A Study of V260 in Healthy Chinese Adults, Children and Infants (V260-028)(COMPLETED): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of V260 in Healthy Chinese Adults, Children and Infants (V260-028)(COMPLETED) (NCT00953056), a randomized phase 1 study. The primary outcome is Number of Participants With Serious Adverse Events.

2. Clinical Question

This was a safety and tolerability study, not a trial designed in the registry record to estimate prevention of rotavirus gastroenteritis. Its primary endpoint was the number of participants with serious adverse events. The results are reported separately for each age cohort and randomized group, so interpretation should retain those cohort distinctions rather than treating the age groups as interchangeable.

The posted serious-event counts were zero in both adult groups and both child groups. In infants, the count was zero in the vaccine group and 3 in the placebo group. These are observed counts over the registry's stated safety collection period. They describe what was recorded in these study groups; they do not establish that a serious adverse event cannot occur, or that the groups would have the same pattern in a different study.

3. Trial Design

The registry describes a randomized, double-blind, parallel-group phase 1 study of RotaTeq™ and placebo in healthy Chinese adults, children and infants. The enrollment listed is 144. Allocation was randomized, masking was double, and the trial model was parallel. Participants were separated into adult, child and infant cohorts, with 1:1 randomization within each cohort.

The cohort ages were 19-47 years for adults, 2-6 years for children, and 6-12 weeks for infants. Adults and children were assigned a single dose of vaccine or matching placebo. Infants were assigned 3 doses of vaccine or matching placebo. The study was conducted sequentially: the registry summary says the adult cohort was followed by the child cohort, then the infant cohort. It also says that the primary investigator and Ethics Review Committee would review blinded safety data and use clinical judgment when deciding whether to move forward between cohorts.

The registry lists 24 participants in each of the six cohort-by-treatment groups. The listed study dates are 2009-09 for start and 2010-03 for primary completion, and the status is completed. The summary describes an anticipated overall duration of approximately 6-9 months. These are registry descriptions; information about adherence, withdrawals, dose completion, or the number included in each endpoint analysis is not reported in the registry record.

Because age cohort and dose schedule both vary, the results are most naturally read within cohort. The adult and child comparisons concern single-dose assignments, while the infant comparison concerns a 3-dose assignment. The registry record does not report a statistical method for pooling these cohorts, and pooling would obscure their different ages and schedules. The listed primary endpoint is a safety count, rather than an efficacy endpoint.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

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.

Only the first 6 of 7 groups are shown.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With Serious Adverse Events, measured over up to 14 days post vaccination.

The primary endpoint is the number of participants with serious adverse events, measured up to 14 days post vaccination. The registry description states that all serious adverse events were collected for 14 days following each dose to obtain the number of affected participants. The result is therefore a participant count: it indicates whether a person experienced at least one serious adverse event during the specified collection period, not the total number of separate serious-event episodes.

Safety and tolerability outcomes are used in early-phase studies to describe adverse events observed after exposure and to compare those observations with a control group. Reporting the number of participants with an event is straightforward to interpret, particularly when the event is serious. It can show whether any such events were recorded in a group during the stated period. However, a small count or a zero count does not by itself establish the underlying frequency with precision, especially when group sizes are limited and events are uncommon.

The posted results give zero serious adverse events in both adult groups and both child groups. For infants, the vaccine group has zero and the placebo group has 3. The endpoint is time-limited: it does not represent all possible safety outcomes over longer follow-up. The registry record does not report longer-term serious adverse event results for this endpoint, nor does it describe the analysis population used to calculate the counts.

