This boy catches Sam Anderson's attention and causes him to panic, which results in his death. He is then seen among the other walkers devouring Sam. After this, he is put down by a member of the Alexandria Safe-Zone.
Unknown Cause (Alive)
Alexandria Safe-Zone Residents (Zombified)
This is a list of victims the young boy has killed:
This zombie child was supposed to appear earlier in Season 6, as there were a few lines of dialogue in the script from a previous episode that were never filmed that explain this child, apparently. Carol saw him at some earlier point outside the walls, nearby, and decided not to kill him because he was a child.