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A Randomized Trial of Hydroxychloroquine as Postexposure Prophylaxis for Covid-19.
N Engl J Med. 2020 08 06; 383(6):517-525.NEJM

Abstract

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; ClinicalTrials.gov number, NCT04308668.).

Authors+Show Affiliations

From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.From the University of Minnesota (D.R.B., M.F.P., A.S.B., K.A.P., S.M.L., E.C.O., C.P.S., A.A.N., M.R.N., M.A., N.W.E., R.R., K.H.H.) and M Health Fairview Investigational Drug Service Pharmacy (D.L.), Minneapolis; and the Research Institute of the McGill University Health Centre and the Clinical Practice Assessment Unit, Department of Medicine, McGill University, Montreal (M.P.C., E.G.M., T.C.L.), the Department of Internal Medicine, University of Manitoba (S.A.L., L.J.M., G.D., N.M., R.Z.), the Research Institute in Oncology and Hematology, CancerCare Manitoba, University of Manitoba (R.Z.), and the George and Fay Yee Centre for Healthcare Innovation (L.E.K.), Winnipeg, and the University of Alberta, Edmonton (I.S.S.) - all in Canada.

Pub Type(s)

Journal Article
Multicenter Study
Randomized Controlled Trial
Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

32492293

Citation

Boulware, David R., et al. "A Randomized Trial of Hydroxychloroquine as Postexposure Prophylaxis for Covid-19." The New England Journal of Medicine, vol. 383, no. 6, 2020, pp. 517-525.
Boulware DR, Pullen MF, Bangdiwala AS, et al. A Randomized Trial of Hydroxychloroquine as Postexposure Prophylaxis for Covid-19. N Engl J Med. 2020;383(6):517-525.
Boulware, D. R., Pullen, M. F., Bangdiwala, A. S., Pastick, K. A., Lofgren, S. M., Okafor, E. C., Skipper, C. P., Nascene, A. A., Nicol, M. R., Abassi, M., Engen, N. W., Cheng, M. P., LaBar, D., Lother, S. A., MacKenzie, L. J., Drobot, G., Marten, N., Zarychanski, R., Kelly, L. E., ... Hullsiek, K. H. (2020). A Randomized Trial of Hydroxychloroquine as Postexposure Prophylaxis for Covid-19. The New England Journal of Medicine, 383(6), 517-525. https://doi.org/10.1056/NEJMoa2016638
Boulware DR, et al. A Randomized Trial of Hydroxychloroquine as Postexposure Prophylaxis for Covid-19. N Engl J Med. 2020 08 6;383(6):517-525. PubMed PMID: 32492293.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A Randomized Trial of Hydroxychloroquine as Postexposure Prophylaxis for Covid-19. AU - Boulware,David R, AU - Pullen,Matthew F, AU - Bangdiwala,Ananta S, AU - Pastick,Katelyn A, AU - Lofgren,Sarah M, AU - Okafor,Elizabeth C, AU - Skipper,Caleb P, AU - Nascene,Alanna A, AU - Nicol,Melanie R, AU - Abassi,Mahsa, AU - Engen,Nicole W, AU - Cheng,Matthew P, AU - LaBar,Derek, AU - Lother,Sylvain A, AU - MacKenzie,Lauren J, AU - Drobot,Glen, AU - Marten,Nicole, AU - Zarychanski,Ryan, AU - Kelly,Lauren E, AU - Schwartz,Ilan S, AU - McDonald,Emily G, AU - Rajasingham,Radha, AU - Lee,Todd C, AU - Hullsiek,Kathy H, Y1 - 2020/06/03/ PY - 2020/6/4/pubmed PY - 2020/8/13/medline PY - 2020/6/4/entrez SP - 517 EP - 525 JF - The New England journal of medicine JO - N Engl J Med VL - 383 IS - 6 N2 - 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; ClinicalTrials.gov number, NCT04308668.). SN - 1533-4406 UR - https://www.unboundmedicine.com/medline/citation/32492293/full_citation L2 - https://www.nejm.org/doi/10.1056/NEJMoa2016638?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -