My grandmother was 36 when she died of the flu in 1918. My grandfather got sick but survived. I wonder if DNA on survivors off spring would be useful. I am ignorant of these things.
SIDE STORY:
My great-grandparents lost three daughters--all under 6--in a week to that horrible flu. My g-grandmother refused to have any more kids. My g-grandpa liked to "play the horses," so he bargained with g-gma that he'd quit gambling if she'd have another child. She had the child (grandpa), but he didn't quit gambling.