More than four doses of hydroxychloroquine, along with the use of personal protective equipment (PPE), appeared to protect healthcare workers from sars cov-2, according to the first such published investigation in India on the drug’s preventive effects by researchers at the Indian Council of Medical Research (ICMR).
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While globally several studies have failed to show HCQ as useful for treating those moderately or severely sick from the disease, studies are under way to establish if it might confer some benefit on the healthy in preventing them from catching the disease. In laboratory studies, HCQ appeared to show antiviral properties and tempering the immune system response, which has what prompted global interest in the drug.
While this study that lists among its authors the Director General of the ICMR and scientists in government committees tasked with managing the COVID-19 response purports benefit from HCQ, it is yet unable to clearly differentiate whether protective gear or external factors had a greater role than HCQ in staving off infection.
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A scientist involved with the study said that this was due to the limitations of the study design and other independent experts told The Hindu that there were too few participants and several “confounding factors.” The study was observational in that it could at best establish correlation rather than prove causation of whether HCQ protected healthcare workers–the highest risk group for COVID-19 from infection.
For the study, published online in the ICMR’s Indian Journal of Medical Research, researchers contacted and interviewed 751 healthcare workers who reported COVID-19 symptoms and whose details were available on an ICMR database. About half tested positive for sars cov-2 and the researchers primarily focused on how many of them were taking HCQ and the frequency of dosage. They also recorded how many of them used masks, gloves, face-shields and how many of them were working in extremely close proximity to aerosols generated by COVID-19 patients, for instance intubating them or collecting swab sample from their throat and nose.
Fifty % of those not on HCQ tested positive and upto 70% of those who’d taken a weekly dose of 400 mg of HCQ for three week tested positive. However, only 40% of those who’d taken 4-5 doses tested positive and—only 10% of those on the drug for six weeks or more reported testing positive.
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Of those on HCQ alone, 130 tested positive and 133 tested negative and of those not on HCQ at all, 206 tested positive and 180 didn’t test positive.
The findings, the authors of the study said, “lend support” to India’s current policy of recommending HCQ as a preventive in healthcare workers and high-risk asymptomatic contacts of those who’ve tested positive for the disease. The current recommendations recommend a weekly dose, on prescription, for 8 weeks and even beyond after an electrocardiogram. Irregular heart rhythm is a risk factor associated with prolonged use of HCQ.
Save for one instance of “palpitation”, the only other side effects reported were nausea, headache and diarrhoea in 5-8% of the population, the authors note.
The study provided useful information to protect healthcare workers, said Samiran Panda, Director, National Aids Research Institute, and among the study authors. He, however, stated that it would be better to wait for results from future trials—that could tease out independent effects of interventions– before expanding HCQ use to groups beyond healthcare workers. “It’s one good step, but let’s cautiously move forward,” he told The Hindu. “HCQ plus PPE plus adequate precautions produce this effect. The protective effect of the higher dosage is something that we need to go deeper but previous experience in public health shows that medicine and behavioural responses to it influence outcomes.”
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Binay Panda, a geneticist at Ganit Labs and familiar with medical statistics, said that a limited dataset and a lack of detail such as how many healthcare workers who took HCQ but didn’t have protective equipment, if any, or how many doctors in close proximity on HCQ tested positive made conclusions hard to quantify. “A detailed supplementary data, that is nowadays typical of all good research paper, would have easily established the relative importance of each intervention.”
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