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 Describe the Safety of a Vaccine (Called 13vPnC) in Healthy People 18 to 49 Years of Age in India (NCT05329259), a na phase 4 study. The primary outcome is Percentage of Participants With Prompted Local Reactions Within 7 Days After Vaccination.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT05329259 |
| Phase | Phase 4 |
| Condition | Pneumococcal Disease |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 200 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Pfizer |
| Results posted | Yes |
2. Clinical Question
Population
Generally healthy adults aged 18 to 49 years in India, with no prior history of pneumococcal vaccination. The primary endpoint’s safety population is defined as participants who received any study intervention and had safety data assessed after vaccination.
Intervention
A single dose of 13-valent pneumococcal conjugate vaccine, called 13vPnC, given into the arm at the first study visit. The study was open-label, so masking was not used.
Comparator
There was no control group or randomized comparator. The study used a single group, so the registry record does not support a like-for-like comparison of vaccine and control outcomes.
Primary question
What percentage of participants had prompted local reactions, including redness, swelling, or pain at the injection site, from Day 1 through Day 7 after vaccination? The registry record identifies this endpoint but does not report its numerical result or confidence interval.
The study is framed as a description of safety in a specified population, rather than as a comparison of treatment effects. Its primary endpoint concerns reactions at the injection site during the period stated in the registry record. Because there is no comparator group, the primary question is about the frequency of recorded reactions among participants who received the vaccine and had post-vaccination safety assessment—not about whether those reactions occurred more or less often than they would have under another intervention.
The registry record lists an enrollment of 200 and describes participation over approximately one month, including two clinic visits. However, it does not report the primary endpoint estimate, the number of participants contributing data to that endpoint, or the interval estimate around it. Those omissions limit how specifically the endpoint can be interpreted.
3. Trial Design
This was a phase 4, open-label, single-arm, multicenter study in India. Its stated purpose was to describe the safety of 13vPnC in healthy adults aged 18 to 49 years. The registry record gives an enrollment of 200 and marks the study as completed. The start date is 2022-10-06, and the primary completion date is 2022-11-30.
Participants were described as generally healthy adults aged at least 18 and less than 50 years, with no prior history of pneumococcal vaccination. The study summary describes a single dose of vaccine administered into the arm at the first clinic visit, followed by a return visit after about a month. Participation was described as lasting approximately one month and involving two clinic visits.
There was one study group, and allocation to different interventions was not applicable. Masking was not used. This design can describe outcomes recorded among participants who received the vaccine, but it does not provide a concurrent control group for estimating a comparative effect. Any interpretation should therefore remain descriptive and should not treat the study as a randomized comparison.
The primary safety endpoint was the percentage of participants with prompted local reactions within 7 days after vaccination. The registry definition includes redness, swelling, and pain at the injection site, assessed from Day 1 through Day 7, with Day 1 defined as the vaccination day. The endpoint population was the safety population: participants who received any study intervention and had safety data assessed after vaccination.
The registry record lists four outcome measures, but the primary endpoint result is not reported in the record. It also lists no analyses. Details such as the exact analysis procedures, handling of missing observations, and any formal sample-size justification are not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: A total of 200 participants were enrolled and vaccinated, all participants completed the 1-month follow-up after vaccination.
Vaccination Period
| Stage | 13vPnC |
|---|---|
| STARTED | 200 |
| COMPLETED | 200 |
| NOT COMPLETED | 0 |
1-Month Follow-Up Period
| Stage | 13vPnC |
|---|---|
| STARTED | 200 |
| COMPLETED | 200 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: The safety population included all participants who received any study intervention and had safety data assessed after 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.
Population: All participants who received any study intervention and had safety data assessed after vaccination.
| Characteristic | Unit | 13vPnC |
|---|---|---|
| Participants analysed | 200 | |
| Age, Continuous | Years | 31.4 (SD 7.98) |
| Age, Continuous | Years | 29.0 (18 to 49) |
| Sex: Female, Male: Female | Participants | 92 |
| Sex: Female, Male: Male | Participants | 108 |
| Race/Ethnicity, Customized: Race_Asian | Participants | 200 |
| Race/Ethnicity, Customized: Ethnicity_Non-Hispanic/Non-Latino | Participants | 200 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants With Prompted Local Reactions Within 7 Days After Vaccination, measured over Within 7 Days After Vaccination.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | Percentage |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the percentage of participants with prompted local reactions within 7 days after vaccination. The registry description identifies redness, swelling, and pain at the injection site as the reactions assessed. Observation starts on Day 1, the day of vaccination, and continues through Day 7. The defined population includes participants who received any study intervention and had safety data assessed after vaccination.
