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 to Evaluate the Immunogenicity and Safety of 'IL-YANG Quadrivalent Influenza Vaccine Inj.' (NCT02677493), a randomized phase 3 study. The primary outcome is Rate of Healthy Adults Aged ≥19 Years With Seroconversion.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02677493 |
| Phase | Phase 3 |
| Condition | Influenza |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 1794 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Il-Yang Pharm. Co., Ltd. |
| Results posted | Yes |
2. Clinical Question
Population
Healthy male and female adults aged 19 years or older were eligible according to the study description. The primary immunogenicity analysis was described as using a Per Protocol Set, but the registry record’s description of that set is incomplete. Further eligibility details are not reported in the registry record.
Intervention
The investigational product was IL-YANG Quadrivalent Influenza Vaccine. Its description says it includes both B strains, Yamagata and Victoria. The study assessed immunogenicity and safety after intramuscular administration.
Comparator
Two active comparator vaccines are listed: IL-YANG Flu Vaccine Prefilled Syringe, described as a trivalent vaccine that includes the B/Yamagata strain and was approved for commercial sale by MFDS; and IL-YANG Trivalent Influenza Vaccine, described as including the B/Victoria strain.
Primary question
The primary endpoint was the rate of healthy adults aged 19 years or older who met the registry’s definition of seroconversion by Day 28. The registry record does not report the observed rate or a comparison result, so it does not establish from the recorded information how the quadrivalent vaccine’s endpoint result relates to either active comparator.
3. Trial Design
This was a completed Phase III, multicenter, randomized, active-controlled, parallel study of the IL-YANG Quadrivalent Influenza Vaccine. The official title describes it as double-blind, while the registry’s masking field specifies quadruple masking. The record does not explain how those descriptions relate to each other or identify which participants or study personnel were masked.
The study enrolled 1794 participants, according to the registry. Its brief description identifies the population as healthy male and female adults aged 19 years or older. The study began in 2015-10 and its primary completion date is recorded as 2016-01. Those dates describe the registry timeline, not the duration of follow-up for each participant. The study status is completed.
Three biological interventions are listed. The quadrivalent vaccine includes the Yamagata and Victoria B strains. The two active comparators are trivalent vaccines: the prefilled-syringe product includes B/Yamagata, and the other IL-YANG trivalent vaccine includes B/Victoria. The registry describes the prefilled-syringe vaccine as approved for commercial sale by MFDS. Details such as dose, administration schedule beyond intramuscular administration, and assignment procedures are not reported in the registry record.
The primary endpoint concerns seroconversion measured on Day 28. The listed secondary outcomes include seroconversion by age group, seroprotection, geometric mean titers and ratios, and differences in seroconversion rates. The registry lists eight outcome measures and one analysis. A detailed statistical analysis plan, including the planned comparison structure and handling of the different outcomes, is 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.
Overall Study
| Stage | IL-YANG Quadrivalent Influenza Vaccine | IL-YANG Flu Vaccine Prefilled Syringe | IL-YANG Trivalent Influenza Vaccine |
|---|---|---|---|
| STARTED | 1197 | 298 | 299 |
| COMPLETED | 1186 | 296 | 296 |
| NOT COMPLETED | 11 | 2 | 3 |
Analysis population for the primary outcome, as defined in the registry: The immunogenicity data obtained from the study subjects were analyzed primarily in the Per Protocol Set that was consists of subjects who had at least one dose of the investigational product and from whom post-treatment primary efficacy endpoint data, and have completed the study up to Visit 3 without a major protocol violation.
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.
| Characteristic | Unit | IL-YANG Quadrivalent Influenza Vaccine | IL-YANG Flu Vaccine Prefilled Syringe | IL-YANG Trivalent Influenza Vaccine | Total |
|---|---|---|---|---|---|
| Participants analysed | 1197 | 298 | 299 | 1794 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 1015 | 254 | 253 | 1522 |
| Age, Categorical: >=65 years | Participants | 182 | 44 | 46 | 272 |
| Age, Continuous | years | 44.7 (SD 14.5) | 44.5 (SD 14.7) | 45.7 (SD 14.6) | 44.8 (SD 14.6) |
| Sex: Female, Male: Female | Participants | 812 | 208 | 204 | 1224 |
| Sex: Female, Male: Male | Participants | 385 | 90 | 95 | 570 |
6. Primary Endpoint
The registry lists the primary outcome as Rate of Healthy Adults Aged ≥19 Years With Seroconversion, measured over Day 28.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | percentage of subjects |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the percentage of healthy adults aged 19 years or older who met the study’s definition of seroconversion by Day 28. The definition uses hemagglutination inhibition (HI) antibody titers measured before vaccination on Day 0 and after vaccination on Day 28. A participant qualifies through either of two routes: a pre-vaccination titer below 1:10 followed by a post-vaccination titer of at least 1:40, or a pre-vaccination titer of at least 1:10 followed by a minimum four-fold rise in the post-vaccination titer.
