Serologic Assay Validation and Proficiency Testing of HIL-214 in Adults: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Serologic Assay Validation and Proficiency Testing of HIL-214 in Adults (NCT05972733), a na phase 2 study. The primary outcome is Primary Immunogenicity for Panel Formation.

2. Clinical Question

The stated purpose was to obtain serum after adults received a pediatric dose of HIL-214, so that proficiency testing could confirm whether assay validity was maintained. The primary outcome concerns the proportion meeting a seroresponse definition, not a direct comparison of vaccine effects against another treatment or a control group. Seroresponse was defined as a ≥4-fold rise in antibody concentration between Day 1 and Day 29. The assays covered norovirus GI.1 and GII.4c, including HBGA-blocking and total immunoglobulin (pan-Ig) assays.

The registry record identifies the percentage of participants with a predefined seroresponse and a 95% confidence interval as the primary immunogenicity outcome. It does not report the observed percentage or interval. Accordingly, the record supports describing the question and its measurement, but not stating how many participants met the response definition or how precise that estimate was.

3. Trial Design

This was a Phase 2, single-group, open-label trial of HIL-214 in adults aged 18 to 49 years. The registry record lists enrollment of 80 and status as completed. The study began on 2023-08-01, with primary completion on 2023-08-14. The intervention was HIL-214, and the arm description states that one dose was given to all participants. No allocation to competing groups or masking was described.

The stated purpose centers on serum collection for proficiency testing and confirmation that assay validity is maintained after dosing. The trial therefore has a measurement and assay-validation focus alongside the listed safety and immunogenicity outcomes. The registry describes the primary immunogenicity endpoint as the percentage of participants with a ≥4-fold rise in antibody concentration from Day 1 to Day 29 for the GI.1 and GII.4c components. Its population is the Safety Analysis Set, defined as all participants who received trial vaccine.

Because there is only one group, the design does not provide a like-for-like control comparison. It can describe outcomes among participants who received HIL-214, but cannot by itself distinguish changes associated with the intervention from other explanations such as time-related changes, measurement variability, or participant characteristics. The registry record does not report a randomized comparison, a control arm, or masking.

Adverse events were among the listed secondary outcomes. These included events leading to withdrawal, solicited local and systemic events within 7 days of vaccine administration, and unsolicited events after the dose. The record lists five outcome measures and zero analyses. Numerical results for the primary immunogenicity outcome and the listed secondary outcomes are not reported in the registry record.

The registry record does not report the protocol’s sample-size justification, any planned interim analyses, or a statistical analysis plan. Those details should not be inferred from the enrollment count or from the descriptive outcomes listed.

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: Healthy volunteers were enrolled in 1 treatment arm and received a single dose of HIL-214, a norovirus vaccine comprising 50 µg GI.1 virus-like particle (VLP) and 150 µg GII.4c VLP, adjuvanted with 500 µg of aluminum hydroxide.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Safety Analysis Set, all participants that received trial vaccine (HIL-214).

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: Safety Analysis Set, all participants that received trial vaccine (HIL-214).

6. Primary Endpoint

The registry lists the primary outcome as Primary Immunogenicity for Panel Formation, measured over Day 1 to Day 29.

The primary endpoint is the percentage of participants with a predefined seroresponse from Day 1 to Day 29. A participant met that definition with a ≥4-fold rise in antibody concentration over that period. The response was assessed for the GI.1 and GII.4c components of HIL-214 using serum samples and HBGA-blocking and total immunoglobulin (pan-Ig) assays. The registry record specifies that the percentage and a 95% confidence interval are reported for the Safety Analysis Set, consisting of all participants who received trial vaccine.

A percentage expresses how common a defined response was within the analyzed group. The confidence interval communicates uncertainty around that estimate; it is not a range containing a known proportion of individual participant responses. In general, confidence intervals are useful because an observed percentage from a study is an estimate, and the interval conveys how much precision the data provide under the analysis assumptions.

The endpoint is used to characterize antibody response and support the trial’s assay-validation and proficiency-testing purpose. It is not, on its own, a direct measure of clinical benefit, nor does it compare HIL-214 with another intervention. The registry record does not report the observed percentage or its confidence interval, so the magnitude and precision of the primary endpoint cannot be described from this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group design estimate?

In a single-group study, participants receive the same intervention and outcomes are described within that group. For this trial, the stated intervention was one dose of HIL-214. The primary outcome is a proportion: the percentage of participants meeting the prespecified seroresponse definition. Such a result describes the observed group; without a comparator group, it is not a randomized estimate of the difference between HIL-214 and another treatment.

General statistical interpretation: a within-group change can reflect the intervention, but can also be influenced by other changes over time, participant characteristics, or measurement variability. A concurrent comparator can help separate these possibilities when allocation and analysis support a valid comparison. The registry record describes no comparator and no randomized allocation.

What does the seroresponse definition mean?

