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 Study of a Quadrivalent Meningococcal Conjugate Vaccine as a Single Dose Compared With a Single Dose of a Meningococcal Reference Vaccine in Children, Adolescents, and Adults 2 to 55 Years of Age (NCT04368429), a randomized phase 3 study. The primary outcome is Percentage of Participants With Vaccine Seroresponse For Meningococcal Serogroup A, C, Y And W Following Vaccination With MenACYW Conjugate and Menactra® Vaccine: Non-Inferiority Analysis.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04368429 |
| Phase | Phase 3 |
| Condition | Meningococcal Immunisation (Healthy Volunteers) |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 360 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Sanofi |
| Results posted | Yes |
2. Clinical Question
Population
Children, adolescents, and adults aged 2 to 55 years were eligible for this study. The listed condition is meningococcal immunisation in healthy volunteers. The primary analysis population was described as the Per-Protocol Analysis Set: participants who received one dose, had a valid post-vaccination blood sample, and had no relevant protocol deviations. The registry description of this population is truncated, so further eligibility or analysis-set details are not reported in the registry record.
Intervention
Participants in Group 1 received one intramuscular dose of MenACYW Conjugate vaccine on Day 0. The vaccine is described as a quadrivalent meningococcal polysaccharide vaccine conjugated to tetanus toxoid, targeting serogroups A, C, Y, and W.
Comparator
Participants in Group 2 received one intramuscular dose of Menactra® vaccine on Day 0. This comparator is described as a meningococcal polysaccharide vaccine conjugated to diphtheria toxoid, targeting groups A, C, Y, and W-135.
Primary question
The primary objective was to assess whether antibody responses to serogroups A, C, Y, and W after MenACYW Conjugate vaccine were non-inferior to responses after Menactra®. The endpoint was the percentage of participants with a vaccine seroresponse at Day 30 post-vaccination. The registry record does not report the response estimates, confidence intervals, or non-inferiority margin, so the comparison's result cannot be determined from this record alone.
This is a comparison of immune-response measurements, not a comparison of clinical disease outcomes. The endpoint uses hSBA antibody titers, a laboratory measure described in the registry, and applies a response definition that depends on participants' pre-vaccination titers. The stated secondary objectives were to describe antibody responses before vaccination and 30 days (+14 days) after vaccination, and to describe the safety profiles of the two vaccines.
3. Trial Design
This phase 3 study used randomized allocation, quadruple masking, and a parallel-group design. The registry lists enrollment of 360 participants. The two groups received different vaccines, with one intramuscular dose administered on Day 0 in each group. The record identifies Sanofi as the sponsor and lists the study status as completed.
The primary completion date is 2020-11-07, and the study start date is 2020-05-22. These dates describe the registry record; they do not, by themselves, establish when analyses were finalized or results were posted. Further details about the randomization sequence, allocation concealment, masking procedures, or any age-based stratification are not reported in the registry record.
The primary objective was non-inferiority of antibody responses to meningococcal serogroups A, C, Y, and W after MenACYW Conjugate vaccine compared with Menactra®. The primary outcome was measured at Day 30 post-vaccination. The listed primary analysis population was the Per-Protocol Analysis Set, defined as participants who received one dose, had a valid post-vaccination blood sample, and had no relevant protocol deviations. The record says that the number analyzed refers to participants with available data for each specified measure, but the full population description is truncated.
Secondary outcomes covered several antibody-response summaries, including seroresponse, hSBA titer thresholds, geometric mean titers, and fourfold rises. The list also includes immediate adverse events, solicited injection-site and systemic reactions, and unsolicited adverse events. The registry lists 10 secondary outcome measures and 4 analyses. Specific analysis methods, timing details beyond those stated, and the handling of each secondary comparison are not reported in the registry record.
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: A total of 360 participants were enrolled and randomized in the study.
