A Randomized Trial of Hydroxychloroquine as Postexposure Prophylaxis for Covid-19

David R Boulware, Matthew F Pullen, Ananta S Bangdiwala, Katelyn A Pastick, Sarah M Lofgren, Elizabeth C Okafor, Caleb P Skipper, Alanna A Nascene, Melanie R Nicol, Mahsa Abassi, Nicole W Engen, Matthew P Cheng, Derek LaBar, Sylvain A Lother, Lauren J MacKenzie, Glen Drobot, Nicole Marten, Ryan Zarychanski, Lauren E Kelly, Ilan S Schwartz, Emily G McDonald, Radha Rajasingham, Todd C Lee, Kathy H Hullsiek
New England Journal of Medicine 2020 June 3

BACKGROUND: Coronavirus disease 2019 (Covid-19) occurs after exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). For persons who are exposed, the standard of care is observation and quarantine. Whether hydroxychloroquine can prevent symptomatic infection after SARS-CoV-2 exposure is unknown.

METHODS: We conducted a randomized, double-blind, placebo-controlled trial across the United States and parts of Canada testing hydroxychloroquine as postexposure prophylaxis. We enrolled adults who had household or occupational exposure to someone with confirmed Covid-19 at a distance of less than 6 ft for more than 10 minutes while wearing neither a face mask nor an eye shield (high-risk exposure) or while wearing a face mask but no eye shield (moderate-risk exposure). Within 4 days after exposure, we randomly assigned participants to receive either placebo or hydroxychloroquine (800 mg once, followed by 600 mg in 6 to 8 hours, then 600 mg daily for 4 additional days). The primary outcome was the incidence of either laboratory-confirmed Covid-19 or illness compatible with Covid-19 within 14 days.

RESULTS: We enrolled 821 asymptomatic participants. Overall, 87.6% of the participants (719 of 821) reported a high-risk exposure to a confirmed Covid-19 contact. The incidence of new illness compatible with Covid-19 did not differ significantly between participants receiving hydroxychloroquine (49 of 414 [11.8%]) and those receiving placebo (58 of 407 [14.3%]); the absolute difference was -2.4 percentage points (95% confidence interval, -7.0 to 2.2; P = 0.35). Side effects were more common with hydroxychloroquine than with placebo (40.1% vs. 16.8%), but no serious adverse reactions were reported.

CONCLUSIONS: After high-risk or moderate-risk exposure to Covid-19, hydroxychloroquine did not prevent illness compatible with Covid-19 or confirmed infection when used as postexposure prophylaxis within 4 days after exposure. (Funded by David Baszucki and Jan Ellison Baszucki and others; number, NCT04308668.).

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Nitin Jagtap

Only 10 percentage chance of infection after high risk exposure with or without HCQS.
Personal protection helps


sirag elsabea

This study unfortunately lacking logical thinking in addition to wrong calculated dose of the drug.
They are taking the exposed cases for 10 minutes as they mentioned without differentiation between those who got the virus or not! Which can be detected by many tests whether direct or in direct.
Secondly, there are people were in contact with positive cases but not exposed to sneezing or coughing for example or the cases not even spoken!! How they will control these variations???!!
No accuracy.
The dose of the Hydroxychloroquine is lower than therapeutic dose ((AS MOST OF THE OTHER STUDIES DID)) , so, the result definitely will be unsatisfactory.
Pharmacokinetics of the Hydroxychloroquine dictating loading dose of 400mg Q6 hourly for two days (i.e. 1600 mg per day)) then ONLY half tab (100 mg)) per day
This in case of prophylaxis or early mild case.


Liang Shi

amazing tentative idea


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