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 of High-dose Inactivated, Split-virion Influenza Vaccine Versus Standard Fluzone Vaccine in the Elderly (NCT00391053), a randomized phase 3 study. The primary outcome is Geometric Mean Titers (GMTs) of Hemagglutination Inhibition Antibody Titers Pre- and Post-vaccination With Fluzone® High Dose or Standard Fluzone® Vaccines..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00391053 |
| Phase | Phase 3 |
| Condition | Orthomyxoviridae Infection, Influenza, Myxovirus Infection |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 3851 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Sanofi Pasteur, a Sanofi Company |
| Results posted | Yes |
2. Clinical Question
Population
Adults aged at least 65 years were eligible for the study. The primary outcome description says antibody titers were assessed in the Full Analysis Set according to the vaccine participants were randomized to receive. That analysis included 3851 participants. The registry summary frames the study around the lower antibody response to vaccination observed in older adults compared with young adults, and the need to improve immune response in an age group at higher risk for influenza-related morbidity and mortality.
Intervention
The intervention was high-dose inactivated, split-virion influenza vaccine. Participants assigned to the high-dose groups received one of three manufacturing lots. The study's immunogenicity objectives included evaluating responses across those lots, as well as comparing the high-dose vaccine with standard-dose vaccine. The registry describes antibody responses to three influenza antigens: A/H1N1 New-Caledonia, A/H3N2 Wisconsin, and B Malaysia.
Comparator
The comparison group received standard-dose inactivated, split-virion Fluzone. This is an active vaccine comparator, not a placebo or an untreated control. The registry lists one standard-dose group alongside the three high-dose lot groups. Outcomes are described by randomized vaccine assignment.
Primary question
The primary endpoint is geometric mean hemagglutination inhibition antibody titer before vaccination and at Day 28 after vaccination. The study objectives were to assess consistency of immune responses across the three high-dose lots and to evaluate superiority of high-dose vaccine compared with standard-dose vaccine. However, numerical primary endpoint results and the registry's inferential comparisons are not reported in the registry record. The stated objectives therefore describe the questions the trial set out to address, but cannot establish from the registry record how those questions were answered.
3. Trial Design
This was a Phase III, randomized, quadruple-masked, parallel-group study. It enrolled 3851 participants and is listed as completed. The record gives a start date of 2006-10 and a primary completion date of 2007-07. Participants were assigned to one of four vaccine groups: three groups receiving different lots of high-dose inactivated, split-virion influenza vaccine, and one group receiving standard-dose Fluzone. The registry does not report the allocation ratio or the randomization procedure.
The parallel-group structure means each participant was assigned to a vaccine group rather than being described as receiving multiple study vaccines in sequence. Quadruple masking indicates that the record classifies the study as masked at four levels, but the specific roles masked are not reported in the registry record. Further details of concealment, vaccine administration, and the operational masking procedures are not reported in the registry record.
The primary immunogenicity outcome was measured at Day 0 and Day 28 after vaccination. It concerned hemagglutination inhibition antibody titers for three influenza antigens. The study also listed secondary outcomes concerning seroprotection before and after vaccination and solicited injection-site and systemic reactions. Safety objectives included solicited and unsolicited adverse events, serious adverse events after vaccination, and additional defined clinical criteria during the six months following vaccination.
The recorded enrollment and the primary outcome population both involve 3851 participants, with the outcome description identifying the Full Analysis Set. The registry does not provide a participant flow account or explain how many participants contributed data to each time point, antigen, or safety outcome. The allocation counts shown for safety outcomes differ among the four groups, but reasons for those analysis-set sizes are not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: A total of 3851 participants who met the inclusion and exclusion criteria were randomized and vaccinated. The vaccine received by 14 participants could not be verified, they were excluded from all analyses except immunogenicity analysis. 4 participants that started the study, but had no post-vaccination assessment were also excluded from analysis.
