The Best Medicine

IN 1979, DANISH anthropologist Peter Aaby, in his mid-30s, was studying malnutrition in the small West African country of Guinea-Bissau when the outbreak hit—a measles epidemic of horrific proportions. At least 20 percent of children under 5 years old who got measles that year would die. He and his colleagues began vaccinating, hoping to save the remaining healthy children.

His team’s effort would lead to a remarkable discovery: The vaccinated children, about 1,500 of them, didn’t die—not from measles or any other declined threefold compared to unvaccinated children. “This is strange,” he began to think. “Something incredible happened here.”