One Seattle morning, Carolina Reid sat in a room with nine other volunteers, each waiting to take part in a clinical trial for a new, experimental malaria vaccine.
Reid's turn came. She put her arm over a cardboard box filled with 200 mosquitoes and covered with a mesh that keeps them in but still lets them bite. "Literally a Chinese food takeout container" is how she remembers it. A scientist then covered her arm with a black cloth, because mosquitoes like to bite at night.
