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 A Study on the Safety, Effectiveness and Immune Response of Meningococcal Combined ABCWY Vaccine in Healthy Adolescents and Adults (NCT04886154), a randomized phase 1, phase 2 study. The primary outcome is Number of Participants With Solicited Administration Site Events in Study Phase I (Safety Lead-in).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04886154 |
| Phase | Phase 1, Phase 2 |
| Condition | Infections, Meningococcal |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 1440 |
| Arms in the primary outcome | n/a |
| Lead sponsor | GlaxoSmithKline |
| Results posted | Yes |
2. Clinical Question
Population
The study included healthy adults in the Phase I safety lead-in and healthy adolescents and adults in Phase II. Phase II included a formulation and schedule-finding part and a blood-sourcing part. The registry record describes the study population as healthy; it does not report results for people with meningococcal disease.
Intervention
The investigational product was MenABCWY-2Gen, tested in low-dose and high-dose formulations. The study used different schedules across its parts, including schedules described as 0, 1-month, 0, 2-month, and 0, 6-month. In the formulation and schedule-finding part, some participants received a placebo dose on a day when vaccine was not scheduled.
Comparator
Placebo was used as a control in Phase I. In the Phase II formulation and schedule-finding part, the control group received Bexsero (MenB) and Menveo (MenACWY). The registry record lists these comparators but does not report a single overall comparison that combines the study parts.
Primary question
The primary endpoint asks how many participants had solicited administration-site events during the 7 days (including the day of vaccination) following vaccination at Day 1 in the Phase I safety lead-in. The listed events are injection-site pain, redness, swelling, and induration. This is a safety question, not a measure of protection against meningococcal disease.
The study also set out to assess immune response and effectiveness, and its secondary outcomes include measures of antibody response against meningococcal serogroups. The registry record describes the study’s purpose and outcome measures, but the primary endpoint results and results for those secondary immune-response measures are not reported in the registry record in the information available for this analysis. Consequently, the central statistical question that can be addressed is limited: what endpoint the investigators selected, how the study was organized to assess safety and immune response, and what the posted adverse-event counts indicate. The record does not establish a clinical benefit or allow a conclusion about protection against invasive meningococcal disease.
3. Trial Design
This was a randomized, controlled, parallel-group Phase I/II study. The registry record describes quadruple masking. Its overall enrollment is listed as 1440, and its status is completed. The listed start date is 2021-06-14 and the primary completion date is 2024-02-02. The sponsor is GlaxoSmithKline.
The study had distinct parts with different aims. Phase I was a first-time-in-human safety lead-in in healthy adults. It evaluated low-dose and high-dose formulations with a 0, 1-month schedule, using placebo control groups. Phase II included a formulation and schedule-finding part in healthy adolescents and young adults. That part compared low-dose and high-dose formulations on schedules described as 0, 2-month and 0, 6-month, with a control group receiving MenB and MenACWY vaccines. Placebo doses were used in some investigational groups to accompany the schedules.
Phase II also included a blood-sourcing part in healthy adults. Its purpose was to collect serum samples for development of assays for the vaccine clinical development program. The listed sourcing groups used low-dose or high-dose vaccine with schedules described as 0, 1-month, 0, 2-month, or 0, 6-month. Those groups serve a different stated purpose from the formulation and schedule-finding groups, so their data should not automatically be treated as interchangeable.
The registry record does not report the randomization procedure, allocation ratio, any stratification factors, or details of how masking was maintained. Nor does it report a single analysis that pools all phases and purposes. The study’s multi-part structure matters when interpreting any group-level results: participants received different formulations, schedules, comparators, and study procedures, and the primary endpoint specifically concerns Phase I.
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.
Only the first 6 of 15 groups are shown.
