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 Safety and Tolerability of COVID-19 Vaccine (ABNCoV2) (NCT04839146), a non-randomized phase 1 study. The primary outcome is Number of at Least Possibly Related Grade 3 Adverse Events (AE) and Serious Adverse Events (SAE).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04839146 |
| Phase | Phase 1 |
| Condition | Covid19, Severe Acute Respiratory Syndrome, SARS-CoV-2 Infection |
| Allocation | Non-Randomized |
| Design model | Sequential |
| Masking | None (open label) |
| Enrollment | 45 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Radboud University Medical Center |
| Results posted | Yes |
2. Clinical Question
Population
Healthy adult volunteers described as SARS-CoV-2-naïve and in good health. The registry lists an enrollment of 45 and identifies the study as phase 1.
Intervention
ABNCoV2, a coronavirus virus-like particle subunit vaccine, given intramuscularly in dose groups with non-adjuvanted or MF59-adjuvanted formulations. The study aim describes two doses.
Comparator
There is no randomized control group. The registry describes sequential groups receiving different doses and formulations; these are not like-for-like randomized comparisons.
Primary question
The primary safety endpoint is the number of at least possibly related Grade 3 adverse events and serious adverse events up to 28 weeks. The broader stated aim is to assess safety and tolerability and identify a dose and formulation balancing immunogenicity and tolerability.
The registry’s brief summary places the immunogenicity-tolerability objective 14 days following first vaccination. That objective is distinct from the posted primary endpoint, which concerns adverse events over a longer stated timeframe. The registry also lists a secondary outcome for participants with at least possibly related solicited adverse events.
These questions are exploratory in character: the study is described as a first-in-human phase 1 trial, with dose and formulation groups arranged sequentially rather than randomly assigned. The record therefore supports describing the safety observations within each group, but it does not establish a randomized comparison of formulations or doses. The registry record does not report a separate untreated or placebo comparison in the intervention descriptions.
3. Trial Design
This was a phase 1, non-randomized, unmasked, sequential study sponsored by Radboud University Medical Center. The registry lists an enrollment of 45 and a completed status. The recorded start date is 2021-03-11, and the primary completion date is 2021-12-30. The official title describes a first-in-human trial in SARS-CoV-2-naïve adult volunteers in good health.
The intervention is ABNCoV2, administered intramuscularly. Groups 1 to 3 are described at 6 μg, 12 μg and 25 μg, with non-adjuvanted and MF59-adjuvanted formulation subgroups. For each of these groups, the description specifies three participants per formulation. Groups 4 and 5 are described at 50 μg and 70 μg, respectively. Groups 6 and 7 are described using doses determined by which dose was achieved in the preceding dose exploration: the next lower dose and the highest dose, respectively. The precise doses in those two descriptions are marked t.b.d. The group descriptions state that participants receive a second vaccination with the same dose and formulation; for Groups 4 to 7, the descriptions state that this is 4 weeks following the first vaccination.
The safety listing presents outcomes for individual dose and formulation groups, including denominators at risk. The registered primary endpoint is the number of at least possibly related Grade 3 adverse events and serious adverse events up to 28 weeks. The registry lists 7 outcome measures and 0 analyses. It does not report further details of a statistical analysis plan, allocation sequence, or sample-size justification. The posted structure should consequently be read as a descriptive safety record, not as a set of prespecified randomized treatment contrasts.
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.
Only the first 6 of 10 groups are shown.
Overall Study
| Stage | Group 1A: 6 Microgram ABNCoV2 Without MF59 Adjuvant | Group 1B: 6 Microgram ABNCoV2 With MF59 Adjuvant | Group 2A: 12 Microgram ABNCoV2 Without MF59 Adjuvant | Group 2B: 12 Microgram ABNCoV2 With MF59 Adjuvant | Group 3A: 25 Microgram ABNCoV2 Without MF59 Adjuvant | Group 3B: 25 Microgram ABNCoV2 With MF59 Adjuvant |
|---|---|---|---|---|---|---|
| STARTED | 3 | 3 | 3 | 3 | 3 | 3 |
| COMPLETED | 3 | 3 | 3 | 3 | 3 | 3 |
| NOT COMPLETED | 0 | 0 | 0 | 0 | 0 | 0 |
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 11 groups are shown.
