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 A Study to Learn About How Trumenba Vaccine Shots Work Against Gonorrhea Infection in Teenagers and Young Adults in the United States. (NCT05873751), a registered phase not stated study. The primary outcome is Number of Participants With Gonococcal Infection After at Least 1 Dose of Trumenba to Determine Vaccine Effectiveness (VE).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT05873751 |
| Phase | Phase not stated |
| Condition | Gonorrhea, Chlamydia, Meningococcal Vaccines |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 1307378 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Pfizer |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns people aged 15-30 years whose records were included in a United States database. Eligibility, as described in the brief summary, required receipt of at least one dose of Trumenba and a MenACWY vaccine, or receipt of MenACWY alone. The primary outcome description refers to all eligible participants whose data were included in the retrospective study. The registry does not report further detail about participant characteristics, eligibility exclusions, or how the database population was assembled.
Intervention
The exposure cohort received at least one dose of Trumenba and MenACWY. The primary outcome title focuses on gonococcal infection after at least one dose of Trumenba. For the exposed cohort, the index date is described as the date of the last Trumenba dose, after at least one dose of MenACWY. This is an observational exposure definition, not an assignment to vaccination by the study.
Comparator
The reference cohort received at least one dose of MenACWY and no Trumenba. Its index date is described as the first date of MenACWY vaccination. The registry record states that this is not a randomized comparison and that the arms are not a like-for-like control comparison. Allocation is not stated. Differences between cohorts, including differences related to vaccination or health-care use, could therefore affect their observed outcomes.
Primary question
The primary question is how often gonococcal infection was recorded in the two vaccination cohorts during follow-up, and what vaccine effectiveness estimate was derived from their relative hazard. The endpoint counts participants with infection, considering only the first occurrence for a participant with repeated infection. The registry defines vaccine effectiveness as one minus the hazard ratio, multiplied by 100. The record does not report the hazard ratio, the effectiveness estimate, or the primary outcome counts, so the comparative result cannot be described from the registry record.
3. Trial Design
This is a retrospective cohort study using records from a database in the United States. The study description says the data had already been collected and were being studied between April and June of 2023. It describes the population as people aged 15-30 years who received Trumenba with MenACWY, or MenACWY alone. The study is marked completed. The registry lists a study start date of 2023-04-24, a primary completion date of 2024-03-31, and enrollment of 1,307,378. These registry fields do not establish how many people were in either vaccination cohort or how many contributed to the primary analysis.
The comparison is between an exposed cohort receiving Trumenba and MenACWY and a reference cohort receiving MenACWY without Trumenba. The registry explicitly characterizes the comparison as nonrandomized, says allocation is not stated, and cautions that the arms are not a like-for-like control comparison. Thus, cohort membership reflects prior vaccination rather than randomized assignment described in the record. The registry does not report a protocol for assigning vaccination, matching participants, or controlling for differences between cohorts.
The primary outcome description gives a maximum follow-up of 83.5 months, beginning 14 days after the index date and ending 31 December 2022. It also says available retrospective data were evaluated for approximately 11 months of this study. The index date differs by cohort: it is the last Trumenba dose, after at least one MenACWY dose, for the exposed cohort, and the first MenACWY date for the reference cohort. These definitions matter because follow-up time is anchored to different vaccination dates. The registry does not report further details about censoring, follow-up completeness, or the analysis model used to estimate the hazard ratio.
The listed interventions are Trumenba Vaccine and MenACWY Vaccine. Secondary outcomes include gonococcal infection after at least 2 doses of Trumenba and chlamydial infection after at least 1 dose and at least 2 doses of Trumenba. The registry record does not describe a randomized treatment trial or establish that observed cohort differences are caused by vaccination.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Exposed Cohort: Vaccinated With Trumenba + MenACWY | Non-Exposed Cohort: Vaccinated With MenACWY Only |
|---|---|---|
| STARTED | 214552 | 1092826 |
| COMPLETED | 214552 | 1092826 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: All eligible participants whose data were included in this retrospective 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.
