This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Immunogenicity, Safety, Reactogenicity and Persistence of an Investigational Respiratory Syncytial Virus (RSV) Vaccine in Adults Aged 60 Years and Above (NCT04732871), a randomized phase 3 study. The primary outcome is Humoral Immune Response in Terms of Respiratory Syncytial Virus (RSV)-A Neutralizing Antibody Geometric Mean Titers (GMTs) at Day 1.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04732871 |
| Phase | Phase 3 |
| Condition | Respiratory Syncytial Virus Infections |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 1720 |
| Arms in the primary outcome | 3 |
| Lead sponsor | GlaxoSmithKline |
| Results posted | Yes |
2. Clinical Question
Population
Adults aged 60 years and above. The registry record describes the primary analysis population as the per-protocol humoral immunity set, including participants in the RSV annual, RSV flexible Revaccination and RSV 1dose groups with Day 1 blood samples collected for humoral immunity testing. Further eligibility details are not reported in the registry record.
Intervention
A single Day 1 dose of the RSVPreF3 OA investigational vaccine, with additional doses scheduled differently across groups. The study evaluates immune response, safety, reactogenicity and persistence, including follow-up extending to Month 60 in the revaccination groups.
Comparator
The registry record describes three randomized parallel groups: RSV annual, RSV flexible Revaccination and RSV 1dose. These are different vaccination schedules, not a placebo or unvaccinated comparison. The posted primary endpoint is reported by group at Day 1.
Primary question
What are the RSV-A neutralizing antibody geometric mean titers at Day 1 in the per-protocol humoral immunity population? The endpoint gives a baseline antibody measure. It is not a post-vaccination change or a direct comparison of the immune response caused by the different schedules.
The broader study question concerns the immune response after a single dose and after additional doses given on different schedules, alongside safety and reactogenicity. The registry summary also describes assessment of long-term persistence of immune response up to 5 years. The posted primary outcome, however, is specifically a Day 1 measurement; the later immune-response outcomes are listed among secondary outcomes.
Because the primary measurement is at Day 1, its group estimates describe the antibody levels at that time rather than the effect of vaccination. A reader looking for evidence about the response following vaccination needs to distinguish this baseline endpoint from the later timepoints. The registry record includes later immune outcomes, but the presence of an outcome listing alone does not establish what the results show.
3. Trial Design
This is a Phase 3, randomized, open-label, parallel-group, multi-country study of the RSVPreF3 OA investigational vaccine in adults aged 60 years and above. The registry record lists enrollment of 1720 and a status of active, not recruiting. The recorded study start date is 2021-02-15, and the primary completion date is 2022-06-06. These dates and status describe the registry record and do not, by themselves, establish that all study follow-up has finished.
Participants were assigned to groups with different revaccination schedules. The RSV annual group received a Day 1 dose followed by revaccination at 12 months and 24 months, with follow-up to Month 60. The RSV flexible Revaccination group received a Day 1 dose and revaccination at 24 months and 48 months, also with follow-up to Month 60. The RSV 1dose group received a Day 1 dose and was followed to Month 36; the record says participants would then be re-randomized, but the description is truncated before the subsequent schedule is fully stated. The remaining details are not reported in the registry record.
Randomization can help balance measured and unmeasured participant characteristics across groups, while the open-label design means masking was not used. The primary endpoint is measured at Day 1, before the schedules diverge through subsequent revaccination. Thus, the randomized schedule comparison is not what the posted primary endpoint estimates. The registry lists 66 outcome measures and 58 posted secondary outcomes, but the registry record lists 0 analyses. Detailed methods for allocation, analysis planning, interim analyses and sample-size justification are not reported in the registry record.
The design is best understood as a study of several vaccination schedules and their immune and safety outcomes over time, rather than as a simple comparison of vaccine against placebo. The primary endpoint provides a starting-point measure; later timepoints are needed to describe post-vaccination response and persistence.
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: Out of 1720 participants enrolled in the study, 1653 participants received the study vaccination and were included in the Exposed Set.
