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 Immunogenicity and Safety of a Booster Dose of an Investigational Quadrivalent Meningococcal Conjugate Vaccine (NCT02752906), a randomized phase 3 study. The primary outcome is Percentage of Participants With Seroresponse to Meningococcal Serogroups A, C, Y, and W Following Vaccination With Either MenACYW Conjugate Vaccine or Menactra® Vaccine.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02752906 |
| Phase | Phase 3 |
| Condition | Meningitis, Meningococcal Meningitis, Meningococcal Infections |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 810 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Sanofi Pasteur, a Sanofi Company |
| Results posted | Yes |
2. Clinical Question
Population
The trial enrolled healthy, meningococcal vaccine-primed adolescents and adults who had received a first dose of a quadrivalent meningococcal conjugate vaccine 4 to 10 years before the booster. Adolescents were at least 15 and younger than 18 years; adults were 18 years or older. The primary immune-response population was the Per-Protocol Analysis Set-2, defined in the registry as participants without specified protocol deviations.
Intervention
Participants assigned to the investigational group received one dose of MenACYW Conjugate vaccine on Day 0. The study aimed to describe antibody responses and safety after booster administration.
Comparator
The comparison group received one dose of Menactra® on Day 0. The registry describes the study as randomized, double-masked, and parallel-group.
Primary question
At Day 30, did the percentage of participants with a seroresponse to meningococcal serogroups A, C, Y, and W after MenACYW meet the study’s objective of non-inferiority relative to the percentage after Menactra? The registry record does not report the primary comparison estimate, confidence intervals, or non-inferiority margin, so the posted information does not establish the answer to that question.
The study also had secondary and observational aims. These included examining seroresponse at Day 6 in a subset of 120 participants, geometric mean antibody titers on Day 0 and Day 30, and antibody titers at Day 0, Day 6, and Day 30. Safety outcomes included solicited injection-site and systemic reactions. The registry record describes the objectives and measures, but does not report numerical results for the primary seroresponse comparison. The question is therefore best understood as a description of the trial’s intended comparison, not as a conclusion about whether one vaccine met the non-inferiority objective.
3. Trial Design
This was a Phase 3, randomized, double-masked, parallel-group study with 810 participants enrolled. The registry lists the study as completed. Its start date was 2016-04-15, and its primary completion date was 2016-12-19. The sponsor was Sanofi Pasteur, a Sanofi Company.
Participants were healthy adolescents or adults who had been primed with a quadrivalent meningococcal vaccine 4 to 10 years before receiving a booster. One group received a single dose of MenACYW Conjugate vaccine on Day 0; the comparator group received a single dose of Menactra® on Day 0. Randomization assigns participants to study groups by chance, and masking is intended to limit the influence of treatment knowledge on participant experiences or study assessments. The registry record does not report further details about how randomization or masking was implemented, nor does it report the allocation ratio.
The primary outcome was the percentage of participants with a Day 30 seroresponse to serogroups A, C, Y, and W, assessed using a human serum bactericidal assay with human complement. The primary immune-response population was PPAS2, defined by the registry as participants without specified protocol deviations, including deviations involving eligibility or vaccine administration. The registry describes secondary assessments of Day 6 seroresponse in a subset of 120 participants and geometric mean titers at Day 0 and Day 30. It also lists safety outcomes, including solicited injection-site and systemic reactions.
The registry record does not report the sample-size justification, the planned allocation ratio, or additional protocol details. Although the study is described as randomized and double-masked, information about the procedures supporting those design features is not reported in the registry record. These omissions limit how fully the design can be reconstructed from the public 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 810 participants who met all of the inclusion criteria and none of the exclusion criteria were enrolled and randomized in the study.
Overall Study
| Stage | MenACYW Conjugate Vaccine | Menactra ® |
|---|---|---|
| STARTED | 403 | 407 |
| Vaccinated | 402 | 407 |
| COMPLETED | 396 | 402 |
| NOT COMPLETED | 7 | 5 |
Reasons for not completing this period:
| Reason | MenACYW Conjugate Vaccine | Menactra ® |
|---|---|---|
| Protocol Violation | 2 | 1 |
| Withdrawal by Subject | 2 | 2 |
| Lost to Follow-up | 3 | 2 |
Analysis population for the primary outcome, as defined in the registry: Per-Protocol Analysis Set-2 (PPAS2): included all participants who had no protocol deviations (not meet inclusion/exclusion criteria, participant did not received vaccine, administration of vaccine not done as per-protocol). PPAS2 defined for evaluating the immune response of MenACYW vaccine measured by hSBA assessed at Day 30 after vaccination.
