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 Phase 1/2 Study of TAK-850 Intramuscular Injection in Healthy Pediatric Participants (NCT02367885), a non-randomized phase 1, phase 2 study. The primary outcome is Number of Participants With Solicited Local and Systemic Adverse Events (AEs) for 3-12 Years Old Group and 13-19 Years Old Group.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02367885 |
| Phase | Phase 1, Phase 2 |
| Condition | Influenza Infection |
| Allocation | Non-Randomized |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 99 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Takeda |
| Results posted | Yes |
2. Clinical Question
Population
Healthy pediatric Japanese participants were enrolled. The study included age groups 6-35 months, 3-12 years, and 13-19 years. The registry record reports enrollment of 99 participants, with 33 in each of the three listed groups.
Intervention
Participants received an intramuscular injection of TAK-850. The 6-35 months group received two 0.25 mL injections, the 3-12 years group received two 0.5 mL injections, and the 13-19 years group received a single 0.5 mL injection.
Comparator
There was no randomized control group. The registry describes a non-randomized, single-group study with no masking. The age and dose groups are not like-for-like control groups, because both age and injection regimen differ.
Primary question
The primary endpoint counted participants in the 3-12 years and 13-19 years groups who had solicited local reactions or systemic events up to 21 days after any vaccination. The study also assessed safety and immunogenicity; specific posted immunogenicity estimates are not reported in the registry record.
The central statistical question is descriptive: how many participants in the specified age groups experienced recorded, solicited events during the stated follow-up period? The endpoint concerns counts of participants, not the total number of event episodes. A participant could contribute to more than one event category, so category counts should not be added as though they represented different people.
The study is not designed in the registry record as a randomized comparison of TAK-850 with another treatment or with no vaccination. Its groups differ in age and dosing regimen, and the registry explicitly cautions that the arms are not a like-for-like control comparison. Consequently, any numerical differences between groups would be descriptive and could not isolate the effect of dose or schedule from differences in participant age and other group characteristics.
3. Trial Design
The registry describes an open-label, multi-center Phase 1/2 study of intramuscular TAK-850 in healthy pediatric participants. It was non-randomized, unmasked, and organized as a single-group study rather than a randomized controlled comparison. Enrollment was 99, and the record lists three age-and-regimen groups with 33 participants each.
Participants aged 13-19 years received a single intramuscular injection of TAK-850 0.5 mL. Participants aged 3-12 years received two intramuscular injections of TAK-850 0.5 mL. Participants aged 6-35 months received two intramuscular injections of TAK-850 0.25 mL. These are different regimens in different age groups, so the groups should not be interpreted as interchangeable arms or as direct dose-comparison groups.
The primary outcome concerns solicited local reactions and systemic events for the 3-12 years and 13-19 years groups. Events were recorded using a diary, with the stated timeframe up to 21 days after any vaccination. The listed local reactions include injection-site pain, redness, swelling, induration, tenderness, and ecchymosis. Listed systemic events include pyrexia, malaise, chills, fatigue, headache, sweating, myalgia, nausea, and vomiting. The registry notes that a participant may be represented in more than one category.
The study also lists immunogenicity outcomes, including antibody seroprotection, seroconversion, geometric mean fold increase, and geometric mean titer measures. The registry record lists 25 outcome measures, but detailed immunogenicity estimates are not reported in the registry record. The record reports the study status as completed. Its start and primary completion are recorded as 2015-02 and 2015-05, respectively. Further details about allocation procedures, a control regimen, or a protocol-specific statistical analysis plan are not reported in the registry record.
Because there is no randomized, like-for-like control group, the design primarily supports description of observed safety and immune-response outcomes in the studied groups. It does not, on the information reported, provide a controlled estimate of a treatment effect.
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: Healthy pediatric participants of age group 6 months-19 years were enrolled in 1 of the 3 treatment groups: TAK-850 0.25 milliliter (mL): 6 - 35 months; TAK-850 0.5 mL: 3-12 Years and TAK-850 0.5 mL: 13-19 Years.
