Efficacy of chloroquine or hydroxychloroquine in COVID-19 patients: a systematic review and meta-analysis

J Antimicrob Chemother. 2021 Jan 1;76(1):30-42. doi: 10.1093/jac/dkaa403.


Objectives: Clinical studies of chloroquine (CQ) and hydroxychloroquine (HCQ) in COVID-19 disease reported conflicting results. We sought to systematically evaluate the effect of CQ and HCQ with or without azithromycin on outcomes of COVID-19 patients.

Methods: We searched multiple databases, preprints and grey literature up to 17 July 2020. We pooled only adjusted-effect estimates of mortality using a random-effect model. We summarized the effect of CQ or HCQ on viral clearance, ICU admission/mechanical ventilation and hospitalization.

Results: Seven randomized clinical trials (RCTs) and 14 cohort studies were included (20 979 patients). Thirteen studies (1 RCT and 12 cohort studies) with 15 938 hospitalized patients examined the effect of HCQ on short-term mortality. The pooled adjusted OR was 1.05 (95% CI 0.96-1.15, I2 = 0%). Six cohort studies examined the effect of the HCQ+azithromycin combination with a pooled adjusted OR of 1.32 (95% CI 1.00-1.75, I2 = 68.1%). Two cohort studies and four RCTs found no effect of HCQ on viral clearance. One small RCT demonstrated improved viral clearance with CQ and HCQ. Three cohort studies found that HCQ had no significant effect on mechanical ventilation/ICU admission. Two RCTs found no effect for HCQ on hospitalization risk in outpatients with COVID-19.

Conclusions: Moderate certainty evidence suggests that HCQ, with or without azithromycin, lacks efficacy in reducing short-term mortality in patients hospitalized with COVID-19 or risk of hospitalization in outpatients with COVID-19.

Publication types

  • Meta-Analysis
  • Systematic Review

MeSH terms

  • Antiviral Agents / therapeutic use*
  • Azithromycin / therapeutic use
  • COVID-19 / drug therapy*
  • COVID-19 / mortality
  • Chloroquine / adverse effects
  • Chloroquine / therapeutic use*
  • Hospitalization / statistics & numerical data
  • Humans
  • Hydroxychloroquine / adverse effects
  • Hydroxychloroquine / therapeutic use*
  • Randomized Controlled Trials as Topic
  • Treatment Outcome


  • Antiviral Agents
  • Hydroxychloroquine
  • Azithromycin
  • Chloroquine