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 | MenACYW Conjugate Vaccine | Menactra ® | Total |
|---|---|---|---|---|
| Participants analysed | 403 | 407 | 810 | |
| Age, Continuous | Years | 20.0 (SD 5.96) | 19.9 (SD 5.59) | 20.0 (SD 5.77) |
| Sex: Female, Male: Female | Participants | 207 | 200 | 407 |
| Sex: Female, Male: Male | Participants | 196 | 207 | 403 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): Asian | Participants | 11 | 3 | 14 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 1 | 1 |
| Race (NIH/OMB): Black or African American | Participants | 40 | 46 | 86 |
| Race (NIH/OMB): White | Participants | 342 | 340 | 682 |
| Race (NIH/OMB): More than one race | Participants | 8 | 17 | 25 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 1 | 0 | 1 |
| Region of Enrollment: United States | Participants | 403 | 407 | 810 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants With Seroresponse to Meningococcal Serogroups A, C, Y, and W Following Vaccination With Either MenACYW Conjugate Vaccine or Menactra® Vaccine, 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 who met the study’s definition of seroresponse to meningococcal serogroups A, C, Y, and W at Day 30 after vaccination. The assay was a serum bactericidal assay using human complement, abbreviated hSBA. For participants whose pre-vaccination hSBA titer was below 1:8, seroresponse required a post-vaccination titer of at least 1:16. For participants whose pre-vaccination titer was at least 1:8, it required at least a 4-fold increase from pre- to post-vaccination.
This definition accounts for participants’ starting antibody titers: the criterion differs depending on whether a participant’s pre-vaccination titer was below or at least 1:8. The endpoint reduces the assay measurements to a binary participant-level outcome: each participant either meets the specified response definition or does not. The group percentage then describes how many participants in the analysis population met that definition.
In general, a seroresponse endpoint is used to describe an immune response according to a prespecified laboratory-based threshold or change. It is not itself a measure of clinical disease prevention. The trial’s stated primary objective was to evaluate non-inferiority of the response percentage after MenACYW compared with Menactra. The registry record does not report the observed percentages, the estimated between-group comparison, or the non-inferiority margin, so the endpoint definition alone cannot show whether that objective was met.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The trial’s primary objective concerned non-inferiority: whether the Day 30 seroresponse with MenACYW was not unacceptably lower than the response with Menactra, according to a prespecified margin. The registry record identifies that objective and defines the seroresponse endpoint, but it does not report the primary outcome percentages, a comparison estimate, confidence intervals, or the margin. Consequently, the posted results do not permit a statistical conclusion about whether non-inferiority was demonstrated.
The endpoint is a binary outcome at the participant level. A participant either meets the stated hSBA response criterion or does not, and the outcome is expressed as a percentage in the relevant analysis population. The registry specifies the Per-Protocol Analysis Set-2 for the primary immune-response assessment. The record’s definition excludes participants with specified protocol deviations. It does not give the number analyzed in each group for this endpoint or explain how participants with missing Day 30 measurements were handled.
In general, a confidence interval communicates uncertainty around an estimated quantity. For a group percentage, it gives a range of values compatible with the observed data and the method’s assumptions. For a between-group comparison, the interval is especially relevant to non-inferiority: interpretation depends on the direction of the comparison and where the interval lies relative to the prespecified margin. Without the estimate, interval, and margin, neither the size nor the precision of the primary comparison can be assessed from the registry record.
The registry also identifies secondary outcomes: Day 6 seroresponse in a subset of 120 participants, geometric mean titers against the four serogroups, and solicited injection-site or systemic reactions. The descriptions identify measurements and time points, but numerical results for these outcomes are not reported in the registry record. Thus, they cannot be used to characterize the magnitude or precision of immune responses or the frequency of solicited reactions.
For safety, the record lists serious adverse events in 5 of 402 participants in the MenACYW group and 4 of 407 participants in the Menactra group. It reports no deaths in either group. It also lists 255 participants in the MenACYW group and 263 participants in the Menactra group in another adverse-event category, but the category’s precise definition is not reported in the registry record. These counts describe the posted safety data; they do not, by themselves, establish a comparative safety effect.
Overall, the registry supports a description of the study question, endpoint definition, design, and selected safety counts. It does not provide enough primary efficacy detail to determine whether the stated non-inferiority objective was met. The absence of numerical immune-response results should not be replaced by inference from the study title, its completion status, or its planned objectives.
