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 to Evaluate the Immunogenicity and Safety of Seqirus Quadrivalent Influenza Vaccine (QIV) in a Pediatric Population 6 Months Through 59 Months of Age. (NCT02914275), a randomized phase 3 study. The primary outcome is The Geometric Mean Titer (GMT) Ratio of Each Virus Strain..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02914275 |
| Phase | Phase 3 |
| Condition | Influenza, Human |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 2250 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Seqirus |
| Results posted | Yes |
2. Clinical Question
The trial asked whether the immune response after Seqirus quadrivalent inactivated influenza vaccine (QIV) was noninferior to the response after a US-licensed quadrivalent inactivated comparator vaccine in a healthy pediatric population 6 months through 59 months of age. The primary comparison used hemagglutination inhibition (HI) antibody geometric mean titers (GMTs) for each virus strain included in the vaccines. The GMT ratio was defined as the comparator QIV postvaccination GMT divided by the Seqirus QIV postvaccination GMT, with antibody measured 28 days after the last vaccination.
The study also assessed safety and additional immune response measures. The registry lists solicited local reactions, solicited systemic events, cellulitis-like reactions, unsolicited adverse events, serious adverse events, strain-specific HI GMTs at the prevaccination and postvaccination visits, seroconversion rates, seroprotection rates, and geometric mean fold increases. These additional outcomes provide different descriptions of immune response and adverse events; they are not interchangeable with the primary GMT ratio.
The central statistical question is whether the strain-specific antibody responses meet a prespecified noninferiority criterion. The numerical GMT ratios, their confidence intervals, and the noninferiority margin are not reported in the registry record. Consequently, the record does not support a determination of whether the primary criterion was met.
Population
Healthy children 6 months through 59 months of age. The primary analysis population was the Per-Protocol Population, defined from the Evaluable Population after excluding protocol deviations medically assessed as potentially affecting immunogenicity results.
Intervention
Seqirus split virion, inactivated Quadrivalent Influenza Vaccine. Participants were assigned to age cohorts of 6 months through 35 months or 36 months through 59 months.
Comparator
A US-licensed 2016/2017 Quadrivalent Influenza Vaccine. The comparator groups used the same age-cohort divisions.
Primary question
For each vaccine strain, was the postvaccination HI GMT with Seqirus QIV noninferior to the GMT with comparator QIV, using the comparator-to-Seqirus GMT ratio 28 days after the last vaccination?
3. Trial Design
This was a Phase 3, randomized, multicenter, observer-blinded, noninferiority study with a parallel-group design. The registry reports an enrollment of 2250 participants and lists the study as completed. The recorded study dates are 2016-09-27 for the start and 2017-03-09 for primary completion. Seqirus was the sponsor.
Participants were assigned to receive either Seqirus QIV or comparator QIV. Each vaccine group was divided into Cohort A, for children 6 months through 35 months of age, and Cohort B, for children 36 months through 59 months of age. The registry describes masking as quadruple. It does not specify the identities of the masked roles in the record summarized for this analysis, so the label alone should not be taken to establish who was masked in practice.
The trial compared immune responses to the vaccine strains and recorded safety outcomes. The primary endpoint was strain-specific HI antibody GMT after vaccination, measured 28 days after the last vaccination. The primary analysis population was the Per-Protocol Population, consisting of evaluable participants without protocol deviations medically assessed as potentially impacting immunogenicity results. The full operational definition of the Evaluable Population is not reported in the registry record.
Randomization can help balance participant characteristics across assigned groups, while a parallel design means participants remain in their assigned vaccine group rather than crossing over between vaccines. These are general features of the design, not evidence that all baseline characteristics were balanced or that masking was maintained without difficulty. Detailed randomization procedures, allocation concealment, the number of centers, and the specific masking procedures are not reported in the registry record.
The record identifies the study as noninferiority but does not report the margin used to define an acceptable difference in immune response. It also does not report the trial's sample-size justification. The enrollment figure describes the planned or recorded trial enrollment; it does not by itself establish how many participants contributed to each primary analysis.
