1/ There is a claim that Hydroxychloroquine has not being tested in clinical trials for either prophylaxis or mild COVID.

A thread:

Mild-to-moderate

https://www.nejm.org/doi/full/10.1056/NEJMoa2019014

2/ Mild https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciaa1009/5872589

3/ Prophylaxis for high-risk or moderate-risk exposure.

https://www.nejm.org/doi/full/10.1056/NEJMoa2016638

4/ Yet to be published (PEP = post exposure prophylaxis)

https://clinicaltrials.gov/ct2/show/NCT04304053

5) What about PrEP (pre-exposure prophylaxis)?

Ongoing study recruiting 40,000 participants

https://clinicaltrials.gov/ct2/show/NCT04303507

6/ Another one ongoing in the UK for PrEP of 1000 participants

7/ And while the May 2020 meta analysis said "Evidence on the benefits and harms of using hydroxychloroquine or chloroquine to treat COVID-19 is very weak and conflicting."

https://www.acpjournals.org/doi/10.7326/M20-2496

It is absolutely untrue (even in May) to say that there are no studies.

8/ Studies in PEP, PrEP and mild disease are important because, let's face it, if you can avoid a disease or catch it early, why not? After all, lots of successful examples: antiretrovirals for HIV; malaria prophylaxis.

9/ But with more and more evidence, unfortunately, hydroxychloroquine does not appear to be useful and increasingly appears harmful. End/