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 Seroprevalence of SARS-Cov-2 Antibodies in Children (NCT04347408), a registered phase not stated study. The primary outcome is Immunoglobulins (G and M) to SARS-Cov2 in Plasma.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04347408 |
| Phase | Phase not stated |
| Condition | COVID, Corona Virus Infection, Multisystem Inflammatory Syndrome in Children |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 1100 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Queen's University, Belfast |
| Results posted | Yes |
2. Clinical Question
Population
The primary population is healthy children of healthcare workers between 2 and 15 years of age. The study also lists children admitted to hospital with Paediatric Multisystem Inflammatory Syndrome and children admitted with serious infections as separate groups. These groups have different eligibility descriptions and clinical contexts, so they should not automatically be treated as comparable populations.
Intervention
The registered antibody testing uses IgG and IgM testing. The primary outcome description specifies mean IgG or total antibody titres to SARS-CoV-2 in plasma, measured using ROCH/ABBOTT and DIASORIN assays. Blood storage is also listed as an intervention. This is a cohort study, not a treatment comparison.
Comparator
No randomized control group is described, and allocation is not stated. The listed hospital groups are not identified as like-for-like controls for the healthy children. The record therefore does not define a causal comparison between receiving one intervention and another, or between assigned treatment groups.
Primary question
The central question is what mean antibody titres are measured in plasma among healthy children of healthcare workers during the six-month timeframe. The registry summary frames the broader aim as following healthy children over six months to measure antibodies and address uncertainty about exposure and antibody presence. The posted record does not give the measured titres, their confidence intervals, or an estimate of the proportion with antibodies.
3. Trial Design
The registry describes a prospective multicentre cohort study titled “Seroprevalence of SARS-Cov-2 Antibodies in Children.” Its stated aim is to follow a cohort of healthy children over six months and measure antibodies to SARS-CoV-2. The record lists an enrollment of 1100 and a status of completed. The listed start date is 2020-05-06, and the primary completion date is 2021-12-01. These are registry entries; they do not provide a recruitment flow, the number who completed follow-up, or the amount of data available for analysis.
Three groups are described: healthy children of healthcare workers between 2 and 15 years of age; children admitted to hospital with Paediatric Multisystem Inflammatory Syndrome; and children admitted to hospital with serious infections. The primary outcome population is the healthy children of healthcare workers. The record does not establish that the hospital groups were recruited as controls for that population, or that the groups were intended for a direct comparative analysis. It explicitly notes that the study is not a randomized comparison and that allocation is not stated.
Registered interventions include Covid-19 Antibody testing (IgG and IgM) and Blood Storage. The primary outcome is mean plasma antibody titres at the six-month timeframe. Secondary outcomes listed are Echocardiogram Ejection Fraction, High-sensitivity Cardiac Troponin Test, and Brain Natriuretic Peptide. The registry record lists four outcome measures, but the fourth is not identified in the available details. It lists 0 analyses. A protocol-level description of recruitment procedures, follow-up visits, assay timing, or analysis populations is 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.
Overall Study
| Stage | Healthy Children |
|---|---|
| STARTED | 992 |
| COMPLETED | 992 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Healthy children of healthcare workers between 2 and 15 years of age
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 | Healthy Children |
|---|---|---|
| Participants analysed | 992 | |
| Age, Continuous | years | 10.1 (2.03 to 15.99) |
| Sex: Female, Male: Female | Participants | 483 |
| Sex: Female, Male: Male | Participants | 509 |
| Race and Ethnicity Not Collected | Participants | — |
6. Primary Endpoint
The registry lists the primary outcome as Immunoglobulins (G and M) to SARS-Cov2 in Plasma, measured over 6 months.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | Titres |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is mean immunoglobulin G and M antibody titres to SARS-CoV-2 in plasma, assessed at the six-month timeframe. The outcome description specifies mean IgG or total antibody titres and names ROCH/ABBOTT and DIASORIN assays. The listed population is healthy children of healthcare workers between 2 and 15 years of age. The registry identifies the measure as continuous and gives titres as its unit, with a 95% confidence interval as the stated dispersion measure.