Overall Study
| Stage | Group 1: MenACYW Conjugate Vaccine | Group 2: Menactra® Vaccine |
|---|---|---|
| STARTED | 180 | 180 |
| Safety Analysis Set | 179 | 180 |
| COMPLETED | 179 | 180 |
| NOT COMPLETED | 1 | 0 |
Reasons for not completing this period:
| Reason | Group 1: MenACYW Conjugate Vaccine | Group 2: Menactra® Vaccine |
|---|---|---|
| Adverse Event | 1 | 0 |
Analysis population for the primary outcome, as defined in the registry: Analysis was performed on Per-Protocol Analysis Set (PPAS) population that included participants who received 1 dose of the study vaccine and had a valid post-vaccination blood sample result with no relevant protocol deviations. Here, 'number analyzed'=participants with available data for each specified category.
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 randomized participants.
| Characteristic | Unit | Group 1: MenACYW Conjugate Vaccine | Group 2: Menactra® Vaccine | Total |
|---|---|---|---|---|
| Participants analysed | 180 | 180 | 360 | |
| Age, Continuous | years | 25.1 (SD 11.09) | 24.1 (SD 10.27) | 24.6 (SD 10.69) |
| Sex: Female, Male: Female | Participants | 84 | 95 | 179 |
| Sex: Female, Male: Male | Participants | 96 | 85 | 181 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 180 | 180 | 360 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): White | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants With Vaccine Seroresponse For Meningococcal Serogroup A, C, Y And W Following Vaccination With MenACYW Conjugate and Menactra® Vaccine: Non-Inferiority Analysis, measured over Day 30 (post-vaccination).
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | percentage of participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the percentage of participants with a vaccine seroresponse to meningococcal serogroups A, C, Y, and W at Day 30 post-vaccination. Antibody titers were measured using a serum bactericidal assay with human complement, abbreviated hSBA. The endpoint combines two routes to meeting the response definition, depending on the participant's pre-vaccination titer.
For participants whose pre-vaccination hSBA titer was below 1:8, a post-vaccination titer of at least 1:16 met the definition. For participants whose pre-vaccination titer was at least 1:8, the definition required at least a fourfold increase from pre-vaccination to post-vaccination. Thus, the measure is not simply the percentage above one post-vaccination threshold: baseline titer determines which response rule applies.
In general, a seroresponse endpoint summarizes the share of participants meeting a defined laboratory-response criterion. It can be used to compare immune-response proportions between groups. For a non-inferiority question, the comparison must also be interpreted against a specified margin and with an appropriate uncertainty estimate. The margin and the numerical response results are not reported in the registry record, so the endpoint definition alone does not establish whether the non-inferiority objective was met.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a randomized comparison of one dose of MenACYW Conjugate vaccine with one dose of Menactra® in participants aged 2 to 55 years. Its primary question concerns the proportion meeting a defined hSBA seroresponse criterion at Day 30. However, the record does not include the group response estimates, the estimated between-group contrast, or a confidence interval for that contrast. The primary outcome is also marked as having several categories or time points and not being reduced to one comparison. Consequently, there is no single numerical primary comparison to interpret.
For a non-inferiority analysis, the key issue is not merely whether the groups appear similar. The estimated difference must be assessed against a prespecified non-inferiority margin, using an uncertainty interval and the decision rule chosen for the analysis. If the margin is not known, a reader cannot determine how much difference was considered acceptable. The margin, the exact contrast direction, and the decision rule are not reported in the registry record. Nor are the outcome estimates or confidence interval. The registry description therefore identifies the intended question, but does not establish its answer.
The endpoint's response rule uses baseline antibody status: participants below the stated baseline threshold have a post-vaccination threshold criterion, while those at or above it need a fourfold increase. This makes the definition relevant to both post-vaccination level and change from baseline. In general, a percentage meeting a criterion is a summary of a binary outcome; it does not show the full distribution of antibody titers. The registry lists additional outcomes that describe titers and other response summaries, but their numerical results are not reported in the registry record.
The safety fields show zero serious adverse events among 179 participants at risk in the MenACYW group and zero among 180 participants at risk in the Menactra® group. The record also lists 98 participants with an event in the other adverse-event field among 179 at risk in the MenACYW group, and 83 among 180 at risk in the Menactra® group. Those counts describe different fields and should not be treated as the primary immune-response result. The registry lists zero deaths in both groups.