A percentage is a descriptive way to express how often an outcome occurred in the assessed population. For a safety study, a prespecified observation period helps define which reports count toward the endpoint. Prompted assessment can focus data collection on particular symptoms, rather than relying only on participants to mention them without being asked. This is a general explanation of endpoint design; the registry record does not provide further detail about the prompts, assessment procedures, or recording rules.
Local reactions are relevant to the stated safety objective because they concern the injection site and are assessed soon after vaccination. The endpoint is not a measure of all possible safety outcomes, nor does it by itself establish whether a reaction is serious. The record identifies the measure but does not report the percentage, the number of participants with reactions, or a confidence interval. Consequently, the extent and precision of the observed primary endpoint cannot be described from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the study’s descriptive aim and identifies the primary safety outcome, but it does not report the numerical primary endpoint result. There is therefore no posted percentage of participants with prompted local reactions, no corresponding confidence interval, and no primary endpoint estimate to interpret. The record also lists zero analyses. As a result, it is not possible to assess the size or precision of the observed local-reaction frequency, or to determine how the primary endpoint was analyzed beyond its registry definition.
The study is single-arm and open-label, with no randomized comparator. This is consistent with a descriptive safety question but limits the scope of statistical interpretation. The study can be understood as intended to characterize outcomes in participants who received 13vPnC; it cannot, on its design alone, distinguish outcomes associated with vaccination from outcomes that might also occur without vaccination or under another intervention. No causal or comparative conclusion follows from the design description.
The enrollment listed in the registry is 200. The separate adverse-event summary lists 200 participants at risk for serious adverse events and zero affected, with zero deaths. It also lists 200 at risk and 1 affected in the other-event category. These are the safety figures reported in that summary. The record does not identify the event term for the single other-category entry, and no serious-event terms are listed. These figures should not be substituted for the missing primary endpoint result: the adverse-event summary and the prompted local-reaction endpoint are distinct reporting items.
For a proportion, a confidence interval would communicate uncertainty around the estimated frequency. General statistical interpretation: a narrow interval indicates greater precision than a wide interval, while the estimate itself describes the observed frequency in the analyzed population. Neither an estimate nor an interval is reported for the primary endpoint, so that precision cannot be evaluated. The risk-set counts in the adverse-event summary do not supply a confidence interval either.
The registry record marks the study completed and gives dates from 2022-10-06 through the primary completion date of 2022-11-30. Completion status describes the registry status; it does not fill in the missing numerical endpoint results. Important analysis details—including missing-data handling and any multiplicity procedure—are not reported in the registry record. Conclusions should therefore stay close to what is explicitly recorded: the design, the defined endpoint, and the adverse-event counts, while recognizing that the primary endpoint’s outcome estimate is unavailable.
Any planning illustration associated with the reported results is not observed power. The stated illustration uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. Those assumptions describe a planning calculation, not this single-arm study’s design or a result from its participants. The record does not report the study’s own sample-size justification.
9. Statistical Methods Explained
What does a percentage endpoint describe?
For a binary outcome such as whether a participant had a specified reaction during a defined period, a percentage describes the share of assessed participants meeting that endpoint. It is a summary of occurrence in the population used for analysis. In this study, the registry defines the endpoint as prompted local reactions within 7 days after vaccination and defines the safety population by receipt of intervention and post-vaccination safety assessment.
General statistical explanation: the numerator is the number of participants meeting the endpoint, while the denominator is the number assessed for that endpoint. The registry record does not report either count for the primary outcome, and it does not report the percentage. The adverse-event risk-set counts are not a substitute for these missing primary endpoint details because they refer to separate adverse-event summaries.
What would a confidence interval add?
The endpoint title specifies a 95% confidence interval as its dispersion measure, but no interval limits are reported. General statistical explanation: a confidence interval presents a range of values compatible with the observed data under a stated statistical method. It helps readers judge the precision of an estimate; it does not remove uncertainty or establish that a value is clinically important. The interval’s width depends on factors including the amount of information in the data and the variability of the outcome.
Without the primary estimate and its interval, readers cannot tell how precisely the local-reaction frequency was measured. It would be inappropriate to infer the interval from the enrollment or from the adverse-event counts. The registry record does not state the confidence-interval calculation method.
Why does the single-arm design matter?
A single-arm study observes outcomes in one intervention group. General statistical explanation: it can estimate the frequency of recorded outcomes in that group, but without a concurrent comparison group it cannot directly estimate a between-group difference. This matters when interpreting events that may occur for reasons other than the intervention. The open-label design also means masking was absent, as stated in the record. The record does not describe additional procedures intended to reduce assessment or reporting bias.
