These developments underscore the idea that an ever-wider range of diseases may respond to vaccines. Researchers are turning their attention to cancer and Alzheimer’s disease, as well as to sexually transmitted diseases that, while treatable, can leave patients with lasting damage. “Probably the most common cause of preventable infertility is such sexually transmitted diseases as chlamydia and gonorrhea,” says Harvard Medical School’s Starnbach. A vaccine against those diseases could save the health care system millions of dollars that now go toward expensive reproductive treatments, he says.

“We’re also beginning to appreciate that some chronic diseases that we haven’t thought of as infectious probably are, at least in part,” he adds. “Diseases such as multiple sclerosis and heart disease may have an infectious trigger, and you can imagine the enormous public health burden that might be lifted with the development of new vaccines to treat them.”

Such possibilities are generating renewed interest in vaccines from major pharmaceutical players. In 2006 U.S. giant Pfizer purchased British manufacturer PowderMed, maker of DNA-based flu vaccines. And in 2007 British company AstraZeneca completed its purchase of MedImmune, a Maryland firm whose products include the nasal flu vaccine FluMist. This interest has increased prices by orders of magnitude, says Edward T. Mathers, executive vice president of MedImmune: “A three-course treatment of Gardasil is about $360, or about $120 per dose. Early vaccines were less than $5 a dose.”

A 26-year veteran of the pharmaceutical industry, Mathers considers vaccine technology extraordinarily exciting, offering benefits to society as well as to manufacturers. When compared with the cost of treating the diseases they prevent, the new higher-priced vaccines are still pretty inexpensive, he says. For pharmaceutical companies, he sees a different advantage: When conventional drugs lose patent protection, generic versions flood the market, greatly reducing the original drug’s profit potential. But developing a process for manufacturing vaccines is costly and complex, so vaccine makers tend to be less vulnerable to competition.

With such barriers to entry improving the business outlook just when medical and technological advances are pointing toward the feasibility of preventing a widening range of diseases, vaccines have clearly returned to relevance. And if they succeed in heading off some of today’s most devastating scourges—Alzheimer’s disease, for example, or breast cancer—vaccines could enter an era that surpasses even their first golden age.

  Dossier

1.Vaccinated: One Man’s Quest to Defeat the World’s Deadliest Diseases, by Paul A. Offit (Smithsonian Books, 2007). The author, a renowned virologist, recounts the fascinating story of Maurice Hilleman, the developer of eight of the 14 vaccines that are routinely recommended.

2. “Bridging the Knowledge Gaps in Vaccine Design,” by Rino Rappuoli, Nature Biotechnology, December 2007. The head of vaccine research at Novartis Vaccines & Diagnostics details the possibilities and challenges of new approaches to vaccine development.

3. “One Step Forward, Two Steps Back—Will There Ever Be an AIDS Vaccine?” by Robert Steinbrook, New England Journal of Medicine, Dec. 27, 2007. A physician examines the frustrating search for an AIDS vaccine.

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