Users Online: 793 Home Print this page Email this page Small font sizeDefault font sizeIncrease font size


Home About us Editorial board Search Ahead of print Current issue Archives Submit article Instructions Subscribe Contacts Login 

 Table of Contents  
Year : 2020  |  Volume : 64  |  Issue : 6  |  Page : 125-127  

Hydroxychloroquine as prophylaxis or treatment for COVID-19: What does the evidence say?

1 Assistant Professor, Department of Epidemiology and Public Health, Central University of Tamil Nadu, Tiruvarur, Tamil Nadu, India
2 Vice-Chancellor; Central University of Tamil Nadu, Tiruvarur, Tamil Nadu, India

Date of Submission30-Apr-2020
Date of Decision20-May-2020
Date of Acceptance21-May-2020
Date of Web Publication2-Jun-2020

Correspondence Address:
Aditya Prasad Dash
Central University of Tamil Nadu, Tiruvarur, Tamil Nadu
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/ijph.IJPH_496_20

Rights and Permissions

Hydroxychloroquine (HCQ), an antimalarial has been proposed as possible treatment for coronavirus disease-2019 (COVID-19). India has approved the use of HCQ for prophylaxis of asymptomatic health workers treating suspected or confirmed COVID-19 cases, and asymptomatic household contacts of confirmed patients. The U.S. Food and Drug Administration has issued Emergency Use Authorization for the use of HCQ to treat COVID-19 in adolescents and adults. In this review, we go over the available evidence for and against HCQ's use as prophylaxis or treatment for COVID-19, especially in the Indian context.

Keywords: Chloroquine, COVID-19, Hydroxychloroquine, Prophylaxis

How to cite this article:
Nina PB, Dash AP. Hydroxychloroquine as prophylaxis or treatment for COVID-19: What does the evidence say?. Indian J Public Health 2020;64, Suppl S2:125-7

How to cite this URL:
Nina PB, Dash AP. Hydroxychloroquine as prophylaxis or treatment for COVID-19: What does the evidence say?. Indian J Public Health [serial online] 2020 [cited 2023 Jan 27];64, Suppl S2:125-7. Available from:

In India, as of April 30, 2020, >33,000 coronavirus disease-2019 (COVID-19) cases have been reported, and the death toll has exceeded 1000. Clinical data indicate that one out of six COVID-19 patients will develop respiratory distress and will need adequate medical care.[1] Acute respiratory failure is a common secondary outcome in severe cases of COVID-19, and despite mechanical ventilation, mortality rates of 40%–65% have been reported.[2] As of now, there is no clinically approved drug or vaccine, and the treatment is mostly supportive. Clinical trials are ongoing worldwide to test the efficacy of antiviral drugs and also hydroxychloroquine (HCQ), an antimalarial drug.[3]

Chloroquine (CQ) is a cheap and relatively safe antimalarial that has been used for decades in India and other malaria-endemic countries. Earlier studies have shown CQ to be highly effectivein vivo to treat avian influenza A (H5N1)[4] andin vitro against severe acute respiratory syndrome coronavirus (SARS-CoV).[5],[6] CQ raises the intracellular pH by sequestering the protons into lysosomes, which affects the fusion and uncoating of the virion, and viral replication.[4],[5],[6] In addition, it has been suggested that CQ can interfere with the terminal glycosylation process of the angiotensin-converting enzyme-2, the cellular receptor for entry of SARS-CoV.[6] CQ and HCQ share a similar chemical structure and action, but HCQ has lower toxicity.[7] HCQ has been shown to augment the early virological response against hepatitis C and also reduce the HIV-1 load.[8],[9] HCQ also has immunosuppressive properties that may help reduce the cytokine storm in severe COVID-19.[10],[11] Even though HCQ is relatively safe, in adverse conditions, it can lead to cardiac disorders such as QT segment prolongation, which could lead to arrhythmia and myocardial arrest.[12]

Recentin vitro studies have shown that both CQ and HCQ can inhibit the replication of SARS-CoV-2.[13],[14],[15] Based on these encouragingin vitro data, CQ was used in multicentric clinical trials involving 100 COVID-19 patients in China to test itsin vivo efficacy. The study concluded that CQ reduced the lung pathology and shortened the disease course without any serious adverse reactions.[16] Another Chinese study with 62 patients showed that HCQ reduced the time to clinical recovery[17] Furthermore, two studies conducted in France have suggested that HCQ, especially in combination with azithromycin (AZM), can reduce the viral load in COVID-19 patients.[18],[19] These encouraging preliminary studies should have guided the Indian Council of Medical Research (ICMR) to recommend HCQ for chemoprophylaxis of asymptomatic health workers treating suspected or confirmed COVID-19 cases and asymptomatic household contacts of confirmed patients.[20] For asymptomatic health workers, the recommended dose is 400 mg twice on day 1, followed by 400 mg once every week for 7 weeks, while for asymptomatic household contacts, the duration is 3 weeks and has to be prescribed by a registered medical practitioner.[20] However, there is no previous research to support the use of CQ and HCQ as prophylaxis to COVID-19. Recently, the US Food and Drug Administration has authorized HCQ for emergency use to treat COVID-19 pneumonia.[21]

