Because overall health affects the efficiency of the vaccine and the article is making it as though he is knocking on death's door. And the link I added pointing to why things don't look good, regardless.
My views are a little different because vaccination status has turned into a tool of discrimination and how would I know if the recipient would live or die, as you don't normally know who is in front of you and haven't know many to keep up with those who received a heart transplant before them.