The study’s stated objective is descriptive safety assessment, so the design should be interpreted in that context. It does not support a randomized treatment comparison. No alternative comparator or allocation procedure is reported.
What does the registry report about analysis?
The registry record lists four outcome measures and zero analyses. For the primary endpoint, it gives the measure, time frame, reaction types, and safety-population definition, but does not report a numerical result. The statistical analysis plan, including the exact method used to calculate the endpoint and its confidence interval, is not reported in the registry record. Neither are details about covariate adjustment, subgroup analysis, or interim analysis.
General statistical explanation: a prespecified analysis plan can clarify how outcomes are defined and how incomplete observations are handled. Without those details, readers should not assume a particular method. The registry’s endpoint definition provides some boundaries for interpretation, but it does not establish all analysis choices.
How should planning calculations be separated from results?
The stated sample-size assumptions describe a planning illustration computed from an observed effect, not the trial’s own design. The illustration assumes a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. For time-to-event tables, the stated convention is a total event count, while other planning tables use participants per arm. These conventions do not change the fact that the clinical study itself is recorded as single-arm.
General statistical explanation: power is a planning concept tied to a specified design, effect, and analysis. A planning illustration based on an observed effect should not be described as observed power or as evidence that a study had a particular chance of finding an effect. No numerical planning outputs are necessary to interpret the registry’s actual design, and the registry record does not report its own sample-size justification.
Why can over-dispersion matter in general?
General statistical explanation: over-dispersion occurs when the variation in count data is greater than a statistical model expects. If a model does not account for that extra variation, uncertainty estimates can be too small and inferential conclusions can appear more precise than warranted. The registry record does not identify a count model or report an over-dispersion assessment for this study. The primary endpoint is described as a percentage, and no model-based analysis details are reported. Over-dispersion is therefore a general statistical consideration, not a reported feature of this analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists four outcome measures, but it does not report the full results for those measures in the information available for interpretation. It lists zero analyses. No multiplicity adjustment, hierarchy of endpoints, or strategy for controlling the chance of false-positive findings is reported in the registry record. General statistical explanation: when several outcomes are tested, multiplicity can increase the chance that at least one appears statistically notable by chance; an analysis plan may address that issue. No such plan should be presumed.
The record does not report how missing safety observations were handled, whether any participants lacked endpoint data, or whether the analysis used imputation or another approach. The primary endpoint population is defined as those who received any study intervention and had safety data assessed after vaccination. This definition indicates who belongs in the safety population, but does not say how participants without a complete reaction assessment were treated.
The adverse-event summary provides risk-set counts, but these do not establish the number contributing data to the primary endpoint. The registry record also does not report a participant flow for the endpoint or explain exclusions from its analysis population. Accordingly, the listed enrollment of 200 should not automatically be treated as the denominator for the primary endpoint.
General statistical explanation: missingness can affect a descriptive estimate if the participants with observed data differ systematically from those without observed data. Without counts and handling rules, the direction or size of any such effect cannot be assessed. The registry record does not report an interim-analysis plan, stopping rule, or sensitivity analysis.
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 |
|---|---|---|---|
| 13vPnC | 0 | 200 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| 13vPnC | 0 of 200 |
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 |
|---|---|
| 13vPnC | 1 of 200 |
Most frequent non-serious adverse event terms
| Event term | Organ system | 13vPnC |
|---|---|---|
| Varicella | Infections and infestations | 1 of 200 |
The adverse-event summary lists 200 participants at risk for serious adverse events, with zero affected, and zero deaths. It separately lists 200 participants at risk and 1 affected in the other-event category. No top serious-event terms are listed in the registry record.
These figures describe the entries in the adverse-event summary; they do not provide the missing numerical result for the primary endpoint of prompted local reactions. The record does not identify the event term represented by the single other-category entry, so its nature cannot be described from the registry record. Nor does the absence of listed serious-event terms provide detail about event types beyond the summary counts.
General statistical explanation: a count of zero observed events is a statement about the recorded data in the stated risk set, not proof that an event cannot occur. The precision of a rate estimate depends on the amount and quality of the data, and no confidence interval for these adverse-event counts is reported. These figures should be read as descriptive safety information, not as a comparison with another group.
12. What the Result Does, and Does Not, Mean
The registry record supports a clear description of the study’s aim and structure: a phase 4, open-label, single-arm, multicenter assessment of 13vPnC in healthy adults aged 18 to 49 years in India. It specifies a primary endpoint focused on prompted local reactions within 7 days after vaccination and defines the safety population. It also reports adverse-event risk-set counts, including zero participants affected by serious adverse events and zero deaths in the listed group.