| Characteristic | Unit | Group 1A: 6 Microgram ABNCoV2 Without MF59 Adjuvant | Group 1B: 6 Microgram ABNCoV2 With MF59 Adjuvant | Group 2A: 12 Microgram ABNCoV2 Without MF59 Adjuvant | Group 2B: 12 Microgram ABNCoV2 With MF59 Adjuvant | Group 3A: 25 Microgram ABNCoV2 Without MF59 Adjuvant | Group 3B: 25 Microgram ABNCoV2 With MF59 Adjuvant |
|---|---|---|---|---|---|---|---|
| Participants analysed | 3 | 3 | 3 | 3 | 3 | 3 | |
| Age, Continuous | years | 31 (21 to 35) | 27 (22 to 52) | 25 (23 to 34) | 37 (22 to 37) | 27 (22 to 28) | 48 (33 to 54) |
| Sex: Female, Male: Female | Participants | 2 | 3 | 2 | 1 | 2 | 2 |
| Sex: Female, Male: Male | Participants | 1 | 0 | 1 | 2 | 1 | 1 |
| Race and Ethnicity Not Collected | Participants | — | — | — | — | — | — |
| Bodyweight (kg) | kg | 79 (61 to 96) | 66 (59 to 69.6) | 78 (76 to 89.4) | 88 (62 to 94) | 70.1 (61.2 to 79) | 81 (72.8 to 91) |
| BMI (kg/m^2) | kg/m^2 | 23 (22.1 to 31.0) | 22.4 (18.4 to 24.4) | 26.0 (24.9 to 32.1) | 24.9 (22.8 to 28.4) | 23.6 (20.5 to 25.4) | 26.4 (24.9 to 26.9) |
6. Primary Endpoint
The registry lists the primary outcome as Number of at Least Possibly Related Grade 3 Adverse Events (AE) and Serious Adverse Events (SAE), measured over up to 28 weeks.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | adverse events |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the number of at least possibly related Grade 3 adverse events and serious adverse events, with a timeframe of up to 28 weeks. It is a safety endpoint: it counts events meeting the stated severity or seriousness criteria and judged at least possibly related to the vaccine. The registry describes it as a number of adverse events, not as a measure of antibody response or protection against infection.
Safety endpoints are important in an early-stage study because they describe unwanted events observed after exposure and can guide further evaluation of a dose or formulation. An event count can be clinically informative, but its interpretation depends on what was counted, how events were graded and attributed, the observation period, and the number of participants under observation. Those details affect how comparable counts are across groups.
In this record, the primary endpoint’s wording is more specific than the posted adverse-event group listing. The listing gives participants at risk and participants affected by serious or other adverse events, but it does not, in the registry record, identify which individual events were Grade 3, at least possibly related, or included in the primary endpoint count. The posted group counts therefore should not be treated as a direct numerical report of the full primary endpoint without that correspondence being stated in the registry record.
The brief summary separately describes assessing immunogenicity and tolerability 14 days following first vaccination. That is part of the trial’s stated aim, but it is not the primary safety endpoint.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted results are safety observations from a small, sequential, non-randomized phase 1 study. The group-level listing records no deaths. It records serious adverse events affecting 1 participant in Group 1B and 1 participant in Group 7; the other listed groups have 0 participants affected by serious adverse events. The denominators shown for these groups differ, so these counts should be read alongside their respective group sizes rather than as a direct comparison of risk.
The listing records participants affected by other adverse events in every group: the affected count matches the at-risk count in each listed group. This is a descriptive feature of the registry table, not evidence that event types, severity, duration, or clinical importance were the same across groups. The serious-adverse-event terms shown at the top of the listing are Superficial basal cell carcinoma (33.3%) and Ligament rupture (16.7%). The record excerpt does not explain the denominator used for those percentages, so they should not be converted into participant counts.
These group summaries do not establish that one dose or formulation is safer than another. Assignment was not randomized, and the record explicitly identifies the design as sequential. As a result, the group comparisons are not controlled like-for-like contrasts. The group sizes are small, and a count of zero in a group does not demonstrate that an event cannot occur. Conversely, an observed event count by itself does not establish that the vaccine caused the event. The endpoint’s attribution criterion is “at least possibly related,” but the group table does not say which listed serious events satisfy that criterion or whether they were Grade 3.
The posted data are therefore best read as a record of reported safety experience within the described groups. They do not supply confidence intervals, hypothesis tests, or adjusted comparisons. The registry lists 0 analyses, and inferential analyses for these group contrasts are not reported in the registry record. The counts can be useful for describing what was recorded during the study, while remaining too limited to support precise comparative conclusions.