General statistical context: A binary endpoint classifies each participant as meeting or not meeting a stated criterion. A percentage expresses the share of the analyzed group meeting that criterion; it is an immunogenicity measure, not a direct measure of clinical influenza illness. Seroconversion is used to describe an antibody response relative to a baseline measurement, with the definition accounting for different starting titers.
The registry identifies Day 28 as the primary endpoint timeframe and a 95% confidence interval as the dispersion measure. It describes the primary analysis as using immunogenicity data from a Per Protocol Set, but the record’s description of the set ends before all its criteria are given. The observed endpoint percentage and confidence interval are not reported in the registry record, so the magnitude and precision of the recorded primary result cannot be assessed from these registry entries.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a primary endpoint and its measurement rules, but it does not report the observed seroconversion rate, the corresponding 95% confidence interval, or an estimate contrasting the quadrivalent vaccine with either active comparator. The record also indicates that the primary outcome has several categories or time points and is not reduced to one comparison. As a result, the posted information does not support a numerical interpretation of the primary immunogenicity result.
This absence matters for interpretation. A study design and a clearly defined endpoint describe what investigators intended to assess; they are not themselves evidence of the observed response. Without the group-level endpoint results and the prespecified comparison details, it is not possible to determine the direction or size of any difference, or how precisely an estimate was measured. The registry record does not report a conclusion about whether the endpoint results met any criterion for comparison or non-inferiority.
General statistical context: A confidence interval communicates uncertainty around an estimate under the assumptions of the analysis. A narrower interval generally indicates greater precision, while a wider interval indicates more uncertainty. An interval does not by itself establish clinical importance, and its interpretation depends on the target quantity and analysis. Although the record names a 95% confidence interval as the dispersion measure, it does not give the interval endpoints for the primary outcome.
The outcomes listed for the study cover more than the primary seroconversion measure. They include seroconversion by age group, seroprotection, geometric mean titers, and geometric mean ratios, as well as a difference in seroconversion rates. These outcome names indicate a broad immunogenicity assessment, but their titles alone do not convey estimates, uncertainty, or whether any differences were considered meaningful. Their results are not reported in the registry record.
The safety information records serious adverse events affecting 0 participants in the quadrivalent vaccine group, 2 in the prefilled-syringe comparator group, and 1 in the other trivalent comparator group. The registry also lists three serious-event terms, each at 0.3%, without arm-level attribution in the information recorded. These counts are descriptive. They do not establish that an intervention caused or prevented an event, and they do not replace the missing immunogenicity results.
Overall, the available record supports a description of the trial question, design, endpoint definition, and selected safety counts. It does not provide enough outcome information to judge the size, precision, or comparative pattern of the primary seroconversion result. That boundary should be kept clear when interpreting the study.
9. Statistical Methods Explained
General statistical context: The study’s primary endpoint is binary at the participant level: each analyzed participant either meets the stated seroconversion criterion or does not. A group percentage summarizes the share meeting that criterion. Such a summary is straightforward to describe, but its interpretation depends on the analyzed population, the handling of missing measurements, and the comparisons selected for inference.
What does the confidence interval add?
The registry names a 95% confidence interval for the primary endpoint. In general, a confidence interval expresses the uncertainty associated with an estimate under the statistical method used. It is not a guarantee that the interval contains the true value, nor does it show whether a result is important in practical terms. To interpret an interval for this trial, a reader would need the estimate, the interval limits, and a clear statement of the quantity being estimated. Those primary result values are not reported in the registry record.