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 2339 subjects were screened. A total of 2250 subjects were randomized to study treatment. Due to not having valid informed consent, 3 subjects were removed from the clinical database. Therefore, overall 2247 subjects gave informed consent and were included in the analysis set.
Overall Study
| Stage | Seqirus QIV | Comparator QIV |
|---|---|---|
| STARTED | 1687 | 563 |
| Included in Clinical Database / FAS | 1684 | 563 |
| COMPLETED | 1566 | 521 |
| NOT COMPLETED | 121 | 42 |
Reasons for not completing this period:
| Reason | Seqirus QIV | Comparator QIV |
|---|---|---|
| Lost to Follow-up | 84 | 29 |
| Withdrawal by Subject | 26 | 10 |
| Protocol Violation | 1 | 1 |
| Physician Decision | 3 | 1 |
| Other | 4 | 1 |
| Excluded due to invalid informed consent | 3 | 0 |
Analysis population for the primary outcome, as defined in the registry: The Per-Protocol Population (PPS) comprised all subjects in the Evaluable Population who did not have any protocol deviations that were medically assessed as potentially impacting on immunogenicity results.
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: The Full Analysis Set was used for analysis of subject characteristics and comprised all subjects whose parent(s)/guardian(s) had given informed consent and who were randomized to treatment. Screening failures were not included in the FAS.
| Characteristic | Unit | Seqirus QIV | Comparator QIV | Total |
|---|---|---|---|---|
| Participants analysed | 1684 | 563 | 2247 | |
| Age, Continuous | months | 36.6 (SD 14.70) | 36.5 (SD 14.68) | 36.6 (SD 14.69) |
| Age, Customized: 6 through 35 months | Participants | 700 | 235 | 935 |
| Age, Customized: 36 through 59 months | Participants | 984 | 328 | 1312 |
| Sex: Female, Male: Female | Participants | 820 | 268 | 1088 |
| Sex: Female, Male: Male | Participants | 864 | 295 | 1159 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 434 | 160 | 594 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 1243 | 400 | 1643 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 7 | 3 | 10 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 5 | 2 | 7 |
| Race (NIH/OMB): Asian | Participants | 15 | 10 | 25 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 13 | 3 | 16 |
| Race (NIH/OMB): Black or African American | Participants | 361 | 123 | 484 |
| Race (NIH/OMB): White | Participants | 1205 | 391 | 1596 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 85 | 34 | 119 |
| Region of Enrollment: United States | Participants | 1684 | 563 | 2247 |
| Weight | kilograms | 15.36 (SD 4.224) | 15.40 (SD 4.149) | 15.37 (SD 4.205) |
| Prevaccination Axillary Temperature | °F | 97.17 (SD 0.963) | 97.25 (SD 0.935) | 97.19 (SD 0.936) |
| Vaccination against influenza 2015/2016 season | Participants | 845 | 294 | 1139 |
6. Primary Endpoint
The registry lists the primary outcome as The Geometric Mean Titer (GMT) Ratio of Each Virus Strain., measured over Postvaccination (28 days after last vaccination).
| Element | Registry entry |
|---|---|
| Result type | Geometric Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | Geometric Mean Titer |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was the geometric mean titer (GMT) of HI antibodies for each viral strain included in the vaccines, measured after vaccination. The reported time point was 28 days after the last vaccination. HI titers are an antibody measure; a GMT summarizes the distribution of titers using a geometric rather than arithmetic average. In general, geometric means are useful for measurements that are positive and may vary multiplicatively across participants.
The comparison was expressed as a ratio: the comparator QIV GMT divided by the Seqirus QIV GMT. A ratio of one would indicate equal GMTs; a ratio above one would indicate a higher comparator GMT, and a ratio below one would indicate a higher Seqirus GMT. These are general interpretations of the ratio definition and are not trial results.
Noninferiority asks whether the response with the study vaccine is not unacceptably lower than the response with the comparator, according to a prespecified margin. This framework is different from simply asking whether the groups have identical responses. A confidence interval communicates the uncertainty around an estimated ratio; the interval's position relative to the noninferiority margin is central to the conclusion. Neither the margin nor the numerical strain-specific ratios and confidence intervals are reported in the registry record, so the endpoint definition alone cannot establish the trial's noninferiority finding.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry defines a clear primary comparison but does not report the numerical results needed to interpret it. In particular, the GMT ratios for the individual viral strains, their 95% confidence intervals, and the noninferiority margin are not reported in the registry record. The available record therefore does not establish whether the primary noninferiority criterion was met, how large any observed differences were, or how precise those estimates were.