Overall Study
| Stage | TAK-850 0.25 mL: 6-35 Months | TAK-850 0.5 mL: 3-12 Years | TAK-850 0.5 mL: 13-19 Years |
|---|---|---|---|
| STARTED | 33 | 33 | 33 |
| COMPLETED | 31 | 33 | 33 |
| NOT COMPLETED | 2 | 0 | 0 |
Reasons for not completing this period:
| Reason | TAK-850 0.25 mL: 6-35 Months | TAK-850 0.5 mL: 3-12 Years | TAK-850 0.5 mL: 13-19 Years |
|---|---|---|---|
| Lost to Follow-up | 1 | 0 | 0 |
| Withdrawal by Subject | 1 | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Safety analysis set included all participants who received at least 1 dose of study vaccination.
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
Population: Safety analysis set included all participants who received at least 1 dose of study vaccination.
| Characteristic | Unit | TAK-850 0.25 mL: 6-35 Months | TAK-850 0.5 mL: 3-12 Years | TAK-850 0.5 mL: 13-19 Years | Total |
|---|---|---|---|---|---|
| Participants analysed | 33 | 33 | 33 | 99 | |
| Age, Customized: 6-35 Months | participants | 33 | 0 | 0 | 33 |
| Age, Customized: 3-12 Years | participants | 0 | 33 | 0 | 33 |
| Age, Customized: 13-19 Years | participants | 0 | 0 | 33 | 33 |
| Sex: Female, Male: Female | Participants | 15 | 16 | 19 | 50 |
| Sex: Female, Male: Male | Participants | 18 | 17 | 14 | 49 |
| Region of Enrollment: Japan | participants | 33 | 33 | 33 | 99 |
| Hemagglutination Inhibition (HI) (Egg-derived) - A/H1N1 Titer at Day 1(Pre-vaccination): Less Than (<) 40 Titer | participants | 31 | 6 | 14 | 51 |
| Hemagglutination Inhibition (HI) (Egg-derived) - A/H1N1 Titer at Day 1(Pre-vaccination): Greater Than or Equal to (>=) 40 Titer | participants | 2 | 27 | 19 | 48 |
| Hemagglutination Inhibition (HI) (Egg-derived) - A/H3N2 Titer at Day 1 (Pre-vaccination): <40 Titer | participants | 26 | 16 | 15 | 57 |
| Hemagglutination Inhibition (HI) (Egg-derived) - A/H3N2 Titer at Day 1 (Pre-vaccination): >=40 Titer | participants | 7 | 17 | 18 | 42 |
| Hemagglutination Inhibition (HI) (Egg-derived) - B Titer at Day 1 (Pre-vaccination): <40 Titer | participants | 33 | 33 | 26 | 92 |
| Hemagglutination Inhibition (HI) (Egg-derived) - B Titer at Day 1 (Pre-vaccination): >=40 Titer | participants | 0 | 0 | 7 | 7 |
| Influenza Infection within 5 years: Infection occurred | participants | 2 | 16 | 7 | 25 |
| Influenza Infection within 5 years: Infection did not occur | participants | 31 | 17 | 26 | 74 |
| Administration of Antipyretics: Antipyretics administered | participants | 2 | 1 | 1 | 4 |
| Administration of Antipyretics: Antipyretics not administered | participants | 31 | 32 | 32 | 95 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Solicited Local and Systemic Adverse Events (AEs) for 3-12 Years Old Group and 13-19 Years Old Group, measured over Up to 21 days after any vaccination.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the number of participants with solicited local and systemic adverse events in the 3-12 years and 13-19 years groups. Local reactions and systemic events were recorded in a diary, with follow-up defined as up to 21 days after any vaccination. The registry’s safety analysis set includes all participants who received at least one dose of study vaccination.
Counting participants with an event gives a straightforward summary of how many people experienced at least one recorded event in a category during the defined period. It differs from counting event episodes: if one participant experiences several types of reaction, that participant can appear in several category counts. The registry explicitly notes that participants may be represented in more than one category. As a result, category totals are not necessarily counts of unique participants and should not be summed to estimate the number of people with any event.
The endpoint includes both local reactions, such as injection-site pain or redness, and systemic events, such as headache or nausea. These are different kinds of observations and may be useful to report separately. The registry’s primary endpoint description does not give a single combined definition for a participant with any local or systemic event, nor does it give category-specific results in the information recorded.
General: solicited-event endpoints use specified symptom categories and a defined observation period, making the scope of collection more explicit than an unrestricted report of any event. Their interpretation still depends on consistent recording and on how event categories and missing diary entries are handled. Those operational details beyond the registry description are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted safety counts describe participants with serious and other adverse events in the three age-and-regimen groups. Each group has 33 participants at risk for both of these summaries. The serious-event counts are 0 for TAK-850 0.25 mL in 6-35 months, 1 for TAK-850 0.5 mL in 3-12 years, and 0 for TAK-850 0.5 mL in 13-19 years. The counts for other adverse events are 21, 29, and 24, respectively. These are descriptive counts; the registry record does not report a randomized control group for comparison.
