Vaccines Stage A Comeback

You seldom see them on the cover of Prevention Magazine, but vaccines are the great prevention success story of modern medicine. They are not perceived as new or sexy; they have been around since the days of George Washington, when Edward Jenner first scraped the scabs from milkmaids infected with cowpox to inoculate people against smallpox. By the end of the 20th century, vaccines had conquered many of man's most dreaded plagues, eliminating smallpox and all but wiping out mumps, measles, rubella, whooping cough, diphtheria and polio, at least in the developed world. Vaccines had done their work so well, in fact, that in the context of 21st century medicine, with its smart drugs and high-tech interventions, they seemed almost quaint and out of date, a kind of biomedical backwater.

That perception changed dramatically after Sept. 11 and the anthrax attacks. Suddenly, vaccines were back in the headlines. The U.S. government was scrambling to build up its supplies of smallpox inoculations, and an anthrax vaccine that had been stuck in a legal and scientific morass for years was thrust back on the fast track.

Yet defense against bioterrorism is only part of the vaccine renaissance. Over the past few years, dramatic advances in the fields of immunology, virology and genetics have jump-started this long-stalled field of medicine. All the easy things that vaccines can do had been done, and researchers were ready to move on to far tougher challenges--using vaccines to fight off cancer, for example, or attack the protein deposits that clog the brains of Alzheimer's patients or even as a potential treatment for heart disease. "We are in a new era of vaccine research," says Dr. Gary Nabel, director of the Vaccine Research Center at the National Institute of Allergy and Infectious Diseases (NIAID). "It's an amazingly exciting time to be in this field."

An important trigger for this turnaround, surprisingly enough, was vaccine research's most notable failure. In the 1980s, as the AIDS epidemic began to spread, scientists tried to fight it as they had polio and chickenpox--by crippling the virus and using it to train a patient's immune system to ward off the real infection. Nobody really understood how the process worked at the molecular level, but until AIDS came along, that didn't matter much.

HIV, however, proved too sophisticated for such crude tactics. The virus managed to take advantage of loopholes that even experts hadn't expected, such as hiding within immune-system cells to avoid detection and mutating so rapidly that the body's defenses couldn't keep up. Immunologists' only hope of closing those loopholes was to delve more deeply into the exquisite complexity of the immune system in an effort to understand its secrets.

That effort has paid off. After more than a decade of research, scientists now know that the immune system doesn't simply flick on and off like a light switch. Instead, it responds to a bacterial, viral or parasitic invasion with a combination of defensive weapons matched precisely to the severity of the threat.