The ratio's direction matters. The numerator is the comparator QIV GMT and the denominator is the Seqirus QIV GMT. As a general interpretation, a ratio greater than one corresponds to a higher comparator GMT, while a ratio less than one corresponds to a higher Seqirus GMT. This direction should be kept in mind when reading any ratio estimate or confidence interval. A ratio near one would indicate similar estimated GMTs, but noninferiority still depends on the prespecified margin and the uncertainty around the estimate.
A 95% confidence interval describes a range of values compatible with the data under the statistical method used. A narrow interval indicates greater precision than a wide interval, but neither width nor location can be assessed without the reported estimates. For noninferiority, the confidence interval is interpreted against a margin selected before examining the trial results. The registry record does not report that margin or the analysis decision rule, so it is not possible to reconstruct the criterion from the endpoint description.
The record names the Per-Protocol Population for the primary endpoint and gives a definition based on evaluability and medically assessed protocol deviations that could affect immunogenicity results. This is important because the population used for analysis can affect the interpretation of a noninferiority comparison. The registry record does not report the number of participants in this analysis population, the number excluded, or the reasons for all exclusions. It also does not report a complementary intention-to-treat analysis for the primary endpoint.
Safety outcomes are reported separately from immunogenicity. The registry lists serious adverse events in both vaccine groups, along with other adverse-event counts and a list of serious-event terms with frequency labels. These figures describe recorded events in the stated groups; they do not resolve the primary immune-response question. Conversely, a primary immune-response result would not by itself characterize every aspect of safety.
In short, the available information supports describing the trial's design, endpoint, analysis population, and recorded safety counts. It does not support a numerical conclusion about strain-specific GMT ratios or noninferiority. Any interpretation that declares success or failure on the primary endpoint would require results and criteria that are not reported in the registry record.
9. Statistical Methods Explained
The trial's primary outcome was based on HI antibody GMTs for each vaccine strain. A geometric mean is calculated on a logarithmic scale and then expressed on the original scale. This approach is generally appropriate for positive measurements whose variation is naturally multiplicative. The endpoint's use of strain-specific GMTs means that each strain has its own estimated immune response and comparison; a single overall value should not be assumed to represent all strains.
How to read the GMT ratio
The ratio is defined as comparator GMT divided by Seqirus GMT. This fixes the direction of the comparison and makes the value interpretable relative to one. In general, a ratio of one represents equal group GMTs; a ratio above one means the comparator GMT is higher, and a ratio below one means the Seqirus GMT is higher. Those descriptions explain the ratio mathematically and do not state what the trial observed. The registry record does not include the numerical strain-specific estimates.
What the confidence interval contributes
The primary outcome specifies a 95% confidence interval. In general, a confidence interval communicates the precision of an estimate by expressing the range of values consistent with the observed data and the method's assumptions. It should be considered together with the point estimate, not treated as a separate result. For a ratio, the interval also helps show whether the data are compatible with meaningful differences in either direction. The actual intervals are not reported in the registry record, so their width and position cannot be assessed.
Why noninferiority needs a margin
Noninferiority is a criterion-based question, not merely a test of whether two estimates differ statistically. A margin specifies how much lower the study vaccine response could be, relative to the comparator, while still satisfying the study's criterion. The confidence interval is evaluated against that margin according to the analysis plan. The registry identifies the study as a noninferiority study, but the margin, its justification, and the exact decision rule are not reported in the registry record. The endpoint label therefore does not reveal whether the criterion was met.
For noninferiority studies, the analysis population is consequential. The registry identifies the Per-Protocol Population as the primary population and defines it as participants in the Evaluable Population without protocol deviations medically assessed as potentially impacting immunogenicity results. This definition indicates that certain deviations were considered relevant to the primary immune-response analysis. The record does not report the full Evaluable Population criteria, the counts excluded, or the handling of participants with missing postvaccination titers.
