It is not necessary to detail every anti-viral failure of this drug (which is an important defense against malaria and an important treatment for Lupus and other autoimmune disorders) to gain some insights into why it was tested again. A major complication of the Covid 19 pandemic is the “cytokine storm”, which is basically an incredibly powerful immune response which turns deadly in many cases. Any anti-inflammatory drug, hypothetically, may help with this. Unfortunately, when emergencies arise, we tend not to think logically. Emotions take over, availability bias raises its head, and the overwhelming need to do something / anything can become preeminent. When a medical emergency hits, I want cool headed doctors, nurses, and hospital/medical staff to do everything they can do to respond. Especially in a pandemic however, we as a society, need them to respond in the most scientifically sound way so as to maximize our resource utilization and impact against the threat. Doctors are not scientists in most cases and vice versa though, and as such we need to be prepared before a crisis hits. Below is a link to an article that discusses not only this tension, but also additional confounding factors.