It is pertinent to note that in the clinical studies conducted in China[16],[17] and France,[18],[19] critically ill COVID-19 patients were not included. The safety of HCQ is yet to be proven (metabolism and clearance) in severe COVID-19 patients with hepatic and renal dysfunction and are administered other medications.[22] The early clinical studies in France that supported the use of HCQ have been criticized by many researchers for its serious shortcomings.[22],[23] A small observational study (11 patients) treated with HCQ and AZM has shown the persistence of viral load and no clinical benefit.[24] A multinational, network cohort, and self-controlled case series study has found an increased risk of 30-day cardiovascular mortality when HCQ was used in combination with AZM but not alone.[25]

Overall, we do not have compelling evidence for and against HCQ's use to treat COVID-19, however, it is unsafe to use HCQ in combination with AZM.[25] We do not know if HCQ can prevent the progression from mild to severe COVID-19 or its role in severely ill patients. We need data from international multicenter, randomized, and open clinical trials such as discovery[26] and solidarity[27] to assess the efficacy of HCQ in the treatment of COVID-19. Given the gravity of the pandemic, and ICMR's experience of using HCQ for treating malaria, the rationale behind the recommendation of HCQ as chemoprophylaxis is understandable. Furthermore, ICMR guidelines prohibit HCQ's use in children <15 years and individuals with retinopathy and known hypersensitivity to HCQ and 4-aminoquinolines.[20] Importantly, by limiting HCQ's use to health workers and household contacts of confirmed patients, information on adverse events, if any, of HCQ can be collected efficiently to guide its future use. If not initiated already, the recommending authorities should conduct a clinical trial on the efficacy of HCQ for chemoprophylaxis of COVID-19 in India. HCQ chemoprophylaxis trials have already commenced in the US (NCT04318444) and Mexico (NCT04318015). The earliest estimated primary completion dates for the Mexico and US trials are December 2020 and March 2021, respectively. These trials may reveal negligible to no effect of HCQ in chemoprophylaxis of COVID-19. However, if the trials prove otherwise, waiting 9–12 months for initial evidence is not desirable, especially with HCQ's low cost and India's ability to manufacture. As of now, in India, self-medication of CQ and HCQ by the public without medical advice is a greater concern. To prevent unauthorized use, the availability of CQ and HCQ has to be tightly regulated.

Evidence from drug discovery efforts in the past strongly indicates that vast majority of the molecules cannot replicate theirin vitro efficacy in biological systems. Unlike antiviral drugs, HCQ has no direct effect on SARS-CoV-2. Its use against COVID-19, even as a prophylaxis, has to be continuously monitored, especially in individuals with preexisting heart conditions.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