Randomization, masking, and group comparison
Random assignment is intended, in general, to reduce systematic differences between groups at study entry. A parallel-group comparison assigns participants to one vaccine group, and this study used two vaccine groups with age-based cohorts within each. The registry labels the study quadruple-masked and observer-blinded. These terms describe the stated design, but the detailed procedures, roles masked, and methods for maintaining masking are not reported in the registry record. Randomization and masking can support a fair comparison, but do not eliminate uncertainty from missing data, protocol deviations, or measurement variation.
Immune response outcomes beyond the primary endpoint
The registry also lists seroconversion rates, seroprotection rates, geometric mean fold increase, and HI GMTs at prevaccination and postvaccination visits. In general, these measures describe different aspects of the antibody response: changes from baseline, attainment of defined antibody levels, or the distribution of titers. Their definitions and numerical results are not reported in the record summarized for these analyses. They should not be treated as substitutes for the primary GMT ratio or as evidence of a primary noninferiority conclusion.
Safety outcomes
Safety was assessed through solicited local reactions and systemic adverse events, cellulitis-like reactions, unsolicited adverse events, and serious adverse events. Solicited events are actively sought within a defined observation process in general, whereas unsolicited events are not limited to a prespecified list; however, the collection windows and case definitions are not reported in the registry record. Serious adverse event counts are participant counts in the listed groups, not a measure of the primary antibody endpoint. The record does not provide enough detail to infer event timing, relatedness to vaccination, or whether any particular event was judged vaccine-related.
Planning calculations are not trial results
Planning illustrations based on an observed effect are distinct from the trial's original design justification. In general, such illustrations depend on an assumed effect, a significance level, an allocation pattern, and a statistical approximation. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation, with the effect expressed as a fraction of the observed effect. For time-to-event settings, the stated convention is total events; other settings use participants per arm. These are planning assumptions, not observed power and not proof that the trial was designed using those assumptions. The trial's own sample-size justification and statistical plan are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The primary endpoint is evaluated for each virus strain, and the registry also lists multiple secondary immune-response and safety outcomes. Multiple outcomes create a general multiplicity concern: when many statistical comparisons are made, the chance of at least one apparently unusual result can increase. The registry record does not report whether multiplicity was controlled, how the primary strain-specific comparisons were organized, or whether any hierarchy or adjustment procedure was used. Because the primary outcome has several categories or time points and is not reduced to one comparison in the available analysis, no single aggregate primary result should be inferred.
Missing-data handling is also relevant to immunogenicity outcomes measured after vaccination. The registry record does not report how missing postvaccination titers were handled, whether any imputation was used, or whether sensitivity analyses were conducted. It does not report participant counts for each strain-specific analysis or the reasons for participants being unavailable for analysis. Without those details, the effect of missing measurements on the estimates cannot be assessed.
The named primary population is the Per-Protocol Population. It includes participants in the Evaluable Population without protocol deviations medically assessed as potentially impacting immunogenicity results. The record does not report the complete Evaluable Population definition or the counts and reasons for exclusions from the Per-Protocol Population. It also does not report whether an intention-to-treat or other analysis population was used to check the primary conclusion. These omissions matter because noninferiority conclusions can depend on analysis population and missing-data assumptions.