Overall Study
| Stage | ABCWY Low Dose Group | Placebo Low Dose Group | ABCWY High Dose Group | Placebo High Dose Group | ABCWY Low dose_06 Group | ABCWY Low dose_02 Group |
|---|---|---|---|---|---|---|
| STARTED | 12 | 4 | 13 | 3 | 239 | 181 |
| COMPLETED | 11 | 4 | 11 | 3 | 209 | 166 |
| NOT COMPLETED | 1 | 0 | 2 | 0 | 30 | 15 |
Reasons for not completing this period:
| Reason | ABCWY Low Dose Group | Placebo Low Dose Group | ABCWY High Dose Group | Placebo High Dose Group | ABCWY Low dose_06 Group | ABCWY Low dose_02 Group |
|---|---|---|---|---|---|---|
| Adverse Event | 0 | 0 | 0 | 0 | 1 | 0 |
| Lost to Follow-up | 1 | 0 | 2 | 0 | 17 | 7 |
| ADVERSE EVENT REQUIRING EXPEDITED REPORT | 0 | 0 | 0 | 0 | 0 | 0 |
| MIGRATED / MOVED FROM THE STUDY AREA | 0 | 0 | 0 | 0 | 1 | 0 |
| Other, Not Specified | 0 | 0 | 0 | 0 | 11 | 8 |
Analysis population for the primary outcome, as defined in the registry: Analysis was performed on the Phase I Exposed set (ES), which included all participants who received at least one dose of the study treatment and have post-vaccination data for the specified analysis at specified timepoints. Allocation per group using the enrolled set is based on the treatment administered.
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.
Only the first 6 of 16 groups are shown.
| Characteristic | Unit | ABCWY Low Dose Group | Placebo Low Dose Group | ABCWY High Dose Group | Placebo High Dose Group | ABCWY Low dose_06 Group | ABCWY Low dose_02 Group |
|---|---|---|---|---|---|---|---|
| Participants analysed | 12 | 4 | 13 | 3 | 239 | 181 | |
| Age, Continuous | years | 28.6 (SD 7.5) | 30.8 (SD 6.2) | 31.7 (SD 6.0) | 28.7 (SD 3.8) | 18.9 (SD 4.7) | 18.6 (SD 4.6) |
| Sex: Female, Male: Female | Participants | 6 | 2 | 7 | 1 | 153 | 96 |
| Sex: Female, Male: Male | Participants | 6 | 2 | 6 | 2 | 86 | 85 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 0 | 0 | 0 | 41 | 29 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 11 | 4 | 13 | 3 | 198 | 152 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 1 | 0 | 0 | 0 | 0 | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Solicited Administration Site Events in Study Phase I (Safety Lead-in), measured over During the 7 days (including the day of vaccination) following vaccination at Day 1.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the number of participants with solicited administration-site events in the Phase I safety lead-in. The assessment covers the 7 days (including the day of vaccination) following vaccination at Day 1. The listed local events are injection-site pain, erythema (redness), swelling, and induration. The endpoint defines any solicited administration-site adverse event as occurrence of the symptom regardless of intensity grade.
This endpoint is used to describe short-term local tolerability after vaccination. Counting participants who experienced at least one listed symptom gives a direct summary of how commonly such events occurred in the analyzed group during the specified observation period. It is a binary participant-level outcome: each participant is classified according to whether an event occurred, rather than having the endpoint measure symptom intensity as a continuous quantity. The definition does not indicate that multiple symptoms in one participant are counted as multiple participants.
The endpoint is limited in scope. It concerns solicited local symptoms after the specified vaccination and observation window; it is not a measure of immune response, effectiveness, or protection from invasive meningococcal disease. It also does not, by itself, describe events outside that window or other types of adverse events. The registry record gives the endpoint definition and says the analysis used the Phase I Exposed set, but the arm-level primary endpoint counts are not reported in the registry record. Without those counts and their corresponding analyzed denominators, the endpoint’s observed frequency and the precision of any between-group comparison cannot be assessed from this record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a safety-focused primary endpoint but does not report its results by arm. It therefore does not support an estimate of the frequency of solicited administration-site events in the Phase I low-dose, high-dose, or placebo groups, nor a comparison of those groups for this endpoint. The record’s definition is informative about what was intended to be counted, but a definition is not an observed result.