In general, antibody titres quantify the level of antibodies detected by an assay. A group mean gives a measure of the average titre, while a confidence interval expresses uncertainty around the estimated mean under the assumptions of the analysis. It is not a range containing most individual children’s measurements. The endpoint can describe antibody measurements in the studied population at the stated timeframe; by itself it does not establish when exposure occurred, whether an individual child had a particular clinical outcome, or how representative the cohort is of children outside the study.
The record does not give the mean titre, confidence interval, number with a measurable antibody response, assay-specific results, or a definition of how results from the named assays were combined. Those outcome details are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the intended outcome and study structure, but it does not contain the numerical primary outcome results. It identifies mean plasma antibody titres as the primary measure and a 95% confidence interval as the dispersion summary. It also lists 0 analyses. Accordingly, the posted record does not support a numerical interpretation of the mean titre, the precision of an estimate, or differences between groups.
The primary outcome concerns healthy children of healthcare workers between 2 and 15 years of age. Any estimate from that population would describe the children who contributed data, subject to the study’s recruitment and measurement procedures. It would not automatically represent all children. The registry record does not report how participants were recruited, the characteristics of those enrolled, how many contributed usable outcome data, or whether follow-up was complete.
The hospital groups are described separately: children admitted with Paediatric Multisystem Inflammatory Syndrome and children admitted with serious infections. Since the record says this is not a randomized comparison, and does not state allocation, their presence does not create a randomized control comparison. Their clinical circumstances also differ by the descriptions in the record. Any contrast between these groups and healthy children would require a defined analysis and careful interpretation; no such estimates or analysis details are reported.
In general, a confidence interval helps readers assess how precisely a mean is estimated, but precision cannot be judged without the interval itself. A narrow interval generally indicates greater statistical precision than a wide interval, under the analysis assumptions. Neither width nor location can be inferred from a study’s enrollment entry alone. The registry record does not provide the primary mean, its confidence interval, a standard deviation, or other result values.
The record’s stated objective concerns antibody measurement over six months. It does not report the observed trajectory over time, whether measurements were repeated for each child, or how missing measurements were handled. Nor does it report a seroprevalence estimate. The title uses the term seroprevalence, but the primary outcome description is a mean titre; these are distinct summaries and should not be treated as interchangeable without a defined analysis.
The appropriate reading is therefore descriptive: the record documents a completed prospective cohort study with a specified antibody endpoint and stated population, but no posted numerical outcome analysis. No conclusion about antibody levels, prevalence, differences among groups, or clinical consequences can be drawn from the registry information alone.
9. Statistical Methods Explained
The registered primary measure is a continuous outcome: mean antibody titres in plasma. A mean describes the central level of measurements in a group. It is sensitive to the distribution of values, so its interpretation depends on how titres are measured and on the observed data. The registry names ROCH/ABBOTT and DIASORIN assays, but does not report whether assay results were analysed separately, harmonised, or combined. That analytical detail is not reported in the registry record.
What does the confidence interval express?
The record names a 95% confidence interval as the dispersion summary for the primary measure. In general, a confidence interval represents uncertainty around an estimated quantity under a specified statistical procedure and its assumptions. It is not a description of the spread of individual titres, and it is not an interval expected to contain a particular proportion of individual children’s measurements. The interval’s endpoints and the corresponding mean are not reported in the registry record, so the estimate’s precision cannot be assessed from the posted information.
A confidence interval is most useful when read alongside the estimate, the outcome definition, the population, and the analysis method. The same interval format may be used for different estimands, such as a group mean or a difference between means, but those answer different questions. Here, the stated primary parameter is a mean, not a between-group difference. No adjusted or unadjusted estimate is listed.
What does the cohort design imply?
In general, a prospective cohort follows defined groups and measures outcomes over time. It can describe outcomes in the observed participants and their change when repeated measurements are collected. It does not, by itself, ensure that differences between groups are caused by group membership or an exposure. Random allocation is not described in this record; it expressly identifies the study as not a randomized comparison and says allocation is not stated. The healthy and hospitalised groups therefore should not be assumed to be exchangeable or suitable controls.
