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 Pivotal Phase 2b/3 ALVAC/Bivalent gp120/MF59 HIV Vaccine Prevention Safety and Efficacy Study in South Africa (NCT02968849), a randomized phase 2, phase 3 study. The primary outcome is Incidence Rate of HIV-1 Infection Diagnosed After Enrollment (Concurrent With First Vaccination) Through 24 Months After Enrollment.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02968849 |
| Phase | Phase 2, Phase 3 |
| Condition | HIV Infections |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 5404 |
| Arms in the primary outcome | n/a |
| Lead sponsor | National Institute of Allergy and Infectious Diseases (NIAID) |
| Results posted | Yes |
2. Clinical Question
The central question was whether the ALVAC-HIV and bivalent subtype C gp120/MF59 vaccine regimen was associated with a different rate of HIV-1 infection than placebo among HIV-seronegative South African adults. The primary outcome counted HIV-1 infections diagnosed from enrollment, concurrent with first vaccination, through 24 months after enrollment. The primary analysis population was the MITT cohort; the registry record does not report the cohort’s detailed membership criteria.
Population
HIV-seronegative adults in South Africa. The primary outcome was analyzed in the MITT cohort, but the registry record does not give the cohort’s eligibility details or explain how participants entered it.
Intervention
ALVAC-HIV (vCP2438) plus bivalent subtype C gp120/MF59. The regimen description lists intramuscular ALVAC-HIV at months 0 and 1, followed by ALVAC-HIV plus bivalent subtype C gp120/MF59 at months 3, 6, and 12.
Comparator
Placebo, described as sodium chloride for injection, 0.9%, administered intramuscularly at months 0, 1, 3, 6, and 12.
Primary question
How did the HIV-1 infection rate through 24 months compare between the vaccine and placebo groups? The registry record gives the planned outcome and analysis methods, but not the observed group rates, effect estimate, confidence interval, or test result.
The trial also listed infection outcomes over other follow-up windows, along with immune-response measures. Those secondary outcomes address questions distinct from the primary comparison and should not be treated as substitutes for its unreported numerical result.
3. Trial Design
This was a randomized, quadruple-masked, parallel-group Phase 2b/3 clinical trial with placebo control. The registry lists 5404 participants enrolled. It describes a vaccine group receiving ALVAC-HIV and bivalent subtype C gp120/MF59, and a placebo group receiving sodium chloride for injection, 0.9%. Each arm description states that 2700 participants would receive its assigned regimen. The registry’s adverse-event record lists safety populations of 2704 for the vaccine group and 2700 for placebo; the reasons for the different counts across these descriptions are not reported in the registry record.
The vaccine schedule included intramuscular ALVAC-HIV at months 0 and 1, then ALVAC-HIV plus bivalent subtype C gp120/MF59 at months 3, 6, and 12. Placebo was scheduled at months 0, 1, 3, 6, and 12. The brief summary describes evaluation over 24 months and potentially up to 36 months from enrollment. The primary outcome timeframe was through 24 months after first vaccination; other listed outcomes extend to 36 months or focus on measurements at month 6.5.
The study is marked completed. Its listed start date is 2016-10-26, and its primary completion date is 2021-11-16. The sponsor is the National Institute of Allergy and Infectious Diseases. Although randomization and masking are recorded, details such as the randomization procedure, allocation concealment, and which roles were included in quadruple masking are not reported in the registry record. The record does not give a detailed account of participant flow or explain how enrollment, treatment assignment, and the analysis cohorts relate to one another.
