Can I lose grafts or hair follicles 7 days after hair transplant by scratching the scubs carefully with my finger and nails?

In general it is relatively hard to actually pull out the grafts about a week after surgery.  You really need to "dig" deep and hard to pull the grafts out.  Dr. Rassman actually wrote about this and published papers on this subject matter.  I personally have, on one occasion, tried to remove two grafts that a particular patient wanted out (because he thought it was in the wrong place).  After 5 days, it was very difficult to coax the grafts out.You may have pulled out a few grafts unintentionally but in the grand scheme of things, there is not much you can do at this point and it probably will not matter much with respect to your overall results.

More than likely no you cannot pull grafts out by simply scratching but you may wish to be cautious anyway. Be gentle.

It is common to see the hair shaft falling with the scabs  7-8 days after the surgery.On the other hand instead of using your nails prefer your fingers and if you see bleeding stop the massage for a few more days.