9. Statistical Methods Explained
The statistical methods can be understood in terms of the endpoint, the planned comparison, and the uncertainty around estimates. The registry record provides the endpoint definition and identifies a confidence interval for the primary percentage, but it does not report a full statistical analysis plan or numerical primary results.
What does a response percentage represent?
The primary endpoint classifies each participant according to whether the Day 30 hSBA result meets the seroresponse rule. Participants with pre-vaccination titers below 1:8 meet the rule if their post-vaccination titers are at least 1:16. Participants with pre-vaccination titers at least 1:8 meet it if their titers rise at least 4-fold. The percentage is a summary of the proportion of the analysis population meeting the rule. It is not the same as the average antibody titer: a percentage records whether a threshold-based criterion was met, whereas a geometric mean titer summarizes measured antibody levels.
How does non-inferiority differ from a test of equality?
In general, a non-inferiority study asks whether the intervention’s outcome is not worse than the comparator by more than a prespecified acceptable amount. The analysis therefore requires a defined margin, a specified comparison direction, and an estimate with uncertainty. A finding is interpreted against that margin, rather than by treating any difference from zero as the sole question. The registry states that the primary objective was non-inferiority of the seroresponse after MenACYW relative to Menactra. It does not report the margin, the exact statistical procedure, or the numerical comparison. Those omissions prevent an independent assessment of the non-inferiority claim from the registry record.
What does a confidence interval contribute?
In general, a confidence interval expresses the statistical uncertainty associated with an estimate under a specified method. For a response percentage, it indicates the precision of the estimated group response. For a contrast between groups, an interval indicates which comparative values remain compatible with the data and assumptions. The primary outcome lists a 95% confidence interval as its dispersion measure, but the interval’s endpoints are not reported in the registry record. Without those values, the precision of either group response cannot be evaluated from the record.
Why use a per-protocol immune-response population?
The primary immune-response population is PPAS2. The registry defines this set as participants without specified protocol deviations, including failures to meet inclusion or exclusion criteria, not receiving vaccine, or vaccine administration not being performed according to protocol. A per-protocol analysis can focus on participants whose study conduct met defined criteria. In general, however, excluding participants can affect which participants contribute to an estimate. Interpretation is stronger when the analysis population and exclusions are transparent and when relevant complementary analyses are also reported. The registry record does not report the number included in PPAS2 by group, a complementary primary analysis population, or details about handling missing endpoint measurements.
How should the secondary measures be understood?
The secondary objectives include Day 6 seroresponse in a subset of 120 participants and geometric mean titers at Day 0 and Day 30. These outcomes address different features of antibody response: the Day 6 measure applies the seroresponse concept at an earlier assessment, while geometric mean titers summarize antibody levels. The record also lists solicited injection-site and systemic reactions. The outcome descriptions do not give numerical results, analysis methods, or detailed definitions for these measures. Their existence therefore does not provide evidence about the size of any treatment-group difference.
What can planning illustrations say?
In general, a sample-size calculation describes how many participants might be needed under stated assumptions to target a specified level of statistical power for a particular effect. Such calculations depend on assumptions about the endpoint, effect size, allocation, significance level, and analysis method. A planning illustration based on an observed effect is not the trial’s original design justification and is not observed power. The registry record does not report the trial’s sample-size justification or detailed planning assumptions. Any planning illustration should therefore be treated as an illustration of assumptions, not as evidence that the trial had a particular power or that an effect was detected.
For this binary endpoint, the key statistical information needed to interpret the main objective would include group response estimates, a between-group contrast with its confidence interval, the non-inferiority margin, the analysis population and its group sizes, and the handling of missing observations. The registry description gives the endpoint rule and analysis-set definition, but the primary comparison details are not reported in the registry record. Statistical concepts can explain what those details would mean, but cannot substitute for their absence.
10. Multiplicity, Missing Data and Analysis Populations
The trial included a primary endpoint and several secondary or observational aims: seroresponse at Day 6 in a subset of 120 participants, geometric mean titers at Day 0 and Day 30, antibody titers at several time points, and safety outcomes including solicited reactions. When a study evaluates multiple outcomes, serogroups, or time points, there can be multiple opportunities to observe apparently favorable or unfavorable results by chance. In general, multiplicity procedures or a prespecified hierarchy can help define how such findings are interpreted.
The registry record does not report a multiplicity adjustment, testing hierarchy, or other approach for controlling interpretation across outcomes and serogroups. It also does not report whether all listed outcomes were tested inferentially or which comparisons were designated confirmatory beyond the stated primary non-inferiority objective. The absence of those details means the secondary outcomes cannot be assumed to have a particular confirmatory status.
