Safety and Immunogenicity of CJCV2 With and Without ALFQ: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Immunogenicity of CJCV2 With and Without ALFQ (NCT05500417), a randomized phase 1 study. The primary outcome is Number and Percentage of Participants With Solicited Local Adverse Events (AEs) Through 7 Days After Each Study Vaccination.

2. Clinical Question

3. Trial Design

This is a randomized Phase 1 trial of CJCV2, a Campylobacter jejuni conjugate vaccine, given with or without ALFQ. The registry classifies the allocation as randomized, the masking as quadruple, and the model as sequential. Its brief summary calls the study double-blind. These descriptions are both present in the registry; the record does not explain how the masking labels correspond or provide further details of who was masked.

The study was described as outpatient and dose-escalating, with three vaccine dose levels: 1 microgram, 3 micrograms, and 10 micrograms. Each dose level had a vaccine-alone regimen and a regimen combining CJCV2 with ALFQ. Planned intramuscular vaccinations were on Days 1, 29, and 57. The brief summary describes approximately 60 subjects in three cohorts of 20 subjects each. The recorded enrollment is 59, which should be distinguished from those approximate planned cohort figures.

The registry summary says the first six participants at each dose level were sentinel participants randomized in a 1:1 fashion between vaccine alone and vaccine with ALFQ. Arm descriptions further state that three sentinel subjects would be dosed first in each arm, with additional dosing dependent on the stated safety observation. Because the arm descriptions are truncated in the registry record, further details of the sequential process are not reported there.

The study began on 2022-09-13, had a primary completion date of 2025-01-02, and is recorded as completed. The registry does not report the randomization sequence, allocation concealment procedures, detailed eligibility criteria, or a full protocol-level description of dose escalation.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The Safety Population includes all participants who received at least one study vaccination.

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.

Only the first 6 of 7 groups are shown.

6. Primary Endpoint

The registry lists the primary outcome as Number and Percentage of Participants With Solicited Local Adverse Events (AEs) Through 7 Days After Each Study Vaccination, measured over Days 1 through 8, Days 29 through 36, and Days 57 through 64.

The primary endpoint is the number and percentage of participants with solicited local adverse events through 7 days after each study vaccination. The listed observation windows are Days 1 through 8, Days 29 through 36, and Days 57 through 64. Local symptoms were collected 30 minutes after vaccination and then daily using a memory aid. The recorded symptoms include ecchymosis, erythema, induration or edema, pain, and tenderness, including measurement-based entries for some symptoms.

Each symptom was graded from 0 (none) through 3 (severe), with intermediate grades for mild and moderate symptoms. Counting participants with events gives a direct description of how many people experienced one or more specified local reactions in the safety population. Reporting both counts and percentages is generally useful because counts convey the observed number of affected participants, while percentages place those counts in the context of the group being described.

As a general statistical rationale, solicited symptom collection uses a defined list and a defined observation period, which can make short-term tolerability descriptions more systematic than relying only on spontaneous reports. The outcome is focused on local events after vaccination; it is not, by itself, a measure of antibody response or protection from infection. Numerical results for this primary endpoint are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Randomization assigns participants to study regimens by chance rather than by a clinician’s choice. In general, this can reduce systematic differences between groups at the outset, although it does not guarantee that groups will be alike, especially when groups are small. The registry identifies the allocation as randomized and says sentinel participants at each dose level were randomized in a 1:1 fashion between CJCV2 alone and CJCV2 with ALFQ. Details of sequence generation and concealment are not reported in the registry record.

What does the sequential design mean?

In general, a sequential dose-escalation design evaluates regimens in an order that allows safety observations at an earlier dose level to inform whether later dosing proceeds. The registry describes the study as sequential and says sentinel participants were dosed first, with further dosing contingent on the stated safety observation. The complete escalation rules, decision authority, and any formal thresholds are not reported in the registry record. It would therefore be inappropriate to infer specific stopping rules or decision procedures beyond the description that is recorded.

The study has three CJCV2 dose levels and, at each, a regimen with and without ALFQ. This structure can describe dose-specific patterns and the contrast between adjuvanted and unadjuvanted vaccine at a given dose. General statistical principle: comparisons across several doses and regimens create more than one possible contrast. The interpretation of any such comparisons depends on which were prespecified and how uncertainty was handled. Those details are not reported in the registry record.

How should the primary endpoint be understood?

The endpoint counts participants with solicited local adverse events during specified post-vaccination observation windows. Events were solicited at 30 minutes after vaccination and then daily for 7 days, with symptoms graded from 0 (none) to 3 (severe). These definitions specify which symptoms and time periods contribute to the outcome. The outcome title refers to both number and percentage of affected participants, but numerical primary endpoint results are not reported in the registry record.

General statistical principle: a count describes the observed number of people with an event, while a percentage expresses that count relative to the relevant group size. The denominator must be clear for the percentage to be interpreted. Repeated vaccination windows also matter: a participant may be observed after more than one vaccination. Whether the primary endpoint is summarized separately by vaccination, combined across visits, or analyzed in another way is not reported in the registry record. No additional calculation across time windows should be inferred from the endpoint description alone.