The adverse-event figures reported separately give serious adverse-event counts and counts of other adverse events for listed groups. Serious adverse events were recorded as 0 of 12 in the ABCWY Low Dose Group, 0 of 4 in the Placebo Low Dose Group, 0 of 13 in the ABCWY High Dose Group, and 0 of 3 in the Placebo High Dose Group. In the Phase II formulation and schedule-finding groups, serious adverse events were 9 of 239 for ABCWY Low dose 06, 7 of 181 for ABCWY Low dose 02, 4 of 238 for ABCWY High dose 06, and 4 of 194 for ABCWY High dose 02. The Control Group had 2 of 197. The sourcing groups had 0 of 54, 0 of 53, 2 of 62, 1 of 62, 0 of 62, and 4 of 63 in the listed low-dose and high-dose groups. No deaths are listed in any of these groups.
These are counts, not adjusted comparisons. The registry record does not report confidence intervals, p-values, or a statistical comparison for these serious-event figures. A count of zero in a group does not establish that the underlying risk is zero; the amount of uncertainty depends on the group size and the event definition. Likewise, the observed counts alone do not establish that one formulation or schedule is safer than another. The groups belong to different study parts and are not all direct randomized comparisons for a common question.
The record lists immune-response outcomes as secondary outcomes, including antibody titers, geometric mean titers, geometric mean ratios, and response classifications. Their results are not reported in the registry record in the information available for this analysis. Thus the listed results do not answer whether the vaccine elicited an immune response of a particular magnitude or whether it was effective against disease. Any interpretation should remain confined to the reported event counts and the stated design, without treating the study’s aims as proof of an outcome.
9. Statistical Methods Explained
Several statistical ideas help distinguish what this registry record can show from what it cannot. The study is randomized and parallel-group, but those design labels do not supply the results of a comparison. Randomization is intended to make assigned groups comparable on average, while masking is intended to reduce the influence of expectations on care and assessment. The record describes the study as quadruple masked, but does not report the masking procedures or the randomization method. A design feature should not be mistaken for evidence that a particular endpoint differed between groups.
What does a participant count measure?
The primary endpoint is a count of participants with at least one solicited administration-site event during the stated observation period. For a binary outcome, each analyzed participant contributes to an event category or a no-event category. The count is most interpretable alongside the number of participants assessed, because the same count can represent different observed frequencies in groups of different sizes. Here, the primary endpoint’s arm-level counts and analyzed denominators are not reported in the registry record, so its observed frequency cannot be reconstructed or compared.
The adverse-event summaries do give counts and group denominators for serious events and other events. These are descriptive summaries. They do not state whether participants were followed for equal lengths of time for every event category, and the record does not report an exposure-adjusted rate analysis. The counts should therefore be read in the terms used by the registry record, rather than converted into a rate or interpreted as a formal treatment effect.
Why do uncertainty intervals matter?
In general, a confidence interval describes the range of effect estimates reasonably compatible with the observed data under a specified statistical method. It conveys precision as well as direction and magnitude. A count without an interval does not show how uncertain an estimated event frequency or group difference is. For a binary outcome, an interval around a proportion or a difference in proportions can be useful, but the choice of interval method depends on the analysis plan and data structure. The registry record does not report confidence intervals for the outcomes, so the precision of the listed counts cannot be described through interval estimates.
General statistical interpretation also distinguishes a lack of evidence for a difference from evidence that groups are equivalent. A non-significant test, if one were reported, would not by itself demonstrate equivalence. Equivalence or non-inferiority requires a defined margin and an analysis designed for that question. Such a margin and such an analysis are not reported in the registry record. No conclusion about equivalence between formulations, schedules, or comparators is justified from the available summaries.