The Novel Coronavirus Pneumonia Emergency Response Epidemiology Team. The epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19) – China, 2020. China CDC Wkly 2020;2:113-22.  Back to cited text no. 1
Yang X, Yu Y, Xu J, Shu H, Xia J, Liu H, et al. Clinical course and outcomes of critically ill patients with SARS-CoV-2 pneumonia in Wuhan, China: A single-centered, retrospective, observational study. Lancet Respir Med 2020;8:475-81.  Back to cited text no. 2
Zhang J, Xie B, Hashimoto K. Current status of potential therapeutic candidates for the COVID-19 crisis. Brain Behav Immun 2020;S0889-1591:30589-4.  Back to cited text no. 3
Yan Y, Zou Z, Sun Y, Li X, Xu KF, Wei Y, et al. Anti-malaria drug chloroquine is highly effective in treating avian influenza A H5N1 virus infection in an animal model. Cell Res 2013;23:300-2.  Back to cited text no. 4
Keyaerts E, Vijgen L, Maes P, Neyts J, Van Ranst M.In vitro inhibition of severe acute respiratory syndrome coronavirus by chloroquine. Biochem Biophys Res Commun 2004;323:264-8.  Back to cited text no. 5
Vincent MJ, Bergeron E, Benjannet S, Erickson BR, Rollin PE, Ksiazek TG, et al. Chloroquine is a potent inhibitor of SARS coronavirus infection and spread. Virol J 2005;2:69.  Back to cited text no. 6
Lim HS, Im JS, Cho JY, Bae KS, Klein TA, Yeom JS, et al. Pharmacokinetics of hydroxychloroquine and its clinical implications in chemoprophylaxis against malaria caused by Plasmodium vivax. Antimicrob Agents Chemother 2009;53:1468-75.  Back to cited text no. 7
Helal GK, Gad MA, Abd-Ellah MF, Eid MS. Hydroxychloroquine augments early virological response to pegylated interferon plus ribavirin in genotype-4 chronic hepatitis C patients. J Med Virol 2016;88:2170-8.  Back to cited text no. 8
Sperber K, Louie M, Kraus T, Proner J, Sapira E, Lin S, et al. Hydroxychloroquine treatment of patients with human immunodeficiency virus type 1. Clin Ther 1995;17:622-36.  Back to cited text no. 9
Sperber K, Chiang G, Chen H, Ross W, Chusid E, Gonchar M, et al. Comparison of hydroxychloroquine with zidovudine in asymptomatic patients infected with human immunodeficiency virus type 1. Clin Ther 1997;19:913-23.  Back to cited text no. 10
Mehta P, McAuley DF, Brown M, Sanchez E, Tattersall RS, Manson JJ, et al. COVID-19: Consider cytokine storm syndromes and immunosuppression. Lancet 2020;395:1033-4.  Back to cited text no. 11
Available from: [Last accessed on 2020 Apr 29].  Back to cited text no. 12
Yao X, Ye F, Zhang M, Cui C, Huang B, Niu P, et al.In vitro antiviral activity and projection of optimized dosing design of hydroxychloroquine for the treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Clin Infect Dis 2020:ciaa237. doi: 10.1093/cid/ciaa237.  Back to cited text no. 13
Liu J, Cao R, Xu M, Wang X, Zhang H, Hu H, et al. Hydroxychloroquine, a less toxic derivative of chloroquine, is effective in inhibiting SARS-CoV-2 infection in vitro. Cell Discov 2020;6:16.  Back to cited text no. 14
Wang M, Cao R, Zhang L, Yang X, Liu J, Xu M, et al. Remdesivir and chloroquine effectively inhibit the recently emerged novel coronavirus (2019-nCoV) in vitro. Cell Res 2020;30:269-71.  Back to cited text no. 15
Gao J, Tian Z, Yang X. Breakthrough: Chloroquine phosphate has shown apparent efficacy in treatment of COVID-19 associated pneumonia in clinical studies. Biosci Trends 2020;14:72-3.  Back to cited text no. 16
Chen Z, Hu J, Zhang Z, Jiang S, Han S, Yan D, et al. Efficacy of Hydroxychloroquine in Patients with COVID-19: Results of a Randomized Clinical Trial. medRxiv; 2020. doi:  Back to cited text no. 17
Gautret P, Lagier JC, Parola P, Hoang VT, Meddeb L, Mailhe M, et al. Hydroxychloroquine and azithromycin as a treatment of COVID-19: Results of an open-label non-randomized clinical trial. Int J Antimicrob Agents 2020. doi: 10.1016/j.ijantimicag.2020.105949.   Back to cited text no. 18
Gautret P, Lagier JC, Parola P, Hoang VT, Meddeb L, Sevestre J, et al. Clinical and microbiological effect of a combination of hydroxychloroquine and azithromycin in 80 COVID-19 patients with at least a six-day follow up: A pilot observational study. Travel Med Infect Dis 2020;34:101663.  Back to cited text no. 19
Indian Council for Medical Research. Recommendation for Empiric use of Hydroxychloroquine for Prophylaxis of SARS-CoV-2 Infection. Available from: ents/HCQ_Recommendation_22March_final_MM_V2.pdf. [Last accessed on 2020 Apr 03].  Back to cited text no. 20
Lenzer J. Covid-19: US gives emergency approval to hydroxychloroquine despite lack of evidence. BMJ 2020;369:m1335.  Back to cited text no. 21
Taccone FS, Gorham J, Vincent JL. Hydroxychloroquine in the management of critically ill patients with COVID-19: The need for an evidence base. Lancet Respir Med 2020. S2213-2600:30172-7.  Back to cited text no. 22
Ferner RE, Aronson JK. Chloroquine and hydroxychloroquine in covid-19. BMJ 2020;369:m1432.  Back to cited text no. 23
Molina JM, Delaugerre C, Le Goff J, Mela-Lima B, Ponscarme D, Goldwirt L, et al. No evidence of rapid antiviral clearance or clinical benefit with the combination of hydroxychloroquine and azithromycin in patients with severe COVID-19 infection. Med Mal Infect 2020;50:384.  Back to cited text no. 24
Lane JC, Weaver J, Kostka K, Duarte-Salles T, Abrahao MTF, Alghoul H, et al. Safety of Hydroxychloroquine, Alone and in Combination with Azithromycin, in Light of Rapid Wide-Spread use for COVID-19: A Multinational, Network Cohort and Self-Controlled Case Series Study. medRxiv; 2020. doi:  Back to cited text no. 25
Trial of treatments for COVID-19 in hospitalized adults (DisCoVeRy). Available from: [Last accessed on 2020 Apr 29].  Back to cited text no. 26
”Solidarity” clinical trial for COVID-19 treatments. Available from: [Last accessed on 2020 Apr 29].  Back to cited text no. 27