What do uncertainty estimates add?

General explanation: a confidence interval gives a range of values compatible with the observed data under a statistical model and expresses the precision of an estimate. Wider intervals indicate less precision; narrower intervals indicate more precision. A p-value, when used, describes how compatible the observed data are with a specified null model, subject to the assumptions of the analysis. Neither measure substitutes for the size and clinical meaning of an effect. The registry record does not report confidence intervals or p-values for the primary endpoint or immune-response outcomes.

Group-level counts in a small early-phase study can be unstable: a small change in the observed number of affected participants can meaningfully alter the descriptive percentage. General statistical principle: estimates based on limited observations are often imprecise, and uncertainty should be considered alongside the point estimate. Because comparative estimates and their uncertainty are not reported, the recorded adverse-event counts should not be interpreted as precise evidence that one regimen has a higher or lower risk than another.

What is reported about immunogenicity?

The listed secondary outcomes concern C. jejuni capsule-specific serum IgG: the percentage of participants with at least a 4-fold rise from baseline, peak fold rise from baseline, and maximum antibody titer. These are distinct summaries of antibody response. In general, a fold rise compares a post-baseline measurement with a baseline measurement, while a maximum or peak summarizes a value over a set of measurements. The registry does not report numerical results, assay details, analysis methods, or the timing of the antibody measurements in the record. No conclusion about the size or precision of immune responses can be drawn from outcome titles alone.

The registry lists 10 outcome measures and 0 analyses. This indicates that no analysis entries are recorded in the registry; it does not establish what analyses may have been conducted outside the registry. A statistical analysis plan, model specifications, covariate adjustments, handling of repeated measurements, and rules for missing observations are not reported in the registry record. No recalculated comparative estimate is available in the recorded information, so there is no recalculated value to set against a sponsor analysis.

10. Multiplicity, Missing Data and Analysis Populations

The study includes multiple dose levels, regimens, outcome measures, and post-vaccination observation windows. General statistical principle: when many outcomes or comparisons are examined, the chance of at least one apparently unusual result can increase unless the analysis plan accounts for multiplicity. Whether multiplicity adjustments or a hierarchy of outcomes were planned is not reported in the registry record. The registry lists 10 outcome measures, while 0 analyses are listed. That registry entry does not identify which comparisons, if any, were intended as confirmatory.

The primary outcome description covers solicited local adverse events after each vaccination, and the secondary outcomes cover several antibody summaries. The record does not state whether the vaccine-alone versus adjuvanted comparisons were planned separately at each dose, whether dose trends were formally tested, or how repeated observations were handled. These analysis details are not reported in the registry record, so the statistical emphasis among possible outcomes cannot be reconstructed from the listed outcome descriptions.

The safety population includes all participants who received at least one study vaccination. That definition is reported for the primary outcome. The registry does not describe an intention-to-treat population, a per-protocol population, or analysis populations for immunogenicity outcomes. It also does not report how missing symptom diaries, missed visits, incomplete vaccination, or unavailable antibody measurements were handled. Whether any observations were excluded from a particular analysis is not reported in the registry record.

General explanation: missing observations can affect estimates when their occurrence is related to participants’ health, treatment, or the outcome being measured. Clear reporting of the amount and handling of missing data helps readers assess possible bias. No missing-data counts or methods are reported in the registry record, so the extent to which missing information could affect the outcome summaries cannot be assessed.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: volvulus (10.0%), breast cancer (10.0%).

The serious adverse-event summary gives affected-participant counts for each regimen: 0 of 10 for 1 µg CJCV2, 0 of 10 for 1 µg CJCV2 + ALFQ, 0 of 10 for 3 µg CJCV2, 1 of 10 for 3 µg CJCV2 + ALFQ, 0 of 9 for 10 µg CJCV2, and 1 of 10 for 10 µg CJCV2 + ALFQ. The registry lists zero deaths in each group. These are descriptive entries; they do not, by themselves, indicate whether an event was caused by study vaccination.

Volvulus and Breast cancer are listed as top serious-event terms, each at 10.0%. The registry does not report the denominator for these percentages or identify which regimen each term occurred in. The event narratives, timing, outcome, and investigator assessment are not reported in the registry record. The percentages should therefore not be assigned to particular groups or interpreted as comparative risks.

General statistical principle: a serious event’s occurrence during a trial is not the same as evidence that a study intervention caused it. Causality requires information about timing, clinical context, and assessment, none of which is posted by group counts alone. Small group counts also make descriptive contrasts imprecise. The registry figures support reporting what was recorded, but not a causal or comparative conclusion about serious-event risk.

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

This record describes a randomized, sequential, first-in-human Phase 1 evaluation of CJCV2 at three dose levels, with and without ALFQ. It identifies short-term solicited local adverse events as the primary outcome and capsule-specific IgG measures as secondary outcomes. It also records group-level counts for serious and other adverse events. These details define the questions the trial was intended to address and provide some descriptive safety information.