The registry lists 10 outcome measures and 8 analyses. Those counts do not identify which analysis corresponds to each outcome or establish a multiplicity strategy. The detailed statistical analysis plan, prespecified handling of missing data, and any sensitivity analyses 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 |
|---|---|---|---|
| Seqirus QIV | 11 | 1673 | 0.7% |
| Comparator QIV | 3 | 559 | 0.5% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Seqirus QIV | 0 of 1673 |
| Comparator QIV | 0 of 559 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 4% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Seqirus QIV | 320 of 1673 |
| Comparator QIV | 80 of 559 |
Most frequent serious adverse event terms
| Event term | Organ system | Seqirus QIV | Comparator QIV |
|---|---|---|---|
| Croup Infectious | Infections and infestations | 2 of 1673 | 0 of 559 |
| Febrile convulsion | Nervous system disorders | 2 of 1673 | 0 of 559 |
| Bronchiolitis | Infections and infestations | 0 of 1673 | 1 of 559 |
| Pneumonia respiratory syncytial viral | Infections and infestations | 1 of 1673 | 0 of 559 |
| Respiratory syncytial virus bronchiolitis | Infections and infestations | 1 of 1673 | 0 of 559 |
| Respiratory syncytial virus infection | Infections and infestations | 1 of 1673 | 0 of 559 |
| Dehydration | Metabolism and nutrition disorders | 1 of 1673 | 0 of 559 |
| Pneumonitis | Respiratory, thoracic and mediastinal disorders | 1 of 1673 | 0 of 559 |
| Dysphagia | Gastrointestinal disorders | 1 of 1673 | 0 of 559 |
| Impaired gastric emptying | Gastrointestinal disorders | 0 of 1673 | 1 of 559 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Seqirus QIV | Comparator QIV |
|---|---|---|---|
| Cough | Respiratory, thoracic and mediastinal disorders | 153 of 1673 | 41 of 559 |
| Rhinorrhoea | Respiratory, thoracic and mediastinal disorders | 134 of 1673 | 53 of 559 |
| Pyrexia | Infections and infestations | 91 of 1673 | 25 of 559 |
| Upper respiratory tract infection | Infections and infestations | 67 of 1673 | 17 of 559 |
Serious events with the highest arm-level rate: bronchiolitis (0.2%), impaired gastric emptying (0.2%), humerus fracture (0.2%), croup infectious (0.1%), febrile convulsion (0.1%).
The registry reports serious adverse events for 1673 participants at risk in the Seqirus QIV group, with 11 affected participants, and for 559 participants at risk in the comparator QIV group, with 3 affected participants. It reports 0 deaths in each group. These are participant counts as recorded; they should not be read as counts of all individual event episodes or as evidence about whether an event was caused by vaccination.
The record separately lists other adverse events as 320 of 1673 participants in the Seqirus group and 80 of 559 participants in the comparator group. The registry also lists serious-event terms with frequency labels: Bronchiolitis, 0.2%; Impaired gastric emptying, 0.2%; Humerus fracture, 0.2%; Croup Infectious, 0.1%; Febrile convulsion, 0.1%; and Pneumonia respiratory syncytial viral, 0.1%. The record does not assign these listed terms to a specific vaccine group in the information, so they should not be attributed to one group.
These safety counts are descriptive. The registry record does not report event relatedness, severity grading beyond serious-event classification, observation windows, or a statistical comparison of safety between groups. Differences in group size also mean raw counts alone are not a complete comparison. The counts should be interpreted as recorded events in this trial, not as proof of causation or as a general estimate for other populations.
12. What the Result Does, and Does Not, Mean
The registry record establishes that this was a randomized Phase 3 noninferiority study comparing Seqirus QIV with a US-licensed comparator QIV in a pediatric population 6 months through 59 months of age. It identifies the strain-specific postvaccination HI GMT ratio as the primary endpoint and names the Per-Protocol Population for that analysis. It also records safety outcomes and participant counts.
Those details explain what the investigators set out to compare, but they do not show the numerical primary outcome. The GMT ratios and 95% confidence intervals for the individual strains are not reported in the registry record, and neither is the noninferiority margin. Without those elements, the endpoint's decision rule cannot be applied and no supported conclusion can be drawn about whether noninferiority was demonstrated. The study title and design label are not substitutes for the results.
Even when numerical estimates are available, a noninferiority finding is specific to the chosen endpoint, margin, analysis population, and methods. It does not mean that two vaccines have identical antibody responses, and it does not automatically establish equivalence for every immune measure or clinical outcome. Those are general features of statistical interpretation, not conclusions about this trial.
The posted safety counts describe reported participants with serious and other adverse events in the groups. They do not establish that an event was caused by a vaccine, and the listed serious-event terms are not assigned to a group in the record. Safety interpretation also depends on definitions, observation periods, and assessment of relatedness, details not reported in the registry record.
