David R. Boulware , M.D., M.P.H., Matthew F. Pullen , M.D., Ananta S. Bangdiwala , M.S., Katelyn A. Pastick , B.Sc., Sarah M. Lofgren , M.D., Elizabeth C. Okafor , B.Sc., Caleb P. Skipper , M.D., Alanna A. Nascene , B.A., Melanie R. Nicol , Pharm.D., Ph.D., Mahsa Abassi , D.O., M.P.H., Nicole W. Engen , M.S., Matthew P. Cheng , M.D., Derek LaBar , Pharm.D., Sylvain A. Lother , M.D., Lauren J. MacKenzie , M.D., M.P.H., Glen Drobot , M.D., Nicole Marten , R.N., Ryan Zarychanski , M.D., Lauren E. Kelly , Ph.D., Ilan S. Schwartz , M.D., Ph.D., Emily G. McDonald , M.D., Radha Rajasingham , M.D., Todd C. Lee , M.D., M.P.H., Kathy H. Hullsiek , Ph.D.
03 June 2020
Keyword part (code): 18Keyword part (keyword): Infectious DiseaseKeyword part (code): 18_1Keyword part (keyword): Infectious Disease GeneralKeyword part (code): 18_6Keyword part (keyword): Viral InfectionsKeyword part (code): 18_9Keyword part (keyword): Global HealthKeyword part (code): 18_11Keyword part (keyword): Influenza , 18, Infectious Disease, Keyword part (code): 18_1Keyword part (keyword): Infectious Disease GeneralKeyword part (code): 18_6Keyword part (keyword): Viral InfectionsKeyword part (code): 18_9Keyword part (keyword): Global HealthKeyword part (code): 18_11Keyword part (keyword): Influenza , 18_1, Infectious Disease General, 18_6, Viral Infections, 18_9, Global Health, 18_11, Influenza
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.
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.
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.
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; ClinicalTrials.gov number, NCT04308668.)