Dental Tribune India

New case control study by ICMR shows Hydroxychloroquine can prevent COVID-19 in healthcare workers

By Rajeev Chitguppi, Dental Tribune South Asia
June 01, 2020

The use of Hydroxychloroquine (HCQ) has generated considerable debate after the US President Donald Trump was seen pushing the drug, against the FDA warning, as a potential treatment or prophylaxis for COVID-19. World Health Organization (WHO) suspended the HCQ trials based on a report in The Lancet which published a poorly conducted study with questionable authenticity and validity. However, the Indian Council of Medical Research (ICMR) continued to recommend HCQ as a prophylactic measure against COVID- 19. Now, the latest case-control study by the ICMR clearly shows the benefits of using HCQ as a prophylactic drug against COVID -19.

Two laboratory findings encouraged the researchers globally to consider Hydroxychloroquine (HCQ) as a primary choice for prophylaxis against SARS-CoV-2 (1). First, the ability of Hydroxychloroquine (HCQ) to inhibit the infection by SARS-CoV-2, as well as viral replication in cell cultures in a time- and dose-dependent manner (2). Second, the effect of HCQ to elevate the pH of endosomes and inhibit SARS-CoV-2 RNA-mediated inflammatory response. (3)

Taking cognizance of this evidence, the National Task Force for COVID-19 in India empirically recommended the use of HCQ as prophylaxis against SARS-CoV-2 infection in asymptomatic Healthcare Workers (HCW) treating suspected or confirmed COVID-19 cases. This advisory (released on March 22, 2020) also covered the asymptomatic household contacts of confirmed COVID-19 cases. (4)

Thus, HCQ that was originally being used for malaria, became a repurposed agent for COVID-19.

Around the same time, doctors in South Korea successfully used HCQ prophylaxis to avert new infections after a large COVID-19 exposure event in a long-term care facility (5).

A recently published report in The Lancet showed distinct harm from HCQ use apart from no benefit against SARS-COV-2. (6) However, this Lancet study has been shamed by the global scientific community for hiding crucial data, lack of transparency, apart from ethical concerns and questionable validity.

Dental Tribune had earlier carried a report on why ICMR was right in recommending HCQ and why WHO was wrong in suspending the drug trial. Click here to read our earlier report "Lancet faces severe criticism from the scientific community: Hydroxychloroquine study is hiding data". Comments to this article from seasoned medical practitioners from India show that they do not care what The Lancet says and that they will trust their decade-long experience with the safe use of Hydroxychloroquine and also the ICMR advisory to use HCQ prophylaxis

Now, the ICMR conducted a case-control study (7) to compare the risks of and protective factors against SARS-CoV-2 infection among HCWs in India. The study concludes that Hydroxychloroquine protects HCWs from COVID- 19.

This study "Healthcare workers & SARS-CoV-2 infection in India: A case-control investigation in the time of COVID-19" has been published (ahead of print) in the Indian Journal of Medical Research.


Background & objectives: Healthcare workers (HCWs) are at an elevated risk of contracting COVID-19. While intense occupational exposure associated with aerosol-generating procedures underlines the necessity of using personal protective equipment (PPE) by HCWs, high-transmission efficiency of the causative agent [severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)] could also lead to infections beyond such settings. Hydroxychloroquine (HCQ), a repurposed antimalarial drug, was empirically recommended as prophylaxis by the National COVID-19 Task Force in India to cover such added risk. Against this background, the current investigation was carried out to identify the factors associated with SARS-CoV-2 infection among HCWs in the country.

Methods: A case-control design was adopted and participants were randomly drawn from the countrywide COVID-19 testing data portal maintained by the ICMR. The test results and contact details of HCWs, diagnosed as positive (cases) or negative (controls) for SARS-CoV-2 using real-time reverse transcription-polymerase chain reaction (qRT-PCR), were available from this database. A 20-item brief-questionnaire elicited information on place of work, procedures conducted and use of PPE.

Results: Compared to controls, cases were slightly older (34.7 vs. 33.5 yr) and had more males (58 vs. 50%). In multivariate analyses, HCWs performing endotracheal intubation had higher odds of being SARS-CoV-2 infected [adjusted odds ratio (AOR): 4.33, 95% confidence interval (CI): 1.16-16.07]. Consumption of four or more maintenance doses of HCQ was associated with a significant decline in the odds of getting infected (AOR: 0.44; 95% CI: 0.22-0.88); a dose-response relationship existed between the frequency of exposure to HCQ and such reductions (χ2 for trend=48.88; P<0.001). In addition, the use of PPE was independently associated with the reduction in odds of getting infected with SARS-CoV-2.

Interpretations & conclusions: Until the results of clinical trials for HCQ prophylaxis become available, this study provides actionable information for policymakers to protect HCWs at the forefront of COVID-19 response. The public health message of sustained intake of HCQ prophylaxis as well as appropriate PPE use need to be considered in conjunction with risk homoeostasis operating at individual levels.

Click here to read the full article


1. 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.

2. 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.

3. Al-Bari MAA. Targeting endosomal acidification by chloroquine analogs as a promising strategy for the treatment
of emerging viral diseases. Pharmacol Res Perspect 2017; 5 :e00293.

4. National Task Force for COVID-19 in India. Recommendation for empiric use of hydroxychloroquine for prophylaxis
of SARS-CoV-2 infection; 2020. Available from the website of Ministry of Health and Family Welfare, accessed on 1st June, 2020.
Click here to read it 

5. Lee SH, Son H, Peck KR. Can post-exposure prophylaxis for COVID-19 be considered as an outbreak response strategy
in long-term care hospitals? Int J Antimicrob Agents 2020. doi: 10.1016/j.ijantimicag.2020.105988

6. Mandeep R Mehra, Sapan S Desai, Frank Ruschitzka, Amit N Patel. Hydroxychloroquine or chloroquine with or without a macrolide for treatment of COVID-19: a multinational registry analysis Published Online May 22, 2020 doi:

7. Healthcare workers & SARS-CoV-2 infection in India: A case-control investigation in the time of COVID-19. Indian J Med Res, Epub ahead of print DOI: 10.4103/ijmr.IJMR_2234_20


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