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, Tolerability, and Immunogenicity of Zika Vaccine mRNA-1893 in Healthy Flavivirus Seropositive and Seronegative Adults (NCT04064905), a randomized phase 1 study. The primary outcome is Number of Participants With Solicited Local and Systemic Reactogenicity Adverse Reaction (ARs)-First Vaccination.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04064905 |
| Phase | Phase 1 |
| Condition | Zika Virus |
| Allocation | Randomized |
| Design model | Sequential |
| Masking | Triple |
| Enrollment | 120 |
| Arms in the primary outcome | n/a |
| Lead sponsor | ModernaTX, Inc. |
| Results posted | Yes |
2. Clinical Question
Population
The study enrolled healthy adults who were flavivirus seropositive or flavivirus seronegative. The registry record does not report the number in each serostatus subgroup or further participant characteristics. The primary safety outcome used a population of participants who had received the first study vaccination and contributed solicited adverse-reaction data during the specified follow-up.
Intervention
Participants received mRNA-1893 at one of the registered dose levels: 10 mcg, 30 mcg, 100 mcg, or 250 mcg. The study evaluated safety, tolerability, reactogenicity, and immune responses. The registry record identifies the vaccine as a biological intervention but does not report further formulation details in the information.
Comparator
The comparator was placebo, described as 0.9% sodium chloride. The registry record describes the study as placebo-controlled and randomized. It does not report the allocation sequence or the specific procedures used to conceal assignments.
Primary question
The primary outcome was the number of participants with solicited local or systemic reactogenicity adverse reactions after the first vaccination, collected through Day 7. The outcome description identifies the reactions monitored, but numerical primary-outcome results by group are not reported in the registry record. The posted adverse-event counts are not a substitute for those primary results.
3. Trial Design
This was a Phase 1, randomized, observer-blind, placebo-controlled, dose-ranging study of mRNA-1893 in healthy flavivirus seropositive and seronegative adults. The registry record describes the masking as triple and the study model as sequential. It does not identify which roles were masked or provide details about the sequence of study conduct, so those aspects cannot be described more specifically.
The registered enrollment was 120. The intervention groups reported for adverse events were placebo and mRNA-1893 at 10 mcg, 30 mcg, 100 mcg, and 250 mcg. The placebo is described as 0.9% sodium chloride. The adverse-event group figures each list 24 participants at risk, but this should not be taken as a complete account of enrollment, the serostatus distribution, or the analysis population for every outcome.
The study started on 2019-07-30, reached primary completion on 2021-03-22, and is listed as completed. ModernaTX, Inc. is identified as sponsor. The registry summary says the study evaluated safety, tolerability, and reactogenicity; the registered secondary outcomes also include neutralizing-antibody titers and seroconversion measures.
The registry record does not report the rationale for the enrollment target, detailed eligibility criteria, dose-escalation or cohort-progression rules, or the planned allocation ratio. The sequential model label alone does not establish how participants moved through dose groups or whether decisions were made between groups. No additional protocol details should be inferred from the design labels.
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 | Placebo | mRNA-1893 10 mcg | mRNA-1893 30 mcg | mRNA-1893 100 mcg | mRNA-1893 250 mcg |
|---|---|---|---|---|---|
| STARTED | 24 | 24 | 24 | 24 | 24 |
| Received First Vaccination | 24 | 24 | 24 | 24 | 24 |
| Received Second Vaccination | 24 | 23 | 23 | 24 | 24 |
| COMPLETED | 24 | 21 | 23 | 20 | 22 |
| NOT COMPLETED | 0 | 3 | 1 | 4 | 2 |
Reasons for not completing this period:
| Reason | Placebo | mRNA-1893 10 mcg | mRNA-1893 30 mcg | mRNA-1893 100 mcg | mRNA-1893 250 mcg |
|---|---|---|---|---|---|
| Lost to Follow-up | 0 | 3 | 1 | 4 | 2 |
Analysis population for the primary outcome, as defined in the registry: The First Vaccination Solicited Safety Set consisted of all participants in the Safety Set who had received the first study vaccination and had contributed any solicited AR data (local or systemic reactogenicity events) from the time of first study vaccination through the following 7 days. Here, number analyzed signifies those participants who were evaluable at specified categories.
