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 Study Evaluating 13-valent Pneumococcal Conjugate Vaccine in Healthy Japanese Infants (NCT00574795), a non-randomized phase 3 study. The primary outcome is Percentage of Participants Achieving Antibody Level ≥ 0.35 μg/mL in the 13vPnC Group After the 3-Dose Infant Series.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00574795 |
| Phase | Phase 3 |
| Condition | Vaccines, Pneumococcal Conjugate Vaccine |
| Allocation | Non-Randomized |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 193 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Wyeth is now a wholly owned subsidiary of Pfizer |
| Results posted | Yes |
2. Clinical Question
Population
Healthy infants of Japanese descent. The study enrolled 193 participants. The primary immunogenicity outcome applies to an evaluable population defined as participants with valid and determinate assay results and no other major protocol violations.
Intervention
The biological intervention was 13vPnC, a 13-valent pneumococcal conjugate vaccine. The primary endpoint was assessed one month after the 3-dose infant series, at 7 months of age.
Comparator
No concurrent comparator group is identified. The study is listed as non-randomized, open-label, and single-group, so its results do not constitute a randomized comparison between treatments.
Primary question
What percentage of evaluable participants achieved the WHO-predefined antibody threshold ≥ 0.35 μg/mL for each of the 7 common pneumococcal serotypes and 6 additional serotypes specific to 13vPnC after the infant series?
The central question is descriptive: how often did participants meet the stated antibody threshold for the individual serotypes at the specified assessment? It is not a question about the difference between vaccine and control groups, because no control group is identified in the registry record. The primary outcome is framed as a percentage, with a corresponding 95% confidence interval for each serotype.
The record also lists secondary immunogenicity outcomes: geometric mean antibody concentrations after the 3-dose infant series and after the toddler dose, and the percentage achieving the antibody threshold after the toddler dose. These are additional measures of antibody response at later or distinct assessment points. Numerical results for the primary and secondary immunogenicity outcomes are not reported in the registry record, so the stated questions can be described, but their answers cannot be quantified from the record.
3. Trial Design
This was a Phase 3, open-label trial with non-randomized allocation and a single-group model. The intervention was 13vPnC. The registry lists an enrollment of 193 and describes the participants as healthy infants of Japanese descent. The trial is marked completed. Its recorded start was 2007-09 and its primary completion was 2008-08.
These design features define what the study can address. A single-group study can describe antibody measurements and adverse-event counts observed among participants receiving the intervention. Because no concurrent control group is identified, the design does not provide a like-for-like estimate of how those outcomes would differ under another intervention or no intervention. Non-randomized allocation also means there is no randomized assignment process to balance participant characteristics across comparison groups. In this record, there is no such comparison group in the first place.
Open-label means the study is not listed as masked. The registry record does not report further details about who knew the assigned intervention or how outcome assessment was conducted. The record identifies the intervention and assessment timing, but does not report a fuller schedule of visits, dosing details, or procedures beyond the infant series and toddler-dose outcomes named in the registered measures.
The primary outcome concerns antibody concentrations one month after the 3-dose infant series, at 7 months of age. It is defined for an evaluable immunogenicity population with valid and determinate assay results and no other major protocol violations. The registry also lists outcomes after the toddler dose, but their assessment timing is not specified in the registry record recorded. The record identifies six outcome measures and no analysis records. It does not report a statistical analysis plan, sample-size justification, interim analyses, or a randomized control comparison.
The study is registered under vaccines and pneumococcal conjugate vaccine. The sponsor is listed as Wyeth, described in the record as now a wholly owned subsidiary of Pfizer. These details identify the registry entry and its general setting; they do not add information about the numerical immunogenicity results, which 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: Participants were enrolled into the study according to inclusion/exclusion criteria without a screening period.
Infant Series
| Stage | 13vPnC |
|---|---|
| STARTED | 193 |
| Vaccinated Dose 1 | 193 |
| Vaccinated Dose 2 | 190 |
| Vaccinated Dose 3 | 190 |
| COMPLETED | 188 |
| NOT COMPLETED | 5 |
Reasons for not completing this period:
| Reason | 13vPnC |
|---|---|
| Withdrawal by Subject | 2 |
| Protocol Violation | 2 |
| Adverse Event | 1 |
After Infant Series
| Stage | 13vPnC |
|---|---|
| STARTED | 188 |
| COMPLETED | 185 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | 13vPnC |
|---|---|
| Withdrawal by Subject | 1 |
| Adverse Event | 2 |
Toddler Dose
| Stage | 13vPnC |
|---|---|
| STARTED | 185 |
| COMPLETED | 184 |
| NOT COMPLETED | 1 |
Reasons for not completing this period:
| Reason | 13vPnC |
|---|---|
| Withdrawal by Subject | 1 |
Analysis population for the primary outcome, as defined in the registry: Evaluable immunogenicity population had valid and determinate assay results and had no other major protocol violations.