Overall, the posted information supports a description of the trial design, endpoint definition, and selected safety counts. It does not support a numerical conclusion about comparative seroresponse or whether the non-inferiority objective was achieved. The calculated tables and plots elsewhere on the page should be read for the summaries they display, while recognizing that the primary registry result is not reduced to one comparison.
9. Statistical Methods Explained
The primary outcome is binary at the participant level: a participant either meets the stated seroresponse definition or does not. In general, a percentage for a binary endpoint is calculated as the number meeting the definition divided by the number included in that endpoint analysis. The registry description says that the number analyzed refers to participants with available data for each specified measure. It does not give the group-specific primary endpoint counts or percentages in the record.
What does non-inferiority mean?
In general, a non-inferiority study asks whether the response under one intervention is not unacceptably lower than the response under a comparator. The conclusion depends on a margin defining how large a reduction could still be considered compatible with the objective. It also depends on the direction used to calculate the group contrast and on the confidence interval relative to that margin. A lack of a statistically significant difference is not, by itself, proof of non-inferiority. The margin, contrast direction, and decision rule for this trial are not reported in the registry record, so the specific non-inferiority procedure cannot be reconstructed.
How should a confidence interval be read?
In general, a confidence interval describes the range of values for an estimated effect that are compatible with the data under the chosen statistical procedure. A narrower interval indicates greater precision for that estimate; a wider interval indicates more uncertainty. It does not mean that the true value has a particular probability of falling within the interval. The primary endpoint identifies a 95% Confidence Interval as its dispersion measure, but the numerical interval is not reported in the registry record. Without the estimate and interval, the precision and decision relative to a non-inferiority margin cannot be assessed.
Why does the response definition use baseline titers?
The response rule separates participants according to their pre-vaccination hSBA titer. For those below 1:8, response requires a post-vaccination titer of at least 1:16. For those at or above 1:8, response requires at least a fourfold rise. In general, using baseline status can distinguish achieving a specified post-vaccination level from increasing substantially when the baseline level is already higher. It also means that the endpoint combines different criteria, so interpretation requires knowing how many participants fall under each rule and how many meet it. Those breakdowns are not reported in the registry record.
What does the analysis population imply?
The stated primary analysis population is the Per-Protocol Analysis Set. The record describes it as participants who received one dose, had a valid post-vaccination blood sample, and had no relevant protocol deviations. In general, a per-protocol analysis focuses on participants who followed specified study requirements and have the required outcome measurement. Excluding participants can affect the analyzed population and the interpretation of a treatment comparison. The record does not give the number included in each primary endpoint analysis or explain how exclusions were handled. The full population description is truncated.
Randomized allocation is intended, in general, to make groups comparable at the point of assignment, while masking can reduce some risks of biased treatment delivery or assessment. This study is listed as randomized and quadruple-masked, but the registry description does not specify how the randomization or masking was implemented. A parallel-group design means the two vaccine groups are compared as separate groups; the record describes one dose in each group.
The sample-size section on the page is a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such figures are planning illustrations, not observed power and not a report of the trial's original design justification. The trial's own sample-size justification is not reported in the registry record. The observed primary effect is not stated in the record, so the illustration should not be confused with a reported trial result.
The registry lists multiple secondary antibody and safety outcomes. In general, testing multiple outcomes can increase the chance of obtaining an apparently notable result by chance if no adjustment or interpretation strategy is used. The registry record does not report whether multiplicity adjustments were planned, which outcomes were treated as confirmatory, or how secondary findings should be prioritized. The titles alone do not establish an analysis method.
10. Multiplicity, Missing Data and Analysis Populations
The primary endpoint is a seroresponse measure for four meningococcal serogroups, and the registry lists multiple additional antibody and safety outcomes. It lists 10 secondary outcome measures and 4 analyses. The record does not state whether the primary endpoint was analyzed separately by serogroup, combined in a particular way, or interpreted using a hierarchy of comparisons. The primary outcome is flagged as having several categories or time points and not being reduced to one comparison.
