key: cord-0706520-1q9bhwpb
authors: Rodrigo, Chaturaka; Fernando, Sumadhya Deepika; Rajapakse, Senaka
title: Clinical evidence for repurposing chloroquine and hydroxychloroquine as antiviral agents: a systematic review
date: 2020-05-26
journal: Clin Microbiol Infect
DOI: 10.1016/j.cmi.2020.05.016
sha: 0dc08af627e0873f4683a36d0aaa944879e348c2
doc_id: 706520
cord_uid: 1q9bhwpb

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.

With the pandemic of severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) or 49 repurposing cheap and accessible drugs for off-label use as antivirals is gaining popularity if they 50 have demonstrated antiviral properties in vitro or in animal studies. Chloroquine (CQ), a well-51 established anti-malarial agent, and hydroxychloroquine (HCQ), a similarly established disease 52 modifying anti-rheumatic (DMARD) agent have received increased attention in recent days for their 53 purported efficacy as antiviral agents in context of . Both drugs are out-of-patent, cheap, 54 and widely available in high, middle-and low-income countries. 55

The antiviral properties of CQ was first explored against viral hepatitis as far back as 1963(1). Since 56 then many observations from in vitro and animal experiments have suggested a beneficial role of 57 HCQ and CQ in viral infections (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) ). Yet, the ultimate test for their benefit as antivirals come from 58 human clinical studies and to our knowledge both these drugs are not used as mainstream antiviral 59 agents for any viral infection. This review focusses on the clinical evidence for using both CQ and 60 HCQ as antiviral agents against any viral infection. This reflection and summary of evidence is 61 needed in current context for judicious, evidence-based recommendations for off-label use of these 62 drugs. Even when such evidence may be incomplete or unavailable for emerging infections such as 63 COVID-19, historical attempts for repurposing these agents for other emerging viral infections from 64 time to time, may draw parallels to the current scenario to inform a rational approach to clinical 65 trials and guideline recommendations. 66

Types of studies: Interventional and observational studies (controlled and non-controlled) including 69 case series were considered, but case reports limited to single patients were excluded. Retrospective 70 studies, animal or in vitro experiments were excluded. 71

Intervention and comparator: All participants (non-controlled studies) or one study arm (controlled 73 studies) must have received either CQ or HCQ as antiviral agents (as stand-alone therapy or in 74 combination with other treatments 

A total of 2267 abstract results were found from all databases after removing duplicates (figure 1). 98

The majority of these (n-2026) were published after 1990. After removing retrospective studies, in 99 vitro and animal studies, reviews, letters, opinion papers and editorials, only 209 abstracts 100 remained. Further examination identified 26 articles for full-text review revealing a significant 101 disparity with the large number of articles demonstrating in vitro evidence for antiviral effects of 102 HCQ and CQ. Only 19 publications (including two preprints) from this subset met the inclusion 103 criteria. One full text paper was in Mandarin but had an English abstract. The studies included 104 randomized and non-randomized controlled trials and uncontrolled prospective studies equivalent 105 to case series. These had tested the efficacy of CQ and HCQ in human immunodeficiency virus (HIV), 106 dengue, chikungunya, Hepatitis C and COVID-19 infections. A meta-analysis was not performed due 107 to unavailability of similar studies. A summary of risk of bias for all controlled clinical trials are given 108 in figure 2. The results are discussed separately for each infection and under each section, 109 randomized clinical trial are discussed first, followed by other study designs. Chronic infections 110 (HIV/HCV) are discussed first as the aim of treatment is viral load suppression rather than cure. 111 Details of study design and setting, participants, interventions, comparators, outcomes and risk of 112 bias for each included study is given in table 2. There are 23 trials in progression, all examining the 113 role of HCQ and CQ in COVID-19 infection ( one trial which had a complex cross-over design, the HIV viral load increased when CQ was 136 administered without any other antiretroviral therapy(21). There was no significant virological or 137 immunological improvement in with CQ in the third (paediatric) trial (19) but significantly more 138 gastrointestinal adverse events were observed with CQ. 139

Use of CQ or HCQ for HCV infection has been evaluated in two RCTs, one a single blinded study 141 (n=120, HCV genotype 4) and another a double blinded study (n=10, HCV genotype 1) (25-27). The 142 first trial used HCQ 400mg/d for 12 weeks added to interferon (IFN) and ribavirin therapy while the 143 control group received IFN and ribavirin only. HCQ was well tolerated and a significantly higher rate 144 of early virological response was noted in the HCQ group (p=0.011). The other trial used CQ 150mg 145 base /d vs. placebo in patients who has already failed IFN and ribavirin therapy and noted a 146 significant drop in viral RNA levels following 8 weeks of therapy (p=0.04), but this effect was 147 transient. 148

