In addition to preventing meningitis and pneumonia, Prevnar has reduced ear infections and limited the growth of antibiotic-resistant pneumococci in American kids. It has just about eliminated what was a serious infection in sickle-cell patients, and has been an unexpected boon for the elderly, preventing an estimated 12,000 cases of major disease in that age group in 2003 alone—although the elderly aren't even vaccinated with Prevnar. (How can this be? Simple. By reducing the number of direct and indirect contacts the elderly have with sick grandkids—a phenomenon known as herd immunity—Prevnar seems to do a better job at protecting them than the older vaccine that is injected into their arms.)