7. Results Posted in the Registry

• Cohort I - RotaTeq™, Adults: 0.0% (0/24) versus 0.0% (0/24) on control; risk difference 0.0 percentage points (95% CI 0.0 to 0.0); unadjusted two-proportion z-test p = n/a.
• Cohort II - RotaTeq™, Children: 0.0% (0/24) versus 0.0% (0/24) on control; risk difference 0.0 percentage points (95% CI 0.0 to 0.0); unadjusted two-proportion z-test p = n/a.
• Cohort II - Placebo, Children: 0.0% (0/24) versus 0.0% (0/24) on control; risk difference 0.0 percentage points (95% CI 0.0 to 0.0); unadjusted two-proportion z-test p = n/a.
• Cohort III - RotaTeq™, Infants: 0.0% (0/24) versus 0.0% (0/24) on control; risk difference 0.0 percentage points (95% CI 0.0 to 0.0); unadjusted two-proportion z-test p = n/a.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary result is a binary participant outcome: each participant either had a serious adverse event recorded during the stated period or did not. For each randomized group, the registry reports the number at risk and the number affected. These counts retain important context. A count of zero means no participant in that group was recorded as having the endpoint during follow-up; it does not mean the underlying risk is known to be zero.

What does a risk difference describe?

A risk difference subtracts one group's event proportion from the other group's event proportion. It is an absolute contrast, expressed on the event-probability scale. For the infant comparison, the registry reports a risk difference of 0.125. The raw counts are 0 of 24 in the vaccine group and 3 of 24 in the placebo group, so the positive estimate reflects the higher observed proportion in the placebo group. The comparison's stated direction matters: a risk difference changes sign if the order of the groups is reversed.

In the adult and child cohorts, neither group had a recorded serious adverse event. The reported comparisons consequently have estimates of 0.0 and bounds of 0.0. These are the numerical comparison results in the registry record, but a point estimate at zero should not be read as demonstrating equivalence or absence of risk. When events are rare and samples are limited, observed counts may be unable to distinguish meaningfully among plausible underlying event rates.

How should the confidence interval be read?

A confidence interval expresses statistical uncertainty around an estimate according to a particular calculation method. In general, intervals that cover a broad range indicate less precision than narrow intervals. The infant interval runs from -0.007 to 0.257. It includes zero and also extends to positive risk differences. This communicates that the estimate is uncertain; it does not assign probabilities to particular values after the data have been observed, and it does not guarantee that the true difference lies within the interval.

The registry record does not state the confidence-interval method for this endpoint. Sparse data and zero event counts make the choice of method especially relevant: different methods can behave differently when event counts are small. Therefore, the reported interval should be interpreted as the interval attached to the posted estimate, without assuming an unreported method or treating it as the only possible interval.

What does the p-value add?

The infant comparison has p = 0.074. In general, a p-value describes how unusual data at least as incompatible with a specified null hypothesis would be under that hypothesis and the assumptions of the test. It is not the probability that the null hypothesis is true, nor does it measure the probability that the result is due to chance. The registry record does not report the test used or the null hypothesis in detail, so the p-value cannot be independently interpreted beyond its posted value. It should be considered with the observed counts, risk difference and interval.

No p-value is listed for the other comparisons. The comparisons with zero events in each group have estimates and bounds of 0.0, but the registry record does not give a separate inferential procedure for those rows. No adjustment for multiple comparisons is reported. Accordingly, the infant p-value should not be treated as if it were the result of a fully described, prespecified family of tests.

What can planning calculations tell us?

The planning illustration is based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It considers effects stated as fractions of the observed effect. In general, such illustrations show how design assumptions relate to a hypothetical future study size. They are not observed power, do not validate the study's design, and do not show that the current study had an adequate sample size. The registry record does not report the trial's own sample-size justification.

The assumptions also matter: a planning calculation based on an observed effect inherits uncertainty in that effect, and a normal approximation may be less dependable for rare binary events or groups with zero counts. The planning results should therefore be regarded as illustrative, not as a substitute for the trial's unreported design rationale or a method tailored to sparse safety outcomes.

More broadly, the registry lists no analysis entries. It does not identify a detailed model, adjustment variables, missing-data approach, analysis population, or statistical test for the primary endpoint. The reported comparisons are therefore best described as numerical summaries whose uncertainty needs cautious interpretation. General statistical principles can explain what the summaries mean, but they cannot fill in methodological details that are not reported in the registry record.

10. Confidence Intervals and Precision

The infant risk difference is 0.125, and its confidence interval extends from -0.007 to 0.257. This interval includes zero, so the data do not rule out no difference under the interval calculation used. It also spans values on either side of zero, indicating uncertainty about the direction and size of the underlying contrast. The posted p-value is 0.074. Taken together, these summaries do not provide a precise estimate of the infant cohort's underlying difference in serious adverse event risk.