The results therefore support a description of study design and recorded outcomes, but not a claim that one vaccine produced a higher immune response, that the primary criterion was met, or that the vaccines were equivalent. Those conclusions would require the relevant estimates, uncertainty intervals, margin, and analysis details, which are not reported in the registry record.
13. Why This Trial Matters Statistically
This trial illustrates why a noninferiority study cannot be interpreted from its title or endpoint name alone. The stated objective is to compare postvaccination antibody GMTs for each vaccine strain, and the ratio is oriented as comparator over Seqirus. To assess noninferiority, a reader needs both the estimated ratios and their uncertainty, as well as the prespecified margin that defines an acceptable difference. The registry record does not report those elements, making the distinction between a study's question and its answer especially important.
The study also highlights how analysis populations contribute to interpretation. The primary endpoint uses a Per-Protocol Population defined in relation to evaluability and potentially influential protocol deviations. In noninferiority work, understanding who was included and how missing outcomes were handled is important because exclusions and assumptions can affect the comparison. The available record does not report participant counts for the primary analysis or the missing-data procedures.
Age cohorts, multiple vaccine strains, and a range of additional immunogenicity and safety outcomes create several dimensions to the trial's results. A strain-specific endpoint cannot be reduced to a single general statement without the estimates and a prespecified approach for combining or interpreting them. Likewise, lists of secondary endpoints do not disclose how multiplicity was handled.
The study's safety reporting demonstrates a separate interpretive task: participant counts and event terms are descriptive, while causation and comparative safety require further details. Overall, the record is useful for understanding the design and intended measurements, while its unreported statistical results and analysis details limit what can be concluded from the posted information.
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 primary limitation for statistical interpretation is that the registry record does not report the strain-specific GMT ratios or their 95% confidence intervals. It also does not report the noninferiority margin or the decision rule. As a result, the primary noninferiority finding cannot be independently interpreted from the information recorded.
The record identifies the Per-Protocol Population but does not report the number of participants included in each strain-specific analysis, the full Evaluable Population definition, or detailed exclusion reasons. Handling of missing postvaccination titers and any sensitivity analyses are not reported. These omissions leave uncertainty about how participant availability and protocol deviations affected the primary estimates.
The registry lists several primary endpoint categories by viral strain and multiple secondary outcomes, but the record does not report a multiplicity strategy or an analysis hierarchy. It also does not provide the detailed statistical analysis plan, the trial's sample-size justification, or information about interim analyses. These items should not be inferred from the noninferiority label or enrollment figure.
For safety, the registry provides participant counts and selected serious-event terms, but the record does not report event relatedness, the observation windows, or a group assignment for the listed terms. Detailed definitions and collection procedures for solicited and unsolicited events are not reported. Thus the counts are informative as recorded safety data but do not, by themselves, establish cause or a complete comparative safety profile.
Finally, the record describes a healthy pediatric population and age-based cohorts. It does not establish how findings would apply to populations outside the stated age range or to groups not described in the record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study to Evaluate the Immunogenicity and Safety of Seqirus Quadrivalent Influenza Vaccine (QIV) in a Pediatric Population 6 Months Through 59 Months of Age. — NCT02914275.
- Registry record last updated 2019-01-23; status last verified 2018-11.
- Results first posted 2019-01-23.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
This completed, randomized Phase 3, multicenter, observer-blinded, noninferiority study compared Seqirus QIV with a US-licensed comparator QIV in healthy children 6 months through 59 months of age. Enrollment was 2250. The study began 2016-09-27 and reached primary completion 2017-03-09. Participants were grouped by age as 6 months through 35 months or 36 months through 59 months.
The primary endpoint was strain-specific HI antibody GMT 28 days after the last vaccination, expressed as comparator GMT divided by Seqirus GMT. The primary analysis population was the Per-Protocol Population. Numerical GMT ratios, 95% confidence intervals, the noninferiority margin, and key analysis details are not reported in the registry record, so the primary conclusion cannot be determined from it.
The record lists multiple immune-response and safety outcomes. Serious adverse events were reported for 11 of 1673 participants in the Seqirus group and 3 of 559 in the comparator group; deaths were 0 in both groups. These counts are descriptive and do not establish causation.