4 or more hydroxychloroquine doses reduced risk of coronavirus in healthcare workers: ICMR study

The Lancet study and the World Health Organization (WHO) solidarity trials may have put a pause on the use of the anti-malarial drug hydroxychloroquine (HCQ) as prophylaxis or treatment to reduce the risk of the novel coronavirus. However, a case-control study by the Indian research body, the ICMR continues to rally for its usage in the healthcare workers (HCWs) who are at an elevated risk of contracting Covid-19.

The case-control investigation of the ICMR reveals that consumption of four or more maintenance doses of hydroxychloroquine led to a significant decline in the odds of healthcare workers getting infected with the coronavirus infection.

The ICMR study indicates that "simply initiating HCQ prophylaxis did not reduce the odds of acquiring Covid-19 infection among HCWs. However, with the intake of four or more maintenance doses of HCQ, the protective effect started emerging. A significant reduction of about 80 per cent in the odds of Covid-19 infection in the HCWs was identified with the intake of six or more doses of HCQ prophylaxis. This dose-response relationship added strength to the study outcomes."

"Biologically, it appears plausible that HCQ prophylaxis, before the onset of infection, may inhibit the virus from gaining a foothold," researchers said in the study.

The National Task Force for coronavirus in India recommended once a week maintenance dose for seven weeks i.e., 400 mg once every week, following the loading dose of 400 mg. Adherence to this recommended regimen is underlined by the findings of the study, researchers said.

Scientists who co-authored the study said, "It has been noticed that 4th week onwards there is a risk reduction of contracting the Covid-19 virus if the maintenance dosage is being taken as prescribed for seven weeks. Of course, this doesn't rule out the risk minimisation of those frontline workers who are treating Covid-19 patients while wearing PPEs and taking further precautions."

Data were collected from May 8 to May 23, 2020. Doctors, nurses, housekeeping staff, security guards as well as laboratory technicians and operation theatre technicians, tested between the first week of April 2020 and in the first week of May 2020, formed the sample pool from which cases and controls were drawn.

The sample size consisted of 378 symptomatic healthcare workers who tested positive for coronavirus. They were defined as cases. 373 symptomatic healthcare workers who tested negative were part of the control group. A total of 751 people formed the sample size for the study.

Of these, 58 per cent of the cases and about half of the controls were males.

"Of the 172 cases and 193 controls reporting HCQ intake, no significant difference in the occurrence of adverse drug reactions was noted," the study noted.

The three most common side effects of HCQ as reported by the cases and controls were nausea (8 per cent), headache (5 per cent), and diarrhea (4 per cent). While none of the controls on HCQ complained of palpitations, only one case (1/172, 0.6 per cent) reported the same.

The study also revealed that gastrointestinal symptoms such as acidity and vomiting following HCQ intake ranged from 0.6 per cent in cases to about two per cent in controls. Very few cases (0.6%) and controls (1.4%) had skin rashes after consuming hydroxychloroquine.

The study also mentions how the international medical research looks at the use of hydroxychloroquine for treatment, like the Lancet Study that stated intake of the HCQ could lead to increased risk of mortality in coronavirus patients.

"While the observational study involving registry-analysis focussed on the treatment of hospitalised Covid-19 patients, our emphasis was on the prevention of infections among healthcare workers. In treatment settings, severe Covid-19 patients are likely to have a very high viral load and cytokine levels, which may not be improved by HCQ therapy. The registry-based analysis further recorded higher frequencies of ventricular arrhythmias in patients receiving HCQ. The toxicities of HCQ are likely to be infrequent in healthy groups undergoing prophylactic therapy as observed in our study participants. Biologically, it appears plausible that HCQ prophylaxis, before the onset of infection, may inhibit the virus from gaining a foothold." it stated.

The study comes as a reckoner for the medical fraternity until the clinical trials on HCQ yield definitive results. "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 coronavirus 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 homeostasis operating at individual levels." ICMR study stated.