Hydroxychloroquine Postexposure Prophylaxis for COVID-19 Fails Save

NEJM has reported that the use of hydroxychloroquine did not prevent symptomatic COVID-19 infection when used within 4 days after SARS-CoV-2 exposure.

Currently for persons who are COVID exposed, the standard of care is quarantine and there is no known preventative therapy.

This trial was a multicenter randomized, double-blind, placebo-controlled trial that enrolled adults (from the USA and Canada) who had been exposed to someone with confirmed Covid-19. Patients were randomized to either placebo or hydroxychloroquine (800 mg once, followed by 600 mg in 6 to 8 hours, then 600 mg qd for 4 days). The primary outcome was either laboratory-confirmed Covid-19 or COVID-19 illness within 14 days.

They enrolled 821 asymptomatic participants. At 12 weeks 11.8% of those treated with HCQ developed confirmed Covid-19 contact. This was not significantlydifferent thann placebo treated patients (14.3%; P=0.35). The number needed to treat (NNT) to prevent COVID would be 42 persons. 

Side effects were more common with HCQ compaed to placebo (40% vs. 17%), but no serious adverse reactions were reported.

These findings show no benefit to HCQ prophylaxis in preventing infection in those exposed to COVID-19.  It is possible that if the entry window were modified, these results may be different. .