Interferon as a Mucosal Adjuvant for Influenza Vaccine Given Intranasally: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Interferon as a Mucosal Adjuvant for Influenza Vaccine Given Intranasally (NCT00436046), a randomized phase 1 study. The primary outcome is Antibody Responses in Nasal Secretions to Influenza A/H1N1 and A/H3N2 at 14 Days After Intranasal Immunization..

2. Clinical Question

Statistically, this is a question about the frequency of a defined immune response in the three treatment groups. It is not a direct measure of influenza illness or infection. Secondary outcomes include solicited local or systemic symptoms, unsolicited adverse events, and serum antibody responses measured at 14 and 28 days after immunization. Those outcomes broaden the description of immune response and safety, but they do not replace the stated primary endpoint. The registry record does not provide a numerical comparison for the primary outcome or enough detail to identify which treatment group had the higher response frequency.

3. Trial Design

The registry identifies this as a Phase 1, randomized, double-masked, parallel-group trial sponsored by the National Institute of Allergy and Infectious Diseases. The study is marked completed. Its listed start and primary-completion dates are 2007-03 and 2007-04. A parallel design assigns participants to one of the treatment groups, rather than having each participant receive each regimen in sequence. Randomization is intended, in general, to help make treatment groups comparable at the outset; masking is intended to limit the influence of treatment knowledge on care or assessment. The registry does not report further details about how randomization or masking was implemented.

The three arm descriptions specify 0.6 ml of vaccine alone, 0.6 ml of vaccine with 1M unit of interferon, and 0.7 ml of vaccine with 10M units of interferon. Each arm description states 30 subjects. The safety results list different numbers at risk by group: 32, 32, and 31. The registry record does not explain these differences or provide a reconciliation of the group counts. Enrollment is listed as 95, while the brief summary says 90 volunteers would participate.

The brief summary describes a single dose sprayed into the nose, three study visits, and a final follow-up by visit, email, or phone call about six months after vaccination. Blood samples and nasal washes were collected to evaluate immune responses. The primary outcome was assessed at 14 days. The record also lists serum antibody outcomes at 14 and 28 days, solicited symptoms, and unsolicited adverse events. It does not report the full schedule for each secondary assessment or how the final follow-up relates to the listed outcome time points. No further protocol detail about allocation procedures, adherence, or treatment discontinuation is 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

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.

6. Primary Endpoint

The registry lists the primary outcome as Antibody Responses in Nasal Secretions to Influenza A/H1N1 and A/H3N2 at 14 Days After Intranasal Immunization., measured over 14 days after immunization..

The primary endpoint is the number of participants whose antibody titer in nasal secretions rose by a 4-fold or greater amount at day 14 after immunization, compared with the pre-immunization level. It is a binary response definition at the participant level: a participant either meets the stated threshold or does not. The reported outcome unit is participants, and the registry describes the result as a frequency.

Using a threshold makes the endpoint interpretable as the proportion or count of participants meeting a prespecified response criterion, rather than as a summary of every individual titer value. In general, antibody measurements can describe an immune response to vaccination. A nasal-secretion measure is relevant to the mucosal route of administration, while serum antibody measurements are listed separately as secondary outcomes. These are immunologic outcomes, not direct counts of influenza infections or illnesses.

The registry record does not report the number meeting the threshold in each group, the group denominators for this endpoint, an effect estimate, or a confidence interval. It also does not report the assay details or the handling of values that could not be measured. Accordingly, the endpoint definition can be described, but its observed group results and their precision cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Randomization assigns participants to treatment groups using a chance-based process. In general, this helps prevent treatment assignment from being systematically linked to participants' characteristics, although randomization does not guarantee that every characteristic will be balanced, particularly in a small study. The registry labels this trial randomized but does not report the sequence-generation method, allocation concealment, or procedures for implementing assignments. Those details are not reported in the registry record.

Double masking means that the record identifies the study as masked for two parties, but the registry does not specify which parties were masked or how masking was maintained. This matters because knowledge of assignment can influence behavior, outcome assessment, or reporting. The record does not say whether the different vaccine volumes or interferon contents could be distinguished by participants or study personnel. No assumptions about the success of masking can therefore be made from the designation alone.

What kind of outcome is the primary endpoint?

The primary endpoint is a binary response summarized as a frequency: whether each participant's nasal antibody titer increased by at least the stated 4-fold threshold at 14 days, relative to baseline. A binary endpoint reduces a measurement to whether a criterion was met. This can make group response counts straightforward to describe, but it also discards information about how far above or below the threshold individual measurements fell. The registry gives the endpoint definition but does not report the underlying measurements or response counts.