Overall Study
| Stage | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 1 | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 2 | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 3 | Active Comparator (Standard Fluzone®) |
|---|---|---|---|---|
| STARTED | 857 | 848 | 870 | 1262 |
| COMPLETED | 848 | 847 | 868 | 1252 |
| NOT COMPLETED | 9 | 1 | 2 | 10 |
Reasons for not completing this period:
| Reason | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 1 | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 2 | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 3 | Active Comparator (Standard Fluzone®) |
|---|---|---|---|---|
| Serious Adverse Events | 1 | 0 | 1 | 4 |
| Protocol Violation | 2 | 0 | 0 | 0 |
| Lost to Follow-up | 1 | 0 | 0 | 5 |
| Withdrawal by Subject | 5 | 1 | 1 | 1 |
Analysis population for the primary outcome, as defined in the registry: The geometric mean titers was assessed in the Full Analysis Set according to the vaccine the subjects were randomized to receive. A total of 3851 participants were included in this analysis.
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 | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 1 | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 2 | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 3 | Active Comparator (Standard Fluzone®) | Total |
|---|---|---|---|---|---|---|
| Participants analysed | 855 | 848 | 870 | 1260 | 3833 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 0 | 0 | 0 | 0 | 0 |
| Age, Categorical: >=65 years | Participants | 855 | 848 | 870 | 1260 | 3833 |
| Age, Continuous | Years | 72.9 (SD 6.15) | 72.9 (SD 6.20) | 72.9 (SD 6.17) | 72.9 (SD 5.99) | 72.9 (SD 6.17) |
| Sex: Female, Male: Female | Participants | 437 | 438 | 445 | 688 | 2008 |
| Sex: Female, Male: Male | Participants | 418 | 410 | 425 | 572 | 1825 |
| Region of Enrollment: United States | participants | 855 | 848 | 870 | 1260 | 3833 |
6. Primary Endpoint
The registry lists the primary outcome as Geometric Mean Titers (GMTs) of Hemagglutination Inhibition Antibody Titers Pre- and Post-vaccination With Fluzone® High Dose or Standard Fluzone® Vaccines., measured over Day 0 and Day 28 Post-vaccination.
| Element | Registry entry |
|---|---|
| Result type | Geometric Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | Titers |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the geometric mean titer (GMT) of hemagglutination inhibition antibodies, measured before vaccination and at Day 28 after vaccination. Titers were assessed for antibodies against three vaccine antigens: A/H1N1 New-Caledonia, A/H3N2 Wisconsin, and B Malaysia. The outcome is described as being assessed in the Full Analysis Set according to randomized vaccine assignment, with 3851 participants included in that analysis.
As a general statistical explanation, a geometric mean summarizes measurements on a multiplicative scale. It is often used for antibody titers because such measurements can span a broad range and are commonly interpreted through relative rather than additive changes. A confidence interval gives a range of values compatible with the data and the statistical procedure used; it communicates uncertainty around an estimate, rather than guaranteeing that the true value lies within the interval.
The registry specifies 95% confidence intervals for the GMT outcome. However, the numerical GMT estimates and confidence intervals are not reported in the registry record. Nor are numerical comparisons between the high-dose lots and standard-dose vaccine reported. As a result, the endpoint's definition and timing can be described, but the magnitude and precision of the antibody responses cannot be assessed from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record defines a randomized comparison of three high-dose vaccine lots with a standard-dose vaccine in adults aged at least 65 years. The primary immunogenicity measure is antibody GMT at baseline and Day 28 for three influenza antigens. The study's stated aims were to evaluate lot consistency and the superiority of high-dose vaccine relative to standard dose. Those aims should not be mistaken for reported findings: the numerical primary outcome results and inferential comparisons are not reported in the registry record.
The record identifies the primary outcome population as the Full Analysis Set, including 3851 participants and analyzed according to randomized vaccine assignment. This describes the population intended for the reported outcome, but it does not provide enough detail to evaluate completeness of endpoint data or how missing measurements were handled. The record lists no statistical analyses. In particular, it does not report estimates of between-group differences, confidence intervals for such comparisons, p-values, or a model used to compare groups.
