The Use PUL-042 to Reduce the Infection Rate and Progression to COVID-19 in Adults Exposed to SARS-CoV-2: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Use PUL-042 to Reduce the Infection Rate and Progression to COVID-19 in Adults Exposed to SARS-CoV-2 (NCT04313023), a randomized phase 2 study. The primary outcome is Severity of COVID-19: Evaluation of the Severity of COVID-19 as Measured by the Maximum Difference From the Baseline Value in the OSCI Within 28 Days From the Start of Experimental Therapy..

2. Clinical Question

3. Trial Design

This was a randomized, quadruple-masked, parallel-group phase 2 study of PUL-042 Inhalation Solution and sterile saline for inhalation. The registry lists COVID-19 as the condition and records an enrollment of 217. The study is marked completed. The listed start date is 2020-06-09, and the primary completion date is 2021-07-31.

Participants had documented exposure to SARS-CoV-2 and were described as asymptomatic at enrollment. The study summary specifies four inhaled doses over 10 days. The arm descriptions identify nebulized doses on Study Days 1, 3, 6, and 10. Participants were followed for incidence and severity over 28 days, and the summary says testing for SARS-CoV-2 occurred at the beginning, middle, and end of the study.

The primary analysis population is described as the ITT population minus one participant assigned to PUL-042 who was excluded because a baseline measurement was absent. The registry gives an ITT total of 210, including 108 placebo participants and 102 PUL-042 participants. The reported primary-endpoint arm sizes are 108 for sterile saline and 101 for PUL-042. The reason the analysis denominators for the infection outcomes differ is not reported in the registry record.

Randomization, masking, and a parallel-group structure describe important features of the comparison, but do not by themselves identify the allocation procedure, masking roles, or full conduct of the study. Those details are not reported in the registry record. The registry also does not report the planned sample-size justification or enough detail to reconstruct the full statistical analysis plan.

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

Analysis population for the primary outcome, as defined in the registry: The population analyzed is the ITT (Intent-to-Treat) population minus one participant on PUL-042 that was excluded due to an absent baseline measurement. ITT total: 210; ITT placebo: 108; ITT PUL-042: 102

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: A total of 217 participants were randomized to the study: 7 participants were randomized but not treated, 210 (96.8%) participants were included in the ITT (Intent-to-Treat) Population and Safety Population.

6. Primary Endpoint

The registry lists the primary outcome as Severity of COVID-19: Evaluation of the Severity of COVID-19 as Measured by the Maximum Difference From the Baseline Value in the OSCI Within 28 Days From the Start of Experimental Therapy., measured over 28 days.

The primary endpoint is COVID-19 severity, measured as the maximum difference from baseline on the Ordinal Scale for Symptom Improvement (OSCI) within 28 days from the start of experimental therapy. The registry describes the OSCI as ranging from 0 to 8, with higher values representing a worse outcome. The listed scale categories include no evidence of infection, infection without limitation of activities, limitation of activities, hospitalization, oxygen support, high-flow oxygen, and mechanical ventilation.

Using a severity scale gives the study a way to record changes in clinical status beyond whether an infection was detected. Taking the maximum difference from baseline within the follow-up period focuses on the greatest recorded worsening or improvement relative to baseline, rather than a single measurement on one day. That can be useful when participants’ status changes during follow-up.

The registry labels the reported measure a least-squares mean and gives 90% confidence intervals for each group. The full model specification and the precise handling of repeated or missing measurements are not reported in the registry record. The endpoint is a score-based measure; it should not be read as an infection rate or as a direct measure of every aspect of illness.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The main reported primary-endpoint summaries are least-squares means with 90% confidence intervals. A least-squares mean is generally a model-based group mean, potentially adjusted for variables included in the model. Its interpretation depends on the model and covariates used. The registry does not report the full model specification, so it is not possible to determine from the record which adjustments were made or how the estimate was obtained.

A confidence interval describes uncertainty around an estimate under the assumptions of the analysis. It is not a guarantee that the true value lies inside the interval, nor is it a range of individual participant outcomes. The 90% intervals reported for the primary endpoint are for each group’s estimate. A confidence interval for the difference between groups would answer a different question: it would quantify uncertainty in the contrast itself. That contrast is not posted for the primary endpoint.

For the infection outcomes, the registry lists participant percentages and 90% confidence intervals by arm. It also includes recalculated, unadjusted comparisons based on the posted counts and denominators. Those comparisons include risk differences and unadjusted p-values. A risk difference expresses an absolute difference in event probabilities; unlike a relative measure, it is stated on the probability scale. The recalculated confidence intervals are wide and include zero for both infection outcomes, so the summaries do not tightly pin down the direction or size of the difference.

