It's set during the second world war and focuses on a man who escapes out of prisoner of war camp at the start. I think it might have been set in Russia and there is a child involved, somewhere. Very vague I know, could be a book for young adults as I read it when I was at Secondary school.
Do you mean I Am David, by Anne Holm? It's not actually set in the Second World War, but during the Cold War that followed. It tells the story of a young boy called David who gets out of a camp in, I guess, Bulgaria and works his way across Europe to Denmark.