The endpoint defines response by a ≥4-fold rise in antibody concentration from Day 1 to Day 29. Each participant is classified according to whether their measured change meets that threshold, and the endpoint is the percentage meeting the definition. The record says serum was collected for validation of the GI.1 and GII.4c HBGA-blocking and total immunoglobulin (pan-Ig) assays.

General statistical interpretation: turning a continuous measurement into a threshold-based response can make a result easy to communicate as a proportion, but it discards information about the size of changes among participants on either side of the threshold. The registry record does not report separate numerical results for the assays or components, so it is not possible to describe their observed response proportions.

How should a confidence interval be read?

The primary outcome description specifies a 95% confidence interval. A confidence interval is an estimate of uncertainty around a sample statistic, under the assumptions of the method used. For a percentage, it helps readers assess precision rather than treating the observed proportion as exact. A narrower interval indicates greater statistical precision under the method; a wider interval indicates more uncertainty.

General statistical interpretation: a confidence interval is not a guarantee about an individual participant and does not show the probability that a fixed true value lies within the particular calculated interval. Interpretation also depends on the analysis population, data completeness, and the method used. Although the record says an interval is reported, its numerical bounds are not reported in the registry record.

What does over-dispersion mean in general?

General statistical explanation: for some outcomes, observations vary more than a basic statistical model assumes. This is called over-dispersion. If it is not accounted for, a model can understate uncertainty and produce confidence intervals that are too narrow. The appropriate model depends on the outcome and design. The registry record does not report a model, an assessment of over-dispersion, or an analysis plan for the primary endpoint; no particular modeling approach should therefore be attributed to the trial.

Why do analysis populations matter?

The primary endpoint description names the Safety Analysis Set and defines it as all participants who received trial vaccine. This makes the intended population for the reported primary percentage explicit. However, the registry record does not report the number included in the immunogenicity analysis, the number with available Day 1 and Day 29 measurements, or how missing measurements were handled. These details affect interpretation because a proportion calculated among participants with complete measurements may differ from one calculated under another missing-data approach.

The safety summary gives denominators of 80 for serious adverse events and 79 for other adverse events. Denominators define the group at risk for each summary and should be read alongside the event counts. The record does not explain why these denominators differ. The primary endpoint population and the adverse-event denominators should not be assumed to be identical for every outcome.

What can and cannot be inferred from the design?

The design can describe measured responses and adverse events within the treated group, subject to the reported data and analysis. General statistical interpretation: a one-group proportion does not estimate a comparative treatment effect, because there is no control-group outcome to contrast with it. No sample-size justification, interim-analysis plan, or detailed statistical analysis plan is reported in the registry record.

The posted sample-size assumptions describe planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Those are illustrations rather than the trial’s own design rationale, and they do not turn this single-group trial into a two-arm study. The registry record does not report that such a two-arm sample-size plan governed this trial. Any sample-size illustration should not be read as observed power or as evidence that the trial could detect a particular effect.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists one primary immunogenicity outcome and several secondary adverse-event outcomes. The secondary outcomes include events leading to withdrawal, solicited local events and solicited systemic events within 7 days of vaccine administration, and unsolicited events after the dose. The record lists five outcome measures overall, but it does not report numerical results for these listed secondary outcomes.

Multiplicity arises when multiple outcomes or statistical tests are considered. General statistical explanation: as the number of tests increases, the chance of at least one apparently unusual result can increase unless the analysis plan addresses that issue. Whether and how to adjust depends on the goals and prespecified testing strategy. The registry record does not report a multiplicity strategy, a hierarchy of hypotheses, or a detailed statistical analysis plan. No correction or testing sequence should be assumed.

The primary endpoint population is the Safety Analysis Set, defined as all participants receiving trial vaccine. The record does not report the number with evaluable Day 1 and Day 29 serum measurements or how missing observations were handled. It also does not report whether all planned endpoint analyses were performed. The record lists zero analyses, so no inferential analysis details are available there.

The safety summary reports 80 participants at risk for serious adverse events and 79 at risk in the other adverse-event category. The reason for the different denominators is not reported in the registry record. Missing-data methods, reasons for missing data, and any sensitivity analyses are not reported in the registry record. These omissions limit assessment of how complete and comparable the outcome-specific data were.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 2% reporting threshold.

Most frequent non-serious adverse event terms

The adverse-event summary records zero serious adverse events among 80 participants at risk in the HIL-214 group. It separately records 52 participants with an event in the other adverse-event category among 79 at risk. These are counts within the listed categories, not comparisons with another group.

The figures should be read with their denominators: the number at risk differs between the two categories. The registry record does not explain that difference. It also does not provide serious adverse-event terms, since no top serious terms are listed, or numerical results for the specified secondary outcomes such as local and systemic events within 7 days and unsolicited events after dosing.

