Known since 2005 - from the NIHs own website

But the pharma corporations need to make their billions - got to keep the stockholders happy.
From Facui's own National Institutes of Health:

Chloroquine is a potent inhibitor of SARS coronavirus infection and spread
Severe acute respiratory syndrome (SARS) is caused by a newly discovered coronavirus (SARS-CoV). No effective prophylactic or post-exposure therapy is currently available.

Results
We report, however, that chloroquine has strong antiviral effects on SARS-CoV infection of primate cells. These inhibitory effects are observed when the cells are treated with the drug either before or after exposure to the virus, suggesting both prophylactic and therapeutic advantage. In addition to the well-known functions of chloroquine such as elevations of endosomal pH, the drug appears to interfere with terminal glycosylation of the cellular receptor, angiotensin-converting enzyme 2. This may negatively influence the virus-receptor binding and abrogate the infection, with further ramifications by the elevation of vesicular pH, resulting in the inhibition of infection and spread of SARS CoV at clinically admissible concentrations.

So Hydroxychloroquine is a very valid prophylactic against the Wuhan Flu.

This being near the first of the month, I took dose one of my monthly Ivermectin prophylaxis. Another one tomorrow - got the injectable version which can be taken orally as well.  1ml per 100lbs bodyweight. Been completely healthy for the last two years - no coof, no colds, no flu.

There is a version which is formulated for pouring over the back of an animal.  That dose gets absorbed through the skin - use that if you want to not do an injection. The pour-over version is NOT for internal consumption and I am betting that the recorded cases of people getting sick are from idiots swallowing this version instead of the horse paste or the injectable.