A p-value is a measure of how incompatible the observed data are with a specified null hypothesis under the assumptions of a statistical test. It is not the probability that the null hypothesis is true, and it does not measure the clinical importance of a result. The reported infection p-values are unadjusted recalculations, not posted sponsor analyses. No reported analyses are listed for these secondary outcomes in the registry record. The sponsor’s own analysis would take precedence if there were a discrepancy; the registry record does not flag a discrepancy.

The planning illustrations use the observed effect as a reference and consider smaller fractions of that effect. They are planning calculations, not observed trial results and not observed power. The listed assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The registry explicitly distinguishes these calculations from the trial’s own design. The trial’s sample-size justification is not reported in the registry record, so the illustrations cannot establish what sample size was originally planned or whether the study was designed to answer a particular comparison with adequate precision.

General statistical context: over-dispersion occurs when outcome variability is greater than a model assumes. If present and not accounted for, it can make standard errors too small and confidence intervals too narrow. The registry does not report whether over-dispersion was assessed or relevant to the OSCI analysis. The OSCI is an ordinal scale, so analyses can also depend on how the ordered categories and changes in score are modeled; the registry’s least-squares-mean label alone does not establish which modeling choices were made.

General statistical context: missing outcome data can affect estimates when the probability of a measurement being missing is related to participants’ outcomes or other characteristics. The registry says one PUL-042 participant lacked a baseline measurement and was excluded from the primary analysis population. It does not describe the amount or handling of any other missing data, or whether missingness was examined by treatment group. The infection-outcome denominators are 94 and 98, but the reason they differ from the primary-analysis denominators is not reported in the registry record.

General statistical context: multiplicity arises when several outcomes, time points, or comparisons are tested. Without a prespecified strategy for controlling multiplicity, repeated testing can increase the chance of at least one apparently notable result arising by chance. The registry lists multiple secondary outcomes and infection time points, but does not report a multiplicity adjustment or a hierarchy of tests. The unadjusted secondary p-values therefore should not be treated as confirmatory evidence.

The primary endpoint is assessed over a 28-day window, and the infection outcomes are listed through Day 29 and Day 15. These time windows and the scale’s maximum-change definition shape what the estimates summarize. They do not tell the reader whether a transient change, a sustained change, or the timing of an event was separately modeled. Those details are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The primary analysis population is described as the ITT population minus one participant assigned to PUL-042 who was excluded because a baseline measurement was absent. The registry gives an ITT total of 210: 108 placebo participants and 102 PUL-042 participants. The primary endpoint summaries include 108 participants in the sterile-saline group and 101 in the PUL-042 group. The record does not explain whether any further exclusions or unavailable measurements contributed to those analysis counts.

For the infection outcomes, the listed denominators are 94 for PUL-042 and 98 for sterile saline. The registry does not report why these denominators differ from the primary analysis counts, how missing infection status was handled, or whether participants were excluded under a stated rule. No missing-data sensitivity analysis is reported in the registry record. Accordingly, the infection estimates describe the denominators used in those posted summaries; they should not automatically be assumed to represent every randomized participant.

The registry lists several secondary endpoints and more than one infection follow-up window. It does not report whether these were ordered by priority, whether a formal testing hierarchy was used, or whether p-values were adjusted for multiple comparisons. Because multiple analyses can increase the chance of a nominally notable result, unadjusted secondary results have less confirmatory weight than a prespecified primary analysis with a reported comparison. The infection p-values are recalculated unadjusted comparisons, and the registry lists no reported analyses for those outcomes.

The full analysis plan, the primary sample-size justification, and the handling of all missing data are not reported in the registry record. These omissions limit assessment of whether the posted populations and analyses follow prespecified rules. They also prevent a clear accounting of how the primary and secondary results relate to the original statistical plan.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry lists zero serious adverse events among 102 participants at risk in the PUL-042 group and zero among 108 participants at risk in the sterile-saline group. It also lists 28 participants with other adverse events in the PUL-042 group and 10 in the sterile-saline group. No deaths are recorded in either group. The registry provides no serious adverse event terms.

These counts describe the safety information posted in the record. Zero recorded serious adverse events does not show that serious events are impossible, and the figures alone do not establish a comparative safety profile. The number of participants with other adverse events is not a measure of event severity, duration, or causal relationship. The registry does not provide those details here, nor does it report additional analyses of adverse-event differences. The group sizes and follow-up context matter when reading the counts, and the posted figures should not be taken as medical advice or as a complete account of safety.

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

The posted data describe group estimates for a 28-day severity endpoint and infection outcomes over two follow-up windows in adults with documented exposure. The primary endpoint estimates are least-squares means, each with a 90% confidence interval. The registry does not post the primary between-group contrast or its uncertainty. Therefore, the arm-level estimates alone do not establish the size or precision of a difference between PUL-042 and sterile saline.