Multiplicity matters in general because repeated statistical tests can make chance findings more likely if each result is interpreted independently. A prespecified hierarchy, adjustment, or clear distinction between confirmatory and descriptive outcomes can help readers understand the evidential role of each result. Whether any such approach was used is not reported in the registry record. The p-values and estimates for the outcomes are also not reported, so no adjustment strategy can be inferred from the outcome list.
The primary analysis population is described as a Per-Protocol Analysis Set, including participants who received one dose, had a valid post-vaccination blood sample, and had no relevant protocol deviations. The record says that the number analyzed means participants with available data for each measure, but the population description is truncated. Group-specific analysis counts, reasons for missing endpoint data, and methods for handling missing data are not reported in the registry record. It is therefore not possible to assess whether missingness differed between groups or whether any imputation or sensitivity analysis was used.
These omissions matter for interpretation: the analysis population, missing-data approach, and multiplicity strategy can affect how much confidence readers place in a reported non-inferiority result. Here, the registry record does not provide enough detail to evaluate those choices.
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 |
|---|---|---|---|
| Group 1: MenACYW Conjugate Vaccine | 0 | 179 | 0.0% |
| Group 2: Menactra® Vaccine | 0 | 180 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Group 1: MenACYW Conjugate Vaccine | 0 of 179 |
| Group 2: Menactra® Vaccine | 0 of 180 |
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 |
|---|---|
| Group 1: MenACYW Conjugate Vaccine | 98 of 179 |
| Group 2: Menactra® Vaccine | 83 of 180 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Group 1: MenACYW Conjugate Vaccine | Group 2: Menactra® Vaccine |
|---|---|---|---|
| Injection Site Pain | General disorders | 72 of 179 | 66 of 180 |
| Myalgia | Musculoskeletal and connective tissue disorders | 38 of 179 | 30 of 180 |
| Headache | Nervous system disorders | 36 of 179 | 17 of 180 |
| Malaise | General disorders | 22 of 179 | 9 of 180 |
| Injection Site Erythema | General disorders | 16 of 179 | 8 of 180 |
| Injection Site Swelling | General disorders | 14 of 179 | 6 of 180 |
The safety summary lists serious adverse events separately from other adverse-event fields. In the MenACYW Conjugate vaccine group, 0 of 179 participants at risk had a serious adverse event; in the Menactra® group, 0 of 180 participants at risk had a serious adverse event. The record lists 0 deaths in each group.
The other adverse-event field lists 98 of 179 participants at risk in the MenACYW group and 83 of 180 in the Menactra® group. These are counts from a separate field and should not be confused with the serious adverse-event counts. The available summary does not provide event terms, severity breakdowns, timing, or participant-level detail for these counts. The registry lists immediate adverse events, solicited injection-site and systemic reactions, and unsolicited adverse events among its secondary outcomes, but their detailed results are not reported in the registry record.
In general, zero recorded serious events in a group does not establish that an event is impossible or that the groups are equivalent in safety. The figures are descriptive counts for participants at risk in this record; they do not provide a comparative statistical analysis. They should be read alongside the study's follow-up and event definitions, which are not fully.
12. What the Result Does, and Does Not, Mean
This record identifies a randomized, quadruple-masked, parallel-group comparison of a single dose of MenACYW Conjugate vaccine with a single dose of Menactra® in participants aged 2 to 55 years. Its primary objective was to compare antibody responses to serogroups A, C, Y, and W using a Day 30 hSBA seroresponse measure. The registry gives the endpoint definition and the planned analysis population, but does not report the numerical primary response results, between-group estimate, confidence interval, or non-inferiority margin.
Accordingly, the information does not establish whether the study met its non-inferiority objective. It also does not establish that the vaccines had identical responses. In general, a non-inferiority conclusion requires the observed comparison to be evaluated with an uncertainty interval against a stated margin; neither the required numerical comparison nor the margin is reported in this registry record.
The endpoint is an immune-response measure, not a direct measure of meningococcal disease occurrence. The listed secondary outcomes include other antibody summaries and adverse-event measures, but their numerical results are not reported in the registry record. The safety summary records zero serious adverse events and zero deaths in both groups, alongside counts in a separate other adverse-event field. These descriptive counts do not, on their own, establish comparative safety.