IFN and ribavirin therapy for HCV is largely outdated nowadays as highly effective directly acting 149 antiviral agents are now available. Neither HCQ nor CQ has been evaluated in combination with 150 these agents. 151

Two studies had assessed CQ for dengue infection (none for HCQ). A double-blind RCT (n=307) in 153 Vietnam administered CQ 1500mg over 3 days (dosage regimen the same as that used for malaria -154

table 2) or placebo to clinically suspected dengue patients within first 3 days of fever. A large 155

proportion of the enrolments (84%) were later confirmed to have dengue. CQ failed to demonstrate 156 a clinical benefit in; clearance of viraemia, clearance of NS1 antigen positivity, fever clearance time, 157 preventing dengue haemorrhagic fever, preventing decrease in platelet count or increase in 158 haematocrit (surrogate markers of dengue associated plasma leakage), but significantly increased 159 gastrointestinal adverse events (p<0.05) (28). The second study enrolled 129 patients with clinically 160 suspected dengue to a two-arm randomized controlled trial to receive either 600mg CQ base/d for 3 161 days or placebo. Only 37 participants were later confirmed to have dengue (19 in CQ group; 18 in 162 placebo group)(29). There was no statistically significant difference in the total duration of illness or 163 adverse events. 164

Chikungunya is a viral illness endemic in the tropics. Acute infection mimics a viral flu and sometimes 166 lead to a debilitating, persistent inflammatory arthritis. There was only one RCT that had evaluated 167 CQ as an antiviral agent (and none for HCQ) in acute chikungunya infection. This double blind RCT, 168 conducted in French Reunion Islands in 2006, enrolled 54 adult patients with virologically confirmed 169 acute chikungunya infection to receive either CQ (600mg of base/day for 3 days followed by 170 300mg/d for 2 days) or placebo (30, 31). There was no statistically significant difference in time for 171 viraemia clearance or fever clearance in CQ treated group. The adverse effects were minor but all 172 (n=7) were reported in the CQ group. When followed up at day 200 (since onset of symptoms) by a 173 telephone interview, the CQ treated group was significantly more likely to have persistent arthralgia. 174

However, a later analysis of cytokines and chemokines from plasma samples revealed higher levels 175 of IFN-α, IL-6, IL-8 and MCP-1 in the group that received CQ (more severe disease at baseline and 176 hence, increased likelihood of persistent arthralgia)(32). 177

Given its established role as a DMARD, HCQ is potentially useful to treat chikungunya induced 178 chronic arthritis. A randomized controlled trial had evaluated HCQ for this purpose after acute 179 chikungunya infection (33). However, as HCQ was not "repurposed" as an antiviral agent, this trial 180 was outside the scope of this review. 181

The ongoing epidemic of SARS-CoV-2 (referred to as COVID -19) is rapidly evolving. Potential use of 183 CQ for COVID-19 associated pneumonia first emerged in February 2020 based on several Chinese 184 studies and an expert consensus from Guangdong Province of China (abstract in English) 185 recommends using CQ 500mg (presumably 300mg of CQ base) two times daily for 10 days to treat 186 patients with COVID-19 associated pneumonia(34). We could not verify the evidence for this 187 recommendation independently as the original full-text articles were not available. We have 188 summarized the evidence for using HCQ or CQ for COVID-19 from full-text articles that were 189 available within our search strategy by 30 th April 2020 below. Pre-prints from MedRxiv are also 190 discussed but these are not peer reviewed publications and hence not considered in certainty of 191 evidence assessment. Ongoing trials are listed in table 3. 192 HCQ for COVID-19: There are two peer reviewed publications (one RCT and a non-randomized 193 controlled study)(35, 36) and two non-peer reviewed pre-prints (two RCTs) on this topic(37, 38). A 194 third study (from USA) available on MedRxiv as a pre-print was excluded as it was a retrospective analysis(39). The only peer reviewed publication of a RCT (in Mandarin, abstract in English) was not 196 indexed in any of the databases searched and was identified from a secondary bibliography search. 197

