysis plan. The original sample-size justification, interim-analysis plan, model specifications, and missing-data methods are not reported in the registry record. The sample-size assumptions describe a planning illustration rather than the trial's own design justification.
Safety information is also limited: serious adverse event counts are listed by group, but timing, attribution, event-level details, and comparative analyses are not reported. The serious-event term percentages are not accompanied by their denominators or group distributions. Deaths are not reported in the registry record. These gaps restrict both statistical interpretation and a fuller understanding of the trial's safety reporting.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Prevention, Randomized, Open Label, Active Control, Parallel Assignment, Safety/Efficacy Study — NCT00381615.
- Registry record last updated 2015-10-09; status last verified 2015-09.
- Results first posted 2015-10-09.
- 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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18. Record Summary
The registry describes NCT00381615 as a completed, randomized, open-label, parallel-group Phase 2 study in healthy infants, with enrollment of 147. The study examined safety and immunogenicity of rMenB with and without OMV-NZ, alongside groups receiving routine vaccines. Its primary endpoint was the percentage of participants with bactericidal titers of at least 1:4 against strains 44/76-SL, 5/99, and NZ98/254, at baseline and one month after the third immunization in the infant series.
The primary endpoint was defined for a per-protocol population, but its estimates, confidence intervals, analysis denominators, and group comparisons are not reported in the registry record. The record lists 17 outcome measures and zero analyses. Serious adverse event counts are reported by group, while deaths and several details needed for comparative interpretation are not reported. The record therefore describes the design and outcome definitions more fully than it reports the study's numerical immunogenicity findings.