For a binary endpoint, a comparison can be expressed in several ways, such as a difference in response frequencies or a ratio of those frequencies. The choice of effect measure affects interpretation, and an uncertainty interval is useful for showing how much statistical precision the data support. These are general statistical options, not methods documented for this trial. The registry record does not identify the effect measure, hypothesis test, confidence-interval method, or any covariate adjustment used for the primary outcome. No result should be attributed to a particular method when that method is not reported.

What does uncertainty add?

In general, an estimate describes the observed pattern in a sample, while a confidence interval communicates uncertainty about the corresponding population quantity under the assumptions of the analysis. A narrow interval indicates greater precision than a wide interval, but neither guarantees that the model assumptions are correct. A p-value, when reported, addresses compatibility between data and a specified null model; it is not the probability that a treatment works or that the null hypothesis is true. The registry record does not report a primary-outcome estimate, confidence interval, or p-value, so those forms of uncertainty cannot be evaluated.

How should the design and planning information be read?

The registry describes a parallel, three-group design. In general, comparing each interferon-containing regimen with vaccine alone could address whether the observed response frequency differs between those assigned regimens. The registry does not report the planned primary contrasts or whether the two interferon groups were also intended to be compared with each other. It also does not report a statistical analysis plan specifying the test, model, or handling of group differences.

The registry's general sample-size assumptions describe planning illustrations based on a fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such calculations are planning illustrations, not observed power and not evidence about the trial's actual design justification. The record does not report a sample-size justification for the trial, and the primary outcome has not been reduced to a single comparison in the posted results used for this description. No specific planning result is reported.

Dispersion or over-dispersion is relevant to some count outcomes when observed variability exceeds what a simple statistical model expects. In general, accounting for over-dispersion can prevent uncertainty from being understated. The primary endpoint is described as a binary participant response, not a count of repeated events per participant; the registry does not report a model or dispersion assessment. It would not be appropriate to infer that a particular count model or adjustment was used.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome and several secondary outcomes: solicited local or systemic symptoms, unsolicited adverse events, and serum antibody responses to influenza A/H1N1 and A/H3N2 at 14 and 28 days. Multiple outcomes and time points create a general statistical issue: the more comparisons examined, the more likely it is that some patterns may appear notable by chance. A prespecified hierarchy or multiplicity adjustment can address that issue, but the registry record does not report whether either was planned or used.

The record does not list analyses, and it does not provide a statistical analysis plan. It is therefore not possible to determine which group comparisons were prespecified, how outcomes were prioritized, or whether any correction for multiple testing was applied. This absence of detail is not evidence that no analyses were conducted; it means that analysis procedures are not reported in the registry record.

Missing-data handling is also not reported. The record does not state how participants without a day-14 nasal measurement were handled, whether any measurements were excluded, or how missing serum or safety assessments were treated. It does not define an analysis population, such as all randomized participants or participants with an available measurement. The listed enrollment, arm descriptions, and safety denominators are not fully reconciled, so they should not be treated as interchangeable populations. Without an account of missingness and analysis populations, the potential influence of incomplete follow-up on the endpoint cannot be assessed.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry records serious adverse-event counts of zero in each listed group: 0 of 32 at risk for IVV with 1M IFN, 0 of 32 for IVV without IFN, and 0 of 31 for IVV with 10M IFN. The serious adverse-event term list is empty. These entries mean that no serious adverse events are listed among the participants counted at risk in these group records; they do not establish that the risk of a serious event is absent.

For other adverse events, the registry lists 29 affected participants among 32 at risk in each of the first two groups, and 26 affected participants among 31 at risk in the third group. These are descriptive counts. The record does not provide an analysis comparing groups, event-level descriptions for these counts, or confidence intervals. Deaths are not reported in the registry record.

The group denominators in the safety data differ from the 30 subjects specified in each arm description. The record does not explain this discrepancy. Safety counts should therefore be interpreted using the denominators attached to those entries, without treating them as the denominators for the primary immune-response outcome.

12. What the Result Does, and Does Not, Mean

The record establishes the trial's question and design: a randomized, double-masked comparison of intranasal inactivated influenza vaccine alone against two regimens combining vaccine and type 1 interferon. The primary endpoint was defined as the number of participants meeting a 4-fold or greater nasal antibody-titer increase at 14 days, relative to baseline. The record also provides descriptive safety counts and identifies additional immune-response and symptom outcomes.