Precision is limited by the small group counts and the rarity of the observed outcome. Three events in one infant group and none in the other produce a visible difference in the sample, but relatively few observations can make the estimated contrast sensitive to individual outcomes. A wider interval reflects that uncertainty. The registry record does not report the method used to construct the interval, which is relevant for binary outcomes with sparse counts.

In the adult and child cohorts, both groups have zero observed events and the reported risk differences and bounds are 0.0. These displayed bounds do not convey the full uncertainty about possible underlying event rates. A zero-width interval around an observed difference of zero should not be interpreted as exact knowledge that the groups have identical risks. The registry record does not state how those intervals were produced.

More generally, confidence intervals are informative only in conjunction with the underlying design and assumptions. They do not incorporate every source of uncertainty, such as incomplete follow-up or outcome ascertainment, unless the method accounts for those factors. Details about missing observations and analysis populations are not reported in the registry record. The event counts and interval therefore give a limited view of precision for the recorded endpoint and time window.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one secondary outcome, number of infants with fecal vaccine virus shedding, but no result for it is included in the endpoint information. It lists three outcome measures and zero analysis entries. The registry record does not report a multiplicity strategy, such as which outcomes or comparisons were primary for formal inference or whether any adjustment was planned. Without that information, the infant p-value should be treated as a single posted comparison rather than as evidence from a fully documented testing plan.

Missing-data handling is not reported in the registry record. The endpoint counts identify participants at risk in each group, but the record does not state whether all randomized participants contributed data, how incomplete follow-up was handled, or how any missing safety information was classified. The registry record also does not identify an intention-to-treat, per-protocol, or other analysis population for these results. The listed group counts should not be assumed to resolve those questions.

The summary describes safety data review between cohorts, but it does not report a statistical interim-analysis plan, stopping boundaries, or formal monitoring rules. The decision to proceed is described as a review of blinded safety data by the primary investigator and Ethics Review Committee using clinical judgment. This is distinct from a reported formal statistical analysis plan; further details are not reported in the registry record.

These gaps affect interpretation, not the arithmetic of the posted counts. They limit the ability to assess whether comparisons were prespecified, how incomplete records could influence them, and whether inferential results were adjusted for multiple looks or endpoints. The registry record does not report those methods, so conclusions should remain descriptive.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: diarrhoea (4.2%), bronchopneumonia (4.2%), encephalitis viral (4.2%).

For the primary safety endpoint, the registry reports the number of participants with serious adverse events. The adult vaccine and placebo groups each had 0 of 24 participants affected. The child vaccine and placebo groups also each had 0 of 24 affected. Among infants, 0 of 24 in the vaccine group and 3 of 24 in the placebo group were reported with serious adverse events.

These are participant counts, not counts of all event episodes, and they refer to the stated collection period: up to 14 days post vaccination, with the description specifying collection for 14 days following each dose. A zero count means that no participants were recorded with the endpoint in that group over the specified period. It does not show that the risk is zero outside the observed participants or follow-up.

The registry also lists other adverse-event counts separately: 6 in the adult vaccine group, 2 in the adult placebo group, 6 in the child vaccine group, 3 in the child placebo group, 18 in the infant vaccine group and 14 in the infant placebo group. These are not the primary serious-event endpoint. Death counts are not reported in the registry record. The serious-event comparison should be interpreted with its small group sizes and the infant confidence interval, rather than as a general safety guarantee.

13. What the Result Does, and Does Not, Mean

The primary result describes serious adverse events recorded in a phase 1 study of healthy Chinese adults, children and infants. No serious adverse events were reported in either randomized group among adults or children. In infants, the posted count was zero in the vaccine group and 3 in the placebo group. This is the observed pattern for the registry's specified endpoint and follow-up period.

The result does not establish that the vaccine caused fewer serious adverse events in infants. The estimate is based on few events, the confidence interval includes zero, and the registry record does not describe the statistical test or analysis plan in detail. Nor do zero-event findings in the adult and child cohorts prove that serious adverse events cannot occur. Limited observations provide limited information about rare events.