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: The Safety Set consisted of all participants who received at least 1 dose of study vaccine (mRNA-1893 or placebo).
| Characteristic | Unit | Placebo | mRNA-1893 10 mcg | mRNA-1893 30 mcg | mRNA-1893 100 mcg | mRNA-1893 250 mcg | Total |
|---|---|---|---|---|---|---|---|
| Participants analysed | 24 | 24 | 24 | 24 | 24 | 120 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 24 | 24 | 24 | 24 | 24 | 120 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 16 | 18 | 11 | 14 | 11 | 70 |
| Sex: Female, Male: Male | Participants | 8 | 6 | 13 | 10 | 13 | 50 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 6 | 5 | 8 | 5 | 5 | 29 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 18 | 19 | 16 | 19 | 19 | 91 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 | 0 | 0 | 0 |
| Race/Ethnicity, Customized: American Indian or Alaska Native | Participants | 0 | 1 | 0 | 0 | 0 | 1 |
| Race/Ethnicity, Customized: Asian | Participants | 0 | 0 | 0 | 1 | 0 | 1 |
| Race/Ethnicity, Customized: Black or African American | Participants | 4 | 2 | 9 | 1 | 12 | 28 |
| Race/Ethnicity, Customized: White | Participants | 20 | 21 | 14 | 22 | 12 | 89 |
| Race/Ethnicity, Customized: Other | Participants | 0 | 0 | 1 | 0 | 0 | 1 |
| Flavivirus Serostatus: Seropositive | Participants | 4 | 4 | 4 | 4 | 4 | 20 |
| Flavivirus Serostatus: Seronegative | Participants | 20 | 20 | 20 | 20 | 20 | 100 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Solicited Local and Systemic Reactogenicity Adverse Reaction (ARs)-First Vaccination, measured over Up to Day 7 after first vaccination (up to 8 days).
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint counts participants with solicited local or systemic reactogenicity adverse reactions after the first vaccination. Solicited reactions were collected in a daily diary through the following 7 days, with the outcome timeframe described as up to Day 7 after first vaccination (up to 8 days). Local reactions included injection site pain, erythema, and induration or swelling. Systemic reactions included oral body temperature, generalized myalgia, generalized arthralgia, headache, fatigue or malaise, nausea or vomiting, chills, and rash.
This participant-count endpoint is useful for describing how many people reported at least one of the specified reactions during the assessment period. As a count, it does not by itself describe the number of episodes, duration, severity, or pattern of each reaction. The registry record states that this endpoint reports data only through 7 days after the first study vaccination. It separately directs readers to the adverse-events section for summaries of serious adverse events and nonserious adverse events classified as “Other,” regardless of causality.
The endpoint’s population is the First Vaccination Solicited Safety Set: participants in the Safety Set who received the first vaccination and contributed any solicited local or systemic reaction data during the stated period. Numerical results for this primary endpoint are not reported in the registry record, so a comparison of the observed primary counts among groups cannot be described.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registered primary question concerns solicited local and systemic reactions after the first vaccination. Although its measurement period and reaction categories are described, numerical results for that endpoint are not reported in the registry record. Consequently, the record does not support a quantitative comparison of primary-endpoint counts across placebo and vaccine dose groups. It also does not provide an effect estimate, confidence interval, or significance test for that primary comparison.
The adverse-event figures do contain group counts. Serious adverse events are listed for 3 participants in the placebo group and 1 participant in the mRNA-1893 250 mcg group; none are listed in the 10 mcg, 30 mcg, or 100 mcg groups. The record lists no deaths in any group. These are descriptive counts, not evidence that a group difference is statistically reliable. No uncertainty interval or inferential comparison for these figures is reported.