Overall Study
| Stage | RSV_annual | RSV_flexible Revaccination | RSV_1dose |
|---|---|---|---|
| STARTED | 993 | 329 | 331 |
| COMPLETED | 938 | 317 | 317 |
| NOT COMPLETED | 55 | 12 | 14 |
Reasons for not completing this period:
| Reason | RSV_annual | RSV_flexible Revaccination | RSV_1dose |
|---|---|---|---|
| Adverse event (AE) requiring expedited reporting | 9 | 1 | 3 |
| Lost to Follow-up | 7 | 4 | 3 |
| Consent withdrawal, not due to a serious adverse event (SAE) | 26 | 7 | 6 |
| Migrated / moved from the study area | 5 | 0 | 0 |
| Other | 1 | 0 | 1 |
| Ongoing | 6 | 0 | 1 |
| Unsolicited non-serious adverse event | 1 | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Analysis was performed on the per-protocol (PP)-humoral immunity (HI) set, which included participants from the RSV\_annual Group, the RSV\_flexible revaccination Group and the RSV\_1dose Group who had blood samples collected for testing of humoral immunity at Day 1 and for whom immunogenicity results were available for the specified assay, minus participants with protocol deviations that lead to exclusion.
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | RSV_annual | RSV_flexible Revaccination | RSV_1dose | Total |
|---|---|---|---|---|---|
| Participants analysed | 993 | 329 | 331 | 1653 | |
| Age, Continuous | YEARS | 70.1 (SD 6.6) | 69.9 (SD 6.7) | 69.9 (SD 6.7) | 70.0 (SD 6.6) |
| Sex: Female, Male: Female | Participants | 542 | 182 | 180 | 904 |
| Sex: Female, Male: Male | Participants | 451 | 147 | 151 | 749 |
| Race/Ethnicity, Customized: American Indian Or Alaska Native | Participants | 2 | 0 | 0 | 2 |
| Race/Ethnicity, Customized: Asian | Participants | 296 | 102 | 98 | 496 |
| Race/Ethnicity, Customized: Black Or African American | Participants | 19 | 8 | 6 | 33 |
| Race/Ethnicity, Customized: Other - Unspecified | Participants | 0 | 0 | 1 | 1 |
| Race/Ethnicity, Customized: White | Participants | 676 | 219 | 226 | 1121 |
6. Primary Endpoint
The registry lists the primary outcome as Humoral Immune Response in Terms of Respiratory Syncytial Virus (RSV)-A Neutralizing Antibody Geometric Mean Titers (GMTs) at Day 1, measured over At Day 1.
| Element | Registry entry |
|---|---|
| Result type | Geometric Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | Titers (ED60) |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is RSV-A neutralizing antibody geometric mean titer (GMT) at Day 1, expressed in ED60 titers. The description defines ED60 as the serum dilution giving a 60% reduction of RSV plaques compared with a control without serum. In general, a neutralization assay measures the ability of antibodies in a sample to inhibit a virus-related laboratory effect. A GMT summarizes antibody measurements on a multiplicative scale, which is commonly used for titers that can vary across a wide range.
The endpoint is reported separately for the three groups, with 95% confidence intervals. The registry identifies the analysis population as the per-protocol humoral immunity set. Its description indicates that participants had Day 1 blood samples collected for humoral immunity testing, but further details of the population description are truncated and are not reported in the registry record.
Neutralizing antibody titers are used as an immune-response measure because they characterize antibody activity in a laboratory assay. They are not themselves a direct measure of clinical protection. In this study, the Day 1 timing is especially important: the endpoint records antibody levels at the start of the vaccination schedule, not the response after vaccination, a change from baseline, or persistence over follow-up. The endpoint therefore gives context for the groups’ starting antibody measurements but cannot answer how antibody levels changed after dosing.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted Day 1 RSV-A neutralizing antibody GMT is 832.4 in the RSV annual group, with a 95% confidence interval of 763.4 to 907.7 and an analysis count of 342. In the RSV flexible Revaccination group, the GMT is 864.9, with a 95% confidence interval of 790.6 to 946.1 and an analysis count of 321. In the RSV 1dose group, the GMT is 896.8, with a 95% confidence interval of 815.9 to 985.8 and an analysis count of 319.
These estimates describe antibody titers measured at Day 1. The confidence intervals express uncertainty around each group’s estimated GMT; they are not ranges containing a specified proportion of individual participants’ titers. The intervals overlap, but overlap is not a formal test of equality or difference. The registry record does not report a primary between-group analysis, a p-value for this endpoint, or an adjusted comparison. It would therefore be inappropriate to treat the ordering of the three point estimates as evidence that the groups differed.