Missing-data methods are also not reported in the registry record. The primary analysis population is described as PPAS2, with exclusions for specified protocol deviations, but the record does not state how missing Day 30 titers or incomplete outcome data were treated. It does not give the number analyzed by group for the primary outcome or describe sensitivity analyses for missing observations. These details matter because analysis-set exclusions and missing measurements can influence which participants contribute to an estimate.
The registry’s PPAS2 definition is useful for understanding the intended primary immune-response population, but it does not replace a full account of participant flow, missingness, and analysis procedures. The available description therefore supports identifying the principal endpoint and its population, while leaving multiplicity and missing-data handling uncertain.
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 | 5 | 402 | 1.2% |
| Group 2: Menactra ® | 4 | 407 | 1.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Group 1: MenACYW Conjugate Vaccine | 0 of 402 |
| Group 2: Menactra ® | 0 of 407 |
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 | 255 of 402 |
| Group 2: Menactra ® | 263 of 407 |
Most frequent serious adverse event terms
| Event term | Organ system | Group 1: MenACYW Conjugate Vaccine | Group 2: Menactra ® |
|---|---|---|---|
| Intestinal Perforation | Gastrointestinal disorders | 0 of 402 | 1 of 407 |
| Chest Pain | General disorders | 0 of 402 | 1 of 407 |
| Cholelithiasis | Hepatobiliary disorders | 1 of 402 | 0 of 407 |
| Allergy To Arthropod Sting | Immune system disorders | 1 of 402 | 0 of 407 |
| Appendicitis | Infections and infestations | 1 of 402 | 0 of 407 |
| Clavicle Fracture | Injury, poisoning and procedural complications | 1 of 402 | 0 of 407 |
| Major Depression | Psychiatric disorders | 0 of 402 | 1 of 407 |
| Suicidal Ideation | Psychiatric disorders | 0 of 402 | 1 of 407 |
| Pulmonary Embolism | Respiratory, thoracic and mediastinal disorders | 1 of 402 | 0 of 407 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Group 1: MenACYW Conjugate Vaccine | Group 2: Menactra ® |
|---|---|---|---|
| Injection Site Pain | General disorders | 178 of 402 | 196 of 407 |
| Myalgia | Musculoskeletal and connective tissue disorders | 147 of 402 | 158 of 407 |
| Headache | Nervous system disorders | 155 of 402 | 137 of 407 |
| Malaise | General disorders | 110 of 402 | 108 of 407 |
Serious events with the highest arm-level rate: cholelithiasis (0.2%), allergy to arthropod sting (0.2%), appendicitis (0.2%), clavicle fracture (0.2%), pulmonary embolism (0.2%).
The registry lists serious adverse events for both groups. In the MenACYW group, 5 of 402 participants were recorded with a serious adverse event; in the Menactra group, 4 of 407 participants were recorded with a serious adverse event. No deaths are listed in either group. The record also lists 255 participants in the MenACYW group and 263 participants in the Menactra group under another adverse-event category. The exact definition of that other category is not reported in the registry record.
The registry lists six serious-event terms, each with a reported frequency of 0.2%: Cholelithiasis, Allergy To Arthropod Sting, Appendicitis, Clavicle Fracture, Pulmonary Embolism, and Intestinal Perforation. These term-level entries should be read as the registry’s reported descriptions, not as a complete clinical assessment of each event or its relationship to vaccination. The record does not report causal attribution, event timing, or further detail for these entries.
In general, counts and percentages describe events recorded during the study; they do not by themselves establish whether an event was caused by an intervention or whether groups differ meaningfully. Interpretation also depends on event definitions, observation periods, and the completeness of reporting. Those details are not fully reported in the registry record. The safety figures therefore summarize the posted counts without supporting a broader causal or comparative conclusion.
12. What the Result Does, and Does Not, Mean
The trial was designed to compare a booster dose of MenACYW Conjugate vaccine with a booster dose of Menactra® in healthy, meningococcal vaccine-primed adolescents and adults. Its primary question concerned non-inferiority in Day 30 seroresponse to serogroups A, C, Y, and W. The registry provides a clear description of the endpoint rule and identifies PPAS2 as the primary immune-response population.
The posted record does not report the primary group percentages, the between-group estimate, its confidence interval, or the non-inferiority margin. It therefore does not establish whether the primary objective was met, how large any difference was, or how precisely that difference was estimated. A trial’s stated objective and completed status do not determine its result.
The record also describes secondary immune-response assessments and safety measures, but numerical results for the listed immune outcomes and solicited reactions are not reported in the registry record. The available safety information includes serious adverse-event counts, no deaths listed in either group, and entries for serious-event terms. These data can be described as posted, but they do not by themselves establish causation or a comparative safety conclusion.