Those safety summaries are not the same as a complete presentation of the primary endpoint. The primary endpoint specifies solicited local and systemic events, in the 3-12 years and 13-19 years groups, up to 21 days after any vaccination. The registry record does not report the category-specific counts for that endpoint in the information recorded. The other adverse-event counts should therefore not be treated as a substitute for the primary solicited-event results or as a count of participants with any particular symptom.
The registry lists 25 outcome measures and includes several immunogenicity outcomes, such as seroprotection and seroconversion. Numerical results for these outcomes are not reported in the registry record. The record also reports zero analysis entries. Without outcome estimates, uncertainty intervals, or a documented inferential analysis, the immune-response outcomes cannot be interpreted quantitatively from the registry information.
General: a count is a descriptive summary of what was recorded in a group. It does not by itself establish whether an event was caused by vaccination, whether a difference between groups is meaningful, or how precisely an underlying event rate has been estimated. A confidence interval, when reported, describes statistical uncertainty around an estimate under the assumptions of the analysis; no confidence intervals for these outcomes are reported in the registry record.
The groups differ in age and in injection regimen, and allocation was not randomized. Any contrast among the three group counts would combine potential differences associated with age, regimen, and other group characteristics. It would not isolate a dose effect. The registry itself cautions that the arms are not a like-for-like control comparison. No causal interpretation of between-group differences is supported by the design details recorded.
The serious adverse-event term list includes clavicle fracture, contusion, pelvic fracture, pubis fracture, and road traffic accident, each listed as 3.0%. The record does not specify in the information recorded how these term-level percentages relate to the group-level serious-event counts, or provide enough detail to assign those terms to a particular group. The listed terms should therefore be read as registry-reported entries, not as evidence of a particular cause or treatment relationship.
The appropriate statistical reading is limited: the record gives group-level adverse-event counts and lists planned or defined outcome measures, but it does not provide a complete set of primary endpoint category results or immunogenicity estimates. It also does not report comparative inferential results. The available counts can be described, while stronger claims about comparative safety, precision, or immune response are not supported by the information in the registry record.
9. Statistical Methods Explained
The registry record identifies the study as non-randomized, unmasked, and single-group. These design descriptions shape what statistical interpretation is possible. In a randomized comparison, allocation is intended to make groups comparable on average with respect to measured and unmeasured characteristics. That protection against systematic group differences is absent when allocation is non-randomized. Here, the groups also differ by age and regimen, so a difference in observed counts cannot be assigned to a dose or schedule alone.
What does a participant count represent?
The primary outcome is a count of participants with solicited events, rather than a count of all event occurrences. A person who reports more than one event category can contribute to more than one category. This distinction matters: adding category counts can count the same participant multiple times. The registry describes diary recording and names the local and systemic event categories, but detailed category-specific primary outcome results are not reported in the registry record.
The adverse-event summary also reports participants at risk and participants affected. A count at risk provides the group denominator for interpreting the corresponding affected count. The listed groups each have 33 participants at risk. A count is not an estimate of uncertainty by itself. Statistical precision depends on the number of observations and on the analysis method, and confidence intervals or other uncertainty summaries for the posted adverse-event counts are not reported in the registry record.
What can a comparison between these groups show?
General: comparing two proportions can describe how often an event was observed in each group and how far apart the observed proportions are. An inferential comparison requires a defined estimand, an appropriate method, and assumptions about the design and data. Randomization can support a causal interpretation when the trial is appropriately conducted, but a non-randomized contrast is vulnerable to differences between groups. In this study, the age groups and dose schedules differ, so a comparison would not isolate the effect of dose. The registry record reports no analysis entries, and comparative tests or adjusted estimates are not reported in the registry record.
The outcome type is binary at the participant level: a participant is counted as having or not having the event for a specified category. General: binary outcomes are often summarized with counts and proportions. Models or tests may be used for comparisons, but their suitability depends on the research question, the group structure, sample size, and analysis plan. No model, test, or adjustment strategy is reported in the registry record. It would be inappropriate to imply that a particular inferential method was used.
