Within 15 days of beard transplant, most of the grafts fallen automatically. How much will it affect the result?

It is normal to lose transplanted hairs weeks after surgery.  It may take 6 to 12 months to see new hairs grow out.

Transplanted graft’s hair starts to shedding in the first week of surgery and may go on untill 4-6 th weeks after surgery. İt is not surprising to lost approx.  %70-80 of all transplanted hair shafts in first month when you are washing, gently rubbing  or touching the face. İt is shock loss and not permanent. …New hair at transplant and donor area starts to grow at 3-4 th month after surgery .

This is typical. You should start to see them grow back in a few months. As for post-op care, after 15 days you can essentially go back to a normal lifestyle, keeping in mind the area likely will be sensitive to sunlight for a few more weeks at least. It's always best to ask any follow up questions you have to your doctor.

Thank you for the post and question. Being only 15 days post beard transplant procedure, this is very normal part of the recovery. It may take up to 4 to 5 weeks for this to occur. You should start seeing results around your 3rd or 4th month post procedure. Hope this helps. Best wishes.

it's normal for the hairs to shed at about 15 says.  The grafts or follicles are still in place and you'll see regrowth in a few months.  
However there are instances that the actual grafts fall out (due to rubbing, inappropriate slit size, etc) but that usually happens in the first few days. 
Good luck 
Ramtin A. Cohanim M.D.