It describes a randomized clinical trial (NCT04261517) that recruited 15 non-severe, confirmed 198 COVID-19 patients to an HCQ arm (400mg/d for 5 days) and a no HCQ arm(36). Clearance of viraemia 199 (RT-PCR of a throat swab) by day 7, fever clearance time and total duration of hospital stay were 200 similar between the two groups. A non-randomized controlled trial from Marseille, France (full-201 paper reviewed) enrolled 26 patients with virologically confirmed COVID-19 to receive HCQ 202 600mg/d(35). Twenty patients completed HCQ treatment (6 patients also received azithromycin) 203 and all had radiological evidence of pneumonia (CT scan). The control group (n=16) was younger 204 (mean age; 51.2 vs. 37.3 years) and had patients treated at another institution or those treated at 205 the same institution but refused HCQ. More patients in the HCQ group were virologically cured by 206 day 6 (70% vs. 12.5%, p=0.001) including all patients who received azithromycin. 207

Results of two more RCTs from China on using HCQ in COVID-19 are available as pre-prints (37, 38). 208

The largest was a multicentre open label clinical trial (ChiCTR2000029868) that enrolled 150 209 virologically confirmed COVID-19 patients (75 per group) to receive HCQ plus standard care (as 210 defined by Chinese guidelines for COVID-19 management) or standard care only(37). HCQ group 211 received 200mg/d for 3 days followed by 800mg/d for 14-21 days. Only two patients (one in each 212 group) had severe illness. There was no statistically significant difference in the proportion of 213 aviraemic patients by day 28 (85.4% in HCQ group vs 81.3% in control group, p>0.05). There was also 214 no difference in time to aviraemia, or symptom resolution by day 28. Many secondary outcomes 215 proposed in methods including all-cause mortality, are not reported in results presumably due to 216 lack of events. The second study (ChiCTR2000029559) enrolled and randomized 62 (31 in each 217 group) virologically confirmed COVID-19 patients with evidence of pneumonia on CT scan to receive 218 HCQ (400mg/d for 5 days) or no HCQ treatment. The respiratory distress was not severe 219 (PaO 2 /FIO 2 >300 or SaO 2 /SPO 2 >93%) at enrolment in all recruits. The authors report faster time to 220 clinical recovery (defined as normalization of body temperature and cough relief maintained for 72 hours) and earlier radiological improvement in the HCQ group, but the calculations and radiological 222 reporting standards for these conclusions are unclear. Four patients in the control group vs none in 223 the HCQ group progressed to severe illness. 224 CQ for COVID-19: There are two published RCTs on using CQ for COVID-19. The first study from 225

China, randomized 22 virologically confirmed COVID-19 patients to receive either Lopinavir/Ritonavir 226 combination or CQ 600mg (base)/day for 10 days (40). There was no statistically significant 227 difference for having a negative RT-PCR by day 14 of illness (10/10 in CQ group vs. 11/12). However, 228 on average, the Lopinavir/Ritonavir group had started treatment later than those in CQ group (2.5 229 vs. 6.5 days since the onset of illness, p<0.001). The second RCT was a dose ranging study for CQ 230 which did not have a no CQ comparator group (41). It randomized 81 patients clinically suspected of 231 having COVID-19 to receive either CQ 12g over 10 days or 2.7g over 5 days. Diagnosis was later 232 confirmed (virologically) in 31 patients in each group. The recruits had severe infection at time of 233 enrolment as defined by tachycardia, tachypnoea, oxygen saturation <90%, and hypotension. 234

Recruitment to the high dose arm was terminated early (by day 13) as mortality was significantly 235 higher in this group (15% vs 39%, p=0.03). 236

Despite being researched for several decades and being supported by a large volume of in vitro and 238 animal study data for plausible mechanisms for antiviral effects, neither HCQ nor CQ are currently 239 recommended as antiviral agents for any of the infections they had been tested for in clinical trials 240 (with the exception of COVID-19 which is an evolving situation at the time of writing). The most 241 researched infection in this regard is HIV. However, mainstream anti-retroviral treatment in HIV is 242 highly successful in viral load suppression allowing reasonable control of disease though it is not a 243 cure. These newer combinations have not been tested against CQ/HCQ and given the inconsistent 244 evidence from existing trials in this regard, there is no need to. The same can be said of HCV 245 infection where pan-genotypic directly antiviral agents can now achieve over 90% cure rates with minimum adverse events(42). Repurposing HCQ/CQ for these infections is largely redundant and of 247 historical interest only. 248

