Small sample size. Did patients have preexisting conditions?
Besides sourcing, there are several problems with relying on hydroxychloroquine (Plaquenil) + azithromycin for COVID-19:
1. Neither is an antiviral, though h-chloroquine is one of the immunity-boosting drugs, prescribed to treat malaria and autoimmune diseases like lupus, Sjogren syndrome and arthritis; it's also FDA-approved, has been used for a long time and is generic so it's relatively cheap.
2. French study that supposedly showed promise of chloroquine was both small (26 people) and non-randomized, which scientifically renders it nearly useless, except as an impetus for more robust clinical trials which are ongoing now in many places all over the world now - this latest Chinese study was also small (30 people) but randomized which gives it much stronger credence.
3. Until clinical trials are completed and FDA gives its (speeded up) approval, major pharma companies may be reluctant to produce more drug for off-label use. If trials prove the efficacy in COVID-19, pharma will be given the immunity from lawsuits and definitely start pumping the production.
4. Off-label use is causing the run on h-chloroquine for people to self-medicate or even for hospitals to stockpile is making it nearly impossible for chronically immuno-deficient patients who take it regularly with legitimate prescriptions to get the drug they actually need.
5. It's also been known for decades that the drug has adverse psychiatric side effects that can occur after taking a single dose, though more likely in larger doses, ranging from anxiety and insomnia to paranoia and suicidal ideation. By disrupting and increasing QT interval the drug can also cause deadly heart complications, which can range from arrhythmia to stroke or heart failure. Older people and those with preexisting conditions are particularly more sensitive to cardiac complications. Azithromycin has also been tied to potentially fatal arrhythmia since 2013, so combination of both may be too much for already fragile CV patients.