Population: All eligible participants whose data were included in this retrospective study.
| Characteristic | Unit | Exposed Cohort: Vaccinated With Trumenba + MenACWY | Non-Exposed Cohort: Vaccinated With MenACWY Only | Total |
|---|---|---|---|---|
| Participants analysed | 214552 | 1092826 | 1307378 | |
| Age, Continuous | Years | 16.97 (SD 1.32) | 17.18 (SD 1.99) | 17.15 (SD 1.9) |
| Sex: Female, Male: Female | Participants | 109013 | 553213 | 662226 |
| Sex: Female, Male: Male | Participants | 105539 | 539613 | 645152 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
| Region of Enrollment: United States – Northeast | Participants | 36193 | 199905 | 236098 |
| Region of Enrollment: United States – South | Participants | 85947 | 390076 | 476023 |
| Region of Enrollment: United States – Midwest | Participants | 68134 | 334106 | 402240 |
| Region of Enrollment: United States – West | Participants | 23963 | 161031 | 184994 |
| Region of Enrollment: United States – Unknown | Participants | 315 | 7708 | 8023 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Gonococcal Infection After at Least 1 Dose of Trumenba to Determine Vaccine Effectiveness (VE), measured over During follow-up of maximum of 83.5 months (from 14 days after the index date up to 31 December 2022; available retrospective data evaluated for approximately 11 months of this study).
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the number of participants with gonococcal infection after at least 1 dose of Trumenba, used to determine vaccine effectiveness. It is a count of participants with the event, not a count of every infection episode: when a participant had repeated infection, only the first occurrence was counted. This rule makes the endpoint a first-event measure for participants rather than a tally of recurrent infections.
The registry defines the effectiveness calculation as one minus the hazard ratio, multiplied by 100. A hazard ratio compares the rate at which an event occurs over follow-up between cohorts, accounting for the time participants remain under observation in the analysis. In general, time-to-event measures can be useful when participants have differing follow-up durations, although their interpretation depends on how follow-up and censoring are handled. Those details are not reported in the registry record.
The described follow-up begins 14 days after the cohort-specific index date and extends to 31 December 2022, with a maximum duration of 83.5 months. The record does not report primary event counts, a hazard ratio, a confidence interval, a p-value, or a vaccine effectiveness estimate. Consequently, the endpoint definition can be explained, but the magnitude and precision of the study's primary result cannot be assessed from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies the primary outcome and the intended comparison, but it does not report the primary outcome data or its statistical estimate. Specifically, no gonococcal infection counts, hazard ratio, vaccine effectiveness estimate, confidence interval, or p-value are reported in the record. Without these quantities, the direction, magnitude, and precision of the primary comparison cannot be characterized. No conclusion about the observed difference between cohorts can be drawn from the endpoint description alone.
The effectiveness measure is defined using a hazard ratio: vaccine effectiveness is one minus that ratio, multiplied by 100. This definition explains how the investigators intended to express the comparison; it is not itself a result. The registry does not provide the hazard ratio or describe the statistical model that generated it. It also does not report enough information to examine whether the estimate reflects adjusted or unadjusted analyses, or how the analysis handled participants who stopped contributing data before the end of follow-up.
The study is retrospective and nonrandomized. The registry states that allocation is not stated and that the cohorts are not a like-for-like control comparison. In general, observational comparisons can be affected by differences between groups that are associated with both exposure and outcome. For example, differences in participant characteristics or patterns of health-care use can influence which infections are identified in records. This is a general concern for interpreting cohort comparisons, not a claim that any particular imbalance occurred in this study. The registry does not report adjustment details that would show how such concerns were addressed.
The endpoint counts only the first recorded infection per participant, even when repeated infections occurred. That choice defines what the measure captures; it does not describe the total burden of recurrent infections. The listed secondary outcomes include gonococcal infection after at least 2 doses of Trumenba and chlamydial infection after at least 1 dose and at least 2 doses. Their outcome values are also not reported in the registry record.