Four safety group entries report counts of participants at risk and participants affected. For serious adverse events, the entries list 56 affected among 855 at risk in high-dose Lot 1, 56 among 848 in high-dose Lot 2, 44 among 870 in high-dose Lot 3, and 93 among 1260 in the standard-dose group. These are descriptive counts, not adjusted comparative estimates. The record does not report a statistical test or confidence interval for safety comparisons. Death counts are not reported in the registry record.
The record also lists serious adverse event terms and percentages, including pneumonia at 0.7%, cerebrovascular accident at 0.6%, and cardiac failure congestive at 0.5%. Chest pain and syncope are each listed at 0.4%, as is coronary artery disease. The denominator and the basis for these percentages are not reported in the registry record, so they should not be treated as group-specific risks or used to compare vaccines.
Overall, the record supports a description of the trial design, endpoint definitions, and selected safety counts. It does not support a conclusion about the size, direction, or statistical uncertainty of the primary immunogenicity comparison. The protocol's sample-size justification and any interim analyses are not reported in the registry record. Any planning illustration based on an observed effect is not an observed trial result, and no such illustration can substitute for the missing primary endpoint estimates.
9. Statistical Methods Explained
The registry describes a randomized, quadruple-masked, parallel-group trial. Randomization is intended to make treatment groups comparable on average with respect to both measured and unmeasured participant characteristics. Masking can reduce the chance that knowledge of assignment influences participant reports, clinical assessments, or study conduct. These are general methodological purposes; the registry does not describe the randomization sequence, allocation concealment, or the specific people masked.
What does the primary outcome measure?
Hemagglutination inhibition antibody titers are laboratory measurements used to characterize antibody response to influenza antigens. The registry reports geometric mean titers and 95% confidence intervals at Day 0 and Day 28 after vaccination. Measurements are specified for A/H1N1 New-Caledonia, A/H3N2 Wisconsin, and B Malaysia. Because there are multiple antigens and time points, interpretation requires attention to which estimate is being considered and how comparisons across them were planned.
As a general statistical explanation, the geometric mean is calculated on a log-transformed scale and then expressed back on the original scale. This can make summaries less dominated by very large observations than an arithmetic mean would be when data are strongly right-skewed. The registry's endpoint description names the geometric mean, but it does not report the transformation details, assumptions, or exact method used to calculate its confidence intervals.
How should confidence intervals be read?
A confidence interval expresses the statistical uncertainty around an estimate under the analysis method used. A narrower interval indicates greater precision than a wider interval, all else equal. For an estimated GMT, the interval concerns the population-level titer represented by that group estimate. A confidence interval for a difference or ratio between groups would address the comparison directly, but comparative intervals are not reported in the registry record. The specified 95% confidence intervals for the primary endpoint do not, on their own, establish whether the high-dose groups differ from standard dose.
Why are multiple groups and outcomes relevant?
The study included three high-dose lots and a standard-dose group. Its objectives included assessing lot consistency and superiority relative to standard dose. The primary outcome also covers multiple antigens and pre- and post-vaccination measurements, while secondary outcomes address seroprotection and reactions. As a general statistical principle, evaluating multiple groups, outcomes, or time points creates multiple opportunities to observe a result that appears notable by chance. A prespecified testing strategy or multiplicity adjustment can help control the interpretation of a family of comparisons. Such a strategy is not reported in the registry record, so it is not possible to determine how multiplicity was addressed.
What can be said about safety counts?
The safety entries give numbers at risk and numbers affected for serious and other adverse event categories. These counts describe how many participants were recorded in each category, but they do not provide adjusted comparisons or account for differences in follow-up. As a general statistical matter, adverse event comparisons may depend on event definitions, observation periods, participant exposure, and how repeated events are handled. Those details are not fully reported in the registry record. The listed counts should therefore be read as descriptive, not as evidence of a statistically tested difference.