In contrast, for acute viral infections such as dengue, chikungunya or COVID-19, effective antivirals 249 are not available. These infections cause epidemics in vulnerable populations exerting an enormous 250 financial burden on resource limited healthcare systems. For dengue fever, given the evidence 251 presented here we conclude that CQ is of no benefit (high certainty evidence). This conclusion is 252 supported by a single well designed RCT with an adequate sample size and a low risk of bias. CQ may 253 have little or no effect in curing acute chikungunya infection (low certainty evidence) and this 254 conclusion is supported by a small clinical trial which may have inadvertently recruited people with 255 more severe disease to the CQ arm despite randomization. 256

For COVID-19 we are unsure if either CQ or HCQ is of any benefit as per currently available evidence 257 (very low certainty evidence). The only peer reviewed publication describing a RCT on using HCQ for 258 COVID-19 was a small trial that did not demonstrate any benefit of HCQ. The other peer reviewed 259 publication which did show a benefit was an open label, non-randomized trial with a serious risk of 260 bias in sample selection, confounders and assessing outcomes. The sample size was small, and there 261 was a marked age discrepancy (of approximately 14 years) between test and control groups. 262

Administration of azithromycin to six subjects who also received HCQ, does not seem to be based on 263 an a priori hypothesis or a study protocol. Some control group patients were from a different centre, 264 and it is unclear if management protocols in both institutions were the same. More importantly, it is 265 now established that most patients (>95%) with COVID-19 will recover after a mild infection 266 regardless of antiviral treatment. Therefore, the primary outcome assessed in this study (clearance 267 of viraemia) is less useful for patient management compared to outcomes that demonstrate a 268 benefit in the more severe end of the disease spectrum such as mortality benefit, reduction in 269 intensive care unit admissions or faster discharge from intensive care (or high dependency units), 270 faster recovery from assisted ventilation or prevention of the need for assisted ventilation. 271

Examining such outcomes require a well-coordinated multi-centre study (preferably with a 272 randomized, double blind, study design) with similar management protocols across all centres. The 273 other two studies from China (available as pre-prints) mentioned in the results section also does not 274 help to resolve this issue due to methodological issues and conflicting conclusions. For example in 275 one of these studies(38), the control group is said to have received "standard" treatment which 276 includes "antivirals, antibiotics and steroids or immunoglobulins". These may have a serious 277 confounding effect on the interpretation of results. 278

The role of CQ in COVID-19 is also unclear and not supported by evidence at the moment. One small 279 RCT reported no benefit of CQ in terms of achieving negative viraemia by day 14 compared to 280 treatment with lopinavir and ritonavir(40). The authors report faster radiological improvement and 281 reduced hospital stay with CQ but on average the CQ group received treatment at an earlier stage of 282 the illness than the comparator group. This plus the small sample size make it difficult to interpret 283 the results. The other RCT did not have a no CQ control group which is rather surprising. Instead of 284 proving the efficacy of CQ, the authors investigated if a higher dose of CQ was safe in patients with 285 severe infection. Notably this CQ dose (1200mg/d for 10 days) was much higher than that used for 286 cure of malaria which is the standard indication for CQ. Mortality was significantly higher in the high 287 CQ dose group and patient recruitment was halted prematurely. Thus, this trial also doesn't help to 288 confirm if CQ is beneficial for Conclusion 290 CQ and HCQ have been examined for their antiviral properties in many in vitro and animal studies for 291 more than five decades and in a limited number of human clinical studies spanning over 25 years. 292

For HIV and HCV infections, the benefit of either drug is doubtful and perhaps no longer relevant as 293 other effective treatments are now available for viral load suppression (HIV) or cure (HCV). There is 294 good evidence that CQ is ineffective for curing dengue infection or preventing dengue haemorrhagic 295 

Treatment of viral hepatitis with chloroquine

In vitro inhibition of severe acute 311 respiratory syndrome coronavirus by chloroquine

Chloroquine is 314 a potent inhibitor of SARS coronavirus infection and spread

Potential antivirals and antiviral strategies against SARS coronavirus infections

Recycling of chloroquine and its hydroxyl analogue to face 318 bacterial, fungal and viral infections in the 21st century

New insights into the antiviral effects 323 of chloroquine

Antimalarial drugs and their metabolites are 325 potent Zika virus inhibitors

Repurposing of the 329 anti-malaria drug chloroquine for Zika Virus treatment and prophylaxis

Chloroquine could be used for the treatment of filoviral infections and other 331 viral infections that emerge or emerged from viruses requiring an acidic pH for infectivity

Antiviral therapies against Ebola and 334 other emerging viral diseases using existing medicines that block virus entry

The Cochrane 338 Collaboration's tool for assessing risk of bias in randomised trials

