The former Reading manager admits the renewal of Somma's contract was "realistically not going to happen" with the striker recovering from a third knee operation.
"He's a great guy who's been really unlucky," McDermott told the Yorkshire Evening Post.
"We'll look after him, try to get him fit and if something comes up for him elsewhere, we'll try to make sure that nothing stops him taking up the opportunity.
"At the moment he just needs to concentrate on getting fit and over all the injuries. You feel for him."