General statistical interpretation: observing zero events in a study group does not establish that the underlying risk is zero. The estimate remains uncertain, particularly when the group is limited in size, and a comparison group would be needed for a comparative safety estimate. An event count also does not establish causality. The registry record does not report an attribution assessment for the listed figures. These counts describe the posted safety summary and should not be treated as a complete characterization of every possible risk.

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

The record establishes that a completed Phase 2, open-label, single-group trial enrolled 80 adults aged 18 to 49 years to receive one dose of HIL-214. Its stated purpose was to obtain serum for proficiency testing and to confirm that assay validity was maintained following dosing. The primary endpoint was defined as the percentage with a ≥4-fold increase in antibody concentration from Day 1 to Day 29 for the GI.1 and GII.4c components, with a 95% confidence interval.

The primary numerical result is not reported in the registry record. The record therefore does not show what percentage met the seroresponse definition or how precise the estimate was. Nor does it report numerical results for the listed secondary adverse-event outcomes. The available safety summary records zero serious adverse events among 80 at risk and 52 participants with an event in the other adverse-event category among 79 at risk.

These data do not establish a comparative effect because there is no control group in the design. They also do not establish that any recorded event was caused by HIL-214. The endpoint is a serologic measurement, not a clinical outcome demonstrating a change in illness. The registry record does not report a numerical efficacy result or a clinical comparison.

Accordingly, the trial’s design and intended measurement can be described, along with the limited safety counts recorded. The unreported primary result, absent comparator, and unavailable analysis details place clear limits on conclusions about the observed antibody response, precision, and comparative effects. The absence of a result in the registry record should not be mistaken for evidence that no outcome was measured in the trial.

13. Why This Trial Matters Statistically

This trial illustrates how a study can have a focused statistical purpose that differs from a conventional treatment-comparison question. The registry describes collection of serum for proficiency testing and assay validation after participants received HIL-214. The primary endpoint is a defined antibody response over time, expressed as a percentage with a confidence interval. Understanding that aim helps distinguish a measurement-validation objective from a randomized estimate of treatment benefit.

The single-group design is important to interpretation. It can provide a description of responses and adverse events in the treated group, but it does not supply a like-for-like control comparison. The endpoint definition also matters: a ≥4-fold rise converts measured antibody concentrations into a response classification. That is clear to communicate, but it does not show the full distribution of individual changes.

The record also demonstrates why the availability of endpoint definitions is not the same as the availability of endpoint results. It describes the primary measure and the intended confidence interval, yet the numerical estimate and interval are not reported in the registry record. Without them, readers cannot assess the observed response or its precision. The same issue applies to listed secondary outcomes whose numerical results are absent.

Finally, safety counts need their denominators and categories to be interpreted carefully. The posted figures use different numbers at risk for serious and other adverse events, and the reason for the difference is not stated. Reporting those details alongside the design and endpoint helps readers identify what the record supports and where uncertainty remains, without turning descriptive findings into comparative claims.

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 interpreting the primary endpoint is that its numerical result is not reported in the registry record. Although the endpoint definition and intended 95% confidence interval are described, neither the observed percentage nor the interval is available. The precision and magnitude of the antibody response therefore cannot be assessed from this record.

The study is single-group and open-label, with no comparator described. Its outcomes are descriptive of participants receiving HIL-214 and do not provide a randomized between-group contrast. The record does not report a sample-size justification, detailed analysis plan, interim-analysis plan, or multiplicity strategy. It also does not report how missing serum measurements were handled or how many participants had evaluable primary endpoint data.

The safety summary reports zero serious adverse events among 80 at risk and 52 participants with an event in the other adverse-event category among 79 at risk. The reason for the different denominators is not reported in the registry record. Numerical results for the listed secondary safety outcomes are not reported in the registry record, limiting a fuller reading of the adverse-event profile.

The endpoint is based on a serologic response definition and is not itself a clinical outcome or a comparison of clinical effects. The record’s assay-validation purpose should be kept distinct from claims about clinical efficacy. These limitations concern the information and design described in the registry record; they do not establish whether further analyses or results exist outside it.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Serologic Assay Validation and Proficiency Testing of HIL-214 in Adults — NCT05972733.
• Registry record last updated 2025-08-19; status last verified 2025-07.
• Results first posted 2025-08-19.
• 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

NCT05972733 is a completed Phase 2, single-group, open-label study of HIL-214 in adults aged 18 to 49 years. The registry record lists enrollment of 80, a start date of 2023-08-01, and primary completion on 2023-08-14. One dose was given to participants.

The stated purpose was to obtain serum for proficiency testing and confirm assay validity after dosing. The primary endpoint was the percentage with a ≥4-fold rise in antibody concentration from Day 1 to Day 29 for the GI.1 and GII.4c components, with a 95% confidence interval. The numerical primary result is not reported in the registry record.

The adverse-event summary lists zero serious adverse events among 80 at risk and 52 participants with an event in the other category among 79 at risk. Numerical results for the listed secondary outcomes are not reported in the registry record. No comparator, detailed statistical plan, or missing-data approach is reported.