How should multiple outcomes be considered?
The registry record lists 46 outcome measures and 20 analyses. In general, when many outcomes or comparisons are examined, the chance of observing an apparently unusual result by chance can increase if no adjustment or hierarchy is used. A multiplicity strategy may specify a primary outcome, a sequence of tests, or an adjustment to inference. The record does not report such a strategy, so it is not possible to determine how any secondary-outcome findings were intended to be interpreted as a family of tests. This issue is especially relevant because the study covers several formulations, schedules, phases, and immune-response measures.
What do the planning assumptions mean?
The record describes a sample-size 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. It states that the effect to detect is a stated fraction of the observed effect. Such an illustration is a planning calculation, not a result from the randomized trial and not observed power. It does not establish that the original study was designed using these assumptions. The record does not report the trial’s sample-size justification or its original statistical plan. A planning illustration cannot compensate for the absence of reported primary endpoint results.
For a binary outcome, planning depends on the event frequency anticipated in each group, the effect considered important, the chosen error rates, and the allocation. For continuous outcomes, assumptions about variability also matter. These are general principles; the registry record does not report the assumptions used to design this trial. The study’s overall enrollment is listed as 1440, but that number does not reveal how many participants contributed to a particular endpoint or comparison. The denominator for an analysis can differ from overall enrollment because of eligibility, treatment receipt, follow-up, and missing measurements.
Why do study parts and populations matter?
The Phase I Exposed set is described as including participants who received at least one dose and had post-vaccination data for the specified analysis at specified timepoints. The record also refers to allocation per group using the enrolled set, but the description is incomplete. In general, an analysis population defines which participants contribute to an estimate and should be stated with each outcome. A safety population based on treatment received can differ from a population based on randomized assignment. The registry record does not provide enough detail to determine the analysis population for every reported outcome.
Finally, immune-response outcomes and event outcomes answer different questions. Antibody titers and response classifications describe measured immune responses; administration-site events describe tolerability; serious adverse-event counts describe another safety category. None substitutes for a clinical effectiveness endpoint. The record’s stated purpose includes effectiveness, but the information does not report a clinical effectiveness result or the analysis method for one. Statistical conclusions should therefore stay tied to the specific outcome and population actually described.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists 46 outcome measures and 20 analyses, spanning safety and immune-response assessments. It does not report a multiplicity strategy explaining whether outcomes were tested in a hierarchy, whether error rates were adjusted, or how exploratory analyses were to be distinguished from confirmatory analyses. In general, examining many outcomes or comparisons can make isolated findings harder to interpret without a prespecified strategy. The absence of a reported strategy does not show that no strategy was used; it means the strategy is not reported in the registry record.
Missing-data methods are also not reported in the registry record. The record does not describe how missing endpoint assessments, withdrawals, or incomplete post-vaccination measurements were handled, or whether any sensitivity analyses were performed. For an event outcome, a participant without an assessment cannot automatically be classified as having had no event. How missing observations are treated can affect both the estimated frequency and the uncertainty of a comparison. The effect cannot be judged without the analysis rules and the amount and pattern of missing data.
The primary endpoint population is described as the Phase I Exposed set: participants who received at least one dose and had post-vaccination data for the specified analysis at specified timepoints. The record’s accompanying description of group allocation is incomplete. It does not provide a full analysis-population definition for every outcome, nor does it give endpoint-specific denominators for the primary endpoint. The overall enrollment of 1440 should not be treated as the denominator for every result.
These omissions limit reproducibility and interpretation. A complete account would identify the analysis population for each outcome, explain missing-data handling, and state how multiple outcomes and comparisons were addressed. Those details are not reported in the registry record.
