Vaccines enter a new era: new bioengineering techniques may soon produce the safest and most effective vaccines yet

摘要

Medical science usually advances in baby steps, as each new study gradually adds to the body of knowledge, and by tiny increments we gain a deeper understanding of how our bodies work, how diseases take hold, how new drugs can preserve health. Sometimes, however, a single discovery leads to an innovation so important that it forever changes the way we live. One such leap forward was made by Edward Jenner. An 18th century English physician, Jenner observed that milkmaids and other people who workedwith cattle often escaped the ravages of smallpox. At the time, smallpox killed more than a million people a year in Europe alone, and the survivors carried grim badges: deep scars, blindness and deformities. Jenner found that by deliberately exposing people to cowpox, a related but relatively harmless disease, he could protect them from smallpox. Over the next generations, Jenner's work served as the vanguard for new research that would make vaccination the primary weapon in the war against epidemics.Diphtheria, typhoid, rabies, poliomyelitis, tetanus, measles--today more than 20 fearsome diseases that once killed or crippled hundreds of millions have lost their menace. In the two centuries since Jenner's breakthrough, vaccines have become more numerous and have been refined for safety, but little has changed in the way they work.