In general, the strength of a study conclusion depends not only on design labels but also on estimates, precision, analysis populations, missing-data handling, and prespecified decision criteria. The registry record provides some design and endpoint information but leaves several of those elements unreported. Readers should therefore distinguish the study's stated aims from conclusions that would require results and methods not present.
13. Why This Trial Matters Statistically
This trial is statistically notable for framing its primary question as non-inferiority rather than simply asking whether the two groups differ. In general, that distinction changes the interpretation: a non-inferiority claim needs a justified margin and a comparison whose uncertainty is sufficiently limited relative to that margin. A statement that groups are not significantly different would not, by itself, answer the non-inferiority question.
The endpoint also illustrates how a binary response can combine multiple rules. Participants with lower baseline hSBA titers have a post-vaccination threshold criterion, while participants with higher baseline titers must meet a fold-rise criterion. That design means the reported percentage summarizes participants evaluated under different baseline-dependent conditions. In general, details of the baseline distribution and the number meeting each criterion can aid interpretation, but those breakdowns are not reported in the registry record.
The trial is listed as randomized, quadruple-masked, and parallel-group, with a Per-Protocol primary analysis population. These features provide important context, but they do not replace numerical results or a full account of analysis decisions. The registry does not report the non-inferiority margin, the numerical primary comparison, missing-data handling, or a multiplicity strategy. Those omissions limit independent assessment of the intended statistical claim.
Finally, the safety counts demonstrate why outcomes should be kept distinct: serious events, deaths, and other adverse-event fields are different summaries. Clear denominators and categories help prevent a descriptive count from being mistaken for a formal comparison. The central statistical lesson is that a well-defined objective and design are only part of the evidence; the estimate, its precision, and the decision rule are also needed to understand the result.
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 registry record describes the primary endpoint and its Day 30 timeframe, but does not report the group-specific seroresponse percentages, the between-group contrast, or its 95% confidence interval. It also does not report the non-inferiority margin or the decision rule. These omissions prevent an independent assessment of whether non-inferiority was demonstrated or how precisely the response comparison was estimated.
The endpoint description gives a baseline-dependent response definition, but no breakdown by serogroup or by which response criterion participants used. The primary analysis population is described as per-protocol, yet the full description is truncated and the number analyzed for each endpoint is not stated. The reasons for missing measurements, handling of missing data, and sensitivity analyses are not reported in the registry record.
Although the study is listed as randomized and quadruple-masked, further implementation details are not reported. The registry record also does not describe the statistical methods used for the primary comparison, the sample-size justification, interim analyses, or the multiplicity strategy. These details should not be inferred from the design labels or the outcome list.
The listed safety summary gives serious-event and death counts, plus counts in another adverse-event field, but does not provide event terms, timing, severity detail, or a statistical comparison. The registry's stated outcomes include more detailed safety categories, but their results are not reported in the registry record. These limitations apply to interpretation of this record and do not establish that the omitted analyses were not conducted.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study of a Quadrivalent Meningococcal Conjugate Vaccine as a Single Dose Compared With a Single Dose of a Meningococcal Reference Vaccine in Children, Adolescents, and Adults 2 to 55 Years of Age — NCT04368429.
- Registry record last updated 2025-09-15; status last verified 2025-09.
- Results first posted 2021-10-06.
- 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
NCT04368429 is a completed phase 3 randomized, quadruple-masked, parallel-group study sponsored by Sanofi. It lists enrollment of 360 participants aged 2 to 55 years and compares one intramuscular dose of MenACYW Conjugate vaccine with one intramuscular dose of Menactra® vaccine.
The primary objective was non-inferiority of antibody responses to meningococcal serogroups A, C, Y, and W. The primary endpoint was the percentage with a Day 30 hSBA vaccine seroresponse, using criteria that depend on pre-vaccination titer. The primary analysis population was described as per-protocol.
The registry lists secondary antibody and safety outcomes. Its safety summary reports zero serious adverse events and zero deaths in each group. The numerical primary endpoint results, confidence interval, non-inferiority margin, and several analysis details are not reported in the registry record.