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 | Vaccine | Placebo |
|---|---|---|
| STARTED | 2704 | 2700 |
| Modified Intent-to-Treat (MITT) Cohort | 2695 | 2689 |
| MITT Infected Cohort | 151 | 143 |
| Week 26 At-Risk Cohort | 2430 | 2393 |
| Immunogenicity Cohort | 120 | 10 |
| COMPLETED | 2557 | 2557 |
| NOT COMPLETED | 147 | 143 |
Reasons for not completing this period:
| Reason | Vaccine | Placebo |
|---|---|---|
| Death | 8 | 10 |
| Lost to Follow-up | 31 | 29 |
| Withdrawal by Subject | 73 | 64 |
| Participant Unable to Adhere to Visit Schedule | 13 | 21 |
| Physician Decision | 6 | 9 |
| Other | 16 | 10 |
Analysis population for the primary outcome, as defined in the registry: MITT cohort
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
Population: Safety Cohort
| Characteristic | Unit | Vaccine | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 2704 | 2700 | 5404 | |
| Age, Continuous: Female | Years | 24 (18 to 35) | 23 (18 to 35) | 24 (18 to 35) |
| Age, Continuous: Male | Years | 26 (18 to 35) | 26 (18 to 35) | 26 (18 to 35) |
| Age, Customized: Female – 18 - 20 years | Participants | 349 | 392 | 741 |
| Age, Customized: Female – 21 - 25 years | Participants | 917 | 877 | 1794 |
| Age, Customized: Female – 26 - 30 years | Participants | 465 | 461 | 926 |
| Age, Customized: Female – 31 - 35 years | Participants | 162 | 163 | 325 |
| Age, Customized: Male – 18 - 20 years | Participants | 114 | 98 | 212 |
| Age, Customized: Male – 21 - 25 years | Participants | 271 | 276 | 547 |
| Age, Customized: Male – 26 - 30 years | Participants | 244 | 254 | 498 |
| Age, Customized: Male – 31 - 35 years | Participants | 182 | 179 | 361 |
| Sex: Female, Male: Female | Participants | 1893 | 1893 | 3786 |
| Sex: Female, Male: Male | Participants | 811 | 807 | 1618 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 2704 | 2700 | 5404 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race/Ethnicity, Customized: Black | Participants | 2672 | 2676 | 5348 |
| Race/Ethnicity, Customized: Colored/Mixed | Participants | 23 | 17 | 40 |
| Race/Ethnicity, Customized: White | Participants | 3 | 3 | 6 |
| Race/Ethnicity, Customized: Indian | Participants | 1 | 1 | 2 |
| Race/Ethnicity, Customized: Asian | Participants | 0 | 1 | 1 |
| Race/Ethnicity, Customized: More than one race | Participants | 5 | 2 | 7 |
| Race/Ethnicity, Customized: Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Region of Enrollment: South Africa | Participants | 2704 | 2700 | 5404 |
6. Primary Endpoint
The registry lists the primary outcome as Incidence Rate of HIV-1 Infection Diagnosed After Enrollment (Concurrent With First Vaccination) Through 24 Months After Enrollment, measured over Measured through 24 months after first vaccination.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | events per 100 person-years |
| Endpoint classification | Event-Rate Endpoint |
The primary endpoint is the incidence rate of HIV-1 infection diagnosed after enrollment, concurrent with first vaccination, through 24 months after enrollment. It is expressed as events per 100 person-years and is analyzed in the MITT cohort. An incidence rate relates the number of diagnosed events to the time participants contribute under observation. Unlike a simple proportion, this measure can reflect differences in observed time at risk among participants.
Rates are useful in a prevention trial because the outcome is the occurrence of an infection over follow-up, and participants may contribute different amounts of observation time. A rate comparison can therefore describe the pace at which events arise during the defined period. General statistical context: person-time methods account for exposure time in the denominator, but the resulting estimate still depends on how events and observation time are defined and recorded.
The registry specifies two approaches to comparing groups. Vaccine efficacy was calculated as one minus the hazard ratio from a sex-stratified Cox proportional-hazards model, with a sex-stratified log-rank test. It also describes a ratio of cumulative incidences estimated from Nelson-Aalen cumulative hazards and tested with a Wald test. These are methods for estimating and testing the group contrast; they are not themselves the observed outcome. The registry record does not report the primary event counts, group incidence rates, hazard ratio, cumulative-incidence ratio, vaccine-efficacy estimate, confidence intervals, or test results. Consequently, the magnitude and precision of the primary comparison cannot be assessed from the registry information presented.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a clear primary comparison: HIV-1 infection rates in the vaccine and placebo groups through 24 months, analyzed in the MITT cohort. It also names the statistical methods intended for that comparison. However, it does not provide the observed infection rates or any numerical estimate of the contrast. The record therefore does not establish, from the information available, the direction, magnitude, or precision of the primary result.