The record lists zero values in its adverse-event fields for both cohorts, including serious events and deaths. These registry entries should be read as reported fields, not as a substitute for a detailed safety analysis: the record does not provide definitions, ascertainment methods, follow-up coverage, or additional safety context. Overall, the available information describes the study question and endpoint but does not support interpretation of an effectiveness estimate or a detailed assessment of safety.
9. Statistical Methods Explained
The primary outcome is a participant count, with each participant counted only once for the first occurrence of gonococcal infection. The registry also states that vaccine effectiveness was calculated as one minus the hazard ratio, multiplied by 100. These two descriptions refer to different parts of the analysis: the event count defines the outcome being tracked, while the hazard ratio compares event occurrence over follow-up between cohorts. The registry does not report how the hazard ratio was estimated.
What does a hazard ratio represent?
General statistical explanation: a hazard is the instantaneous rate of an event among people who have not yet experienced it and remain under observation. A hazard ratio contrasts this rate between groups over time. It is not simply a comparison of raw event counts, because the time participants contribute to follow-up can differ. A hazard ratio also does not, by itself, describe the absolute probability of infection. Its interpretation depends on the model and assumptions used to estimate it. The registry record does not name the model, report its assumptions, or provide the estimate.
The outcome description says follow-up began 14 days after the index date and continued through 31 December 2022, with a maximum of 83.5 months. The index date was defined differently for the cohorts: the last Trumenba dose after at least one MenACWY dose for the exposed cohort, and the first MenACWY vaccination date for the reference cohort. In general, a clearly specified time origin is important for a time-to-event comparison because it determines when participants begin contributing event-free follow-up. Different index-date rules may also affect comparability if they result in cohorts being followed from different points in their vaccination history. The registry does not report analyses assessing the consequences of these definitions.
How is vaccine effectiveness defined?
General statistical explanation: expressing a hazard ratio as one minus the ratio, multiplied by 100, transforms a relative hazard comparison into a percentage-scale effectiveness measure. That transformation does not remove uncertainty in the hazard ratio. A confidence interval around the hazard ratio would ordinarily be needed to understand the range of values compatible with the data and, after transformation, the precision of the effectiveness estimate. No hazard ratio, confidence interval, or effectiveness estimate is reported in the registry record. The definition alone cannot establish the estimate's size or precision.
Why does the cohort design matter?
This is a retrospective cohort study, not a randomized comparison. The registry says allocation is not stated and identifies the arms as not being a like-for-like control comparison. General statistical explanation: in a nonrandomized study, characteristics that differ between cohorts can be associated with both exposure and outcome. Such confounding can make an observed association differ from the effect that would be seen if cohorts were otherwise comparable. Adjustment methods can sometimes address measured differences, but they cannot automatically address unmeasured or poorly measured factors. The registry record does not report covariates, adjustment methods, matching, weighting, or other approaches to confounding, so it is not possible to assess whether or how these issues were handled.
In general, time-to-event analyses also need rules for censoring: participants may stop contributing observed time for reasons other than experiencing the endpoint. If those reasons differ across cohorts or are related to infection risk, the comparison may be affected. The registry record does not report censoring rules, losses to follow-up, or how incomplete observation was handled. The maximum follow-up description does not establish that every participant was followed for the same duration.
What do the planning assumptions mean?
The registry describes sample-size illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. For time-to-event outcomes, the description says the illustration gives the total number of events using the Schoenfeld method; other illustrations give participants per arm. These are planning calculations, not observed power and not evidence that the study was designed around those assumptions. The registry does not report a sample-size justification in its own design or the values of the planning illustrations in the information available for this description. No such values can be used to infer the actual precision of the study's primary estimate.
More generally, p-values and confidence intervals answer different questions. A p-value, when reported, measures how compatible the data are with a specified null hypothesis under the analysis assumptions; it is not the probability that the null hypothesis is true. A confidence interval describes uncertainty around an estimated effect under the statistical procedure used. Neither quantity is reported for the primary outcome in the registry record. Without the estimates and their uncertainty, the statistical strength of the primary comparison cannot be evaluated.