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 |
|---|---|---|---|
| ABCWY Low Dose Group | 0 | 12 | 0.0% |
| Placebo Low Dose Group | 0 | 4 | 0.0% |
| ABCWY High Dose Group | 0 | 13 | 0.0% |
| Placebo High Dose Group | 0 | 3 | 0.0% |
| ABCWY Low dose_06 Group | 9 | 239 | 3.8% |
| ABCWY Low dose_02 Group | 7 | 181 | 3.9% |
| ABCWY High dose_06 Group | 4 | 238 | 1.7% |
| ABCWY High dose_02 Group | 4 | 194 | 2.1% |
| Control Group | 2 | 197 | 1.0% |
| ABCWY Low dose_01 Group | 0 | 54 | 0.0% |
| ABCWY High dose_01 Group | 0 | 53 | 0.0% |
| ABCWY Low doseS_02 Group | 2 | 62 | 3.2% |
| ABCWY High doseS_02 Group | 1 | 62 | 1.6% |
| ABCWY Low doseS_06 Group | 0 | 62 | 0.0% |
| ABCWY High doseS_06 Group | 4 | 63 | 6.3% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| ABCWY Low Dose Group | 0 of 12 |
| Placebo Low Dose Group | 0 of 4 |
| ABCWY High Dose Group | 0 of 13 |
| Placebo High Dose Group | 0 of 3 |
| ABCWY Low dose_06 Group | 0 of 239 |
| ABCWY Low dose_02 Group | 0 of 181 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| ABCWY Low Dose Group | 12 of 12 |
| Placebo Low Dose Group | 3 of 4 |
| ABCWY High Dose Group | 13 of 13 |
| Placebo High Dose Group | 2 of 3 |
| ABCWY Low dose_06 Group | 229 of 239 |
| ABCWY Low dose_02 Group | 170 of 181 |
Most frequent serious adverse event terms
| Event term | Organ system | ABCWY Low Dose Group | Placebo Low Dose Group | ABCWY High Dose Group | Placebo High Dose Group | ABCWY Low dose_06 Group | ABCWY Low dose_02 Group |
|---|---|---|---|---|---|---|---|
| Migraine | Nervous system disorders | 0 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 0 of 239 | 2 of 181 |
| Blood loss anaemia | Blood and lymphatic system disorders | 0 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 1 of 239 | 0 of 181 |
| Arrhythmia | Cardiac disorders | 0 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 1 of 239 | 0 of 181 |
| Myocarditis | Cardiac disorders | 0 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 1 of 239 | 0 of 181 |
| Benign familial haematuria | Congenital, familial and genetic disorders | 0 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 0 of 239 | 1 of 181 |
| Appendicitis | Infections and infestations | 0 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 1 of 239 | 0 of 181 |
| Pharyngeal abscess | Infections and infestations | 0 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 0 of 239 | 1 of 181 |
| Pneumonia bacterial | Infections and infestations | 0 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 0 of 239 | 1 of 181 |
| Pyelonephritis | Infections and infestations | 0 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 0 of 239 | 1 of 181 |
| Tonsillitis bacterial | Infections and infestations | 0 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 1 of 239 | 0 of 181 |
Most frequent non-serious adverse event terms
| Event term | Organ system | ABCWY Low Dose Group | Placebo Low Dose Group | ABCWY High Dose Group | Placebo High Dose Group | ABCWY Low dose_06 Group | ABCWY Low dose_02 Group |
|---|---|---|---|---|---|---|---|
| Administration site pain | General disorders | 11 of 12 | 2 of 4 | 13 of 13 | 1 of 3 | 226 of 239 | 160 of 181 |
| Fatigue | General disorders | 6 of 12 | 3 of 4 | 12 of 13 | 2 of 3 | 152 of 239 | 104 of 181 |
| Headache | Nervous system disorders | 7 of 12 | 2 of 4 | 5 of 13 | 2 of 3 | 140 of 239 | 110 of 181 |
| Myalgia | Musculoskeletal and connective tissue disorders | 4 of 12 | 1 of 4 | 6 of 13 | 1 of 3 | 53 of 239 | 34 of 181 |
| Nausea | Gastrointestinal disorders | 1 of 12 | 1 of 4 | 4 of 13 | 0 of 3 | 57 of 239 | 34 of 181 |
| Administration site swelling | General disorders | 1 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 48 of 239 | 34 of 181 |
| Administration site erythema | General disorders | 2 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 46 of 239 | 25 of 181 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 2 of 12 | 2 of 4 | 4 of 13 | 1 of 3 | 27 of 239 | 26 of 181 |
| Administration site induration | General disorders | 1 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 32 of 239 | 27 of 181 |
| Nasopharyngitis | Infections and infestations | 0 of 12 | 0 of 4 | 0 of 13 | 0 of 3 | 21 of 239 | 14 of 181 |
Serious events with the highest arm-level rate: atrial fibrillation (1.6%), colitis ulcerative (1.6%), pneumonia (1.6%), cyst (1.6%), pilonidal disease (1.6%).
