COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

Primary Prevention Abella BS, Jolkovsky EL, Biney BT, et al. Efficacy and Safety of Hydroxychloroquine vs Placebo for Pre-exposure SARS-CoV-2 Prophylaxis Among Health Care Workers: A Randomized Clinical Trial. JAMA Intern Med. 2020 Sep 30. pii: 2771265. doi: 10.1001/jamainternmed.2020.6319.

Importance: Health care workers (HCWs) caring for patients with coronavirus disease 2019 (COVID-19) are at risk of exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Currently, to our knowledge, there is no effective pharmacologic prophylaxis for individuals at risk.

Objective: To evaluate the efficacy of hydroxychloroquine to prevent transmission of SARS-CoV-2 in hospital-based HCWs with exposure to patients with COVID-19 using a pre-exposure prophylaxis strategy.

Design, Setting, and Participants: This randomized, double-blind, placebo-controlled clinical trial (the Prevention and Treatment of COVID-19 With Hydroxychloroquine Study) was conducted at 2 tertiary urban hospitals, with enrollment from April 9, 2020, to July 14, 2020; follow-up ended August 4, 2020. The trial randomized 132 full-time, hospital-based HCWs (physicians, nurses, certified nursing assistants, emergency technicians, and respiratory therapists), of whom 125 were initially asymptomatic and had negative results for SARS-CoV-2 by nasopharyngeal swab. The trial was terminated early for futility before reaching a planned enrollment of 200 participants.

Interventions: Hydroxychloroquine, 600 mg, daily, or size-matched placebo taken orally for 8 weeks.

Main Outcomes and Measures: The primary outcome was the incidence of SARS-CoV-2 infection as determined by a nasopharyngeal swab during the 8 weeks of treatment. Secondary outcomes included adverse effects, treatment discontinuation, presence of SARS-CoV-2 antibodies, frequency of QTc prolongation, and clinical outcomes for SARS-CoV-2-positive participants.

Results: Of the 132 randomized participants (median age, 33 years [range, 20-66 years]; 91 women [69%]), 125 (94.7%) were evaluable for the primary outcome. There was no significant difference in infection rates in participants randomized to receive hydroxychloroquine compared with placebo (4 of 64 [6.3%] vs 4 of 61 [6.6%]; P > .99). Mild adverse events were more common in participants taking hydroxychloroquine compared with placebo (45% vs 26%; P = .04); rates of treatment discontinuation were similar in both arms (19% vs 16%; P = .81). The median change in QTc (baseline to 4-week evaluation) did not differ between arms (hydroxychloroquine: 4 milliseconds; 95% CI, -9 to 17; vs placebo: 3 milliseconds; 95% CI, -5 to 11; P = .98). Of the 8 participants with positive results for SARS-CoV-2 (6.4%), 6 developed viral symptoms; none required hospitalization, and all clinically recovered.

Conclusions and Relevance: In this randomized clinical trial, although limited by early termination, there was no clinical benefit of hydroxychloroquine administered daily for 8 weeks as pre-exposure prophylaxis in hospital-based HCWs exposed to patients with COVID-19.

Trial Registration: Identifier: NCT04329923.

Discipline / Specialty Area Score
Emergency Medicine
Intensivist/Critical Care
Public Health
Occupational and Environmental Health
Hospital Doctor/Hospitalists
Internal Medicine
Infectious Disease
Comments from MORE raters

Emergency Medicine rater

This study could be criticised as under-powered, having been terminated early for futility, but I think it is reasonable for the researchers to limit the time and effort they spend on testing a hypothesis that never had a strong rationale.

Hospital Doctor/Hospitalists rater

This small, well conceived study adds another nail in the OH-Cloroquine coffin. It is only valuable in context of other articles showing no value of this agent for COVID-19 and one box too few to address prophylaxis. By itself, this is too small to warrant attention.

Infectious Disease rater

Unfortunately, early termination provides inconclusive results. However, the current knowledge in the subject is mostly consistent that there is no any room for hydroxychloroquine in COVID-19.

Intensivist/Critical Care rater

It is very important to perform rigorous analysis of proposed treatments that may have broad application if suggestion of benefit occurs rather than acting on hypotheses alone especially in consideration of the need for safety data. This is a good, important trial.

Internal Medicine rater

There is increasing evidence that HCQ prophylaxis does not reduce COVID infection and it is good that more randomized trials, such as this one, are able to provide this information.