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.
Proportions (Active vs. Placebo) of Subjects With Progressive Respiratory Insufficiency (PRI) on or Before Day 14.Primary· Day 14
Progressive respiratory insufficiency defined as a ≥ 2-tier increase in respiratory support methods required to maintain satisfactory oxygenation (SpO2 ≥ 93%), using the 6-tier hierarchical scale of respiratory support methods, within the 14-day study period.
Level 1:Normal oxygenation on room air (SpO2 ≥93), no need for supplemental O2 Level 2:Persistent hypoxemia on room air (SpO2 \<93) with requirement for low-level supplemental O2 by nasal cannula/mask (up to 2L/min) to maintain SpO2 ≥93 Level 3:Requirement for higher levels of passive supplemental O2 by nasal cannula or mask (≥2 L/min) t
Group
Value
95% CI
AT-527 - 550 mg BID
3
Placebo for 550 mg BID
4
Placebo for 1100 mg BID
0
Change From Baseline in Amount of SARS-CoV-2 Virus RNA by Nasopharyngeal SwabSecondary· Through Day 14
Change in the viral load as measured by swab of the upper part of the pharynx.
Change from baseline to Day 2
Group
Value
95% CI
AT-527 - 550 mg BID
-0.55
± 1.175
Placebo for 550 mg BID
-0.02
± 1.838
Placebo for 1100 mg BID
-1.37
± 1.57
Change from baseline to Day 5
Group
Value
95% CI
AT-527 - 550 mg BID
-1.00
± 1.316
Placebo for 550 mg BID
-0.80
± 1.853
Placebo for 1100 mg BID
-2.51
± 0.66
Change from baseline to Day 8
Group
Value
95% CI
AT-527 - 550 mg BID
-1.64
± 1.534
Placebo for 550 mg BID
-1.38
± 1.281
Placebo for 1100 mg BID
-3.78
± 1.39
Change from baseline to Day 10
Group
Value
95% CI
AT-527 - 550 mg BID
-1.72
± 1.734
Placebo for 550 mg BID
-2.26
± 1.452
Placebo for 1100 mg BID
-4.78
± 2.13
Change from baseline to Day 12
Group
Value
95% CI
AT-527 - 550 mg BID
-2.13
± 2.065
Placebo for 550 mg BID
-2.08
± 1.584
Placebo for 1100 mg BID
-4.78
± 2.13
Change from baseline to Day 14
Group
Value
95% CI
AT-527 - 550 mg BID
-2.61
± 1.873
Placebo for 550 mg BID
-2.26
± 1.747
Placebo for 1100 mg BID
-4.13
± 1.21
Adverse events — posted to ClinicalTrials.gov
Time frame: 28 days.
Reporting threshold: 5%.
Adverse-event reports describe events observed during the trial — not all are caused by the drug.
The objectives of this study are to evaluate the safety, tolerability, antiviral activity and efficacy of AT-527 in adult subjects ≥18 years of age with moderate COVID-19 and risk factors for poor outcomes (such as obesity (BMI\>30), hypertension, diabetes or asthma). Eligible subjects will be randomized to blinded AT-527 (nucleotide analog) tablets or matching placebo tablets to be administered orally for 5 days. Part A will evaluate an AT-527 dose of 550 mg BID and Part B will evaluate a second dose of AT-527 (1100 mg BID). Local supportive standard of care (SOC) will be allowed for all subjects. Efficacy, antiviral activity and safety observations will be compared for treatment with active AT-527 tablets vs. placebo tablets.
Publications & conference data
8 peer-reviewed publications reference this trial (live from Europe PMC):
NCT04709835 — Study to Evaluate the Effects of AT-527 in Non-Hospitalized Adult Patients With Mild or Moderate COVID-19
· Phase 2
· completed
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 Atea Pharmaceuticals, Inc.
Last refreshed: 9 March 2023
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/NCT04396106.