For a percentage, the interval depends on the number of observed responses and the number of participants included in the analysis, along with the interval method. The registry identifies a Per Protocol Set for the primary immunogenicity analysis, but the description of its membership is incomplete. The record does not provide the analyzed group counts for the primary endpoint or explain how participants without usable Day 28 data were handled. Therefore, the stated confidence-interval approach cannot be independently interpreted from the endpoint definition alone.
How should the seroconversion definition be read?
The endpoint combines two baseline-dependent routes to meeting the response criterion. Participants whose Day 0 HI titer is below 1:10 qualify if the Day 28 titer reaches at least 1:40. Participants starting at 1:10 or higher qualify if their Day 28 titer shows a minimum four-fold rise. The two routes avoid applying the same absolute threshold to participants with different starting titers. The endpoint is therefore a defined antibody-response measure, not simply a comparison of post-vaccination titers.
General statistical context: When the same binary outcome is measured in several groups, investigators may report each group’s percentage, a difference between percentages, a ratio, or another contrast. Each answers a different question. A group percentage describes that group; a contrast describes how groups compare. The registry lists a secondary outcome for a difference in seroconversion rates and geometric mean comparisons, but the primary comparison estimate and its result are not reported in the registry record.
What is the role of the listed secondary outcomes?
The secondary outcome descriptions include seroconversion by age group, seroprotection in age groups, geometric mean titer on Day 28, a comparator-to-test-vaccine geometric mean ratio, the difference in seroconversion rates, and geometric mean titers and ratios before and after vaccination. These measures address related but distinct features of antibody response. A titer summarizes the measured antibody level; a geometric mean summarizes values on a multiplicative scale, which is useful when measurements are skewed. A geometric mean ratio compares such summaries. These are general descriptions of the statistical measures, not claims about the trial’s results.
Multiple endpoints and subgroup summaries can create a multiplicity issue: when many statistical questions are examined, the chance of finding an apparently notable result by chance can increase if each is treated as an independent confirmatory test. The registry lists eight outcome measures and one analysis, but it does not describe a multiplicity adjustment, a hierarchy among outcomes, or which outcomes were intended as confirmatory. Those details are not reported in the registry record. The list of outcomes alone does not show whether or how multiplicity was addressed.
What does a planning illustration mean?
General statistical context: A sample-size calculation is a planning exercise about how many participants a future or planned study might require under specified assumptions. The registry’s planning description refers to a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; it describes the effect to detect as a stated fraction of the observed effect. These are planning assumptions, not evidence that the trial was designed using them. The record explicitly characterizes the illustration as based on the observed effect rather than the trial’s own design.
Such an illustration should not be read as observed power. Observed power is not a substitute for examining the effect estimate and its uncertainty; after a study, the confidence interval and the observed data are more informative about precision. The registry’s primary endpoint is not reduced to one comparison, and the numerical planning values and fractions are not reported in the information available for this explanation. No new sample-size result can therefore be stated.
For time-to-event outcomes, a planning calculation may use event totals, while other designs may express a target as participants per arm. The registry’s planning note distinguishes those conventions. This trial’s primary endpoint is a percentage, so the relevant planning convention in that note is participants per arm. This does not establish the actual allocation or the study’s original sample-size rationale; that rationale is not reported in the registry record.
What cannot be reconstructed?
The registry entries do not provide the primary event counts, group percentages, interval limits, detailed analysis model, or the full Per Protocol Set definition. They also do not give a detailed statistical analysis plan. Without these details, the endpoint calculation and comparison cannot be reproduced from the record description. General explanations of percentages, intervals, geometric summaries, and planning assumptions clarify the methods’ purpose, but they do not fill in missing trial results.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists eight outcome measures, including the primary seroconversion endpoint, age-group measures, seroprotection, and several antibody-titer summaries or comparisons. It records one analysis. These entries describe the scope of the outcome record, but they do not specify which comparisons were confirmatory or how the outcomes were ordered for interpretation.
Whether the analysis adjusted for multiple comparisons, used a testing hierarchy, or treated secondary outcomes as exploratory is not reported in the registry record. The record also does not report an interim-analysis plan or a detailed statistical analysis plan. Without those details, the reader cannot assess how the study addressed the possibility of chance findings across multiple outcomes and comparisons.