For nonserious adverse events classified as “Other,” the registry lists 17 participants in the placebo group, 21 in the 10 mcg group, 21 in the 30 mcg group, 22 in the 100 mcg group, and 20 in the 250 mcg group. These figures are distinct from the solicited reactogenicity endpoint: the primary outcome is restricted to specified reactions collected by diary during the period after the first vaccination, whereas the “Other” summary is described as covering nonserious adverse events regardless of causality. The categories should not be treated as interchangeable.
The study also registered immune-response outcomes, including geometric mean neutralizing-antibody titers measured by PRNT50 and seroconversion or fold-increase measures at specified follow-up times. The outcome names indicate what was planned for assessment, not what was observed. Numerical results for those outcomes are not reported in the registry record, so no conclusion about the magnitude, precision, or pattern of immune responses can be drawn from these entries.
In general, a confidence interval communicates the range of values compatible with an estimate under the statistical model, and its width helps describe precision. Because the primary endpoint and immune-response estimates and their uncertainty are not reported in the registry record, their precision cannot be assessed. The adverse-event counts likewise lack reported uncertainty intervals. The absence of such statistics in this record does not establish that no analyses were performed elsewhere; it means the record does not report them.
9. Statistical Methods Explained
The registered primary outcome is a binary participant-level measure: whether a participant had a solicited local or systemic reactogenicity adverse reaction during the specified period after first vaccination. The registry describes the result as a number of participants. In general, a binary endpoint records whether an event occurred for each participant, rather than the number of times it occurred. The listed local and systemic symptoms define the reactions considered for this outcome. The registry does not report a numerical result by group, nor does it report a specific statistical model or test for comparing groups.
What does a participant count tell us?
A count is a direct descriptive summary of the participants recorded as having an event. To interpret a count as a frequency, the relevant denominator and the definition of the analysis population also matter. The primary population is described as participants in the Safety Set who received the first vaccination and contributed any solicited reaction data through the following 7 days. The registry record does not provide the primary endpoint’s group-specific counts or denominators in the information, so event proportions should not be inferred or calculated.
General statistical explanation: a comparison of binary outcomes can be expressed in several ways, such as a difference in event proportions or a relative measure. Each answers a different question, and estimates are more informative when accompanied by uncertainty intervals. No such primary-endpoint comparison or interval is reported in the registry record. Recalculations from posted summary statistics are therefore not applicable to this primary endpoint.
How should the antibody outcomes be understood?
The registered secondary outcomes include geometric mean titers of neutralizing antibody against Zika virus, measured by plaque reduction neutralization test (PRNT50). Separate outcomes name initially seronegative and initially seropositive participants. A geometric mean is a summary suited to measurements that are analyzed on a multiplicative scale; in general, it describes a central level after accounting for that scale rather than an ordinary arithmetic average. The registry lists these outcomes but does not report their numerical values or uncertainty in the information.
Other registered outcomes include the percentage of participants who seroconverted from Day 1 to Day 29, from Day 1 to Day 57, from Day 1 to Month 7, and from Day 1 to Month 13. Further outcomes count initially seronegative participants with a seroresponse and initially seropositive participants with a 2-fold or 4-fold increase in neutralizing-antibody titers compared with baseline. These are distinct definitions and populations. The outcome labels alone do not establish the results, denominators, or statistical methods used for each analysis.
Why can over-dispersion matter?
General statistical explanation: over-dispersion occurs when observed variability is greater than a model assumes. It is especially relevant to count data when events cluster within participants or when participants differ in their underlying event rates. This primary endpoint is defined as a count of participants with a reaction, not a recurrent-event count, and the registry does not report an over-dispersion assessment or a model that would require such an adjustment. Therefore, over-dispersion should not be assumed to have been present or addressed in the trial analysis.
What do the planning assumptions mean?
The sample-size assumptions describe planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The stated effect to detect is a fraction of the observed effect. These are planning assumptions, not a report of the trial’s original design rationale or an observed-power calculation. The registry record does not report the trial’s sample-size justification. It also does not provide numerical planning estimates in the information, so none can be reproduced or interpreted.