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 | 13vPnC |
|---|---|---|
| Participants analysed | 193 | |
| Age Continuous | months | 3.7 (SD 1.5) |
| Sex: Female, Male: Female | Participants | 93 |
| Sex: Female, Male: Male | Participants | 100 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants Achieving Antibody Level ≥ 0.35 μg/mL in the 13vPnC Group After the 3-Dose Infant Series, measured over one month after 3-dose infant series (at 7 months of age).
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | percentage of participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the percentage of participants achieving an antibody level ≥ 0.35 μg/mL one month after the 3-dose infant series, at 7 months of age. The threshold is identified as a World Health Organization predefined antibody threshold. The endpoint is reported separately for 7 common pneumococcal serotypes—serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F—and 6 additional serotypes specific to 13vPnC—serotypes 1, 3, 5, 6A, 7F, and 19A.
This is a binary-threshold outcome at the participant level: each assay result is classified according to whether it reaches the stated threshold, and the percentage describes the share meeting that criterion. The endpoint therefore presents the proportion above a defined concentration rather than the full distribution of antibody concentrations. The registry specifies corresponding 95% confidence intervals, which are intended to convey uncertainty around each estimated percentage.
A threshold-based percentage is useful for expressing how many participants meet a predefined benchmark, while the listed geometric mean concentration outcomes retain information about antibody levels on a different scale. Neither measure alone describes every feature of the underlying response distribution. The registry record defines the endpoint and analysis population but does not report the observed percentages, confidence interval limits, or serotype-specific results. It is therefore not possible to assess the size or precision of the observed response from this record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record sets out a clear primary immunogenicity measure: the percentage of evaluable participants reaching ≥ 0.35 μg/mL for each of 13 serotypes one month after the infant series. It also specifies 95% confidence intervals. However, the numerical estimates and interval limits are not reported in the registry record. The primary endpoint’s observed results therefore cannot be interpreted quantitatively from this entry. There is no basis in the record for describing which serotypes had higher or lower percentages, or how precise any estimate was.
The study’s single-group design is central to interpretation. The registry does not identify a concurrent control arm, and the listed allocation is non-randomized. Consequently, any antibody measurements or safety counts are descriptive observations in the study group. They are not estimates of a between-group treatment effect. A response observed after vaccination cannot, from this design alone, be contrasted with what would have occurred in a comparable control group. This is a design limitation, not evidence for or against a particular outcome.
The safety entries report serious adverse events across three named periods: 9 of 193 participants in the 13vPnC Infant Series group, 14 of 193 in the 13vPnC Post-Infant Series group, and 1 of 185 in the 13vPnC Toddler Dose group. Other adverse events are also counted in each period: 192 of 193, 19 of 193, and 171 of 185, respectively. These counts should be read within their separate registry group labels. The record does not establish that the periods represent independent sets of participants, so the counts should not be added to create a participant total. Nor does a count alone describe event duration, severity beyond the serious classification, or causal attribution.
The registry lists several serious-event terms with percentages, including Bronchiolitis, Febrile convulsion, Pertussis, Pneumonia, and Pneumonia respiratory syncytial viral at 1.0% each, and Asthma at 0.5%. The denominators and exposure windows corresponding to these listed percentages are not reported in the registry record. The death counts are also not reported in the registry record.
Overall, the entry describes the design, endpoint definition, analysis population, and selected safety counts, but it does not include the numerical primary immunogenicity results. The evidence available from this record supports a description of what was planned to be measured and some reported safety counts, not a quantified assessment of antibody responses or a comparative conclusion.
9. Statistical Methods Explained
What does the primary percentage represent?
The primary endpoint classifies assay results relative to the threshold ≥ 0.35 μg/mL. For each serotype, the percentage is the share of participants in the relevant analysis population whose measured antibody level reaches that threshold. In general, a percentage of this kind is a proportion: it condenses individual yes-or-no classifications into one summary. It does not show how far above or below the threshold individual results lie, nor does it describe the full spread of measured concentrations.