The primary immunogenicity population is described as a Per Protocol Set, with participants having at least one dose and post-treatment primary efficacy data and completing the study up to Visit 3. The registry’s sentence describing the set is incomplete, so additional membership criteria are not reported in the registry record. The record does not describe how missing Day 28 titers were handled, whether any participants were excluded from the endpoint analysis, or whether a complementary analysis population was used.
These omissions affect interpretation of the endpoint percentage and its confidence interval: the analyzed population and missing-data approach determine what the estimate represents. They do not imply that the methods were inadequate; they mean the relevant details cannot be evaluated from 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 |
|---|---|---|---|
| IL-YANG Quadrivalent Influenza Vaccine | 0 | 1194 | 0.0% |
| IL-YANG Flu Vaccine Prefilled Syringe | 2 | 298 | 0.7% |
| IL-YANG Trivalent Influenza Vaccine | 1 | 299 | 0.3% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| IL-YANG Quadrivalent Influenza Vaccine | 0 of 1194 |
| IL-YANG Flu Vaccine Prefilled Syringe | 0 of 298 |
| IL-YANG Trivalent Influenza Vaccine | 0 of 299 |
Most frequent serious adverse event terms
| Event term | Organ system | IL-YANG Quadrivalent Influenza Vaccine | IL-YANG Flu Vaccine Prefilled Syringe | IL-YANG Trivalent Influenza Vaccine |
|---|---|---|---|---|
| Anal fistula | Gastrointestinal disorders | 0 of 1194 | 1 of 298 | 0 of 299 |
| Vascular headache | Nervous system disorders | 0 of 1194 | 1 of 298 | 0 of 299 |
| Herpes zoster | Infections and infestations | 0 of 1194 | 0 of 298 | 1 of 299 |
Serious events with the highest arm-level rate: anal fistula (0.3%), vascular headache (0.3%), herpes zoster (0.3%).
The registry records serious adverse events affecting 0 participants in the IL-YANG Quadrivalent Influenza Vaccine group, 2 in the IL-YANG Flu Vaccine Prefilled Syringe group, and 1 in the IL-YANG Trivalent Influenza Vaccine group. The corresponding at-risk counts recorded for these groups are 1194, 298, and 299. The registry reports no deaths as a numerical value for these groups; the death entries are null, so death results are not reported in the registry record.
The listed serious-event terms are anal fistula, vascular headache, and herpes zoster, each reported at 0.3%. The record does not attribute these term-specific percentages to particular treatment groups in the information. It also records 0 affected participants in the other-adverse-event field for each group. These fields should be read as recorded counts, not as proof that no other events occurred beyond the categories represented by those fields.
General statistical context: Adverse-event counts describe what was recorded during the study; by themselves, they do not establish causation. The group counts are also not a complete safety comparison without details about event definitions, observation time, collection procedures, and statistical analysis. Those details are not reported in the registry record. The safety figures should therefore be interpreted descriptively and separately from the unreported primary immunogenicity result.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a randomized, active-controlled Phase III study assessed immunogenicity and safety of the IL-YANG Quadrivalent Influenza Vaccine in healthy adults. It describes the primary endpoint as Day 28 seroconversion under a definition based on baseline and post-vaccination HI titers. It also identifies two active trivalent vaccine comparators and reports selected serious adverse-event counts.
What the record does not establish from the information reported is the observed primary endpoint percentage, the 95% confidence interval, or the size and direction of a comparison with either comparator. It therefore does not permit a judgment about the magnitude or precision of the primary result. The outcome descriptions and the study’s randomized design do not replace the missing endpoint results.
General statistical context: An immunogenicity endpoint measures an antibody response according to a defined laboratory criterion. It is not itself a direct measure of clinical influenza outcomes. A favorable-looking antibody result, if reported, would need to be interpreted in light of the endpoint, comparator, uncertainty, population, and analysis plan. The registry entries do not report a result that would allow such an assessment.
The safety counts are similarly limited. They show recorded serious adverse events affecting participants in the two comparator groups and none in the quadrivalent vaccine group, while the death entries are null. The three listed serious-event terms each have a reported rate of 0.3%, but their group attribution is not specified in the record. These observations are descriptive and do not establish that vaccination caused, prevented, or changed the risk of an event.