The serious adverse-event figures are participant counts with the corresponding group counts at risk. In the Phase I groups, the listed serious-event counts were 0 of 12 for ABCWY Low Dose, 0 of 4 for Placebo Low Dose, 0 of 13 for ABCWY High Dose, and 0 of 3 for Placebo High Dose. In the Phase II formulation and schedule-finding groups, they were 9 of 239 for ABCWY Low dose 06, 7 of 181 for ABCWY Low dose 02, 4 of 238 for ABCWY High dose 06, 4 of 194 for ABCWY High dose 02, and 2 of 197 in the Control Group. The sourcing groups had counts of 0 of 54, 0 of 53, 2 of 62, 1 of 62, 0 of 62, and 4 of 63, respectively, as listed in the registry record. No deaths are listed for these groups.
These figures are descriptive, not adjusted estimates of comparative risk. The groups differ by study part, formulation, schedule, and comparator, so not every pair of counts represents a direct randomized comparison for the same question. The registry record does not report confidence intervals or statistical tests for these figures. A zero count does not show that an event is impossible, and a larger count alone does not establish a higher underlying risk.
The record also lists “other” adverse-event counts, but those are a separate category from serious adverse events. The serious-event figures should not be read as the primary endpoint: that endpoint concerns solicited administration-site symptoms during the specified period, and its results are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a randomized, controlled Phase I/II study was conducted to assess the safety, effectiveness, and immune response of MenABCWY-2Gen. It describes a Phase I safety lead-in and Phase II work on formulation and schedule selection and on blood sourcing. It also defines a primary endpoint for solicited administration-site events and lists serious adverse-event counts for the study groups. These are useful descriptions of the study’s design and reported safety summaries.
The record does not report arm-level results for the primary endpoint, so it cannot show how often the specified local events occurred in the Phase I groups or how those groups compared. The listed serious adverse-event counts likewise do not establish a causal difference between groups. Their interpretation is limited by the distinct study parts and schedules, and by the absence of reported comparative estimates and uncertainty intervals.
The study’s stated goals include effectiveness and immune response, and the listed secondary outcomes include antibody measurements and response classifications. But those goals and outcome listings are not results. The information available for this analysis does not report the corresponding immune-response findings or a clinical effectiveness result. It therefore does not support a conclusion about protection against invasive meningococcal disease, nor does it establish that a formulation or schedule is preferable.
More generally, a completed study does not automatically answer every question posed by its aims. A statistical conclusion depends on the outcome definition, analyzed population, observed data, comparison method, and uncertainty. Several of those elements—especially primary endpoint counts, endpoint-specific denominators, missing-data handling, and multiplicity strategy—are not reported in the registry record. The most defensible reading is consequently narrow: the record describes the trial and reports specified adverse-event counts, while leaving the primary endpoint and immune-response results unavailable for interpretation.