However, the record does not report the numerical result for the primary endpoint or its confidence interval. It is therefore not possible to state how common the prompted local reactions were in the assessed population or how precisely that frequency was estimated. The registry record also does not give the event term for the single participant in the other-event category. These gaps constrain interpretation of the posted safety information.
The single-arm design means there is no concurrent control group for comparison. The study can be viewed as describing outcomes recorded among participants who received 13vPnC, but the design does not establish how those outcomes compare with outcomes under another intervention or without vaccination. No comparative effect should be inferred from the stated design.
General statistical explanation: estimates describe observed data, while confidence intervals communicate uncertainty around estimates. Both are important for understanding a safety frequency. In this record, the primary estimate and interval are not reported, so neither the magnitude nor the precision of that endpoint can be assessed. The listed adverse-event counts are informative as counts, but they do not answer the primary endpoint question.
The record does not report the detailed statistical analysis plan, missing-data procedures, multiplicity handling, or study-specific sample-size justification. These omissions do not alter the design details, but they limit assessment of how the outcomes were processed and how complete the endpoint data were. The result is a registry description that supports cautious, descriptive reading rather than a broad claim about comparative safety.
13. Why This Trial Matters Statistically
This study matters statistically because it illustrates the difference between a well-defined safety question and a fully interpretable estimate. The registry record identifies the population, intervention, observation period, reaction types, and safety-population definition for the primary endpoint. Those elements help specify what the endpoint is intended to measure. Yet without the reported percentage and confidence interval, readers cannot evaluate the observed frequency or its precision.
The design also makes clear why study purpose and design must be read together. A single-arm study can describe events recorded among participants receiving an intervention, but it does not create a randomized comparison. The absence of a comparator is not a flaw relative to a purely descriptive objective, but it limits the conclusions that can be drawn about relative event rates or causal effects.
The adverse-event summary gives concrete descriptive counts: zero of 200 at risk affected by serious adverse events, zero deaths, and 1 of 200 affected in the other-event category. These figures have a distinct role from the primary local-reaction endpoint, whose numerical result is not reported. Keeping separate outcomes separate prevents one safety summary from being mistaken for another.
Finally, the record highlights the importance of transparent analysis reporting. Details on missing data, confidence-interval methods, multiplicity, and the study’s own sample-size justification are not reported in the registry record. Such information helps readers assess precision and the limits of inference. The available record permits a focused account of design and reported counts, while leaving the primary endpoint’s actual result unresolved.
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 interpretation is that the numerical result for the primary endpoint is not reported in the registry record. The primary endpoint’s confidence interval is also absent. Although the registry defines the reaction types, observation window, and safety population, it does not report the number of participants with a local reaction or the number contributing primary endpoint data.
The study has one group and no randomized comparator. As a result, the posted data cannot establish a comparative frequency of events. The open-label design means masking was not used; the registry record does not describe additional steps to limit possible influence on symptom reporting or assessment. These features are especially relevant when the outcome depends on participant-reported or prompted symptoms, although the specific assessment procedures are not reported.
The registry record lists four outcome measures but does not provide numerical results for the primary endpoint in the material described. It lists zero analyses and does not report the analysis plan, missing-data approach, multiplicity strategy, subgroup procedures, or interim analyses. The study’s own sample-size justification is not reported. The enrollment figure does not establish the primary endpoint denominator, because the endpoint population is defined separately and its analyzed count is not stated.
The adverse-event summary lists 200 participants at risk for serious events and 200 at risk in the other-event category, but does not identify the event term for the single other-category entry. No confidence intervals are reported for these counts. These limitations constrain interpretation to the recorded study design and adverse-event summaries.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study to Describe the Safety of a Vaccine (Called 13vPnC) in Healthy People 18 to 49 Years of Age in India — NCT05329259.
- Registry record last updated 2024-04-26; status last verified 2023-11.
- Results first posted 2024-04-26.
- 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 NCT05329259 as a completed phase 4, open-label, single-arm, multicenter study of 13vPnC in healthy adults aged 18 to 49 years in India. Enrollment is listed as 200. The study summary describes a single dose and two clinic visits over approximately one month.
The primary endpoint is the percentage of participants with prompted local reactions within 7 days after vaccination, including redness, swelling, and pain at the injection site. Its numerical result and confidence interval are not reported in the registry record. The record lists zero analyses.
The adverse-event summary lists 200 at risk and zero affected for serious adverse events, zero deaths, and 1 affected among 200 at risk in the other-event category. No top serious-event terms are listed. Details of the analysis plan, missing-data handling, multiplicity, and study-specific sample-size justification are not reported in the registry record.