In general, a planning illustration asks how much information a hypothetical study might need under specified assumptions. It does not show the probability that the completed trial detected an effect, and it does not change the uncertainty in the observed results. Any illustrations based on fractions of an observed effect depend on the chosen assumptions and should not be confused with the trial’s prespecified plan. The registry record does not establish whether these assumptions were used by the sponsor.
Which analysis details are missing?
The registry record reports zero analyses in the analysis listing. It does not report the statistical test, model, covariate adjustment, confidence-interval method, or handling of multiple comparisons for the primary or secondary outcomes. The record also does not report whether interim analyses were planned or conducted. These items are not reported in the registry record and should not be inferred from the study’s randomized or masked design.
10. Multiplicity, Missing Data and Analysis Populations
The record names multiple outcomes: solicited reactions after first vaccination, several neutralizing-antibody geometric mean titer outcomes, seroconversion at multiple follow-up times, and seroresponse or fold-increase counts for serostatus subgroups. When many outcomes or time points are assessed, general statistical practice considers multiplicity because repeated testing can increase the chance of at least one apparently unusual result. The registry record does not report a multiplicity adjustment, a hierarchy among outcomes, or a prespecified strategy for interpreting these results.
Numerical primary-endpoint results are not reported in the registry record, and the secondary immune-response outcomes are listed without numerical results in the information. Therefore, it is not possible to assess how missing observations affected those outcomes or whether analyses used a particular missing-data method. Imputation, censoring rules, sensitivity analyses, and reasons for missing measurements are not reported in the registry record.
The primary outcome population is described as the First Vaccination Solicited Safety Set, including participants in the Safety Set who received the first vaccination and contributed any solicited reaction data during follow-up. The broader Safety Set definition and the analysis populations for secondary outcomes are not reported in the registry record. The registered enrollment and adverse-event group figures do not establish the denominators used for every endpoint. Analysis population definitions, exclusions, and outcome-specific missingness should therefore not be inferred.
The registry record does not report whether interim analyses were conducted, nor does it specify stopping rules or other sequential decision procedures. The study model is labeled sequential, but that label does not supply those details.
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 |
|---|---|---|---|
| Placebo | 3 | 24 | 12.5% |
| mRNA-1893 10 mcg | 0 | 24 | 0.0% |
| mRNA-1893 30 mcg | 0 | 24 | 0.0% |
| mRNA-1893 100 mcg | 0 | 24 | 0.0% |
| mRNA-1893 250 mcg | 1 | 24 | 4.2% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Placebo | 0 of 24 |
| mRNA-1893 10 mcg | 0 of 24 |
| mRNA-1893 30 mcg | 0 of 24 |
| mRNA-1893 100 mcg | 0 of 24 |
| mRNA-1893 250 mcg | 0 of 24 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 2% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Placebo | 17 of 24 |
| mRNA-1893 10 mcg | 21 of 24 |
| mRNA-1893 30 mcg | 21 of 24 |
| mRNA-1893 100 mcg | 22 of 24 |
| mRNA-1893 250 mcg | 20 of 24 |
Most frequent serious adverse event terms
| Event term | Organ system | Placebo | mRNA-1893 10 mcg | mRNA-1893 30 mcg | mRNA-1893 100 mcg | mRNA-1893 250 mcg |
|---|---|---|---|---|---|---|
| Nephrolithiasis | Renal and urinary disorders | 0 of 24 | 0 of 24 | 0 of 24 | 0 of 24 | 1 of 24 |
| Diverticulitis | Infections and infestations | 1 of 24 | 0 of 24 | 0 of 24 | 0 of 24 | 0 of 24 |
| Hand fracture | Injury, poisoning and procedural complications | 1 of 24 | 0 of 24 | 0 of 24 | 0 of 24 | 0 of 24 |
