A new study in NEJM about hydroxychloroquine for post-exposure prophylaxis of COVID-19.
https://www.nejm.org/doi/full/10.105...elated_article
People (almost all healthcare workers) who were in close contact with known cases were either given hydroxychloroquine or placebo.
We included participants who had household or occupational exposure to a person 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).
The biggest issue I'd have with this trial is that the drugs (hydroxychloroquine or placebo) were mailed to the patients (who were randomized and double-blinded). As it was not done in clinic, it's difficult to ascertain if people actually took all of the drugs, but as they were double-blind, patients would be no less likely to take the placebo or the active drug and would stop due to side effects.
Full adherence to the trial intervention differed according to trial group, with 75.4% of participants in the hydroxychloroquine group (312 of 414) and 82.6% of those in the placebo group (336 of 407) having taken all 19 prescribed tablets over a period of 5 days (P=0.01)
However, the trial was fully powered (had a sufficient sample size).
Findings:
The incidence of new illness compatible with Covid-19 did not differ significantly between those receiving hydroxychloroquine (49 of 414 [11.8%]) and those receiving placebo (58 of 407 [14.3%]) (P=0.35). The absolute difference was −2.4 percentage points (95% confidence interval, −7.0 to 2.2).
As the confidence interval spanned 0 and the p> 0.05, there was no benefit from taking hydroxychloroquine to prevent COVID-19 after initial exposure.