The measurement precedes the subsequent revaccination schedules, so it cannot show the effect of annual, flexible or single-dose scheduling. It also cannot demonstrate the magnitude of response after vaccination or the durability of that response. Those questions require post-dose outcome results and an appropriate analysis of change or between-group differences. Although several later immune outcomes are listed, the outcome listings and the Day 1 values alone do not establish their results.
The analysis counts for the primary endpoint are smaller than the overall enrollment of 1720. The endpoint is described as using a per-protocol humoral immunity population with Day 1 samples, but the record does not give enough detail to account for the difference or to assess how missing measurements were handled. The group-specific analysis counts should therefore be read as the numbers contributing to these estimates, not as the total enrollment in each randomized group.
The posted secondary outcomes include antibody measurements at later timepoints and a report of participants with potential immune-mediated disease. Those outcomes address different questions and should not be conflated with the primary baseline endpoint. The registry lists 0 analyses, so no registry-reported inferential analysis accompanies these primary GMT estimates. The estimates are descriptive as posted; they do not establish equivalence, superiority, or a causal effect of a schedule.
9. Statistical Methods Explained
The primary outcome is a geometric mean, and its uncertainty is presented as a 95% confidence interval. The following general explanations describe how these statistics are commonly interpreted; they do not establish methods that the study protocol used beyond what is stated in the registry record.
What does a geometric mean summarize?
In general, a geometric mean is calculated by transforming measurements to a logarithmic scale, averaging on that scale, and transforming the average back. This approach can be suitable for titers because antibody measurements may be multiplicative and span a broad range. The GMT is a summary of the group’s measurements; it does not say that every participant had a value near the group estimate, nor does it describe the full distribution of individual titers.
The endpoint is expressed in ED60 titers. As defined in the registry record, ED60 is the serum dilution associated with a 60% reduction of RSV plaques compared with a control without serum. This makes clear that the reported value comes from a laboratory neutralization assay. It is an assay-based measure of antibody activity, rather than a count of clinical events or a direct estimate of protection.
How should the confidence intervals be read?
In general, a confidence interval gives a range of values compatible with the observed data under the statistical procedure used to construct it. A narrower interval indicates greater precision for the group estimate, while a wider interval indicates more uncertainty. A 95% confidence interval does not mean that 95% of individual participant measurements fall inside its bounds. Nor does separate group-specific confidence intervals, by themselves, provide a formal test comparing those groups.
The primary endpoint has a separate GMT estimate and confidence interval for each group. The intervals overlap. General statistical guidance is that overlap or non-overlap between separate confidence intervals is not a substitute for a prespecified contrast and its uncertainty estimate. No primary contrast or p-value is posted in the registry record, and no conclusion about group differences should be inferred from the point estimates alone.
What does the analysis population mean?
The registry describes the primary population as the per-protocol humoral immunity set and says that it includes participants from the three groups who had blood collected at Day 1 for humoral immunity testing. In general, a per-protocol analysis population applies eligibility or adherence criteria defined for the study analysis. The complete criteria and the number of participants excluded under them are not reported in the registry record. This means that the posted analysis counts should be interpreted as the counts contributing to the reported outcome, without assuming that all randomized participants were included.
In general, an analysis restricted to participants with measurements can be affected if the availability of measurements is related to participant characteristics or outcomes. Assessing that possibility requires information about missingness and the analysis strategy. Such information is not reported in the registry record. Randomization remains relevant to the study design, but the primary Day 1 estimates are descriptive group summaries and are not a post-randomization treatment-effect contrast.
Why does timing matter?
The primary outcome is measured at Day 1, while the groups differ in their later revaccination schedules. A starting measurement cannot describe a response after the initial dose or the persistence of a response. For a post-dose comparison, the relevant results would need to be tied to later timepoints and interpreted using the analysis population and method specified for those outcomes. The registry record lists later immune measurements, but it does not report a primary endpoint analysis comparing the schedules.
General longitudinal analyses can account for repeated measurements within the same participant and can estimate change over time or differences in patterns across groups. The choice of model, handling of incomplete follow-up, and any adjustment for baseline measurements matter to those interpretations. These details are not reported in the registry record, so no particular longitudinal method should be attributed to this study based on the outcome listings alone.
What can be said about secondary comparisons?