A rate is interpretable only alongside its event count, person-time denominator, and follow-up definition. The registry gives the unit as events per 100 person-years, but does not provide the group-specific rates or the underlying event and person-time summaries. Without those results, readers cannot judge how much observed information contributed to the comparison. A hazard ratio, if reported, would describe the relative event hazard under the model; the record’s efficacy definition transforms that estimate as one minus the hazard ratio. Neither estimate is present in the registry record.
The record also describes a cumulative-incidence ratio based on Nelson-Aalen estimates. This is a second stated way to compare the groups, distinct from the Cox-model hazard ratio. No numerical cumulative-incidence estimates, ratio, uncertainty interval, or Wald test result is reported. The registry’s description of multiple methods should not be read as evidence that either comparison favored a group.
Precision matters because an estimate is not a complete account of uncertainty. In general, a confidence interval communicates a range of values compatible with the data and model at a specified confidence level. No confidence interval for the primary outcome is reported in the registry record, so the precision of the estimated effect cannot be assessed. The record also does not report a p-value for the primary test. Thus, no conclusion about statistical evidence for a group difference can be drawn from the stated methods alone.
The registry lists secondary infection outcomes through 36 months and from month 6.5 through 24 months, as well as immune-response outcomes at month 6.5. Their presence indicates that the study assessed more than the primary comparison, but numerical results for these outcomes are not included in the record details. They cannot fill the gap in the primary result or be used to infer it.
The safety entries describe counts for serious events, other events, and deaths, plus selected serious-event terms. These are descriptive safety data, not estimates of vaccine efficacy. The registry record does not provide uncertainty estimates, event-attribution details, or the observation period for those safety counts. Their interpretation should remain separate from the infection endpoint.
Overall, the record supports a description of the design, endpoint, and planned analytic framework, but not a quantitative interpretation of efficacy. The observed effects and their uncertainty are not reported in the registry record.
9. Statistical Methods Explained
The registry describes a time-to-event analysis for the primary infection outcome. General statistical context: time-to-event methods use information about when an event occurs and can account for participants whose event time is not observed during the full follow-up period. Such methods require definitions for the event, time origin, follow-up, and censoring. The primary outcome begins at enrollment, which the record describes as concurrent with first vaccination, and follows diagnoses through 24 months after enrollment. Detailed censoring rules are not reported in the registry record.
What does the Cox model contribute?
The specified model is a sex-stratified Cox proportional-hazards model. General statistical context: a Cox model compares event hazards between groups over follow-up while leaving the underlying baseline hazard unspecified. Stratification allows the baseline hazard to differ across the stated strata; in this trial, the record says the model was stratified by sex. The registry does not report further model covariates, diagnostics, or any assessment of the proportional-hazards assumption.
The record defines vaccine efficacy as one minus the hazard ratio for HIV-1 infection. General statistical context: a hazard ratio compares the instantaneous event rates between groups among participants still at risk at a given time, under the model. Transforming it to one minus the ratio expresses the contrast as an efficacy measure. This definition alone does not tell readers the observed hazard ratio or efficacy estimate. Neither is reported in the registry record.
Why use a log-rank test?
The primary description says the Cox-model comparison was tested using a sex-stratified log-rank test. In general, a log-rank test compares event-time experience across groups over follow-up; stratification allows the comparison to account for the designated strata. A test result would need to be reported to assess the evidence against its null hypothesis. The registry record does not give the test statistic or p-value.
What is the cumulative-incidence comparison?
The registry also describes vaccine efficacy using a ratio of cumulative incidences in the vaccine group compared with placebo. Those cumulative incidences were to be calculated using Nelson-Aalen cumulative hazard estimates and compared with a Wald test. General statistical context: cumulative incidence describes the accumulation of event occurrence over time, while a Wald test evaluates a contrast using an estimate and its uncertainty. The record does not give either group’s cumulative-incidence estimate, the resulting ratio, its uncertainty, or the test result. The relationship between this analysis and the Cox analysis, including any prespecified priority between them, is not reported in the registry record.