It does not report numerical primary-outcome results. There is no reported response count by group, no treatment-effect estimate, and no uncertainty interval for the primary endpoint. Therefore, the record does not show whether adding interferon was associated with a larger or smaller frequency of participants meeting the endpoint. It also does not support a conclusion about statistical significance or the precision of any difference.

The immune-response endpoint is not the same as a clinical outcome such as influenza infection or illness. A measured antibody response can describe an aspect of immune activity, but the record's stated primary endpoint alone cannot establish whether participants were protected from infection or experienced a change in illness. No such clinical efficacy result is reported in the registry record.

The safety entries indicate no serious adverse events listed in the groups, alongside recorded counts for other adverse events. Those counts are descriptive and do not establish comparative safety. The record does not report adjusted analyses or uncertainty around group differences, and the safety denominators are not reconciled with the arm descriptions.

In short, the registry makes the intended comparisons and outcome definitions clear, but the reported information does not permit a numerical assessment of the primary immune-response comparison. The safety counts can be described as recorded, with the stated denominator and reporting limitations, but they should not be interpreted as a definitive estimate of risk.

13. Why This Trial Matters Statistically

This trial is statistically interesting because it combines a three-group randomized design with an immune-response endpoint defined by a participant-level threshold. That setup highlights the distinction between an outcome definition and an outcome result: a clearly specified response criterion does not by itself reveal how often participants met it or how groups differed. Without the numerical primary results, the central comparison cannot be estimated from the registry record.

The record also illustrates why denominators and analysis populations matter. The arm descriptions state 30 subjects in each group, whereas the safety entries report 32, 32, and 31 at risk. Enrollment is listed as 95, and the brief summary says 90 volunteers would participate. The registry does not explain these differences. A reader should not merge these counts or assume that they refer to the same population or analysis.

Another statistical issue is the breadth of outcomes. The registry includes a primary nasal antibody measure, serum antibody outcomes at more than one time point, solicited symptoms, and unsolicited adverse events. Considering many endpoints and time points can complicate interpretation unless priorities and multiplicity procedures are described. Those procedures are not reported in the registry record.

Finally, the trial's Phase 1 label and immune-focused outcomes frame the evidence as an early assessment of immune response and safety, not as a direct clinical efficacy comparison. The record's missing primary results limit interpretation more than a choice between statistical models would: without the observed group outcomes, no model can supply the comparison. This makes transparent reporting of outcome counts, denominators, analysis populations, and uncertainty especially important for understanding the study.

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 outcome is described but has no numerical results in the registry record. This prevents assessment of response frequency, group differences, or precision. The record also does not report the assay procedures, measurement handling, or the exact primary-outcome denominators. Without those details, the endpoint cannot be independently evaluated beyond its stated threshold and time point.

Several participant counts appear in the record: enrollment is 95, the brief summary says 90 volunteers, each arm description states 30 subjects, and the safety data list at-risk counts of 32, 32, and 31. The registry does not explain why these figures differ. They may refer to different reporting contexts, but that cannot be determined from the record.

The analysis plan is not reported. The record gives no analysis population, approach to missing data, statistical test, effect measure, confidence-interval method, or multiplicity procedure. It also does not report whether the intended comparisons were limited to each interferon group against vaccine alone. The listed outcomes cover immune measures, symptoms, and adverse events, but their relative priority beyond the stated primary endpoint is not explained.

Trial conduct details are also limited. The registry does not report how randomization was generated or concealed, which parties were masked, or how masking was maintained. Although the study is marked completed, the registry record does not include numerical primary findings that would allow an outcome-based comparison. These limitations mean the design and outcome definitions can be described, but the main comparative result and its uncertainty cannot be assessed.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Interferon as a Mucosal Adjuvant for Influenza Vaccine Given Intranasally — NCT00436046.
• Registry record last updated 2011-06-13; status last verified 2009-10.
• Results first posted 2008-11-18.
• 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.

18. Record Summary

The registry record describes NCT00436046, a completed Phase 1 randomized, double-masked, parallel trial sponsored by the National Institute of Allergy and Infectious Diseases. It compared intranasal trivalent inactivated influenza vaccine alone with vaccine combined with type 1 interferon at two stated dose levels. The primary outcome was the number of participants with a 4-fold or greater increase in nasal antibody titer at 14 days relative to baseline.

The record lists secondary immune-response, symptom, and adverse-event outcomes. It reports safety counts by group, including zero serious adverse events listed in each group and counts for other adverse events. The numerical primary-outcome results, statistical analysis methods, missing-data approach, and multiplicity procedures are not reported in the registry record. Differences among the enrollment, arm-description, and safety denominators are not explained.