One posted secondary outcome counts participants with any potential immune-mediated disease from first vaccination through Month 6. The reported counts are 0 of 993 in RSV annual, 1 of 329 in RSV flexible Revaccination and 0 of 331 in RSV 1dose. For flexible revaccination compared with annual, the posted risk difference is 0.003, with a 95% confidence interval from -0.003 to 0.009 and an unadjusted p-value of 0.082. For the 1dose group compared with annual, the posted risk difference is 0.0, with a 95% confidence interval from 0.0 to 0.0; no p-value is listed for that comparison.
In general, a risk difference expresses the difference between two event proportions on an absolute scale. A confidence interval describes uncertainty around that difference. The p-value for the flexible revaccination comparison is explicitly unadjusted. It should not be treated as a multiplicity-adjusted result. The registry record lists 0 reported analyses, so the status of these posted secondary calculations relative to a prespecified statistical plan is not reported.
What do the sample-size assumptions represent?
The study’s sample-size justification is not reported in the registry record. The planning illustration described for the posted results uses a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation, with the effect to detect defined as a stated fraction of the observed effect. For time-to-event outcomes, such illustrations refer to total events; for other outcomes, they refer to participants per arm. Such calculations are planning illustrations, not observed power, and should not be represented as the design rationale for this trial.
The registry record gives no basis for attributing a particular target effect, multiplicity strategy, interim analysis plan, or missing-data method to the trial. General explanations of these methods cannot fill in those study-specific details.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists 66 outcome measures and 58 posted secondary outcomes. It also lists 0 analyses. The primary endpoint is a Day 1 GMT summary, and the record does not post a primary between-group hypothesis test. It does not report a family-wise error strategy, hierarchical testing procedure, adjustment method, or other multiplicity plan. These details are not reported in the registry record, so it is not possible to determine how the many endpoints and timepoints were handled in confirmatory inference.
In general, testing many outcomes or comparisons increases the opportunity for chance findings. An unadjusted p-value reflects a single comparison without accounting for other tests. The reported unadjusted p-value for the potential immune-mediated disease comparison should therefore be read as unadjusted; it does not establish that a multiplicity procedure was or was not used elsewhere. The record does not describe a full analysis plan that would clarify the intended role of each secondary result.
Missing-data handling is also not reported in the registry record. The primary endpoint population is described as per-protocol humoral immunity and includes participants with Day 1 blood samples for testing. The endpoint estimates have group-specific analysis counts of 342, 321 and 319, while the total enrollment is 1720. The record does not give the full randomized group denominators for this endpoint, explain why measurements were unavailable, or describe imputation or sensitivity analyses. Therefore, the degree to which missing measurements could affect the estimates cannot be assessed from the posted information.
Analysis populations matter because a per-protocol population can differ from the set of all randomized participants. The available description identifies the general population type and sample collection condition, but the complete eligibility criteria are not reported in the registry record. It is also not reported whether the secondary outcomes used the same population or different analysis sets. These gaps limit assessment of selection, completeness and consistency across endpoints.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| RSV_annual | 46 | 993 | 4.6% |
| RSV_flexible Revaccination | 16 | 329 | 4.9% |
| RSV_1dose | 19 | 331 | 5.7% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| RSV_annual | 3 of 993 |
| RSV_flexible Revaccination | 1 of 329 |
| RSV_1dose | 3 of 331 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| RSV_annual | 744 of 993 |
| RSV_flexible Revaccination | 251 of 329 |
| RSV_1dose | 253 of 331 |
Most frequent serious adverse event terms
| Event term | Organ system | RSV_annual | RSV_flexible Revaccination | RSV_1dose |
|---|---|---|---|---|
| Death | General disorders | 7 of 993 | 4 of 329 | 5 of 331 |
| Atrial fibrillation | Cardiac disorders | 2 of 993 | 2 of 329 | 2 of 331 |
| Coronary artery disease | Cardiac disorders | 3 of 993 | 1 of 329 | 0 of 331 |
| Breast cancer | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 1 of 993 | 1 of 329 | 1 of 331 |
| COVID-19 | Infections and infestations | 2 of 993 | 0 of 329 | 1 of 331 |
| Syncope | Nervous system disorders | 3 of 993 | 0 of 329 | 0 of 331 |
| Myocardial infarction | Cardiac disorders | 1 of 993 | 1 of 329 | 0 of 331 |
