01:00 AM EDT on Sunday, June 18, 2006

Gardasil, the new vaccine against cervical cancer, is one of the most significant public-health breakthroughs of our time. Only one other effective cancer vaccine -- against hepatitis B -- exists. Developed by Merck & Co., Gardasil stands to save thousands of American lives annually, and even more lives across the globe. But much will depend on how vigorously it is deployed.

This month, Gardasil took a major step forward when it won approval from the federal Food and Drug Administration. A key recommendation on whether the vaccine should be required is set for later this month.

Gardasil disarms four strains of the human papillomavirus (HPV). Two cause roughly 70 percent of cervical-cancer cases; the other two account for 90 percent of genital warts. The FDA has requested further study on Gardasil's effectiveness in males, but the early data look promising. Apart from genital warts, men can develop head and neck cancers from HPV. They can also transmit the virus to females.

The stakes are high. Every year, a half-million of the world's women develop cervical cancer. In the United States, where aggressive screening programs have sharply cut the incidence of cervical cancer, the disease still causes 3,700 deaths per year. Thus, requiring girls and women to be vaccinated would appear prudent.

Obstacles loom, however. One is cost. The three-shot series is priced at $360 per person. Many states already cannot afford the childhood vaccinations they require; Gardasil would cost millions more.

Public-health officials tend to favor requiring the vaccine for girls at, say, age 11 or 12, before they become sexually active. But getting these youngsters into the doctor's office during the recommended six-month schedule could prove difficult.

Further, some conservative organizations oppose requiring the vaccine. They argue that it will promote promiscuity, and that sexual abstinence before marriage is the better route to preventing illness.

That seems farfetched. Few adolescents struggling over a decision to have sex will be deterred by fears that they could contract cancer in adulthood. Moreover, depriving anyone of this life-saving vaccine for "moral" purposes is a reckless roll of the dice. HPV infections are extremely common: Some 20 million Americans are hit by the virus every year, and by the time they are 50, 80 percent of American women have been infected. Which of them will go on to develop cervical cancer is hard to predict.

The states will ultimately decide whether to require this vaccine. We hope they will embrace it, and that Merck will work with public-health agencies to ensure that it reaches low-income women.