The stated aim also includes identifying a dose and formulation that optimize the immunogenicity-tolerability ratio. The registry entries do not include immunogenicity results or an analysis of that ratio. That part of the aim cannot be evaluated from the safety counts alone. The registry’s completed status indicates that the study is recorded as completed, but completion does not by itself resolve the evidential limitations of its design or the completeness of the posted endpoint reporting.
9. Statistical Methods Explained
What the design implies
In a randomized comparison, random assignment is intended to make groups more comparable on average, so observed differences can be interpreted more directly as treatment contrasts. This study is listed as non-randomized and sequential. In a sequential dose exploration, later groups may be enrolled after earlier groups, and their assigned doses may depend on what was achieved in earlier groups. Differences between groups can therefore reflect more than dose or formulation alone. The registry record does not report enough detail to characterize the sequence beyond the group descriptions.
The study is also listed as having no masking. In general, masking can reduce the influence of knowledge of treatment assignment on participant reporting or investigator assessment. Without masking, subjective assessments may be more open to such influence. The registry record does not state whether any particular outcome assessment was independently reviewed or otherwise protected from this possibility.
Counts, denominators and precision
A count reports how many events or participants meeting a definition were observed. A denominator describes how many participants were at risk or assessed. Both are needed to understand the scope of a count. Here, the safety listing gives at-risk and affected counts by group, with group sizes that vary. The posted results are descriptive; they do not include uncertainty intervals for these figures.
In general, a confidence interval expresses a range of values compatible with the observed data under a specified statistical model. It can show how imprecise a result is, especially when group sizes are small or events are uncommon. No confidence intervals for the reported safety counts are included in the registry record. The registry record does not report a statistical model or inferential method for these outcomes.
Counts of participants affected and counts of events are not interchangeable. One participant can experience more than one event, and event listings may use different rules for grouping or attribution. The primary endpoint is written as a number of events meeting severity, seriousness, and relatedness criteria. The adverse-event table instead gives affected-participant counts for serious and other events. Since the registry entries do not map those entries to the primary endpoint’s exact criteria, the table should not be treated as a complete endpoint analysis.
Why the sequential comparison matters
With non-randomized group assignment, a difference in observed counts may have several explanations, including chance variation, group composition, timing, dose, or formulation. The registry does not report enough information to separate these explanations. The descriptions of Groups 6 and 7 also define dose by reference to doses achieved earlier, rather than specifying a fixed dose in advance. This makes the group structure relevant to interpretation and cautions against treating every row as an independent, planned head-to-head comparison.
Over-dispersion is a general issue for count data: it occurs when observed variability is greater than a simple count model expects. In that situation, methods that assume less variability can give intervals that are too narrow or tests that are too confident. The record does not report an over-dispersion assessment or a count model, so it is not possible to say whether this issue was evaluated in the trial analysis.
Multiplicity and analysis choices
Multiplicity arises when many outcomes or comparisons are examined. In general, the more statistical tests conducted, the greater the chance of finding an apparently notable result by chance unless the analysis plan accounts for the number of tests. The registry lists 7 outcome measures and 0 analyses. It does not report a multiplicity strategy, a hierarchy of outcomes, or which comparisons, if any, were intended for formal testing. No p-values or adjusted estimates for the group comparisons are included in the registry record.
The primary endpoint combines events described by grade and seriousness, with an attribution threshold of at least possibly related. For a reproducible analysis, definitions and rules for event handling would matter: for example, whether repeated events in one participant are counted separately and how events meeting more than one category are handled. These operational details are not reported in the registry record. They should not be assumed from the endpoint title alone.
Sample-size illustrations
The sample-size section is a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Its calculations are illustrations of what a future study might require under those assumptions; they are not the design justification for this trial and are not observed power. The registry entries do not include the calculated planning values, so no such values are repeated.
More generally, sample-size planning depends on the outcome, target effect, variability or event frequency, allocation, and analysis method. Those assumptions can be especially influential for rare safety outcomes. A planning calculation cannot substitute for the observed evidence, and an observed count cannot retrospectively establish the power of a study. The registry record does not report the trial’s own sample-size justification.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists 7 outcome measures, including the primary safety endpoint and a secondary outcome for the number of participants with at least possibly related solicited adverse events. It also lists 0 analyses. The registry entries do not give a multiplicity procedure, a prespecified hierarchy among outcomes, or a plan for selecting comparisons. Consequently, the reported group summaries should be treated as descriptive rather than as results from a documented family of confirmatory tests.