How should uncertainty be understood?
General: a confidence interval presents a range of values compatible with the data under a statistical model and its assumptions. A narrow interval generally indicates greater precision than a wide interval, but an interval is not a guarantee that the true value lies within it. The registry record does not report confidence intervals for the adverse-event or immunogenicity outcomes in the information recorded. Therefore, the posted counts should not be described as having a particular degree of statistical precision beyond their exact observed values.
The record includes planning assumptions for sample-size illustrations: a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect stated as a fraction of the observed effect. These are assumptions for planning illustrations, not evidence of the study’s own design rationale. The record does not report the protocol’s sample-size justification. Any planning illustrations based on an observed effect are not observed power, and they do not convert this non-randomized study into a controlled comparison. The record does not report the values of those illustrations in the information recorded.
Why do the event definitions matter?
Solicited outcomes use a list of specified local and systemic symptoms and a defined period of follow-up. A diary is identified as the recording method. General: a defined symptom list can make outcome collection more structured, but the statistical interpretation also depends on the rules for severity grading, onset, duration, missing diary entries, and whether repeated reports count as one participant with an event or multiple events. The registry description identifies participant counts and event categories, but details for those additional rules are not reported in the registry record.
The registry lists immune-response measures using geometric means and categories such as seroprotection and seroconversion. General: geometric mean measures are commonly used for positive values that are skewed on their original scale; taking logarithms before averaging can make their distribution more suitable for analysis. A geometric mean fold increase describes a multiplicative change rather than an arithmetic difference. However, the registry record does not provide the corresponding estimates, uncertainty intervals, or detailed analysis methods, so these general concepts cannot be used to reconstruct study results.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 25 outcome measures, including the primary solicited adverse-event endpoint and multiple immunogenicity outcomes. Assessing many outcomes creates a multiplicity issue: when many statistical tests are performed, the chance of at least one apparently notable result can increase. General: investigators may address multiplicity by identifying a hierarchy of outcomes, adjusting significance thresholds, or treating secondary analyses as descriptive. The registry record does not report a multiplicity strategy, a hierarchy among the secondary outcomes, or inferential results for these outcomes.
Missing-data handling is also not reported in the registry record. The primary endpoint description identifies a safety analysis set that includes all participants who received at least one dose of study vaccination. It does not describe how participants with incomplete diaries, missing visits, or unavailable event information were handled. The record does not state whether missing observations were excluded, imputed, or addressed through another method. No missingness counts are reported in the information recorded.
The safety population definition should not be assumed to apply to every immunogenicity outcome. The analysis population for those outcomes is not reported in the registry record. The record also does not provide participant flow details, the number included in each outcome analysis, or reasons for any exclusions or missing assessments. These omissions limit assessment of whether the participants contributing to each result represent the full enrolled groups.
General: missing data can affect an estimate when the availability of an observation is related to the participant’s outcome or characteristics. The direction and size of any resulting bias cannot be determined without information about the amount, pattern, and handling of missing data. Likewise, a list of many outcomes does not establish that every outcome was tested or that tests were adjusted. The registry record reports zero analysis entries, so a statistical testing plan and its implementation are not described.
