18 and older, any sex, with COVID-19. Patients with the condition only — healthy volunteers not accepted.
Results — posted to ClinicalTrials.gov
Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.
Change From Baseline in the Amount of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) Virus RNA for AT-527 550 mg and Matched PlaceboPrimary· Baseline, Day 3, Day 5, Day 7
SARS-CoV-2 virus RNA was measured by reverse-transcription polymerase chain reaction (RT-PCR) from nasopharyngeal (NP) swabs. The change from baseline was estimated from an ANCOVA model with baseline viral load as a covariate. Reported here is the adjusted mean change from baseline. A negative change from baseline indicates an improvement.
Day 3
Group
Value
95% CI
Placebo Matched to AT-527 550 mg
-1.16
± 0.203
AT-527 550 mg (1x550 mg)
-1.26
± 0.206
Day 5
Group
Value
95% CI
Placebo Matched to AT-527 550 mg
-2.42
± 0.230
AT-527 550 mg (1x550 mg)
-2.11
± 0.226
Day 7
Group
Value
95% CI
Placebo Matched to AT-527 550 mg
-3.13
± 0.220
AT-527 550 mg (1x550 mg)
-3.38
± 0.220
Time to Cessation of SARS-CoV-2 Viral SheddingSecondary· Up to Day 7
Time to cessation of viral shedding was defined as the time between the initiation of any study treatment and the first time when a negative or below the limit of detection RT-PCR test result was obtained. RT-PCR was measured from NP swabs. Median, 25th and 75th percentiles were estimated from the Kaplan-Meier curve.
Group
Value
95% CI
Pooled Placebo
NA
144.2 – NA
AT-527 550 mg (1x550 mg)
NA
143.8 – NA
AT-527 1100 mg (4x275 mg)
NA
141.1 – NA
Time to Sustained Non-Detectable SARS-CoV-2 Virus RNASecondary· Up to Day 7
Time to sustained non-detectable SARS-CoV-2 virus RNA was defined as the time between the initiation of any study treatment and first time when a negative or below the limit of detection test result by RT-PCR is obtained after which no positive test above or equal to the limit of detection was reported. RT-PCR was measured from NP swabs. Median, 25th and 75th percentiles were estimated from the Kaplan-Meier curve.
Group
Value
95% CI
Pooled Placebo
NA
NA – NA
AT-527 550 mg (1x550 mg)
NA
NA – NA
AT-527 1100 mg (4x275 mg)
NA
NA – NA
Percentage of Participants Positive for SARS-CoV-2 Virus RNA at Specified TimepointsSecondary· Baseline, Day 3, Day 5, Day 7
Reported here is the percentage of participants with a positive virus RNA by RT-PCR test result above or equal to the limit of quantification (LOQ). RT-PCR was measured from NP swabs.
Baseline
Group
Value
95% CI
Pooled Placebo
100
AT-527 550 mg (1x550 mg)
100
AT-527 1100 mg (4x275 mg)
96.7
Day 3
Group
Value
95% CI
Pooled Placebo
95.0
AT-527 550 mg (1x550 mg)
100
AT-527 1100 mg (4x275 mg)
93.1
Day 5
Group
Value
95% CI
Pooled Placebo
84.2
AT-527 550 mg (1x550 mg)
90.0
AT-527 1100 mg (4x275 mg)
83.3
Day 7
Group
Value
95% CI
Pooled Placebo
76.9
AT-527 550 mg (1x550 mg)
79.3
AT-527 1100 mg (4x275 mg)
76.7
Area Under the Curve (AUC) in the Amount of SARS-CoV-2 Virus RNASecondary· Baseline, Day 3, Day 5, Day 7
AUC is the amount of SARS-CoV-2 virus RNA from baseline to the last sample timepoint and was calculated using the trapezoidal method. RT-PCR was measured from NP swabs.
