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HCQ study #143 of 230
9/30 Pre-Exposure Prophylaxis study (treated before exposed to the virus)
Abella et al., JAMA Internal Medicine, doi:doi:10.1001/jamainternmed.2020.6319 (Peer Reviewed)
Efficacy and Safety of Hydroxychloroquine vs Placebo for Pre-exposure SARS-CoV-2 Prophylaxis Among Health Care Workers
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Very small early-terminated underpowered PrEP RCT with 64/61 HCQ/control patients and only 8 infections, HCQ infection rate 6.3% versus control 6.6%, RR 0.95 [0.25 - 3.64].
There was no hospitalization or death, no significant difference in QTc, no severe adverse events, no cardiac events (e.g., syncope and arrhythmias) observed. Medication adherence was 81%. Therapeutic levels of HCQ may not have been reached by the time of the infection in the first week.
2 infections were reported to be after discontinuation of the medication, but the authors do not specify which arm these were in. Hypothetically, if these were both in the HCQ arm, the resulting RR for treatment would be much lower.

Abella et al., 9/30/2020, Randomized Controlled Trial, USA, North America, peer-reviewed, 18 authors.
risk of COVID-19 case, 5.0% lower, RR 0.95, p = 1.00, treatment 4 of 64 (6.2%), control 4 of 61 (6.6%).
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