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 |
|---|---|---|---|
| TAK-850 0.25 mL: 6-35 Months | 0 | 33 | 0.0% |
| TAK-850 0.5 mL: 3-12 Years | 1 | 33 | 3.0% |
| TAK-850 0.5 mL: 13-19 Years | 0 | 33 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| TAK-850 0.25 mL: 6-35 Months | 21 of 33 |
| TAK-850 0.5 mL: 3-12 Years | 29 of 33 |
| TAK-850 0.5 mL: 13-19 Years | 24 of 33 |
Most frequent serious adverse event terms
| Event term | Organ system | TAK-850 0.25 mL: 6-35 Months | TAK-850 0.5 mL: 3-12 Years | TAK-850 0.5 mL: 13-19 Years |
|---|---|---|---|---|
| Clavicle fracture | Injury, poisoning and procedural complications | 0 of 33 | 1 of 33 | 0 of 33 |
| Contusion | Injury, poisoning and procedural complications | 0 of 33 | 1 of 33 | 0 of 33 |
| Pelvic fracture | Injury, poisoning and procedural complications | 0 of 33 | 1 of 33 | 0 of 33 |
| Pubis fracture | Injury, poisoning and procedural complications | 0 of 33 | 1 of 33 | 0 of 33 |
| Road traffic accident | Injury, poisoning and procedural complications | 0 of 33 | 1 of 33 | 0 of 33 |
Most frequent non-serious adverse event terms
| Event term | Organ system | TAK-850 0.25 mL: 6-35 Months | TAK-850 0.5 mL: 3-12 Years | TAK-850 0.5 mL: 13-19 Years |
|---|---|---|---|---|
| Injection site pain | General disorders | 3 of 33 | 24 of 33 | 19 of 33 |
| Pyrexia | General disorders | 12 of 33 | 3 of 33 | 1 of 33 |
| Upper respiratory tract inflammation | Respiratory, thoracic and mediastinal disorders | 9 of 33 | 4 of 33 | 0 of 33 |
| Injection site swelling | General disorders | 0 of 33 | 6 of 33 | 3 of 33 |
| Vomiting | Gastrointestinal disorders | 6 of 33 | 2 of 33 | 0 of 33 |
| Malaise | General disorders | 0 of 33 | 5 of 33 | 3 of 33 |
| Injection site erythema | General disorders | 0 of 33 | 6 of 33 | 1 of 33 |
| Fatigue | General disorders | 0 of 33 | 4 of 33 | 2 of 33 |
| Somnolence | Nervous system disorders | 5 of 33 | 1 of 33 | 0 of 33 |
| Rhinorrhoea | Respiratory, thoracic and mediastinal disorders | 6 of 33 | 0 of 33 | 0 of 33 |
Serious events with the highest arm-level rate: clavicle fracture (3.0%), contusion (3.0%), pelvic fracture (3.0%), pubis fracture (3.0%), road traffic accident (3.0%).
The registry reports serious adverse-event counts of 0 among 33 participants in the TAK-850 0.25 mL: 6-35 Months group, 1 among 33 in the TAK-850 0.5 mL: 3-12 Years group, and 0 among 33 in the TAK-850 0.5 mL: 13-19 Years group. The corresponding counts for other adverse events are 21, 29, and 24 among 33 participants in each group. These are group-level counts, not adjusted comparisons.
The serious-event term list names clavicle fracture, contusion, pelvic fracture, pubis fracture, and road traffic accident, each at 3.0%. The registry record does not report the group assignment or further event-level context for these terms in the information recorded. It also does not state whether any event was judged related to vaccination. The term list should not be used to infer causation or to reconcile the term-level entries with group-level counts without additional information.
Death counts are not reported in the registry record. The serious-event summary does not provide further details about timing, duration, outcome, or participant characteristics. In addition, the stated 21-day timeframe applies to the primary solicited local and systemic endpoint; the registry information recorded does not establish that the same timeframe applies to the serious-event summary.
General: serious adverse events and solicited symptoms are distinct kinds of safety information, and their counts should not be combined. A serious-event count describes recorded events under the registry’s reporting conventions; it does not establish that vaccination caused an event. These figures are descriptive and should be interpreted within the non-randomized design and the limited event details recorded.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a completed Phase 1/2 study enrolled 99 healthy pediatric participants across three age-and-regimen groups. It describes the injection schedules and identifies a primary safety endpoint based on solicited local and systemic events in the 3-12 years and 13-19 years groups. It also reports group-level counts of participants with serious and other adverse events. Those details support a description of the design and the recorded safety summaries.
The counts do not by themselves show that TAK-850 caused or prevented an event. There is no randomized control group, allocation was non-randomized, and the groups differ in both age and regimen. Comparisons among them cannot isolate an age effect, dose effect, or schedule effect. The registry record itself warns that the groups are not a like-for-like control comparison.
The figures also do not establish the full frequency of each solicited symptom, because category-specific results for the primary endpoint are not reported in the registry record. Nor do they show the total number of unique participants with any event across all categories, since a participant may be counted in more than one category. The safety summaries should not be substituted for the defined primary endpoint results.
The record lists immunogenicity outcomes but does not report their numerical estimates in the information recorded. Therefore it does not support a quantitative conclusion about seroprotection, seroconversion, antibody titer, or fold increase. It also does not report confidence intervals or comparative inferential analyses. Statistical precision and the strength of evidence cannot be judged from the counts alone.
General: an observed result is a description of the data collected, while a conclusion about a broader population or a causal effect requires additional design and analysis assumptions. Uncertainty intervals and transparent analysis details help show how much the data can support. Those details, including handling of missing data and multiplicity, are not reported in the registry record. The defensible interpretation is therefore confined to the study’s recorded design, outcome definitions, and posted counts.