The endpoint also does not measure protection against rotavirus gastroenteritis. Although that condition is listed, the primary outcome is a safety count, and the registry entries do not provide an efficacy result. Fecal vaccine virus shedding is listed as a secondary outcome, but its results are not available in the endpoint information. The findings therefore cannot answer questions about efficacy, shedding, longer-term safety, or outcomes not included in this measure.

Finally, the age cohorts received different schedules: adults and children were assigned a single dose, while infants were assigned 3 doses. The comparisons should be interpreted within their cohort and schedule. They do not support treating all ages as one common population or applying these small-cohort observations to other populations or settings. The registry record supports a narrow description of recorded events, not a broader claim about safety or clinical benefit.

14. Why This Trial Matters Statistically

This study illustrates why safety results need to be read at the level of the randomized cohort and endpoint. The adult, child and infant groups differ in age, and the infant schedule differs from the single-dose schedules in the older cohorts. Reporting the results separately preserves those distinctions and avoids implying that one pooled estimate necessarily represents every group.

The event is rare in these observations: the adult and child groups have no recorded serious adverse events, while the infant comparison has only 3 events in one group. Such sparse data make the difference between an observed count and an underlying rate especially important. A zero estimate is a description of the sample, not proof of zero risk. A confidence interval and the raw group counts help readers assess the uncertainty, while also reminding them that few events cannot support highly precise conclusions.

The study also shows how a p-value can be overread when separated from design details. The infant comparison's p-value is 0.074, but the record does not describe the test or a multiple-comparison plan. The p-value should not serve as a simple verdict. The magnitude of the reported difference, its confidence interval, cohort context and limitations in the registry's methods reporting all matter.

Finally, the registry describes sequential safety review between cohorts, while formal statistical details are not reported. This is a useful distinction for clinical researchers: operational review and statistical inference are related but are not interchangeable. The posted counts can inform a careful account of observed events, but the available registry information does not justify stronger conclusions about causation, precision or generalizability.

15. 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 small group sizes and sparse serious-event counts limit precision. The infant comparison rests on 3 events in the placebo group and none in the vaccine group, while there are no events in either adult or child group. These observations cannot characterize uncommon risks with high precision. The infant confidence interval is broad relative to the point estimate and includes zero.

The registry record does not report the confidence-interval method, statistical test, analysis population, missing-data approach, or multiplicity plan. It also does not provide a detailed statistical analysis plan or sample-size justification. As a result, the calculations cannot be assessed against a fully described prespecified analysis. The record lists no analysis entries.

Follow-up for the primary endpoint is limited to the stated period up to 14 days post vaccination, with collection described for 14 days following each dose. These results do not provide information on longer-term serious adverse events. The registry record does not report death counts. The secondary outcome of infant fecal vaccine virus shedding is listed, but its result is not included in the endpoint details.

The study enrolled healthy Chinese participants in specific age ranges and used distinct dose schedules by cohort. These characteristics limit how broadly the counts can be generalized. The sequential cohort structure and safety review are described, but detailed decision criteria are not reported in the registry record. These limitations mean that the findings are best understood as a small, short-term, cohort-specific description of serious adverse events rather than a comprehensive safety assessment.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Study of V260 in Healthy Chinese Adults, Children and Infants (V260-028)(COMPLETED) — NCT00953056.
• Registry record last updated 2015-11-02; status last verified 2015-10.
• Results first posted 2011-04-15.
• 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.

19. Record Summary

This completed phase 1 study randomized healthy Chinese adults aged 19-47 years, children aged 2-6 years, and infants aged 6-12 weeks to RotaTeq™ or matching placebo. It was double-blind and parallel-group, with 1:1 randomization within each cohort. Adults and children were assigned a single dose; infants were assigned 3 doses.

The primary endpoint was the number of participants with serious adverse events up to 14 days post vaccination. The posted counts were zero in both adult groups and both child groups, zero in the infant vaccine group, and 3 in the infant placebo group. The infant risk difference was 0.125, with a confidence interval from -0.007 to 0.257 and p = 0.074. The registry record does not report detailed analysis methods, missing-data handling, or a multiplicity plan.