How should the rate unit be understood?
The outcome is an event rate per 100 person-years. General statistical context: person-years combine participants’ observed time at risk, allowing rates to account for differing follow-up duration. A rate is not the same as a proportion of participants who experienced an event. To interpret a rate comparison, readers need the event counts, person-time, and observation rules for each group. Those numerical details are not reported in the registry record.
What do the planning assumptions mean?
The record describes a sample-size planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect, and that time-to-event planning tables give total events using the Schoenfeld method; other planning tables give participants per arm. These are planning assumptions, not observed trial results and not observed power. Numerical planning illustrations are not reported in the registry record. The trial’s own sample-size justification and design assumptions are not reported in the registry record.
General statistical context: planning calculations depend on assumptions about the effect size, variability, event frequency, follow-up, and analysis. If an illustration uses an effect estimated from the trial, it should not be interpreted as an independent estimate of how well the trial was powered. The record does not report whether the trial used other planning methods or how its enrollment target was chosen.
The record does not report an interim-analysis plan, stopping boundaries, missing-outcome procedures, or sensitivity analyses. Those omissions prevent a fuller assessment of how the planned methods were implemented and how robust the analysis may be to alternative assumptions. The methods listed describe the primary analysis framework, not its results or every operational detail.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 30 outcome measures and 10 analyses. It identifies one primary outcome and also lists secondary outcomes, including infection outcomes over different time windows and immune-response measures at month 6.5. The presence of several outcomes and analyses raises general questions about multiplicity: when many hypotheses are assessed, the chance of at least one apparently notable finding can increase. This general issue does not establish that any finding is false or that an adjustment was required in this study.
The registry record does not report a multiplicity-adjustment procedure, a hierarchy among secondary outcomes, or which analyses were confirmatory versus exploratory. The relationship between the two stated primary efficacy approaches is also not described in terms of inferential priority. As a result, readers cannot determine from the registry record how the study planned to control or interpret the collection of statistical tests.
The primary analysis population is named as the MITT cohort, but the registry does not report its detailed definition, inclusion criteria, exclusions, or how it differs from other analysis populations. The record does not report how participants with missing infection assessments, incomplete follow-up, or deviations from assigned treatment were handled. Censoring rules and imputation procedures are not reported in the registry record either.
General statistical context: missing follow-up can affect time-to-event analyses if loss to observation is related to the chance of experiencing the outcome. The consequences depend on why data are missing and on the analysis assumptions. Without the trial’s missing-data procedures and participant-flow details, the extent and handling of missing information cannot be assessed. These reporting gaps do not establish that data were missing or that the analysis was biased; they mean the registry information does not describe how those issues were 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 |
|---|---|---|---|
| Vaccine | 103 | 2704 | 3.8% |
| Placebo | 95 | 2700 | 3.5% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Vaccine | 8 of 2704 |
| Placebo | 10 of 2700 |
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 |
|---|---|
| Vaccine | 1707 of 2704 |
| Placebo | 1704 of 2700 |
Most frequent serious adverse event terms
| Event term | Organ system | Vaccine | Placebo |
|---|---|---|---|
| Any Event in SOC | Injury, poisoning and procedural complications | 42 of 2704 | 38 of 2700 |
| Any Event in SOC | Infections and infestations | 15 of 2704 | 17 of 2700 |
| Any Event in SOC | Psychiatric disorders | 11 of 2704 | 12 of 2700 |
| Any Event in SOC | Pregnancy, puerperium and perinatal conditions | 9 of 2704 | 12 of 2700 |
| Stab wound | Injury, poisoning and procedural complications | 7 of 2704 | 7 of 2700 |
| Any Event in SOC | Gastrointestinal disorders | 3 of 2704 | 4 of 2700 |