10. Exact Estimates for Each Arm
No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.
| Arm | Participants | Events | Observed % | Clopper-Pearson 95% CI | Wilson 95% CI | Bayesian 95% credible interval |
|---|---|---|---|---|---|---|
| Exposed Cohort: Vaccinated With Trumenba + MenACWY | 214552 | 316 | 0.1% | 0.1% to 0.2% | 0.1% to 0.2% | 0.1% to 0.2% |
| Non-Exposed Cohort: Vaccinated With MenACWY Only | 1092826 | 2327 | 0.2% | 0.2% to 0.2% | 0.2% to 0.2% | 0.2% to 0.2% |
R code and output
arm <- c("Exposed Cohort: Vaccinated With Trumenba + MenACWY", "Non-Exposed Cohort: Vaccinated With MenACWY Only")
n <- c(214552, 1092826)
events <- c(316, 2327)
for (i in seq_along(n)) {
ci <- binom.test(events[i], n[i])$conf.int # Clopper-Pearson exact interval
cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i]) # Bayesian, uniform Beta(1,1) prior
wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}
ARM Exposed Cohort: Vaccinated With Trumenba + MenACWY 214552 316 0.1 0.1 0.2 0.1 0.2 0.1 0.2
ARM Non-Exposed Cohort: Vaccinated With MenACWY Only 1092826 2327 0.2 0.2 0.2 0.2 0.2 0.2 0.211. Multiplicity, Missing Data and Analysis Populations
The registry lists four outcome measures and four analyses. Alongside the primary gonococcal infection outcome after at least 1 dose of Trumenba, the listed secondary outcomes include gonococcal infection after at least 2 doses and chlamydial infection after at least 1 dose and at least 2 doses. The registry record does not report whether the analyses were designated as confirmatory or exploratory, or whether any adjustment for multiple comparisons was planned or used.
General statistical explanation: when several outcomes or analyses are considered, the chance of obtaining at least one apparently notable result can increase if each is assessed separately without accounting for the family of tests. Multiplicity procedures can define how inference is controlled across a set of comparisons. Whether such adjustment is appropriate depends on the study aims and analysis plan. Because that plan and the results are not reported, the role of multiplicity in interpreting the study cannot be assessed.
The primary outcome population is described as all eligible participants whose data were included in the retrospective study. The record does not report the analysis population in more detail, cohort-specific analyzed counts, missing-data amounts, or methods for handling missing or incomplete records. It also does not report details on outcome ascertainment, loss to follow-up, or whether the analysis excluded any eligible records. In general, missing data can affect a cohort comparison when completeness differs between groups or is related to infection risk; the registry record does not provide information to assess those possibilities.
The registry does not report interim analyses, a statistical analysis plan, or methods for handling protocol deviations. No assumptions about these procedures can be made from the study description.
12. What the Result Does, and Does Not, Mean
The study asks whether the occurrence of recorded gonococcal infection differed between a cohort that received Trumenba with MenACWY and a reference cohort that received MenACWY alone. Its primary endpoint is the number of participants with infection after at least 1 dose of Trumenba, counting only the first infection for each participant. The registry describes a hazard-ratio-based vaccine effectiveness calculation and a retrospective follow-up period.
What the registry record does not provide is the primary outcome result. The infection counts, hazard ratio, vaccine effectiveness estimate, confidence interval, and p-value are not reported. Therefore, the available record does not establish the direction or size of the observed association, or how precisely it was estimated. The endpoint's definition and study objective are not substitutes for outcome results.
Even if an association were reported, a retrospective nonrandomized comparison would not by itself establish that vaccination caused the difference. The registry identifies the arms as not being a like-for-like control comparison and says allocation is not stated. In general, differences between cohorts and differences in how infections are recorded can affect observational estimates. The record does not report sufficient adjustment or ascertainment details to evaluate these issues.
The record also lists secondary outcomes involving gonococcal and chlamydial infection after different Trumenba dose thresholds, but their results are not reported. Zero values in the adverse-event fields should not be taken as a complete safety conclusion without information about definitions, capture, and follow-up. Overall, the registry record describes a question and a design, but does not provide the results or methodological detail needed to judge the estimated effectiveness or broader clinical implications.