| Adjustment disorder with depressed mood | Psychiatric disorders | 1 of 24 | 0 of 24 | 0 of 24 | 0 of 24 | 0 of 24 |
| Anxiety | Psychiatric disorders | 1 of 24 | 0 of 24 | 0 of 24 | 0 of 24 | 0 of 24 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Placebo | mRNA-1893 10 mcg | mRNA-1893 30 mcg | mRNA-1893 100 mcg | mRNA-1893 250 mcg |
|---|---|---|---|---|---|---|
| Injection site pain | General disorders | 3 of 24 | 14 of 24 | 16 of 24 | 20 of 24 | 17 of 24 |
| Headache | Nervous system disorders | 8 of 24 | 12 of 24 | 12 of 24 | 11 of 24 | 13 of 24 |
| Fatigue | General disorders | 5 of 24 | 9 of 24 | 11 of 24 | 11 of 24 | 14 of 24 |
| Myalgia | Musculoskeletal and connective tissue disorders | 2 of 24 | 12 of 24 | 7 of 24 | 11 of 24 | 16 of 24 |
| Chills | General disorders | 3 of 24 | 2 of 24 | 6 of 24 | 11 of 24 | 14 of 24 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 3 of 24 | 6 of 24 | 5 of 24 | 9 of 24 | 8 of 24 |
| Pyrexia | General disorders | 1 of 24 | 2 of 24 | 4 of 24 | 8 of 24 | 11 of 24 |
| Nausea | Gastrointestinal disorders | 2 of 24 | 5 of 24 | 3 of 24 | 6 of 24 | 6 of 24 |
| Injection site erythema | General disorders | 0 of 24 | 0 of 24 | 1 of 24 | 3 of 24 | 3 of 24 |
| Injection site swelling | General disorders | 0 of 24 | 0 of 24 | 2 of 24 | 2 of 24 | 3 of 24 |
Serious events with the highest arm-level rate: nephrolithiasis (4.2%), diverticulitis (4.2%), hand fracture (4.2%), adjustment disorder with depressed mood (4.2%), anxiety (4.2%).
The serious adverse-event figures list 3 affected participants among 24 at risk in the placebo group, none among 24 at risk in the mRNA-1893 10 mcg group, none among 24 at risk in the 30 mcg group, none among 24 at risk in the 100 mcg group, and 1 among 24 at risk in the 250 mcg group. The registry lists no deaths in any of these groups. These are descriptive figures; the record does not report a statistical comparison or uncertainty interval for them.
The serious-event terms listed are nephrolithiasis, diverticulitis, hand fracture, adjustment disorder with depressed mood, and anxiety, each reported as 4.2%. The registry information does not connect those terms to particular treatment groups, so group attribution should not be inferred. The percentages are reproduced as reported and are not recalculated.
Nonserious adverse events classified as “Other” are reported regardless of causality and are separate from solicited reactogenicity. The registry record does not establish that every event was caused by study treatment. Serious-event counts, nonserious “Other” counts, and the primary solicited-reaction endpoint have different definitions and should be read as separate summaries.
12. What the Result Does, and Does Not, Mean
The registry record describes a randomized, placebo-controlled, dose-ranging Phase 1 study that assessed safety and immune-response outcomes in healthy flavivirus seropositive and seronegative adults. It identifies the primary safety endpoint and the reactions included in its definition. It also records group-level counts for serious adverse events, nonserious events classified as “Other,” and deaths.
Those adverse-event counts are descriptive. Without an inferential comparison and uncertainty estimates, they do not establish whether observed differences between groups are larger than would be expected from chance variation. The record also does not report whether events were judged related to vaccination, apart from describing the “Other” summaries as regardless of causality. Serious-event counts should not be treated as a measure of all solicited reactions, and “Other” events should not be substituted for the defined primary endpoint.
The primary endpoint’s numerical results are not reported in the registry record. Nor are numerical results for the registered neutralizing-antibody and seroconversion outcomes included in the information. Consequently, the posted information does not support a quantitative statement about the primary endpoint’s group pattern, the precision of any treatment contrast, or the immune-response results.
