BACKGROUND: Repurposing hydroxychloroquine (HCQ) and chloroquine (CQ) as antiviral agents is a re-emerging topic with new viral epidemics. OBJECTIVES: To summarize evidence from human clinical studies for using HCQ or CQ as antiviral agents for any viral infection. DATA SOURCES: PubMed, EMBASE, Scopus, Web of Science for published studies without time or language restrictions. Cochrane Clinical Trial Registry and Chinese Clinical Trials Registry for trials registered after 2015. MedRxiv for pre-prints within the last 12 months. STUDY ELIGIBILITY CRITERIA: Interventional and prospective observational studies (with or without a control group) PARTICIPANTS: Adults and children with a confirmed viral infection. INTERVENTION: Use of chloroquine or hydroxychloroquine as antiviral agents in one or more groups of the study. METHODS: Two authors independently screened abstracts and all authors agreed on eligible studies. A meta-analysis was planned if similar studies were available in terms of participants, intervention, comparator and outcomes. RESULTS: Nineteen studies were eligible (HIV: 8, HCV: 2, Dengue: 2, Chikungunya: 1, COVID-19: 6) including two pre-prints. Nine and ten studies assessed CQ and HCQ respectively. Benefits of either drug for viral load suppression in HIV is inconsistent. CQ is ineffective in curing dengue (high certainty evidence) and may have little or no benefit in curing chikungunya (low-certainty evidence). The evidence for COVID-19 infection is rapidly evolving but at this stage we are unsure if CQ or HCQ has any benefit in clearing viraemia (very low certainty evidence). CONCLUSIONS: Using HCQ or CQ for HIV/HCV infections is clinically irrelevant now as other effective antivirals are available for viral load suppression (HIV) and cure (HCV). There is no benefit of CQ in dengue and the same conclusion is likely for chikungunya infection. More evidence is needed to confirm if HCQ or CQ is beneficial in COVID-19 infection.
Clinical evidence for repurposing chloroquine and hydroxychloroquine as antiviral agents: a systematic review