13. Why This Trial Matters Statistically
This study is statistically notable for using a retrospective cohort comparison to examine an outcome over time. Rather than assigning participants to vaccination groups, it compares records for people who received Trumenba with MenACWY against records for people who received MenACWY alone. That design can make use of previously collected data, but the validity of the comparison depends on the cohorts' comparability, the quality of outcome recording, and the handling of follow-up.
The endpoint is defined as first gonococcal infection per participant, while the effectiveness measure is defined through a hazard ratio. This distinction matters: a count of participants with an event and a time-to-event comparison are related but are not interchangeable summaries. Follow-up is anchored to different index dates in the two cohorts, making the chosen time origin part of the interpretation. The registry's description of a maximum follow-up of 83.5 months and a period of approximately 11 months for evaluation underscores the importance of understanding precisely which records and follow-up periods contributed to the analysis.
The registry also illustrates the boundary between a study question and an interpretable result. It identifies the intended comparison and lists secondary outcomes, yet does not report the primary estimates or their uncertainty. Without those results, statistical interpretation cannot progress from design to effect magnitude or precision. The nonrandomized design and absence of reported adjustment details further limit what can be concluded from the registry record.
These points are relevant to biostatisticians and clinical researchers assessing evidence from large health-record studies: enrollment size alone does not describe endpoint information, cohort balance, or estimate precision. The registry lists enrollment of 1,307,378, but does not report the outcome data needed to evaluate the primary comparison.
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 central limitation of the registry record is that it does not report the primary outcome counts or the estimate of vaccine effectiveness. Without the hazard ratio, confidence interval, or other statistical results, the observed association and its precision cannot be evaluated. The record likewise does not report results for the listed secondary outcomes.
The comparison is retrospective and nonrandomized, and the registry says the arms are not a like-for-like control comparison. Allocation is not stated. The record does not describe cohort characteristics, potential confounders, adjustment methods, matching, or other methods for addressing differences between groups. It is therefore not possible to assess comparability or how confounding was handled.
The endpoint uses the first infection occurrence and does not count repeated infections as separate events. This is a defined analysis choice, but it means the endpoint does not describe the total number of infection episodes. The registry does not report detailed methods for confirming or capturing infections, censoring, follow-up completeness, or handling incomplete records. The different index-date definitions may also matter to the comparison, but the record does not report sensitivity analyses or other evaluations of their effects.
The record gives a maximum follow-up of 83.5 months and says available retrospective data were evaluated for approximately 11 months of the study. It does not provide enough detail to determine the distribution of follow-up across cohorts or how the timing descriptions relate to the analytic dataset. Multiplicity procedures, missing-data methods, interim analyses, and a detailed statistical analysis plan are not reported in the registry record. Finally, the adverse-event fields are recorded as zero, but definitions and ascertainment details are not reported, limiting interpretation of those fields.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study to Learn About How Trumenba Vaccine Shots Work Against Gonorrhea Infection in Teenagers and Young Adults in the United States. — NCT05873751.
- Registry record last updated 2025-04-17; status last verified 2025-03.
- Results first posted 2025-04-17.
- 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
The registry record describes a completed retrospective cohort study using a United States database. It compares people aged 15-30 years who received at least one dose of Trumenba and MenACWY with a reference cohort that received MenACWY without Trumenba. The listed enrollment is 1,307,378. The record gives a start date of 2023-04-24 and a primary completion date of 2024-03-31.
The primary endpoint is the number of participants with gonococcal infection after at least 1 dose of Trumenba, counting only a participant's first occurrence. Vaccine effectiveness is defined as one minus the hazard ratio, multiplied by 100. The registry describes follow-up beginning 14 days after the cohort-specific index date, with a maximum of 83.5 months through 31 December 2022.
The study is nonrandomized, allocation is not stated, and the cohorts are described as not being a like-for-like control comparison. Primary and secondary outcome results, effect estimates, uncertainty measures, and detailed analysis methods are not reported in the registry record.