I highly suggest that you do not just use prescriptions to treat symptoms, though they may help reduce some symptoms and discomfort they are not treating the ROOT CAUSE of Covid and long-haul. Many people have had really excellent results with holistic practitioners who look at the body as one WHOLE UNIT. And treat the underlying causes of long-haul symptoms. For brain fog and fatigue, taking B-3 (single supplement, niacinamide form only, 500mg 2-3x per day is what I used) will allow your body to make more NAD quickly and effectively. NAD is needed for absolutely all bodily functions/systems to work properly. This alone works very well for many people. I wish you all the best!