The only preventive would be vitamin d, that I take now.
The others could be taken preventative if you were at risk of infection every day. Since I am not I do not take them. Plus they can have negative effects on the body if taken in excess or regularly. That said, this virus needs to be attacked from the moment of infection. Since you will not know when that happens, we are already behind the virus. When I hear of possible exposure, I have started my program at that moment. When the unknown settles out I stop the program. If I was to get a positive result, a call to the doctor would supersede anymore self medicating.
Next, this virus comes in two waves, the second wave is accompanied with or caused by our own body. Chemical signaling and viral location leads to clotting by way immune cells and or blood clotting factors. The second wave is not a viral resurgence. The virus is all but defeated. The problems and death are coming at this point, a consequence of the body's reaction to the viral outbreak. Thus why it is so important to limit viral reproduction before the body can overcome the invasion.
Just my opinion. I've got no experience.