The serious adverse event terms are accompanied by percentages, but the record does not state the denominator or clarify whether the percentages are pooled across groups or calculated another way. Without that information, they cannot be interpreted as comparable group-specific rates. In addition, death counts are not reported in the registry record.
What do the analysis and planning details establish?
The primary outcome description says that the Full Analysis Set included 3851 participants and followed randomized assignment. This identifies the stated analysis population but does not reveal the number with observed values at each time point or the approach to missing data. The registry lists no statistical analyses, so details such as the comparison model, covariate adjustment, hypothesis tests, and handling of missing observations are not reported in the registry record.
The sample-size assumptions described for planning illustrations specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of an observed effect. These are planning assumptions, not proof of the trial's original design rationale or observed power. The trial's own sample-size justification is not reported in the registry record. Sample-size illustrations should be understood as hypothetical planning aids rather than as additional results from the trial.
10. Multiplicity, Missing Data and Analysis Populations
The primary outcome involves three influenza antigens and measurements at Day 0 and Day 28. The study also includes three high-dose lots, a standard-dose group, and secondary outcomes for seroprotection and adverse reactions. As a general statistical concern, assessing multiple groups, outcomes, and time points can increase the chance of apparently notable findings arising by chance if all are tested independently. A prespecified hierarchy, adjustment, or other strategy may address this issue, but a multiplicity strategy is not reported in the registry record.
The registry lists no statistical analyses. It therefore does not report the comparison model, inferential tests, adjustment for covariates, or the handling of repeated measurements. The primary outcome description identifies the Full Analysis Set, says participants were analyzed according to randomized assignment, and states that 3851 participants were included. It does not state the number with observed results for each antigen and time point or how missing data were treated. Missing-data assumptions and sensitivity analyses are not reported in the registry record.
The allocation counts in the safety entries are stated by outcome group, but reasons for the counts and details of follow-up completeness are not reported. The registry's six-month safety objective is described, while the precise observation windows for each safety count are not given. Protocol deviations, exclusions, interim analyses, and a prespecified statistical analysis plan are not reported in the registry record. Consequently, the available record is insufficient to evaluate whether all planned outcomes and analyses were reported or how the analysis protected against selective emphasis.
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 |
|---|---|---|---|
| High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 1 | 56 | 855 | 6.5% |
| High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 2 | 56 | 848 | 6.6% |
| High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 3 | 44 | 870 | 5.1% |
| Standad Dose Inactivated, Split-Virion Influenza Vaccine | 93 | 1260 | 7.4% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5.0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 1 | 455 of 855 |
| High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 2 | 454 of 848 |
| High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 3 | 449 of 870 |
| Standad Dose Inactivated, Split-Virion Influenza Vaccine | 544 of 1260 |
Most frequent serious adverse event terms
| Event term | Organ system | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 1 | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 2 | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 3 | Standad Dose Inactivated, Split-Virion Influenza Vaccine |
|---|---|---|---|---|---|
| Pneumonia | Infections and infestations | 6 of 855 | 5 of 848 | 6 of 870 | 4 of 1260 |
| Cardiac failure congestive | Cardiac disorders | 4 of 855 | 3 of 848 | 0 of 870 | 2 of 1260 |
| Coronary artery disease | Cardiac disorders | 2 of 855 | 3 of 848 | 0 of 870 | 4 of 1260 |
| Myocardial infarction | Cardiac disorders | 2 of 855 | 1 of 848 | 2 of 870 | 4 of 1260 |
| Transient ischaemic attack | Nervous system disorders | 1 of 855 | 1 of 848 | 3 of 870 | 4 of 1260 |