The record also does not report how missing endpoint data were handled, the complete Per Protocol Set definition, multiplicity procedures, or a full statistical analysis plan. Those omissions limit assessment of the analysis and the strength of any conclusion. The appropriate reading is therefore narrow: the registry documents the study question, design, endpoint definition, and some safety information, but does not report the primary efficacy result needed for a comparative interpretation.
13. Why This Trial Matters Statistically
This trial is statistically notable for a clear, baseline-dependent seroconversion definition paired with an active-controlled randomized design. The endpoint distinguishes participants by their starting HI titer and defines a response using either a post-vaccination threshold or a fold-rise criterion. That structure illustrates why endpoint definitions matter: the response being counted depends on both baseline and follow-up measurements.
The study also lists two active trivalent comparators that include different B strains, while the quadrivalent vaccine description includes both Yamagata and Victoria B strains. This makes the comparison structure relevant to interpretation, but the registry record does not report the group-specific primary results or the planned contrast needed to evaluate them. Design features alone do not determine the statistical conclusion.
General statistical context: Randomization can support a fair comparison when allocation and follow-up are implemented appropriately, while masking can reduce some forms of bias. The registry identifies randomization and quadruple masking, and its official title describes the study as double-blind. It does not explain the masking roles or provide enough operational detail to assess implementation. These design labels are informative, but they do not eliminate the need to examine outcome data and analysis methods.
The record is also a useful example of the distinction between a registered outcome and a reported result. It names a primary endpoint and a confidence-interval measure, yet the endpoint estimate and interval are not reported in the registry record for interpretation. The presence of outcome definitions should not be mistaken for evidence about the observed response.
Finally, the registry’s planning note explicitly distinguishes an illustrative calculation based on an observed effect from the trial’s own design rationale. This distinction matters because a planning illustration is not a record of the original sample-size justification and is not observed power. The rationale behind the trial’s planned size is not reported in the registry record.
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 main limitation for statistical interpretation is that the registry record does not report the observed primary seroconversion rate or its 95% confidence interval. It also does not give a primary comparison estimate against either active comparator. The primary outcome is identified as having several categories or time points and is not reduced to one comparison, so a single comparative result cannot be inferred from the endpoint title.
The primary analysis population is described as a Per Protocol Set, but the registry’s description is incomplete. Further criteria for inclusion in that set are not reported in the registry record. The record does not explain how missing Day 28 measurements were handled, whether participants were excluded from the analysis, or how any departures from protocol were treated.
The registry identifies eight outcome measures and one analysis, but it does not report a detailed analysis plan, multiplicity procedures, or the intended hierarchy of primary and secondary comparisons. The record also does not describe interim analyses. These gaps prevent assessment of how the listed outcomes were handled statistically.
Although the study title calls the design double-blind and the masking field says quadruple, the registry does not explain those terms or identify the masked roles. The operational details of randomization, allocation concealment, adherence, and follow-up are not reported in the registry record.
Safety reporting is also limited in the recorded information. Death entries are null, the three serious-event terms are not linked to treatment groups, and further details about event definitions and observation procedures are not reported in the registry record. These limitations restrict conclusions to the descriptive details recorded and do not establish whether the trial’s conduct or analyses were sound or unsound.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study to Evaluate the Immunogenicity and Safety of 'IL-YANG Quadrivalent Influenza Vaccine Inj.' — NCT02677493.
- Registry record last updated 2023-09-28; status last verified 2020-07.
- Results first posted 2017-02-06.
- 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
NCT02677493 is a completed Phase III, multicenter, randomized, active-controlled, parallel study of IL-YANG Quadrivalent Influenza Vaccine in healthy adults aged 19 years or older. The study enrolled 1794 participants and lists two IL-YANG trivalent vaccines as active comparators. The official title describes a double-blind study; the registry masking field specifies quadruple masking.
The primary endpoint is the Day 28 seroconversion rate, defined using HI antibody titers measured before and after vaccination. The primary immunogenicity analysis is described as using a Per Protocol Set, but that population description is incomplete. The observed primary result and its 95% confidence interval are not reported in the registry record.
Serious adverse events affected 0 participants in the quadrivalent vaccine group, 2 in the prefilled-syringe comparator group, and 1 in the other trivalent comparator group. Death results are not reported in the registry record. The available information supports a description of the study design and selected outcomes, but not a numerical interpretation of the primary comparative result.