In general, clinical interpretation requires attention to the endpoint, analysis population, effect estimate, uncertainty, and study conduct. A laboratory seroresponse is an immune-response measure defined by assay thresholds and change from baseline; it is not, by itself, a direct measure of clinical disease prevention. Non-inferiority interpretation additionally depends on the margin and confidence interval. Since those primary comparison details are not reported in the registry record, conclusions should remain limited to the study’s design, stated aims, endpoint definition, and posted safety counts.
13. Why This Trial Matters Statistically
This trial is statistically notable for its non-inferiority question and its threshold-based immune-response endpoint. Non-inferiority analyses are not interpreted simply by asking whether two group estimates look similar. In general, they require a defined margin and an estimate with enough precision to assess whether the intervention is acceptably close to the comparator. The registry states the objective but does not report the margin or primary comparison results, illustrating why a study description alone is insufficient to evaluate a non-inferiority conclusion.
The endpoint also makes baseline antibody status relevant to classification. Participants with pre-vaccination hSBA titers below 1:8 were evaluated using a post-vaccination threshold of at least 1:16, while participants with pre-vaccination titers at least 1:8 were evaluated by a rise of at least 4-fold. This rule combines a post-vaccination threshold and a change-from-baseline criterion within one binary outcome. Understanding that definition is necessary before interpreting any group response percentage.
The registry’s use of PPAS2 is another important statistical feature. A per-protocol population can describe responses among participants who met specified conduct criteria, but interpretation depends on transparent reporting of exclusions, group sizes, missing observations, and any complementary analyses. Those details are not fully reported in the registry record.
Finally, the trial includes multiple serogroups, time points, immune-response measures, and safety outcomes. In general, multiplicity and the distinction between primary and secondary aims affect how a collection of results should be interpreted. The registry record identifies these aims but does not report its approach to multiplicity. Taken together, the record is a useful example of how design and endpoint definitions frame a statistical question, while also showing why effect estimates and analysis details are needed to answer it.
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 central limitation for statistical interpretation is that the registry record does not report numerical results for the primary Day 30 seroresponse endpoint. It gives the response definition and the stated non-inferiority objective, but not group percentages, a between-group estimate, confidence intervals, or the non-inferiority margin. The primary objective therefore cannot be assessed from the posted information.
Numerical results for the described secondary immune-response outcomes are also not reported in the registry record. The record identifies Day 6 seroresponse in a subset of 120 participants and geometric mean titers at Day 0 and Day 30, but does not give their estimates or uncertainty. It likewise does not report numerical results for the solicited injection-site and systemic reactions listed as outcomes.
The primary analysis population is defined, but the number analyzed in each group and participant flow into PPAS2 are not reported in the registry record. Missing-data handling, sensitivity analyses, and the presence of any complementary analysis population are also not reported. These omissions limit assessment of how exclusions or incomplete measurements may have influenced the immune-response results.
The registry record does not report the sample-size justification, the non-inferiority margin, a detailed statistical analysis plan, or an approach to multiplicity. It describes randomization and double masking, but additional implementation details are not reported in the registry record. For safety, serious adverse-event counts and selected terms are listed, while further details about attribution, timing, and the definition of the other adverse-event category are not reported. These limitations do not alter the stated trial design, but they constrain conclusions that can be drawn from the public record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Immunogenicity and Safety of a Booster Dose of an Investigational Quadrivalent Meningococcal Conjugate Vaccine — NCT02752906.
- Registry record last updated 2022-04-05; status last verified 2022-03.
- Results first posted 2020-06-05.
- 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
NCT02752906 was a completed Phase 3 randomized, double-masked, parallel-group study enrolling 810 participants. It compared a single Day 0 booster dose of MenACYW Conjugate vaccine with a single Day 0 dose of Menactra® in healthy meningococcal vaccine-primed adolescents and adults whose prior quadrivalent meningococcal conjugate vaccination occurred 4 to 10 years earlier.
The primary outcome was Day 30 seroresponse to meningococcal serogroups A, C, Y, and W, defined using hSBA thresholds and change from pre-vaccination titers. The primary immune-response population was PPAS2. The registry record does not report numerical results for the primary comparison or the non-inferiority margin. It lists serious adverse events in 5 of 402 MenACYW participants and 4 of 407 Menactra participants, with no deaths listed in either group. The record’s outcome descriptions and safety counts support a limited account of the study, not a conclusion about comparative immune response or safety.