| Pulmonary embolism | Respiratory, thoracic and mediastinal disorders | 2 of 855 | 2 of 848 | 3 of 870 | 1 of 1260 |
| Chest pain | General disorders | 0 of 855 | 2 of 848 | 0 of 870 | 5 of 1260 |
| Atrial fibrillation | Cardiac disorders | 0 of 855 | 2 of 848 | 1 of 870 | 3 of 1260 |
| Cerebrovascular accident | Nervous system disorders | 0 of 855 | 5 of 848 | 0 of 870 | 1 of 1260 |
| Syncope | Nervous system disorders | 1 of 855 | 0 of 848 | 0 of 870 | 5 of 1260 |
Most frequent non-serious adverse event terms
| Event term | Organ system | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 1 | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 2 | High-Dose Inactivated, Split-Virion Influenza Vaccine Lot 3 | Standad Dose Inactivated, Split-Virion Influenza Vaccine |
|---|---|---|---|---|---|
| Injection site pain | General disorders | 295 of 855 | 292 of 848 | 328 of 870 | 306 of 1260 |
| Myalgia | Musculoskeletal and connective tissue disorders | 197 of 855 | 175 of 848 | 178 of 870 | 230 of 1260 |
| Malaise | General disorders | 173 of 855 | 150 of 848 | 139 of 870 | 176 of 1260 |
| Headache | Nervous system disorders | 146 of 855 | 138 of 848 | 147 of 870 | 182 of 1260 |
| Injection site erythema | General disorders | 136 of 855 | 125 of 848 | 123 of 870 | 136 of 1260 |
| Injection site swelling | General disorders | 79 of 855 | 76 of 848 | 75 of 870 | 73 of 1260 |
Serious events with the highest arm-level rate: pneumonia (0.7%), cerebrovascular accident (0.6%), cardiac failure congestive (0.5%), chest pain (0.4%), syncope (0.4%).
The registry reports serious adverse event counts by vaccine group. It lists 56 affected among 855 at risk for high-dose Lot 1, 56 among 848 for high-dose Lot 2, and 44 among 870 for high-dose Lot 3. For standard-dose vaccine, it lists 93 affected among 1260 at risk. These are the recorded participant counts; they are not adjusted estimates of comparative risk.
The record separately lists serious adverse event terms with percentages: pneumonia, 0.7%; cerebrovascular accident, 0.6%; cardiac failure congestive, 0.5%; chest pain, 0.4%; syncope, 0.4%; and coronary artery disease, 0.4%. The denominator and whether these percentages refer to all groups together or another population are not reported in the registry record. They should therefore be read as listed event summaries rather than as group-specific percentages.
The record does not report death counts, a statistical test of between-group safety differences, or confidence intervals for the serious adverse event counts. The counts alone do not establish whether groups differ beyond what could be due to chance, and the registry does not provide enough information to assess differences in follow-up or event ascertainment.
12. What the Result Does, and Does Not, Mean
The trial addresses an important statistical question in vaccine research: whether immune responses differ across three manufacturing lots of a high-dose vaccine and how those responses compare with a standard-dose vaccine. Its randomized, parallel-group design and stated Full Analysis Set provide a framework for evaluating those questions. The primary outcome is clearly defined by assay, antigens, time points, and summary measure.
However, the registry record does not report the numerical GMT results, their confidence intervals, or comparative estimates. It therefore does not show the magnitude or precision of any difference in antibody response between high-dose and standard-dose groups, or among the high-dose lots. The objectives describe what investigators intended to assess, not what the results demonstrated. The registered record alone cannot establish whether the lot consistency or superiority objectives were met.
The safety entries offer counts of participants affected by serious adverse events, and the record lists selected serious event terms with percentages. Those descriptive data should not be treated as a complete comparative safety analysis. No group-level inferential estimates, confidence intervals, or death counts are reported. The denominator for the listed event percentages is also not reported in the registry record.
As a general statistical distinction, an absence of reported results is not evidence that an effect is absent, nor does it establish that an effect is present. Precision cannot be judged without estimates and uncertainty intervals. Likewise, a sample-size planning illustration is not an observed power calculation and does not resolve the absence of outcome results. The record provides the trial's structure and outcome definitions, but not enough numerical efficacy or comparative safety information to draw conclusions about the size or certainty of treatment differences.