The endpoint is assessed separately for 7 common serotypes and 6 additional serotypes specific to 13vPnC. Keeping the serotypes separate matters because an overall percentage across serotypes would answer a different question from the listed endpoint. No combined, pooled, or averaged primary result is reported in the registry record.
How should the confidence intervals be understood?
In general, a confidence interval expresses statistical uncertainty around an estimate. For a percentage, its width depends on factors such as the amount of information in the sample and the observed distribution of classifications. A narrower interval indicates greater precision under the method used to construct it; a wider interval indicates less precision. A confidence interval is not a guarantee that the true value lies within its particular limits, and it does not resolve limitations in study design.
The registry specifies 95% confidence intervals for the serotype-specific percentages, but it does not report the interval limits or the method used to calculate them. No specific interval method should therefore be attributed to this analysis. Since the numerical estimates and intervals are not reported in the registry record, readers cannot assess their precision or compare their uncertainty across serotypes.
What do the geometric mean outcomes add?
The secondary outcomes include geometric mean antibody concentration after the 3-dose infant series and after the toddler dose. In general, a geometric mean summarizes measurements using their logarithmic scale and then expresses the average back on the original concentration scale. This type of summary can be useful for positive concentration measurements that vary multiplicatively. It is distinct from the threshold percentage: the geometric mean summarizes measured levels, whereas the percentage records how many participants crossed a specified cutoff. The numerical geometric means, their uncertainty estimates, and any method used to calculate them are not reported in the registry record.
Who is included in the primary analysis?
The registry defines the evaluable immunogenicity population as participants with valid and determinate assay results and no other major protocol violations. This definition indicates that the primary immunogenicity analysis is not necessarily based on every enrolled participant. The record does not state how many participants met this definition, how many were excluded, or why any individual assay results were unavailable or indeterminate. It also does not describe a separate intention-to-treat analysis or other analysis populations.
In general, an evaluable-population analysis can focus on participants with interpretable measurements, but excluding participants may affect how representative the analyzed group is of everyone enrolled. The direction or size of any such effect cannot be determined without information about exclusions and missing results. The record’s population definition alone is not enough to assess this issue.
What can the design support?
With a single group and no randomized comparator, the primary percentages describe observed antibody-threshold attainment within the study population. They do not estimate a randomized difference between groups. In general, a comparison group can help distinguish changes associated with an intervention from changes that may occur for other reasons; without one, that comparative separation is unavailable. The open-label designation also means the record does not identify a masking procedure. The registry does not report enough detail to assess whether knowledge of the intervention could have affected any aspect of outcome measurement.
The registry lists six outcome measures and no analysis records. It does not report a statistical analysis plan, the methods for handling multiple outcomes, or the method used for the confidence intervals. These omissions mean the analysis choices cannot be reconstructed from this record. They should not be inferred from the endpoint descriptions alone.
How should planning illustrations be read?
In general, a sample-size planning illustration based on an observed effect is a hypothetical design calculation, not an observed trial result and not observed power. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. The assumptions describe a hypothetical two-arm comparison even though this trial is listed as single-group and has no like-for-like control comparison. Such planning figures, when available, would not be the trial’s own sample-size justification. That justification is not reported in the registry record, and no numerical planning results are reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists six outcome measures, including a primary immunogenicity outcome and secondary outcomes concerning geometric mean antibody concentrations and threshold attainment. The primary outcome itself is assessed across 13 serotypes. Multiple outcomes or serotype-specific assessments create multiple opportunities to summarize or test results. In general, multiplicity matters because interpreting many estimates or tests together can increase the chance of a seemingly notable result arising by chance. The registry record does not report a multiplicity adjustment, a testing hierarchy, or a plan identifying which comparisons would be confirmatory.
The record specifies the evaluable immunogenicity population: participants had to have valid and determinate assay results and no other major protocol violations. It does not report the number meeting that definition, the number excluded, the amount or pattern of missing assay data, or how indeterminate results were handled. It also does not report an imputation method or a sensitivity analysis for missing data. Thus the consequences of missing or excluded measurements cannot be assessed from the record.
The record lists no analysis records. It does not report an analysis plan, a method for calculating confidence intervals, or additional analysis populations. These details are important for understanding how registered outcomes were estimated and how robust the results might be to analysis choices. Their absence does not establish that no such procedures were used; it means they are not reported in the registry record.