| Lung adenocarcinoma | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 1 of 993 | 1 of 329 | 0 of 331 |
| Prostate cancer | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 2 of 993 | 0 of 329 | 0 of 331 |
| Rectal cancer | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 2 of 993 | 0 of 329 | 0 of 331 |
Most frequent non-serious adverse event terms
| Event term | Organ system | RSV_annual | RSV_flexible Revaccination | RSV_1dose |
|---|---|---|---|---|
| Injection site pain | General disorders | 595 of 993 | 201 of 329 | 200 of 331 |
| Myalgia | Musculoskeletal and connective tissue disorders | 337 of 993 | 108 of 329 | 110 of 331 |
| Fatigue | General disorders | 307 of 993 | 101 of 329 | 110 of 331 |
| Headache | Nervous system disorders | 192 of 993 | 72 of 329 | 81 of 331 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 162 of 993 | 50 of 329 | 50 of 331 |
| Injection site erythema | General disorders | 99 of 993 | 38 of 329 | 23 of 331 |
| Injection site swelling | General disorders | 77 of 993 | 33 of 329 | 17 of 331 |
| Pyrexia | General disorders | 14 of 993 | 6 of 329 | 8 of 331 |
| Injection site pruritus | General disorders | 8 of 993 | 2 of 329 | 0 of 331 |
| Cough | Respiratory, thoracic and mediastinal disorders | 5 of 993 | 3 of 329 | 2 of 331 |
Serious events with the highest arm-level rate: death (1.5%), atrial fibrillation (0.6%), coronary artery disease (0.3%), myocardial infarction (0.3%), breast cancer (0.3%).
The registry reports serious adverse events for three groups. For RSV annual, 993 participants were listed as at risk, 46 as affected, and 3 deaths were reported. For RSV flexible Revaccination, 329 were listed as at risk, 16 as affected, and 1 death was reported. For RSV 1dose, 331 were listed as at risk, 19 as affected, and 3 deaths were reported. These are group-level counts; the record excerpt does not specify the full adverse-event observation period or provide adjusted comparisons between groups.
The leading serious adverse-event terms listed in the registry are Death at 1.5%, Atrial fibrillation at 0.6%, Coronary artery disease at 0.3%, Myocardial infarction at 0.3%, Breast cancer at 0.3% and Lung adenocarcinoma at 0.3%. The denominator and exact scope for these listed percentages are not reported in the registry record. The listed terms should not be interpreted as events caused by vaccination, and the counts alone do not establish whether event rates differ across schedules.
In general, serious adverse-event counts describe events meeting a seriousness definition; they do not by themselves establish causation. Interpretation depends on exposure and follow-up time, event definitions, participant characteristics, and comparative analyses. Those details are not fully reported in the registry record, so the figures are best read as descriptive safety reporting rather than as a causal comparison.
12. What the Result Does, and Does Not, Mean
The primary result describes RSV-A neutralizing antibody GMTs at Day 1 in the per-protocol humoral immunity population. It establishes that the registry reports measurable baseline group estimates with confidence intervals. It does not establish that vaccination increased antibody levels, that one schedule produced a greater response, or that any immune response persisted over time. The endpoint timing is central: Day 1 is not a post-dose assessment.
In general, antibody measurements from a neutralization assay are laboratory measures. Their interpretation as evidence of clinical protection requires additional evidence and is not determined by a GMT alone. The registry record does not report a threshold linking these Day 1 values to clinical outcomes. The primary result should therefore be understood as an immunogenicity measurement, not a direct estimate of prevention of RSV illness.
The group estimates and their confidence intervals are descriptive. There is no posted primary contrast or p-value to support a formal claim of difference or equivalence between schedules. A visual comparison of group estimates cannot replace a prespecified inferential analysis. The randomized design is relevant to later comparisons of the schedules, but the Day 1 endpoint does not measure the effect of the schedules after the groups begin to receive different doses.
The study is designed to assess a broader set of questions, including post-dose antibody response, persistence, safety and reactogenicity. Later outcomes are listed, but the registry information does not provide a complete set of later results or the analysis plan. The 58 posted secondary outcomes should not be interpreted as if they were a single confirmatory test, and the unadjusted secondary comparison should not be given the same weight as a prespecified primary result.
The safety counts describe serious adverse events and deaths reported by group. Without complete information on observation periods, event attribution and comparative analyses, those counts cannot show that the vaccine caused or prevented events. Overall, the posted information characterizes baseline neutralizing antibody titers and provides selected secondary and safety data; it does not answer every clinical or causal question raised by the broader study objectives.