Group
Value
95% CI
Pooled Placebo
651.56
± 189.10
AT-527 550 mg (1x550 mg)
733.70
± 146.63
AT-527 1100 mg (4x275 mg)
618.62
± 194.88
Time to Alleviation or Improvement of COVID-19 Symptoms (21.5 Hours)Secondary· Up to 28 Days
COVID-19 symptoms were evaluated using the first 12 items in the COVID-19 Symptom Diary, which included the following 12 items: nasal congestion or runny nose, sore throat, cough, shortness of breath, muscle or body aches, fatigue, headache, chills/sweats, feeling hot or feverish, nausea, vomiting, and diarrhea. The symptoms were scored on the 4-point Likert scale (0=none, 1=mild, 2=moderate, 3=severe).Time to alleviation or improvement is defined as the length of time taken from start of treatment to the point at which all of the following three criteria are met and maintained for a concurren
Group
Value
95% CI
Pooled Placebo
43.4
9.3 – 104.7
AT-527 550 mg (1x550 mg)
57.2
9.0 – 115.8
AT-527 1100 mg (4x275 mg)
56.4
2.5 – 96.4
Time to Alleviation or Improvement of COVID-19 Symptoms (43 Hours)Secondary· Up to 28 Days
COVID-19 symptoms were evaluated using the first 12 items in the COVID-19 Symptom Diary, which included the following 12 items: nasal congestion or runny nose, sore throat, cough, shortness of breath, muscle or body aches, fatigue, headache, chills/sweats, feeling hot or feverish, nausea, vomiting, and diarrhea. The symptoms were scored on the 4-point Likert scale (0=none, 1=mild, 2=moderate, 3=severe). Time to alleviation or improvement is defined as the length of time taken from start of treatment to the point at which all of the following three criteria are met and maintained for a concurre
Group
Value
95% CI
Pooled Placebo
43.4
9.3 – 104.7
AT-527 550 mg (1x550 mg)
57.2
9.0 – 141.2
AT-527 1100 mg (4x275 mg)
58.1
2.5 – 118.2
Time to Alleviation of COVID-19 Symptoms (21.5 Hours)Secondary· Up to 28 Days
COVID-19 symptoms were evaluated using the first 12 items in the COVID-19 Symptom Diary, which included the following 12 items: nasal congestion or runny nose, sore throat, cough, shortness of breath, muscle or body aches, fatigue, headache, chills/sweats, feeling hot or feverish, nausea, vomiting, and diarrhea. The symptoms were scored on the 4-point Likert scale (0=none, 1=mild, 2=moderate, 3=severe). Time to alleviation of COVID-19 symptoms is defined as the length of time taken from start of treatment to the point at which the following criterion is met and maintained for at least 21.5 hou
Group
Value
95% CI
Pooled Placebo
43.4
9.3 – 104.7
AT-527 550 mg (1x550 mg)
57.2
9.0 – 115.8
AT-527 1100 mg (4x275 mg)
56.4
8.2 – 96.4
Time to Alleviation of COVID-19 Symptoms (43 Hours)Secondary· Up to 28 Days
COVID-19 symptoms were evaluated using the first 12 items in the COVID-19 Symptom Diary, which included the following 12 items: nasal congestion or runny nose, sore throat, cough, shortness of breath, muscle or body aches, fatigue, headache, chills/sweats, feeling hot or feverish, nausea, vomiting, and diarrhea. The symptoms were scored on the 4-point Likert scale (0=none, 1=mild, 2=moderate, 3=severe). Time to alleviation of COVID-19 symptoms is defined as the length of time taken from start of treatment to the point at which the following criterion is met and maintained for at least 43 hours
Group
Value
95% CI
Pooled Placebo
43.4
9.3 – 104.7
AT-527 550 mg (1x550 mg)
57.2
9.0 – 141.2
AT-527 1100 mg (4x275 mg)
58.1
8.2 – 118.2
Duration of FeverSecondary· Up to 28 Days
Duration of fever was defined as the time from start of treatment to return to an afebrile state (temperature ≤ 37.5°C) maintained for at least 21.5 hours.
Group
Value
95% CI
Pooled Placebo
10.6
9.6 – 11.7
Percentage of Participants With COVID-19 Related ComplicationsSecondary· Up to 33 Days
COVID-19 related complications include death, hospitalization, radiologically confirmed pneumonia, acute respiratory failure, sepsis, coagulopathy, pericarditis, myocarditis, and cardiac failure.