Missing-data handling is not reported in the registry record. The registry entries do not state whether every enrolled participant completed follow-up, whether any observations were unavailable, how incomplete adverse-event reporting was handled, or whether the denominator changed over the endpoint timeframe. The at-risk counts in the safety listing are useful context, but they do not by themselves explain follow-up completeness or missingness.
The analysis populations are also not reported in the registry record. The registry entries do not identify a safety population, an immunogenicity population, or rules for including participants who did not receive all planned vaccinations. No imputation method or sensitivity analysis is described. These omissions limit assessment of how the analyzed groups were defined and whether missing observations could affect the summaries.
These points matter because multiplicity, incomplete follow-up, and population definitions can influence how results are summarized and interpreted. They do not show that a particular problem occurred; they mean the registry information does not establish how it was addressed.
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 |
|---|---|---|---|
| Group 1A: 6 Microgram ABNCoV2 Without MF59 Adjuvant | 0 | 3 | 0.0% |
| Group 1B: 6 Microgram ABNCoV2 With MF59 Adjuvant | 1 | 3 | 33.3% |
| Group 2A: 12 Microgram ABNCoV2 Without MF59 Adjuvant | 0 | 3 | 0.0% |
| Group 2B: 12 Microgram ABNCoV2 With MF59 Adjuvant | 0 | 3 | 0.0% |
| Group 3A: 25 Microgram ABNCoV2 Without MF59 Adjuvant | 0 | 3 | 0.0% |
| Group 3B: 25 Microgram ABNCoV2 With MF59 Adjuvant | 0 | 3 | 0.0% |
| Group 4: 50 Microgram ABNCoV2 Without MF59 Adjuvant | 0 | 6 | 0.0% |
| Group 5: 70 Microgram ABNCoV2 Without MF59 Adjuvant | 0 | 6 | 0.0% |
| Group 6: 25 Microgram ABNCoV2 Without MF59 Adjuvant | 0 | 9 | 0.0% |
| Group 7: 50 Microgram ABNCoV2 Without MF59 Adjuvant | 1 | 6 | 16.7% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Group 1A: 6 Microgram ABNCoV2 Without MF59 Adjuvant | 0 of 3 |
| Group 1B: 6 Microgram ABNCoV2 With MF59 Adjuvant | 0 of 3 |
| Group 2A: 12 Microgram ABNCoV2 Without MF59 Adjuvant | 0 of 3 |
| Group 2B: 12 Microgram ABNCoV2 With MF59 Adjuvant | 0 of 3 |
| Group 3A: 25 Microgram ABNCoV2 Without MF59 Adjuvant | 0 of 3 |
| Group 3B: 25 Microgram ABNCoV2 With MF59 Adjuvant | 0 of 3 |
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 |
|---|---|
| Group 1A: 6 Microgram ABNCoV2 Without MF59 Adjuvant | 3 of 3 |
| Group 1B: 6 Microgram ABNCoV2 With MF59 Adjuvant | 3 of 3 |
| Group 2A: 12 Microgram ABNCoV2 Without MF59 Adjuvant | 3 of 3 |
| Group 2B: 12 Microgram ABNCoV2 With MF59 Adjuvant | 3 of 3 |
| Group 3A: 25 Microgram ABNCoV2 Without MF59 Adjuvant | 3 of 3 |
| Group 3B: 25 Microgram ABNCoV2 With MF59 Adjuvant | 3 of 3 |
Most frequent serious adverse event terms
| Event term | Organ system | Group 1A: 6 Microgram ABNCoV2 Without MF59 Adjuvant | Group 1B: 6 Microgram ABNCoV2 With MF59 Adjuvant | Group 2A: 12 Microgram ABNCoV2 Without MF59 Adjuvant | Group 2B: 12 Microgram ABNCoV2 With MF59 Adjuvant | Group 3A: 25 Microgram ABNCoV2 Without MF59 Adjuvant | Group 3B: 25 Microgram ABNCoV2 With MF59 Adjuvant |
|---|---|---|---|---|---|---|---|
| Superficial basal cell carcinoma | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 0 of 3 | 1 of 3 | 0 of 3 | 0 of 3 | 0 of 3 | 0 of 3 |
| Ligament rupture | Musculoskeletal and connective tissue disorders | 0 of 3 | 0 of 3 | 0 of 3 | 0 of 3 | 0 of 3 | 0 of 3 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Group 1A: 6 Microgram ABNCoV2 Without MF59 Adjuvant | Group 1B: 6 Microgram ABNCoV2 With MF59 Adjuvant | Group 2A: 12 Microgram ABNCoV2 Without MF59 Adjuvant | Group 2B: 12 Microgram ABNCoV2 With MF59 Adjuvant | Group 3A: 25 Microgram ABNCoV2 Without MF59 Adjuvant | Group 3B: 25 Microgram ABNCoV2 With MF59 Adjuvant |