| Gun shot wound | Injury, poisoning and procedural complications | 5 of 2704 | 2 of 2700 |
| Any Event in SOC | Respiratory, thoracic and mediastinal disorders | 4 of 2704 | 3 of 2700 |
| Any Event in SOC | Musculoskeletal and connective tissue disorders | 5 of 2704 | 1 of 2700 |
| Abortion spontaneous | Pregnancy, puerperium and perinatal conditions | 2 of 2704 | 4 of 2700 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Vaccine | Placebo |
|---|---|---|---|
| Any Event in SOC | Infections and infestations | 1243 of 2704 | 1295 of 2700 |
| Genitourinary chlamydia infection | Infections and infestations | 661 of 2704 | 689 of 2700 |
| Genitourinary tract gonococcal infection | Infections and infestations | 286 of 2704 | 272 of 2700 |
| Any Event in SOC | General disorders | 206 of 2704 | 198 of 2700 |
| Any Event in SOC | Reproductive system and breast disorders | 167 of 2704 | 176 of 2700 |
| Influenza like illness | General disorders | 166 of 2704 | 171 of 2700 |
| Any Event in SOC | Nervous system disorders | 165 of 2704 | 151 of 2700 |
| Vulvovaginitis trichomonal | Infections and infestations | 150 of 2704 | 165 of 2700 |
| Any Event in SOC | Gastrointestinal disorders | 151 of 2704 | 162 of 2700 |
| Any Event in SOC | Skin and subcutaneous tissue disorders | 136 of 2704 | 134 of 2700 |
Serious events with the highest arm-level rate: any event in soc (1.6%), stab wound (0.3%), gun shot wound (0.2%), abortion spontaneous (0.1%), suicide attempt (0.1%).
The adverse-event record lists serious events and other events for the vaccine and placebo groups, along with deaths. For serious events, it gives 2704 as the vaccine group population at risk and 2700 for placebo; the number affected is 103 and 95, respectively. For other events, the populations at risk are also listed as 2704 and 2700, with 1707 and 1704 affected. The record lists 8 deaths in the vaccine group and 10 in the placebo group. These figures are counts and should be read with their stated group context, not as proof that an event was caused by the assigned intervention.
The registry lists selected serious-event terms with percentages: “Any Event in SOC,” 1.6%; “Stab wound,” 0.3%; “Gun shot wound,” 0.2%; “Abortion spontaneous,” 0.1%; “Suicide attempt,” 0.1%; and “Intentional self-injury,” 0.1%. The denominator and exact calculation basis for these percentages are not reported in the registry record, so they should be quoted as listed rather than converted into counts or compared with assumed denominators.
The record does not report the safety observation period, event-attribution rules, confidence intervals, or statistical comparisons for these entries. Counts alone do not establish whether group differences are meaningful, and the listed terms do not describe all possible safety outcomes. The safety data should be interpreted separately from the primary HIV-1 infection endpoint.
12. What the Result Does, and Does Not, Mean
The record establishes that the study was designed to compare a vaccine regimen with placebo for prevention of HIV-1 infection in HIV-seronegative adults in South Africa. It describes random allocation, quadruple masking, a parallel-group structure, the dosing schedules, the primary follow-up window, and the statistical methods named for the primary comparison. These features help define the question the study was intended to answer.
However, the registry record does not report the numerical primary outcome results. There are no group infection rates, event counts for the primary endpoint, hazard ratio, cumulative-incidence ratio, vaccine-efficacy estimate, confidence interval, or primary test result. It is therefore not possible to characterize the observed effect’s direction, magnitude, or precision from these registry entries. Describing the planned analysis is not equivalent to reporting its findings.
The secondary outcomes include infection measures at other follow-up windows and immune responses to vaccine proteins. Those outcomes address related but different questions. Their numerical results are not reported in the registry record, and no inference about the primary endpoint should be drawn from their listing alone. Likewise, the safety counts and selected event percentages do not answer the efficacy question.
General statistical context: estimates are most informative when accompanied by uncertainty intervals and enough information to understand the analyzed population and follow-up. The record does not provide those efficacy results or a detailed account of the MITT cohort. It also does not report the handling of missing data, multiplicity, or interim analyses. These limits constrain interpretation of the record; they do not establish that the trial lacked analyses or that its results were unfavorable.
