Perhaps in no area is the divide between the developed and developing worlds as striking as it is for vaccines: While healthcare consumers in economically advantaged nations worry about risk, in developing nations compelling need forces a focus on potential benefit. "People in the United States want a quick solution, not prevention, so they prefer drugs to vaccines. Elsewhere, people are afraid of drugs and side effects, and prefer vaccines," says Shan Lu, a primary-care physician who has worked in many countries. He is developing an HIV vaccine at the University of Massachusetts, Amherst, where he is associate professor of infectious diseases and immunology.