|---|---|---|---|---|---|---|---|
| Pain | Skin and subcutaneous tissue disorders | 2 of 3 | 3 of 3 | 3 of 3 | 3 of 3 | 3 of 3 | 3 of 3 |
| Headache | General disorders | 1 of 3 | 3 of 3 | 2 of 3 | 2 of 3 | 3 of 3 | 2 of 3 |
| Tenderness | Skin and subcutaneous tissue disorders | 0 of 3 | 3 of 3 | 3 of 3 | 2 of 3 | 1 of 3 | 3 of 3 |
| Fatigue | General disorders | 1 of 3 | 2 of 3 | 2 of 3 | 3 of 3 | 0 of 3 | 2 of 3 |
| Induration | Skin and subcutaneous tissue disorders | 1 of 3 | 1 of 3 | 0 of 3 | 1 of 3 | 1 of 3 | 1 of 3 |
| Chills | General disorders | 0 of 3 | 1 of 3 | 0 of 3 | 0 of 3 | 1 of 3 | 0 of 3 |
| Drowsiness | General disorders | 0 of 3 | 0 of 3 | 0 of 3 | 0 of 3 | 0 of 3 | 1 of 3 |
| Erythema | Skin and subcutaneous tissue disorders | 0 of 3 | 0 of 3 | 0 of 3 | 0 of 3 | 0 of 3 | 0 of 3 |
| Fever | General disorders | 0 of 3 | 0 of 3 | 0 of 3 | 0 of 3 | 0 of 3 | 0 of 3 |
Serious events with the highest arm-level rate: superficial basal cell carcinoma (33.3%), ligament rupture (16.7%).
The safety listing gives, for each group, the number at risk and the number affected by serious and other adverse events, as well as deaths. It records 0 deaths in every listed group. For serious adverse events, the affected counts are 1 in Group 1B and 1 in Group 7, and 0 in the other listed groups. Read these counts together with the denominators shown in the table; the groups are not all the same size.
The listing also shows an affected count for other adverse events equal to the at-risk count in each group. This is a participant-level summary as represented in the table, not a count of every individual event. It does not establish that all events had the same grade, duration, or relationship to vaccination. The primary endpoint is narrower: it counts at least possibly related Grade 3 adverse events and serious adverse events. The registry entries do not identify which of the serious events in the table meet all of those primary-endpoint criteria.
The serious-event terms and percentages are Superficial basal cell carcinoma (33.3%) and Ligament rupture (16.7%). The registry excerpt does not state the denominator for those percentages. These figures should therefore be read as the terms and percentages posted, without deriving additional counts from them.
These data describe reported events; they do not alone establish causation or support a reliable ranking of dose groups.
12. What the Result Does, and Does Not, Mean
The record documents a completed phase 1 study of ABNCoV2 in healthy adult volunteers, with dose and formulation groups arranged sequentially and without randomization or masking. Its primary safety endpoint is the number of at least possibly related Grade 3 adverse events and serious adverse events up to 28 weeks. The posted listing provides group-level counts of participants affected by serious and other adverse events and reports no deaths.
Those observations are useful as descriptive safety information from this study. They show what the registry lists for each group, including the presence of serious adverse events in two groups and other adverse events in every group. They do not reveal the complete clinical details of each event, establish whether every serious event met the primary endpoint’s grade and relatedness criteria, or quantify uncertainty around the group counts.
The record does not support a causal conclusion from an event count alone. Nor does it allow a sound head-to-head comparison of dose or adjuvant formulation: assignment was non-randomized, groups were sequential, group sizes varied, and a randomized control comparison is not described. A zero count in a group is an observation in that group, not proof that the event is impossible. A nonzero count does not, on its own, show that vaccination caused the event.