This article has been cited by
1 A sentiment and content analysis of tweets on monkeypox stigma among the LGBTQ+ community: A cue to risk communication plan
Viola Savy Dsouza, Priyobrat Rajkhowa, B. Rashmi Mallya, D.S. Raksha, V. Mrinalini, K. Cauvery, Rohit Raj, Indu Toby, Sanjay Pattanshetty, Helmut Brand
Dialogues in Health. 2023; 2: 100095
[Pubmed] | [DOI]
2 Pain in COVID-19: Quis est culpa?
Oleksandr Dobrovanov, Dmytro Dmytriiev, Augustin Prochotsky, Marian Vidiscak, Katarina Furkova
Electronic Journal of General Medicine. 2023; 20(1): em435
[Pubmed] | [DOI]
3 Effect of Graphite Exfoliation Way on the Efficiency of Exfoliated Graphene for the Determination of Hydroxychloroquine in Urine and Waste Water
M. Matrouf, A. Loudiki, F.Z. Ouatmane, B. Chhaibi, O. Tahiri Alaoui, F. Laghrib, A. Farahi, M. Bakasse, S. Lahrich, M. A. EL Mhammedi
Journal of The Electrochemical Society. 2022; 169(9): 097505
[Pubmed] | [DOI]
4 Potential of Nanotechnology-based Formulations in Combating Pulmonary Infectious Diseases: A Current Scenario
Manisha Patel, Rupa Mazumder, Rakhi Mishra, Kamal Kant Kaushik
Current Pharmaceutical Design. 2022; 28(42): 3413
[Pubmed] | [DOI]
5 Overview of SARS-CoV-2 and Possible Targets for the Management of COVID-19 Infections
Arunachalam Muthuraman, Muthusamy Ramesh, Aswinprakash Subramanian, Jagadeesh Dhamodharan, Lim Khian Giap
Coronaviruses. 2022; 3(5)
[Pubmed] | [DOI]
6 Early Outpatient Treatment of COVID-19: A Retrospective Analysis of 392 Cases in Italy
Marco Cosentino, Veronica Vernocchi, Stefano Martini, Franca Marino, Barbara Allasino, Maria Antonietta Bālzola, Fabio Burigana, Alberto Dallari, Carlo Servo Florio Pagano, Antonio Palma, Mauro Rango
Journal of Clinical Medicine. 2022; 11(20): 6138
[Pubmed] | [DOI]
7 The Rise and Fall of Hydroxychloroquine for the Treatment and Prevention of COVID-19
Zelyn Lee,Craig R. Rayner,Jamie I. Forrest,Jean B. Nachega,Esha Senchaudhuri,Edward J. Mills
The American Journal of Tropical Medicine and Hygiene. 2021; 104(1): 35
[Pubmed] | [DOI]
8 Side effects of hydroxychloroquine prophylaxis against COVID-19 in healthcare workers
Prashant Kumar Dixit,Salil Gupta,Ajay Shankar Prasad,Kinshuk Kohli,Parthasarathi Ghana
Medical Journal Armed Forces India. 2021; 77: S513
[Pubmed] | [DOI]
9 COVID-19, hydroxychloroquine and sudden cardiac death: implications for clinical practice in patients with rheumatic diseases
Hussain Ahmed Raza,Javeria Tariq,Vikas Agarwal,Latika Gupta
Rheumatology International. 2021; 41(2): 257
[Pubmed] | [DOI]
10 Cancer vs. SARS-CoV-2 induced inflammation, overlapping functions, and pharmacological targeting
Sreedhar Amere Subbarao
Inflammopharmacology. 2021; 29(2): 343
[Pubmed] | [DOI]
11 Situation of India in the COVID-19 Pandemic: India’s Initial Pandemic Experience
Azizah F. Siddiqui,Manuel Wiederkehr,Liudmila Rozanova,Antoine Flahault
International Journal of Environmental Research and Public Health. 2020; 17(23): 8994
[Pubmed] | [DOI]


    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

  In this article

 Article Access Statistics
    PDF Downloaded1955    
    Comments [Add]    
    Cited by others 11    

Recommend this journal