In general, a Phase 1 study can provide descriptive information about outcomes measured in its enrolled participants, while estimates remain dependent on the study population, outcome definitions, follow-up, and analysis methods. The registry record does not report enough detail to assess every one of those aspects, including the statistical plan and handling of missing data. The design and outcome descriptions do not, by themselves, establish a clinical benefit or lack of benefit. They define what the trial set out to evaluate; interpretation of results requires reported outcome estimates and their uncertainty.
13. Why This Trial Matters Statistically
This study is statistically notable for separating a defined solicited-reactogenicity endpoint from broader adverse-event summaries and from immune-response outcomes. That distinction matters because each outcome uses different measurements and may involve a different analysis population. A count of participants with specified diary-reported reactions is not interchangeable with a summary of serious events or with a geometric mean antibody titer.
The study also registered outcomes by initial flavivirus serostatus. This makes the distinction between initially seronegative and initially seropositive participants part of the outcome structure, rather than a detail that can be ignored when interpreting antibody summaries. The registry record names serostatus-specific outcomes but does not report their numerical results or subgroup denominators in the information. The subgroup questions therefore remain descriptive aims, not results that can be reconstructed from the outcome titles.
For biostatistical interpretation, the central limitation is the gap between detailed outcome definitions and the absence of numerical primary and immune-response results in the registry record. The safety counts allow limited description, but do not provide estimated contrasts or uncertainty intervals. A randomized design is valuable for a comparative question, yet the design label alone cannot supply the estimates or analysis details needed to judge precision.
The record also illustrates why multiplicity and analysis-population definitions matter in studies with several immune outcomes and time points. Without a reported testing strategy, missing-data approach, or analysis plan, readers cannot determine how those outcomes were jointly interpreted. These are important statistical context, not grounds for assuming that a particular method was used.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The primary solicited-reactogenicity outcome is described in detail, but its numerical group results are not reported in the registry record. This prevents a direct assessment of the principal registered safety outcome and precludes estimation of its between-group uncertainty from these data.
The registry lists multiple antibody and seroconversion outcomes but does not report their numerical findings in the information. The record also does not report the statistical methods used for these outcomes, the approach to multiplicity, or the handling of missing measurements. It does not give outcome-specific denominators or define all analysis populations.
The primary population description refers to participants in the Safety Set who received the first vaccination and contributed solicited reaction data. The broader Safety Set definition is not reported in the registry record. The adverse-event figures give group counts and numbers at risk, but they do not establish that the same analysis population or follow-up applies to every other outcome.
The event summaries have different scopes. Solicited reactions were collected by daily diary through the stated period after the first vaccination. The “Other” adverse-event summary is described as covering nonserious events regardless of causality, and serious adverse events are listed separately. The registry information does not provide enough detail to reconcile these categories or assign each listed serious-event term to a treatment group.
Finally, the record does not report the sample-size justification, detailed masking procedures, allocation ratio, interim-analysis plans, or the full statistical analysis plan. These limitations constrain interpretation of both design intent and inferential precision. They should be treated as unreported details, not filled in through assumptions.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Safety, Tolerability, and Immunogenicity of Zika Vaccine mRNA-1893 in Healthy Flavivirus Seropositive and Seronegative Adults — NCT04064905.
- Registry record last updated 2024-08-21; status last verified 2024-07.
- Results first posted 2024-06-17.
- 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
NCT04064905 is listed as a completed Phase 1 randomized, observer-blind, placebo-controlled, dose-ranging study of mRNA-1893 in healthy flavivirus seropositive and seronegative adults. The study used a sequential model and triple masking, with registered enrollment of 120. The intervention groups in the adverse-event summary were placebo and mRNA-1893 at 10 mcg, 30 mcg, 100 mcg, and 250 mcg.
The primary outcome was the number of participants with solicited local or systemic reactogenicity adverse reactions after first vaccination through Day 7. Numerical primary results are not reported in the registry record. Serious adverse-event counts and nonserious “Other” counts are reported by group, with no deaths listed. Secondary outcomes include PRNT50 neutralizing-antibody titers and seroconversion measures, but numerical results for those outcomes are not reported in the information. The registry record does not report the statistical analysis plan or key details of missing-data and multiplicity handling.