Hydroxychloroquine for Early Treatment of Adults With Mild Coronavirus Disease 2019: A Randomized, Controlled Trial

Clin Infect Dis. 2021 Dec 6;73(11):e4073-e4081. doi: 10.1093/cid/ciaa1009.


Background: No effective treatments for coronavirus disease 2019 (COVID-19) exist. We aimed to determine whether early treatment with hydroxychloroquine (HCQ) would be efficacious for outpatients with COVID-19.

Methods: Multicenter open-label, randomized, controlled trial conducted in Catalonia, Spain, between 17 March and 26 May 2020. Patients recently diagnosed with <5-day of symptom onset were assigned to receive HCQ (800 mg on day 1 followed by 400 mg once daily for 6 days) or usual care. Outcomes were reduction of viral load in nasopharyngeal swabs up to 7 days after treatment start, disease progression up to 28 days, and time to complete resolution of symptoms. Adverse events were assessed up to 28 days.

Results: A total of 293 patients were eligible for intention-to-treat analysis: 157 in the control arm and 136 in the intervention arm. The mean age was 41.6 years (SD, 12.6), mean viral load at baseline was 7.90 log10 copies/mL (SD, 1.82), and median time from symptom onset to randomization was 3 days. No differences were found in the mean reduction of viral load at day 3 (-1.41 vs -1.41 log10 copies/mL in the control and intervention arm, respectively) or at day 7 (-3.37 vs -3.44). Treatment did not reduce risk of hospitalization (7.1% control vs 5.9% intervention) nor shorten the time to complete resolution of symptoms (12 days, control vs 10 days, intervention). No relevant adverse events were reported.

Conclusions: In patients with mild COVID-19, no benefit was observed with HCQ beyond the usual care.

Keywords: COVID-19; SARS-CoV-2; hydroxychloroquine; randomized controlled trial; therapy.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • COVID-19 Drug Treatment*
  • Humans
  • Hydroxychloroquine* / therapeutic use
  • SARS-CoV-2
  • Treatment Outcome


  • Hydroxychloroquine