The broader study aim includes assessing immunogenicity and tolerability and identifying a dose and formulation that optimize their balance. The registry entries do not include immunogenicity results or a quantitative assessment of that balance, so that aim cannot be judged from these safety summaries. Likewise, the record does not provide the trial’s sample-size justification or a detailed statistical analysis plan.
In short, the page should be read as an account of posted safety observations and the design context needed to interpret them. It is not a definitive comparison of formulations, a complete analysis of all primary-endpoint criteria, or evidence about outcomes beyond those recorded in the registry.
13. Why This Trial Matters Statistically
This trial matters statistically because it illustrates the distinction between describing early safety observations and estimating a comparative treatment effect. The record lists multiple dose and formulation groups, but the study is non-randomized and sequential. A row-by-row comparison can look like a treatment contrast even when the design does not make groups directly comparable. Recognizing that distinction prevents descriptive counts from being read as proof that one formulation or dose differs from another.
The endpoint definition also matters. The primary endpoint refers to events that are at least possibly related and either Grade 3 or serious, while the posted table summarizes participants affected by serious or other adverse events. These are not interchangeable descriptions. Clear alignment between an endpoint definition and the reported data is necessary to understand whether the results answer the stated primary question.
Small group counts call for particular care. With few participants, event counts can change substantially in relative terms when only a small number of observations differ, while uncertainty remains substantial. In general, intervals and transparent denominators help convey that uncertainty. No confidence intervals or inferential analyses are reported in the registry record.
Finally, the trial’s broader aim concerns both immunogenicity and tolerability, but the safety listing alone addresses only part of that objective. Keeping endpoint scope, design, denominator, and analysis distinct is central to reading early-phase registry results accurately. The record offers a useful example of why the strength of a conclusion must match the strength and type of evidence available.
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.
Several limitations specific to this trial constrain interpretation. The study is listed as non-randomized, unmasked, and sequential, so its groups are not randomized, like-for-like controls. The record describes dose selection in Groups 6 and 7 in relation to doses achieved earlier, and the exact doses in those groups are marked t.b.d. Group sizes shown in the safety listing vary. These features make direct comparisons across dose or formulation groups particularly limited.
The endpoint and safety table do not fully align in the registry record presented. The primary endpoint is a number of at least possibly related Grade 3 adverse events and serious adverse events, whereas the safety table reports participants affected by serious and other adverse events. The record does not specify which listed events meet the primary endpoint’s grade and relatedness criteria. It therefore does not permit reconstruction of the primary endpoint count from the group summaries alone.
The information presented does not include confidence intervals, p-values, adjusted comparisons, or a stated statistical model. Although the registry lists 7 outcome measures, it lists 0 analyses. A multiplicity strategy, analysis populations, missing-data handling, and sample-size justification are not reported in the registry record. These gaps limit assessment of the planned and performed analyses.
The serious-event terms are accompanied by percentages, but their denominator is not stated in the registry record. The record also does not provide detailed event narratives or follow-up completeness. Finally, the stated immunogenicity-tolerability objective cannot be assessed from these safety counts because immunogenicity results are not included in the registry record presented.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Safety and Tolerability of COVID-19 Vaccine (ABNCoV2) — NCT04839146.
- Registry record last updated 2026-02-17; status last verified 2022-03.
- Results first posted 2024-02-12.
- 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
This page analyzes NCT04839146, titled “Safety and Tolerability of COVID-19 Vaccine (ABNCoV2).” The registry describes a phase 1, non-randomized, unmasked, sequential trial sponsored by Radboud University Medical Center, with an enrollment of 45 and completed status. The recorded start date is 2021-03-11, and the primary completion date is 2021-12-30.
The study evaluated ABNCoV2 dose and formulation groups in healthy adult volunteers described as SARS-CoV-2-naïve. Its primary endpoint was the number of at least possibly related Grade 3 adverse events and serious adverse events up to 28 weeks. The posted safety listing records no deaths, serious adverse events in two groups, and other adverse events among participants in every listed group.
Because the design was sequential and non-randomized, the group counts are descriptive and do not constitute randomized comparisons. The registry lists 7 outcome measures and 0 analyses. Detailed statistical methods, analysis populations, missing-data handling, and sample-size justification are not reported in the registry record.