13. Why This Trial Matters Statistically
This study is statistically informative as an example of how pediatric safety and immunogenicity outcomes can be organized across age-specific regimens, while also illustrating the limits of non-randomized evidence. The registry makes the age groups and injection schedules explicit, and it identifies a diary-based primary endpoint with a defined set of local reactions and systemic events. Clear endpoint definitions are important because the meaning of a count depends on who is counted, what qualifies as an event, and the observation period.
The design also makes comparability a central issue. The three groups vary in age and regimen, rather than differing only by a randomly assigned treatment. Thus, even if group counts differ, the contrast would not isolate the effect of dose or injection schedule. Recognizing this is important in biostatistical reporting: descriptive group summaries can be useful, but they should not be presented as though they came from a controlled treatment comparison.
The distinction between participant counts and event counts is another important statistical point. A participant can be recorded in several symptom categories, so separate category counts do not necessarily represent separate people. Similarly, broad adverse-event summaries should not be mistaken for the specifically defined solicited endpoint. Readers need to keep outcome definition, analysis population, and follow-up period aligned when interpreting results.
Finally, a registry may list numerous outcomes without presenting detailed estimates or analysis methods. Here, the record lists 25 outcome measures but does not report numerical immunogenicity results or a statistical analysis plan in the information recorded. This makes transparent reporting of estimates, uncertainty, missingness, and multiplicity particularly relevant. The study’s statistical value lies in the questions and groups it documents, as well as in the need to distinguish recorded descriptions from conclusions that require controlled comparisons and fuller reporting.
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 design limitation is the absence of randomization and a like-for-like control group. The registry describes a non-randomized, single-group study and explicitly cautions that the arms are not a like-for-like control comparison. The age groups also receive different regimens: one 0.5 mL injection for participants aged 13-19 years, two 0.5 mL injections for participants aged 3-12 years, and two 0.25 mL injections for participants aged 6-35 months. Group differences therefore cannot isolate the effect of dose or schedule.
The primary endpoint is specified for the 3-12 years and 13-19 years groups, whereas the safety summary also includes the 6-35 months group. The registry record does not report detailed primary endpoint category counts in the information recorded. The published group-level adverse-event counts cannot fill that gap, because they are not identified as the complete category-specific primary endpoint results.
Although the registry lists 25 outcome measures, it does not report numerical immunogenicity estimates or analysis entries in the information recorded. It also does not report confidence intervals, the protocol’s sample-size justification, a statistical analysis plan, interim analyses, or a multiplicity approach. Missing-data rules and analysis populations for the immunogenicity outcomes are not reported in the registry record.
The serious-event term list gives each of five terms as 3.0%, but the registry information recorded does not clarify their group assignment or how they relate to the group-level serious-event counts. Death counts are not reported in the registry record. Additional event-level details, including timing and assessed relationship to vaccination, are not reported in the registry record.
These limitations restrict interpretation to the described design and posted counts. They do not support causal comparisons, a full assessment of precision, or quantitative conclusions about immunogenicity.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Phase 1/2 Study of TAK-850 Intramuscular Injection in Healthy Pediatric Participants — NCT02367885.
- Registry record last updated 2016-04-07; status last verified 2016-03.
- Results first posted 2016-04-07.
- 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 describes a completed, open-label, multi-center Phase 1/2 study of intramuscular TAK-850 in healthy pediatric participants. It was non-randomized, unmasked, and listed as a single-group study. Enrollment was 99, with three age-and-regimen groups of 33 participants each: TAK-850 0.25 mL for ages 6-35 months, TAK-850 0.5 mL for ages 3-12 years, and TAK-850 0.5 mL for ages 13-19 years.
The primary endpoint counted participants with solicited local and systemic events in the 3-12 years and 13-19 years groups, up to 21 days after any vaccination. Group-level serious adverse-event counts were 0, 1, and 0; other adverse-event counts were 21, 29, and 24. The record lists immunogenicity outcomes but does not report their numerical results in the information recorded.
Because the groups differ in age and regimen and were not randomized as a like-for-like comparison, their counts are descriptive rather than controlled treatment contrasts. Detailed primary endpoint results, inferential analyses, uncertainty intervals, and missing-data methods are not reported in the registry record.