Accordingly, the record supports a description of the trial’s design and stated analysis plan, but not a conclusion about the vaccine regimen’s effect on HIV-1 infection. Any statement about whether the primary comparison favored either group, or how certain that comparison was, would require results not reported in the registry record.
13. Why This Trial Matters Statistically
This study is statistically notable for framing prevention as a time-to-event question. HIV-1 infection was assessed over a defined follow-up window, and the primary measure was an incidence rate expressed per person-time. The registry also names a Cox-model hazard ratio and a cumulative-incidence comparison. Together, these approaches illustrate how a trial can describe group differences using event timing as well as accumulated outcome occurrence.
The record specifies sex stratification for the Cox model and log-rank test. This makes the planned handling of sex visible in the primary analysis description, while leaving many implementation details unreported. The study also includes outcomes over different time windows and measures of immune response. That breadth can support several scientific questions, but it makes transparent outcome definitions, analysis priorities, and multiplicity procedures important for interpreting results.
The registry lists randomized allocation, quadruple masking, and placebo control. These design features describe the intended comparison framework; they do not alone establish that all potential sources of bias were eliminated. Understanding the analysis population, missing follow-up, censoring, and participant flow is also important, and those details are not reported in the registry information.
Most importantly, the record illustrates the distinction between a statistical plan and a statistical finding. It gives methods and endpoint definitions, but not the primary numerical results or their uncertainty. Statistical interpretation requires both: methods explain how an estimate was intended to be produced, while results show what the data yielded and how precisely. Without those results, the comparison cannot be quantitatively evaluated from the registry record.
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 main limitation for statistical interpretation is that the registry record does not report numerical results for the primary infection endpoint. Group event counts, person-time, incidence rates, effect estimates, confidence intervals, and test results are absent. Without them, neither the size of the observed contrast nor its precision can be described.
The primary population is named as the MITT cohort, but the record does not specify its exact definition or provide participant-flow details. It also does not explain the differences between the enrollment count, the arm descriptions, and the safety populations listed for adverse events. These figures refer to different registry descriptions, and the record does not explain their relationship.
The endpoint description gives the time origin and follow-up window, but detailed event-adjudication procedures, censoring rules, and handling of incomplete follow-up are not reported in the registry record. Nor does it report model diagnostics, covariate adjustments beyond sex stratification, or sensitivity analyses. These details would help assess the assumptions and robustness of the time-to-event analysis.
The record lists multiple outcomes and analyses but does not state how multiplicity was handled or how the two primary efficacy methods were prioritized. It does not report interim analyses or stopping rules. The safety entries also lack the observation period, attribution criteria, and percentage denominators. These reporting limitations constrain what can be inferred; they do not by themselves show that the trial failed to collect or analyze the relevant information.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Pivotal Phase 2b/3 ALVAC/Bivalent gp120/MF59 HIV Vaccine Prevention Safety and Efficacy Study in South Africa — NCT02968849.
- Registry record last updated 2026-05-04; status last verified 2026-04.
- Results first posted 2023-02-08.
- 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
NCT02968849 is a completed randomized, quadruple-masked, parallel-group Phase 2b/3 placebo-controlled study sponsored by the National Institute of Allergy and Infectious Diseases. It enrolled 5404 participants and evaluated ALVAC-HIV (vCP2438) plus bivalent subtype C gp120/MF59 in HIV-seronegative South African adults. The primary outcome was HIV-1 infection diagnosed from enrollment through 24 months, measured as an incidence rate per 100 person-years in the MITT cohort.
The registry describes a sex-stratified Cox proportional-hazards analysis, a sex-stratified log-rank test, and a cumulative-incidence comparison using Nelson-Aalen estimates and a Wald test. It does not report the numerical primary efficacy results or their uncertainty. Secondary infection and immune-response outcomes are listed, as are adverse-event counts and selected serious-event percentages. Details about missing data, multiplicity, and several analysis procedures are not reported in the registry record.