The stated aim is to follow a cohort of healthy children over six months. The primary outcome timeframe is six months. The record does not specify the number or timing of measurements within that period, whether the primary endpoint is a single measurement or a change from baseline, or how repeated observations were modelled. Those details are not reported in the registry record. Without them, it is not possible to determine whether the mean is a cross-sectional summary at the endpoint or a summary derived from repeated measurements.
What can planning calculations say?
The planning assumptions describe an illustration using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They state that the effect to detect is a specified fraction of the observed effect. These are planning conventions, not evidence that the original study used those choices to design or analyse the cohort. The record does not report a sample-size justification for the study, an observed effect estimate to use for planning, or a protocol-based allocation between two arms.
Any sample-size values based on an observed effect are planning illustrations, not observed power. In general, a sample-size calculation estimates how much information a future study might require under chosen assumptions. It cannot establish whether the completed study had adequate precision, and it does not replace examination of the confidence interval for the observed outcome. Because no outcome estimate or confidence interval is reported in the registry record, the planning illustration cannot be interpreted as an evaluation of the primary result.
What is not documented about the analysis?
The registry lists 0 analyses. It does not report a statistical analysis plan, transformations of titres, handling of assay detection limits, covariate adjustment, subgroup definitions, or methods for repeated measures. It also does not report how confidence intervals were constructed. These are consequential choices for continuous antibody outcomes, particularly if the distribution is asymmetric or contains values outside an assay’s measurable range. In general, statistical methods should match the outcome’s distribution and the study design; the suitable method cannot be inferred without the data and prespecified plan.
For a continuous outcome, a mean and its confidence interval can convey the estimated average and uncertainty, while a distributional summary can help show whether the mean represents the observed data well. The registry identifies a mean and confidence interval but supplies no underlying distributional summaries. No recalculated estimate can be derived from the record. The posted information is therefore sufficient to identify the intended endpoint and some planning assumptions, but not to reproduce or evaluate the statistical analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists four outcome measures. The primary outcome is mean antibody titres, and the listed secondary outcomes are Echocardiogram Ejection Fraction, High-sensitivity Cardiac Troponin Test, and Brain Natriuretic Peptide. The available record does not identify the fourth measure. It also does not report a multiplicity strategy, such as a prespecified hierarchy, adjusted significance thresholds, or a distinction between confirmatory and exploratory tests. Without that information, the effect of multiple outcome testing on interpretation is not reported in the registry record.
The record lists 0 analyses and gives no numerical results. It does not report missing-data counts, reasons for missingness, imputation, complete-case methods, or sensitivity analyses. The enrollment entry of 1100 does not show how many participants contributed to the primary outcome or whether the same participants had data at each assessment. Those details are not reported in the registry record.
The registry also does not define the analysis population beyond identifying healthy children of healthcare workers between 2 and 15 years of age as the primary outcome population. It does not say whether eligibility, enrolment, follow-up, assay availability, or another criterion determined inclusion in the analysis. In general, the analysis population and missing-data approach affect the meaning and precision of estimates; they should be stated alongside outcome results. Here, neither is described in enough detail to evaluate possible selection or missingness effects.
11. What the Result Does, and Does Not, Mean
The record supports a limited set of conclusions about study intent and design. It describes a completed prospective multicentre cohort study, lists an enrollment of 1100, and identifies mean plasma SARS-CoV-2 antibody titres at six months as the primary outcome for healthy children of healthcare workers between 2 and 15 years of age. It also lists hospitalised groups and secondary outcomes. These details identify what the study set out to measure, not what it found.
The record does not report primary outcome estimates, confidence interval endpoints, seroprevalence, or comparisons between groups. It therefore does not establish the observed antibody level, the precision of that level, or whether antibody measurements differed over time or among the listed groups. A title referring to seroprevalence is not itself a numerical result, and the primary endpoint stated in the record is a mean titre.
In general, antibody measurements can inform a description of immune markers in a studied population, but interpretation depends on assay characteristics, timing, eligibility, and the analytic definition of a positive result. Those details and any clinical outcome relationship are not reported sufficiently in the registry record. The listed secondary cardiac measures do not provide evidence about their results or their relationship to antibody titres.