13. Why This Trial Matters Statistically
This trial is statistically notable because its primary endpoint is a baseline immune measurement within a study whose schedules diverge later. That timing creates an important distinction between describing groups at study start and estimating the effect of different revaccination strategies. A clearly labeled timepoint is essential: a Day 1 GMT cannot serve as evidence of response after vaccination or persistence over follow-up.
The study also illustrates how a randomized design and a descriptive endpoint can coexist. Randomization supports fair comparisons when outcomes are analyzed across assigned groups using suitable methods. But an endpoint measured before later schedule differences emerge is not itself an estimate of those schedule effects. Readers need to match the question, timepoint, population and analysis before interpreting a group contrast.
Precision and inference are separate. Group estimates have 95% confidence intervals, which communicate uncertainty in each GMT. They do not, on their own, establish a statistically significant difference between groups. A direct contrast and its uncertainty would be needed for that purpose. The absence of a posted primary comparison is therefore consequential, particularly when the aim is to compare schedules rather than describe starting values.
The record also demonstrates why statistical transparency matters when a study has many outcomes and follow-up timepoints. A clear analysis plan would help readers understand which outcomes were confirmatory, how multiplicity was addressed, how missing measurements were handled, and which populations contributed to each analysis. Those details are not reported in the registry record. This limits the strength of conclusions that can be drawn from secondary results, especially unadjusted comparisons.
Finally, safety counts and immune measurements answer different questions. Laboratory antibody summaries do not establish clinical outcomes, and adverse-event counts do not establish causation without contextual and comparative analysis. Keeping these distinctions clear allows the posted estimates to be interpreted for what they are: useful descriptive information, with limits on causal and clinical conclusions.
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 most important limitation for interpreting the primary endpoint is its timing. The endpoint is a Day 1 measurement, not a post-vaccination response or a change from baseline. It therefore cannot directly evaluate the different revaccination schedules. The registry lists later immune outcomes, but the record does not provide a complete analysis account for those outcomes in the information described.
The primary outcome is reported as group-specific GMTs and confidence intervals, without a posted primary comparison or p-value. This supports description of each group’s starting estimate but not a formal claim about differences between groups. The intervals overlap, and their overlap should not be used as a substitute for a direct comparison.
The population description is incomplete. It identifies a per-protocol humoral immunity set and mentions Day 1 blood collection, but the remaining criteria are truncated and are not reported in the registry record. The record does not explain the relationship between the primary analysis counts and all randomized participants, or report how missing measurements were handled. These gaps prevent a full assessment of selection and missing-data bias.
The study is open-label, and the registry does not report detailed procedures for outcome assessment or allocation implementation. It is not possible to assess from the record whether any safeguards were used to address possible effects of the unmasked design. In general, laboratory assays may be less subjective than many clinical assessments, but that general point does not fill in the study-specific procedures.
The description of the RSV 1dose group’s later follow-up is truncated after stating that participants would be re-randomized at Month 36. The subsequent schedules are not reported in the registry record. In addition, a complete multiplicity plan, sample-size justification, interim-analysis plan, and full statistical analysis plan are not reported. Serious adverse-event figures lack a fully specified observation period and event-attribution detail in the available record. These limitations constrain conclusions about later response, safety comparisons and confirmatory evidence.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Immunogenicity, Safety, Reactogenicity and Persistence of an Investigational Respiratory Syncytial Virus (RSV) Vaccine in Adults Aged 60 Years and Above — NCT04732871.
- Registry record last updated 2026-09-28; status last verified 2026-09.
- Results first posted 2023-12-21.
- 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 NCT04732871, a randomized, open-label, parallel-group Phase 3 study of RSVPreF3 OA in adults aged 60 years and above. Enrollment is listed as 1720. The study compares annual, flexible revaccination and 1dose schedules, with follow-up plans varying by group. The recorded status is active, not recruiting.
The primary outcome is RSV-A neutralizing antibody GMT at Day 1, measured in ED60 titers and reported with 95% confidence intervals. The posted group estimates are baseline summaries, not post-vaccination comparisons. Later immune outcomes and safety outcomes are also listed. The record lists 66 outcome measures, 58 posted secondary outcomes and 0 analyses.
Interpretation is limited by the baseline timing of the primary endpoint and by the absence of a posted primary between-group analysis. The complete analysis plan, missing-data methods, multiplicity approach and sample-size justification are not reported in the registry record. The available estimates and event counts are descriptive and should be interpreted within those limits.