The record does not include numerical results for the primary local adverse-event endpoint or for the antibody outcomes. It therefore does not show the frequency of solicited local events across the observation windows, nor does it quantify the immune response or the difference between vaccine alone and vaccine with ALFQ. The absence of those numerical results in the registry record is not evidence that an outcome did or did not occur; it means that the outcome estimate is not available in the recorded information.

The serious and other adverse-event counts can be read as descriptive summaries for the listed groups. They cannot establish whether events were caused by vaccination, and the listed serious-event terms cannot be linked to a particular regimen from the information reported. No comparative estimate or uncertainty interval is reported. Any apparent difference in observed counts should not be treated as a precise estimate of a difference in risk.

General statistical explanation: an early-phase study can characterize observed events and generate information for later research, but a small study is generally limited in its ability to estimate uncommon outcomes precisely. The registry does not report a sample-size justification or the statistical plan, so the intended precision and formal inferential goals are not reported. The record also does not provide results that establish efficacy against Campylobacter infection. The trial’s immune-response outcomes are not themselves evidence of clinical protection.

13. Why This Trial Matters Statistically

Statistically, the trial is notable for combining dose escalation with a comparison of CJCV2 alone against CJCV2 with ALFQ at each dose level. That design makes the distinction between vaccine dose and adjuvant use important when interpreting any group summaries. The sequential and sentinel description also means that the order and safety observations were part of the trial structure. However, the full decision rules and analysis plan are not reported in the registry record.

The primary outcome is based on solicited symptoms collected at defined times and graded by severity. This specificity matters: a result for the listed local symptoms would answer a focused short-term safety question, not every possible safety question. The registry also lists antibody outcomes that summarize different aspects of serum IgG response. Keeping the endpoint types distinct prevents a symptom count from being confused with an immune-response measure.

The registered enrollment is 59, and the six regimen groups have small recorded at-risk counts. General statistical principle: estimates from small groups can have substantial uncertainty, particularly for uncommon events. Reporting counts is useful for transparency, but comparison requires attention to group size, follow-up, outcome definitions, and uncertainty. The record does not report comparative estimates or confidence intervals for the primary or immune-response outcomes.

The record’s gaps are statistically consequential. Without numerical endpoint results, a defined analysis plan, missing-data handling, or multiplicity procedures, readers cannot determine the precision of the planned comparisons or how the many outcomes were prioritized. The trial is therefore informative as a description of design and recorded adverse-event counts, while its comparative outcome evidence cannot be assessed from the registry record alone.

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 trial-specific limitation for interpretation is that numerical results for the stated primary endpoint are not reported in the registry record. The same is true for the listed IgG outcomes. The registry therefore does not permit an assessment of the size or precision of the planned safety and immunogenicity comparisons. No confidence intervals, p-values, or model-based estimates are reported for those outcomes.

The reported serious-event counts are sparse, and the group sizes recorded as at risk are small. Such counts support description but provide limited precision for comparisons. The registry does not give event-level narratives, timing, relatedness assessments, or the treatment group associated with each top serious-event term. Volvulus and Breast cancer are each listed at 10.0%, but the denominator and group mapping are not reported in the registry record.

Other adverse events are recorded as affected-participant counts, but event types and severity details are not given in the recorded summary. The primary endpoint’s collection method and grading are described, but its actual results by symptom, severity, vaccination, or regimen are not reported. The registry record also does not describe how repeated observations were analyzed.

Further limitations arise from unreported methods: eligibility criteria, randomization implementation, analysis populations beyond the stated safety population, missing-data handling, multiplicity procedures, and the statistical analysis plan are not reported in the registry record. The brief summary describes double-blinding while the structured masking field says quadruple; the record does not clarify the terminology. These omissions prevent a full assessment of potential bias and the intended inferential framework.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Safety and Immunogenicity of CJCV2 With and Without ALFQ — NCT05500417.
• Registry record last updated 2026-06-15; status last verified 2025-02-07.
• Results first posted 2026-01-30.
• 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.

18. Record Summary

NCT05500417 is recorded as a completed randomized Phase 1 trial of CJCV2 with and without ALFQ for Campylobacter infection. It used a sequential, dose-escalating design with 1 microgram, 3 micrograms, and 10 micrograms of CJCV2, and planned intramuscular vaccinations on Days 1, 29, and 57. The registry reports enrollment of 59 and defines the safety population as participants who received at least one study vaccination.

The primary outcome concerns the number and percentage of participants with solicited local adverse events during specified post-vaccination periods. Secondary outcomes concern capsule-specific IgG responses. Numerical results for these endpoints and their comparative analyses are not reported in the registry record. Group-level serious and other adverse-event counts are recorded, along with zero deaths in each group, but event attribution and further clinical details are not reported. The study began on 2022-09-13, and primary completion is recorded as 2025-01-02.