13. Why This Trial Matters Statistically
This trial is statistically notable for combining two related but distinct immunogenicity questions. One concerns consistency across three high-dose manufacturing lots; the other concerns comparison with standard-dose vaccine. Those questions require clear definitions of the groups and comparisons, as well as interpretation of results across multiple antigens and time points. The four-group randomized design makes the distinction between lot-to-lot evaluation and high-dose versus standard-dose evaluation especially important.
The endpoint uses geometric mean antibody titers, a summary suited to measurements interpreted on a multiplicative scale. Reporting the measurement at baseline and Day 28 allows the outcome definition to reflect both pre-vaccination status and a post-vaccination time point. The registry also describes seroprotection and reaction outcomes, broadening the assessment beyond the primary GMT measure.
At the same time, the record illustrates why outcome definitions and study objectives are not substitutes for numerical results. Without the GMT estimates, confidence intervals, and comparative analyses, readers cannot assess effect size, precision, or whether the stated objectives were met. With several lots, antigens, time points, and secondary outcomes, reporting the planned multiplicity strategy would also be important for interpreting inferential claims; that strategy is not reported in the registry record.
The safety entries show how descriptive counts can inform a basic account of events while still leaving key comparative questions unanswered. Group-specific counts are available, but adjustment, uncertainty, event denominators for listed percentages, and death counts are not. The trial is therefore useful as an example of the value of transparent outcome reporting: design and endpoint details establish what was intended, while complete estimates and analysis methods are needed to judge what the data support.
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 principal limitation for interpreting this trial from the registry record is that numerical primary endpoint results are not reported. GMT estimates and the specified 95% confidence intervals are absent, as are direct comparisons between the high-dose lots and standard-dose vaccine. The record therefore does not allow evaluation of the size or precision of the immunogenicity findings.
The registry lists no statistical analyses. The analysis model, testing procedures, covariate adjustments, and multiplicity strategy are not reported in the registry record. This matters because the primary outcome encompasses multiple antigens and time points, and the study has three high-dose lots as well as a standard-dose group. The record also does not describe missing-data handling, the number with observed endpoint measurements by antigen and time point, or sensitivity analyses.
Although the Full Analysis Set is identified as including 3851 participants according to randomized assignment, participant flow and reasons for exclusions or missing measurements are not described. Safety group counts are reported, but outcome-specific follow-up, event ascertainment details, and statistical comparisons are not. The denominator for the percentages accompanying serious adverse event terms is not reported in the registry record, and death counts are not reported.
The protocol's sample-size justification, interim analyses, and prespecified statistical plan are not reported in the registry record. The available planning assumptions do not establish the original sample-size rationale. These limitations restrict what can be inferred from the registry entry; they do not establish that analyses or information were absent from other study documents.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Immunogenicity of High-dose Inactivated, Split-virion Influenza Vaccine Versus Standard Fluzone Vaccine in the Elderly — NCT00391053.
- Registry record last updated 2016-04-14; status last verified 2016-04.
- Results first posted 2010-04-30.
- 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
NCT00391053 is a completed randomized, quadruple-masked, parallel-group Phase III study with 3851 enrolled participants. It compared three lots of high-dose inactivated, split-virion influenza vaccine with standard-dose Fluzone in adults aged at least 65 years. The record gives a start date of 2006-10 and a primary completion date of 2007-07.
The primary outcome was geometric mean hemagglutination inhibition antibody titers at Day 0 and Day 28 for A/H1N1 New-Caledonia, A/H3N2 Wisconsin, and B Malaysia, with 95% confidence intervals specified. The outcome population was the Full Analysis Set according to randomized assignment. Secondary outcomes included seroprotection and solicited injection-site and systemic reactions. The record also describes safety objectives during the six months following vaccination.
Numerical primary endpoint results and statistical analyses are not reported in the registry record. Serious adverse event counts are listed by group, along with selected event terms and percentages, but comparative safety analyses and the denominator for those percentages are not reported.