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 Infant Series | 9 | 193 | 4.7% |
| 13vPnC Post-Infant Series | 14 | 193 | 7.3% |
| 13vPnC Toddler Dose | 1 | 185 | 0.5% |
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 Infant Series | 192 of 193 |
| 13vPnC Post-Infant Series | 19 of 193 |
| 13vPnC Toddler Dose | 171 of 185 |
Most frequent serious adverse event terms
| Event term | Organ system | 13vPnC Infant Series | 13vPnC Post-Infant Series | 13vPnC Toddler Dose |
|---|---|---|---|---|
| Pneumonia respiratory syncytial viral | Infections and infestations | 2 of 193 | 1 of 193 | 0 of 185 |
| Asthma | Respiratory, thoracic and mediastinal disorders | 0 of 193 | 1 of 193 | 1 of 185 |
| Bronchiolitis | Infections and infestations | 2 of 193 | 0 of 193 | 0 of 185 |
| Exanthema subitum | Infections and infestations | 1 of 193 | 1 of 193 | 0 of 185 |
| Febrile convulsion | Nervous system disorders | 0 of 193 | 2 of 193 | 0 of 185 |
| Gastroenteritis | Infections and infestations | 1 of 193 | 1 of 193 | 0 of 185 |
| Pertussis | Infections and infestations | 0 of 193 | 2 of 193 | 0 of 185 |
| Pneumonia | Infections and infestations | 0 of 193 | 2 of 193 | 0 of 185 |
| Adenovirus infection | Infections and infestations | 1 of 193 | 0 of 193 | 0 of 185 |
| Bronchitis | Infections and infestations | 0 of 193 | 1 of 193 | 0 of 185 |
Most frequent non-serious adverse event terms
| Event term | Organ system | 13vPnC Infant Series | 13vPnC Post-Infant Series | 13vPnC Toddler Dose |
|---|---|---|---|---|
| Injection site erythema | General disorders | 163 of 193 | 0 of 193 | 115 of 185 |
| Erythema (Any) | Skin and subcutaneous tissue disorders | 138 of 186 | 0 of 193 | 113 of 166 |
| Injection site swelling | General disorders | 121 of 193 | 0 of 193 | 94 of 185 |
| Erythema (Mild) | Skin and subcutaneous tissue disorders | 125 of 183 | 0 of 193 | 84 of 156 |
| Pyrexia | General disorders | 108 of 193 | 0 of 193 | 80 of 185 |
| Induration (Any) | Skin and subcutaneous tissue disorders | 83 of 176 | 0 of 193 | 93 of 163 |
| Induration(Mild) | Skin and subcutaneous tissue disorders | 80 of 174 | 0 of 193 | 68 of 154 |
| Hypersomnia | Nervous system disorders | 101 of 193 | 0 of 193 | 34 of 185 |
| Erythema (Any) | Skin and subcutaneous tissue disorders | 134 of 180 | 0 of 193 | 0 of 185 |
| Any fever (≥37.5°C) | General disorders | 56 of 170 | 0 of 193 | 76 of 150 |
Serious events with the highest arm-level rate: bronchiolitis (1.0%), febrile convulsion (1.0%), pertussis (1.0%), pneumonia (1.0%), pneumonia respiratory syncytial viral (1.0%).
The registry reports serious adverse-event counts for three named periods. The 13vPnC Infant Series group has 9 serious adverse events among 193 at risk; the 13vPnC Post-Infant Series group has 14 among 193; and the 13vPnC Toddler Dose group has 1 among 185. These are counts within the registry’s period-specific categories. The registry does not report whether the same participant could contribute events in more than one period, so the counts should not be combined as though they described distinct people.
The listed serious-event terms include Bronchiolitis, Febrile convulsion, Pertussis, Pneumonia, and Pneumonia respiratory syncytial viral at 1.0% each, and Asthma at 0.5%. The denominator and exposure window for those term-specific percentages are not reported in the registry record. The record also gives counts for other adverse events, but these are separate from the serious-event counts and should not be treated as interchangeable categories.
Adverse-event counts describe events recorded in the study; by themselves, they do not establish that the intervention caused an event. There is no concurrent control group for a comparative safety estimate. Death counts are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The registry record is useful for identifying the study’s population, intervention, design, endpoint definition, and some safety counts. It makes clear that the primary immunogenicity question concerned the percentage reaching ≥ 0.35 μg/mL for each of 13 serotypes one month after the 3-dose infant series. It also defines the evaluable population and indicates that 95% confidence intervals were intended for the serotype-specific percentages.
Those endpoint definitions are not the same as endpoint results. The numerical percentages and confidence interval limits are not reported in the registry record, so the record does not establish how many participants met the threshold for any serotype or how precisely those percentages were estimated. The listed secondary geometric mean concentration outcomes likewise have no numerical results reported in the registry record. A reader therefore cannot use this entry to quantify the observed immunogenicity outcomes.