GRADE: an 342 emerging consensus on rating quality of evidence and strength of recommendations

Hydroxychloroquine treatment of 345 patients with human immunodeficiency virus type 1

Comparison of 347 hydroxychloroquine with zidovudine in asymptomatic patients infected with human 348 immunodeficiency virus type 1

Therapeutic potential of chloroquine added to zidovudine plus didanosine for HIV-1 infected 351 children

Effects of 353 hydroxychloroquine on immune activation and disease progression among HIV-infected patients not 354 receiving antiretroviral therapy: a randomized controlled trial

Outcomes of 406 hydroxychloroquine usage in United States veterans hospitalized with Covid-19

Treating COVID-19 with Chloroquine

Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection: A Randomized Clinical Trial

Direct antiviral agents (DAAs) -A new age in the treatment of hepatitis C virus 415 infection

Clinical trials / studies in progression on using CQ or HCQ as antiviral agents Name* Reference ID Source Post-exposure Prophylaxis for SARS

Chloroquine Prevention of Coronavirus Disease (COVID-19) in the Healthcare Setting NCT04303507 ClinicalTrials.gov Treatment of Mild Cases and Chemoprophylaxis of Contacts as Prevention of the COVID-19 Epidemic NCT04304053 ClinicalTrials

Various Combination of Protease Inhibitors, Oseltamivir, Favipiravir, and Chloroquine for Treatment of COVID19 : a Randomized Control Trial NCT04303299 ClinicalTrials

New Treatment for Radical Cure of Dengue Fever with Antiviral and Anti-cytokine CTRI/2017/12/010834 WHO ICTRP A prospective, open label, randomized, control trial for chloroquine or hydroxychloroquine in patients with mild and common

ChiCTR2000030054 Chinese Clinical Trials Registry A prospective, randomized, open label, controlled trial for chloroquine and hydroxychloroquine in patients with severe novel coronavirus pneumonia

ChiCTR2000029992 Chinese Clinical Trials Registry Evaluation the Efficacy and Safety of Hydroxychloroquine Sulfate in Comparison with Phosphate Chloroquine in Mild and Common Patients with Novel Coronavirus Pneumonia (COVID-19): a Randomized, Open-label, Parallel, Controlled Trial ChiCTR2000029899 Chinese Clinical Trials Registry Evaluation the Efficacy and Safety of Hydroxychloroquine Sulfate in Comparison with Phosphate Chloroquine in Severe Patients with Novel Coronavirus Pneumonia (COVID-19): a Randomized, Open-Label, Parallel, Controlled Trial ChiCTR2000029898 Chinese Clinical Trials Registry A prospective, randomized, open-label

ChiCTR2000029803 Chinese Clinical Trials Registry A multicenter, single-blind, randomized controlled clinical trial for chloroquine phosphate in the treatment ChiCTR2000031204 Chinese Clinical Trials Registry 25 of novel coronavirus pneumonia

A Randomized Controlled Trial for Favipiravir Tablets Combine With Chloroquine Phosphate in the Treatment of Novel Coronavirus Pneumonia

Clinical Study of Chloroquine Phosphate in the Treatment of Severe Novel Coronavirus Pneumonia (COVID-19)

Controlled Clinical Trial for Chloroquine Phosphate in the treatment of Novel Coronavirus Pneumonia

ChiCTR2000029939 Chinese Clinical Trials Registry A Single-arm Clinical Trial for Chloroquine Phosphate in the treatment of Novel Coronavirus Pneumonia

ChiCTR2000029935 Chinese Clinical Trials Registry Efficacy of Chloroquine and Lopinavir/ Ritonavir in mild/general novel coronavirus (CoVID-19) infections: a prospective, open-label, multicenter randomized controlled clinical study ChiCTR2000029741 Chinese Clinical Trials Registry A prospective, open-label, multiple-center study for the efficacy of chloroquine phosphate

ChiCTR2000029609 Chinese Clinical Trials Registry Study for the efficacy of chloroquine in patients with novel coronavirus pneumonia

 Sperber et al. 1995, USA(17) Randomized, double blind, placebocontrolled trial HIV infected patients with CD4+ cell count between 200-500/µl and not taking antiretroviral (ART) therapy 1) HCQ 800mg/d for 8 weeks (n=20) or 2) Placebo for same duration (n=20) Study terminated due to safety concerns -risk of bias not evaluated *Risk of bias not assessed for uncontrolled studies as results from these studies were not used to grade evidence. For non-randomized trials with more than one intervention, risk of bias assessed with ROBINS-I tool