The unadjusted recalculations for infection provide direct comparisons, but their confidence intervals include zero and span differences in either direction. They are not evidence of equivalence, and they do not exclude differences that the estimates cannot precisely resolve. No equivalence margin or non-inferiority framework is reported. The recalculated p-values also do not measure the probability that the groups are the same.

The findings do not by themselves establish whether PUL-042 prevents infection, changes COVID-19 severity, or has a particular benefit-risk balance. Such conclusions would require interpretation of a prespecified comparison, its uncertainty, the analysis population, missing data, and the full outcome record. The registry’s available primary summary lacks a formal contrast, while the posted secondary comparisons are unadjusted and should be viewed cautiously.

The trial’s randomized, masked, parallel design is relevant context for comparing groups, but the registry record does not provide enough statistical detail to assess every design and analysis choice. Nor should planning illustrations based on observed effects be mistaken for observed power or proof that the study was adequately sized. The results are best read as limited statistical summaries of this trial, rather than as a definitive answer to every question about infection, severity, or safety.

13. Why This Trial Matters Statistically

This trial illustrates why a clinical endpoint and a between-group statistical comparison are not the same thing. The registry reports a least-squares mean for each arm on the primary severity measure, but does not report the contrast between those means. Separate arm estimates can describe the groups, yet the treatment comparison depends on the difference and its uncertainty. Without that contrast, the primary result is difficult to assess as a comparative estimate.

The infection outcomes illustrate a second statistical issue: small observed differences can have wide confidence intervals when event counts and denominators are limited. The recalculated comparisons are close to zero, but their uncertainty spans values on both sides of zero. A near-zero point estimate is not, by itself, a precise demonstration of no difference. Precision matters as much as the point estimate when judging what the data can distinguish.

The record also highlights the importance of analysis populations and missing-data reporting. The primary endpoint excludes one participant without a baseline measure, while infection outcomes use smaller denominators. Without an account of those denominators and missing-data handling, readers cannot fully reconcile the populations underlying the estimates.

Finally, multiple secondary outcomes require care. Unadjusted results across several outcomes and time points are less persuasive as confirmatory evidence than a clearly reported primary analysis. These are general statistical lessons illustrated by the registry record, not conclusions about how the study should guide care.

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 most direct limitation for interpreting the primary endpoint is the absence of a posted between-group estimate, confidence interval, and p-value. The registry gives arm-level least-squares means and 90% confidence intervals, but does not report the model specification or explain how the primary estimate was adjusted. This prevents a full assessment of the primary comparison and its precision.

The analysis population is not identical to the ITT population: one PUL-042 participant without a baseline measurement was excluded from the primary analysis. Infection outcomes have smaller denominators, and the record does not explain why. The registry does not report the extent of other missing data, how it was handled, or sensitivity analyses. These details are important for understanding whether the posted estimates could be affected by the availability of measurements.

Several secondary outcomes and follow-up windows are listed, but no multiplicity strategy is reported. The posted infection comparisons are unadjusted recalculations rather than registry-reported analyses. Other listed severity and event-count outcomes do not have corresponding numerical two-arm results in the registry record. The absence of posted estimates should not be interpreted as a zero event count or as evidence of no difference.

The registry does not report the sample-size justification, a full protocol-level statistical analysis plan, or details of any interim analyses. The planning illustrations are based on observed effects and cannot fill those gaps. The registry’s safety summary gives counts but not serious-event terms or detailed event characteristics. Together, these reporting limits constrain assessment of the magnitude, precision, and robustness of the trial’s comparative findings.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: The Use PUL-042 to Reduce the Infection Rate and Progression to COVID-19 in Adults Exposed to SARS-CoV-2 — NCT04313023.
• Registry record last updated 2023-05-17; status last verified 2023-04.
• Results first posted 2023-05-17.
• 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.

18. Record Summary

NCT04313023 is a completed randomized, quadruple-masked, parallel-group phase 2 study of inhaled PUL-042 versus sterile saline in adults with documented exposure to SARS-CoV-2. The registry lists 217 participants enrolled. The primary outcome is the maximum difference from baseline on the OSCI within 28 days, with higher scores indicating worse outcomes.

The primary analysis population excludes one PUL-042 participant without a baseline measurement. The registry posts arm-level least-squares means and 90% confidence intervals, but no formal primary between-group analysis. Recalculated unadjusted infection comparisons have wide intervals that include zero. The record lists no serious adverse events or deaths in either group, alongside other adverse-event counts. Important details about the statistical plan, missing-data handling, and multiplicity are not reported in the registry record.