The cohort design also limits causal interpretation. The record does not describe random assignment and explicitly says the study is not a randomized comparison. The different groups should not be treated as equivalent comparison groups without information about their selection and analysis. No claim about cause, prevention, treatment effect, or an individual child’s status follows from the registry description alone.
Thus, the registry record is informative about the research question and registered measurements, but not about the numerical findings. Interpretation of results would require posted estimates, uncertainty intervals, analysis details, and participant-flow information.
12. Why This Trial Matters Statistically
This study is statistically relevant because it defines a population-based measurement question in a setting where the record describes uncertainty about children’s exposure and antibodies. Measuring titres in a cohort can provide a quantitative description, while a stated timeframe makes clear when the primary outcome is intended to be assessed. The record identifies a continuous mean outcome and a confidence interval, which are useful components of reporting when their values and methods are available.
The design also illustrates why the research question and comparison structure must be distinguished. Healthy children and children admitted to hospital with serious conditions are not automatically comparable groups. The record explicitly says the study is not a randomized comparison and allocation is not stated. A group difference, if reported, would need to be interpreted in light of how those groups were assembled and analysed, rather than as a randomized treatment effect.
Assay-specific measurement is another important statistical consideration. The primary outcome names ROCH/ABBOTT and DIASORIN assays, but does not explain how readings from the assays are related or combined. In general, measurement procedures affect the scale and comparability of outcomes; clear assay definitions and analysis rules help readers understand what a mean represents.
The registry record’s missing numerical results also demonstrate a reporting distinction: a completed study record and a specified endpoint do not, on their own, communicate an estimate or its precision. Without the mean, confidence interval, analysis population, and missing-data information, readers cannot assess the statistical strength or generalizability of the findings. The record’s value is therefore in documenting the intended cohort and measurement framework, while the outcome evidence remains unavailable in the registry information.
13. 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.
A central limitation of the available record is that it does not include numerical results for the primary or secondary outcomes. Although it identifies a mean titre and a 95% confidence interval as the intended summary, neither the mean nor interval is reported. The registry lists 0 analyses, so the posted information does not permit evaluation of the statistical methods or precision.
The primary outcome is defined for healthy children of healthcare workers between 2 and 15 years of age. The record does not report recruitment procedures, participant characteristics, geographic distribution, or how representative the cohort may be of children beyond this group. The listed enrollment of 1100 does not establish the number with complete follow-up or with an available primary outcome.
Three groups are described, but the registry does not specify their comparative role, common eligibility criteria, or whether they were assessed at equivalent times. It states that this was not a randomized comparison and that allocation is not stated. Consequently, the hospital groups cannot be assumed to be appropriate controls for the healthy children.
Other important details are not reported in the registry record: the timing and number of antibody measurements, assay-specific analysis procedures, handling of missing observations, definition of an antibody-positive result, and the analysis population. The record lists four outcome measures but identifies only the primary outcome and three secondary outcomes. It does not state how multiplicity was addressed. These gaps limit interpretation of both the intended measurement and any prospective planning assumptions.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Seroprevalence of SARS-Cov-2 Antibodies in Children — NCT04347408.
- Registry record last updated 2023-12-07; status last verified 2023-11.
- Results first posted 2021-08-18.
- 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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17. Record Summary
NCT04347408 is a completed prospective multicentre cohort study titled “Seroprevalence of SARS-Cov-2 Antibodies in Children.” The sponsor is Queen's University, Belfast. The registry lists an enrollment of 1100, a start date of 2020-05-06, and a primary completion date of 2021-12-01.
The stated aim is to follow healthy children over six months and measure SARS-CoV-2 antibodies. The primary population is healthy children of healthcare workers between 2 and 15 years of age. The primary outcome is mean plasma IgG or total antibody titres, with a 95% confidence interval specified as the dispersion measure. ROCH/ABBOTT and DIASORIN assays are named. The record also describes hospitalised groups with Paediatric Multisystem Inflammatory Syndrome and serious infections, and lists three secondary cardiac outcomes.
The study is not a randomized comparison, and allocation is not stated. The registry lists 0 analyses and does not report numerical outcome results, so estimates and their precision cannot be assessed from the record.