The safety information is descriptive. Counts are reported for serious and other adverse events across named study periods, and a set of serious-event terms is listed with percentages. These observations do not, on their own, identify whether events were caused by the intervention. The study is single-group, non-randomized, and open-label, with no concurrent comparator identified. It therefore cannot supply a like-for-like estimate of differences in safety or immunogenicity between treatment groups.
In general, conclusions should be matched to the design and the information actually reported. Here, the design supports describing the registered questions and the listed counts, but the absent immunogenicity estimates prevent a numerical reading of the primary endpoint. The absent analysis details also limit assessment of how results were calculated, how missing measurements were addressed, and how multiple outcomes were handled. The record should not be treated as a complete account of every analysis or as evidence for a comparative conclusion.
13. Why This Trial Matters Statistically
This trial is statistically notable for the contrast between a clearly specified immunogenicity endpoint and the limited numerical results reported in the registry record. The primary question is expressed as a serotype-specific percentage reaching a predefined antibody threshold, with corresponding 95% confidence intervals. The analysis population is also defined. These elements help clarify what the endpoint was intended to measure, even though the actual estimates and interval limits are not reported.
The design makes the scope of interpretation especially important. A single-group, non-randomized study can document measurements and event counts among participants, but it does not create a randomized control comparison. Descriptive percentages should not be read as estimates of between-group differences. This distinction is essential when considering both immunogenicity and safety.
The record also illustrates why a defined threshold and a concentration summary answer different statistical questions. The threshold percentage describes how often participants met a criterion, while geometric mean concentration summarizes measured antibody levels on a different scale. The registered outcomes include both types of summaries, but numerical results for either are not reported in the registry record. This leaves the intended breadth of measurement visible without allowing assessment of the observed levels or their precision.
Finally, the entry identifies six outcome measures but does not report analysis records, multiplicity handling, missing-data procedures, or the confidence-interval method. Those details influence how estimates should be interpreted. Their absence is a reason to keep conclusions narrow: the record establishes the study design and outcome definitions, while key results and analysis details remain unreported.
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 primary limitation for statistical interpretation is that the registry record does not report numerical results for the primary antibody-threshold endpoint. Although the endpoint definition names the assessment time, population, threshold, serotypes, and intended confidence intervals, the corresponding percentages and interval limits are absent. The secondary immunogenicity outcomes also have no numerical results reported in the registry record. As a result, the immunogenicity findings cannot be quantified or assessed for precision from this entry.
The design is another specific limitation. The trial is single-group, non-randomized, and open-label, with no concurrent comparator identified. Observed measures can be described within the study group, but the record does not support a randomized between-group contrast. The lack of a comparator also limits comparative interpretation of the safety counts.
The primary endpoint applies to an evaluable immunogenicity population rather than an explicitly stated full enrolled population. The record does not report the number of participants in that analysis set, exclusions, missing assay results, or handling of indeterminate measurements. It is therefore not possible to judge how the analyzed population relates to the enrollment of 193 participants.
Further analysis details are not reported in the registry record, including the confidence-interval method, multiplicity approach, and a statistical analysis plan. The serious-event terms are accompanied by percentages, but their denominators and exposure windows are not reported. Death counts are not reported in the registry record. These gaps constrain interpretation of both efficacy-related measurements and safety information without implying that unreported procedures or outcomes were absent from the study itself.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study Evaluating 13-valent Pneumococcal Conjugate Vaccine in Healthy Japanese Infants — NCT00574795.
- Registry record last updated 2012-08-08; status last verified 2012-06.
- Results first posted 2012-08-08.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT00574795 is a completed Phase 3, open-label, non-randomized, single-group study of 13vPnC in healthy Japanese infants. The registry lists 193 enrolled participants, a start date of 2007-09, and primary completion in 2008-08.
The primary endpoint is the percentage reaching ≥ 0.35 μg/mL for 7 common and 6 additional pneumococcal serotypes one month after the 3-dose infant series, at 7 months of age. The record defines an evaluable immunogenicity population and specifies 95% confidence intervals, but numerical primary and secondary immunogenicity results are not reported in the registry record.
Serious adverse-event counts are reported for three named periods, along with selected serious-event terms and percentages. The record lists six outcome measures and no analysis records. It does not report a concurrent comparator or key details such as the statistical analysis plan, multiplicity handling, or missing-data procedures.