Soul of a Man

The first infected was a young soldier from Sergeant Gere's unit. The other two were refugees — a man in his thirties and a woman who seemed old enough to be Sunny's grandmother.

All three were outside the usual age for a Sleeper, but the soldier, at least, was young and strong. He had a higher chance of survival, from what Sunny could tell… not that anyone knew a lot about how and why people survived the First Nightmare. It was a mystery why the Spell had eventually settled for teenagers of about sixteen to eighteen years old after devastating the First Generation indiscriminately.

But even back then, younger people had been more likely to survive. Humans might have not known the reason, but they were very good at gathering statistics.