13. Why This Trial Matters Statistically
This study is statistically notable for combining multiple purposes within a single Phase I/II program. The Phase I part served as a safety lead-in, the Phase II formulation and schedule-finding part was intended to select a formulation and schedule for later development, and the blood-sourcing part aimed to collect serum for assay development. Those aims are related to vaccine development but are not identical statistical questions. Treating every group as part of one pooled comparison would obscure the different populations, schedules, comparators, and purposes.
The record also illustrates why endpoint definitions and reported results must be read together. The primary endpoint is clearly described as a participant count for solicited administration-site events within a specified post-vaccination window. Yet the corresponding arm-level results are not reported in the registry record. Without those results, readers cannot assess the observed event frequency or its precision, even though the endpoint definition is detailed.
Another statistical issue is the breadth of the outcome program. The registry record lists 46 outcome measures and 20 analyses, including several immune-response measures. Multiple outcomes can be appropriate in a development program, but their interpretation depends on prespecification, analysis populations, and any strategy for handling multiplicity. Those details are not reported in the registry record. The distinction between an exploratory signal and a confirmatory conclusion is therefore not available from the record.
Finally, the posted serious adverse-event counts show why descriptive summaries should not be overread. Counts across groups are not necessarily direct treatment comparisons, and a count by itself does not express precision or adjust for design differences. The study matters statistically as an example of a broad, multi-part vaccine evaluation whose design and aims are documented more fully than the primary outcome results and analysis details available for interpretation.
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 important trial-specific limitation for interpretation is that the primary endpoint results are not reported in the registry record. The record identifies the endpoint, its event definition, observation period, and Phase I analysis population, but does not give the arm-level counts or analyzed denominators needed to describe the observed frequency or compare groups. The record also does not report the primary endpoint’s uncertainty estimates or statistical test.
The study’s several parts complicate cross-group interpretation. Phase I involved healthy adults and a placebo-controlled safety lead-in, while Phase II included formulation and schedule-finding in healthy adolescents and young adults and a separate blood-sourcing part in healthy adults. Different vaccine doses, schedules, comparators, and purposes mean that group counts should not be combined or treated as if they arose from one uniform comparison. The registry record does not report a pooled analysis that would justify doing so.
The information available does not report the immune-response results or a clinical effectiveness result, despite those being among the study’s stated aims. The listed secondary outcomes describe intended measurements, not observed findings. Thus this record cannot be used to characterize the magnitude of antibody responses or clinical protection.
Analysis details are also limited. The record does not report the randomization method, allocation ratio, missing-data handling, multiplicity strategy, or a complete analysis-population definition for every outcome. It does not report the trial’s sample-size justification. The Phase I Exposed set is described, but the group-allocation description is incomplete. These gaps make it difficult to assess precision, reproduce analyses, or determine whether reported summaries address the prespecified questions.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study on the Safety, Effectiveness and Immune Response of Meningococcal Combined ABCWY Vaccine in Healthy Adolescents and Adults — NCT04886154.
- Registry record last updated 2025-05-31; status last verified 2025-05.
- Results first posted 2025-02-26.
- 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 record describes a completed randomized, controlled, parallel-group Phase I/II study of MenABCWY-2Gen in healthy adults and healthy adolescents and adults. It lists quadruple masking and overall enrollment of 1440. The study included a Phase I safety lead-in, Phase II formulation and schedule-finding, and Phase II blood sourcing. Low-dose and high-dose vaccine formulations were assessed on different schedules, with placebo controls in Phase I and MenB and MenACWY vaccines in the Phase II control group.
The primary endpoint is the number of participants with solicited administration-site events during the 7 days (including the day of vaccination) following Day 1 vaccination. Its arm-level results are not reported in the registry record. Serious adverse-event counts and group counts at risk are reported, with no deaths listed. The record lists immune-response outcomes but does not report their results in the information available for this analysis. Missing-data methods, multiplicity strategy, and several analysis details are not reported in the registry record.