ATLANTA — When the security guard reached the top of the steps in the small bus parked at the checkpoint of the U.S. Centers for Disease Control and Prevention, he did a double take.

Sitting in the rows were six blazer-clad teenage girls, holding notebooks and ready to show him their photo IDs.

Most of them aren’t even old enough for a driver’s license — a fact that made the security guard chuckle as he walked down the aisle.

“We don’t really ever have students here,” he explained to Hannah Vann, coordinator for the group.

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