Group
Value
95% CI
Pooled Placebo
0
AT-527 550 mg (1x550 mg)
3.3
AT-527 1100 mg (4x275 mg)
3.3
Time to Alleviation of an Individual SymptomSecondary· Up to 28 Days
The COVID-19 Symptom Diary included the following 14 items: nasal congestion or runny nose, sore throat, cough, shortness of breath, muscle or body aches, fatigue, headache, chills/sweats, feeling hot or feverish, nausea, vomiting, diarrhea, sense of smell over the past 7 days and sense of taste over the past 7 days. The severity of items 1-12 was recorded on a 4-point Likert scale (none=0, mild=1, moderate=2, severe=3). Items 13-14 were recorded on a 3-point Likert scale (same as usual=0, less than usual=1, no sense=2). Time to alleviation of an individual symptom was defined as the time take
Nasal Congestion/Runny Nose
Group
Value
95% CI
Pooled Placebo
27.6
11.3 – 59.9
AT-527 550 mg (1x550 mg)
34.2
15.8 – 82.4
AT-527 1100 mg (4x275 mg)
32.7
10.0 – 57.7
Sore Throat
Group
Value
95% CI
Pooled Placebo
20.5
14.1 – 22.7
AT-527 550 mg (1x550 mg)
24.1
9.8 – 45.0
AT-527 1100 mg (4x275 mg)
111.7
22.1 – 201.4
Cough
Group
Value
95% CI
Pooled Placebo
22.6
11.8 – 129.3
AT-527 550 mg (1x550 mg)
90.7
23.7 – 140.4
AT-527 1100 mg (4x275 mg)
33.9
20.5 – 119.2
Shortness of Breath
Group
Value
95% CI
Pooled Placebo
23.9
11.5 – NA
AT-527 550 mg (1x550 mg)
68.9
68.5 – 69.2
AT-527 1100 mg (4x275 mg)
11.6
11.6 – 11.6
Aches and Pains
Group
Value
95% CI
Pooled Placebo
33.1
11.8 – 60.4
AT-527 550 mg (1x550 mg)
22.3
16.3 – 62.2
AT-527 1100 mg (4x275 mg)
94.4
48.1 – 177.7
Fatigue
Group
Value
95% CI
Pooled Placebo
47.8
22.6 – 178.1
AT-527 550 mg (1x550 mg)
44.4
10.5 – 94.5
AT-527 1100 mg (4x275 mg)
70.6
22.6 – 106.0
Headache
Group
Value
95% CI
Pooled Placebo
32.0
10.1 – 95.8
AT-527 550 mg (1x550 mg)
11.7
9.8 – 93.6
AT-527 1100 mg (4x275 mg)
34.4
21.8 – 105.4
Chills/Sweats
Group
Value
95% CI
Pooled Placebo
11.8
9.8 – 24.1
AT-527 550 mg (1x550 mg)
12.0
9.0 – 35.8
AT-527 1100 mg (4x275 mg)
25.0
17.1 – 41.4
Adverse events — posted to ClinicalTrials.gov
Time frame: Up to 33 days.
Reporting threshold: 5%.
Adverse-event reports describe events observed during the trial — not all are caused by the drug.
This randomized study evaluates the antiviral activity, safety, efficacy and pharmacokinetics of AT-527 versus a placebo in participants with mild or moderate coronavirus disease (COVID-19) who are not hospitalized.
Publications & conference data
8 peer-reviewed publications reference this trial (live from Europe PMC):
NCT04396106 — Safety and Efficacy of AT-527 in Subjects With Moderate Coronavirus Disease (COVID-19) in a Hospital Setting
· Phase 2
· terminated
NCT04019717 — Study of AT-527 in Combination With Daclatasvir in Subjects With Hepatitis C Virus (HCV) Infection
· Phase 2
· completed
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Publications: Europe PMC API search by NCT ID, retrieved 10 June 2026
Drug + disease cross-links: matched in real time against Drug Landscape's normalised drug + company + condition tables
Sponsor: as reported to ClinicalTrials.gov by Hoffmann-La Roche
Last refreshed: 26 October 2022
Drug Landscape aggregates and links these public records for informational use only. Always verify against the primary source before clinical or regulatory decisions. Canonical URL: https://druglandscape.com/trial/NCT04709835.