Last spring the FDA approved a long-awaited vaccine to protect against cervical cancer. Now people are wondering who should be vaccinated and when.

Cancer of the cervix (the outer end of the uterus) causes nearly 4,000 deaths a year among women in the U.S. Most cervical cancers are caused by infections with certain strains of the human papillomavirus (HPV), which also can produce warts. In trials, the vaccine Gardasil has completely prevented infections caused by about half of these cancer-causing strains of HPV. The vaccine is given in a series of three shots over a six-month period.

The ideal time for vaccinating girls is before they become sexually active. Some public health officials have advocated mandatory vaccination for all girls before they reach puberty, just as certain other vaccines are required before children can enter public schools.

But conservative groups have argued that immunizing preteens would encourage sexual activity. They oppose a requirement for immunization. Some of them may even prefer a delay in voluntary administration of the vaccine.

I can't believe that a young girl would be encouraged to engage in sex by thinking, "Well, it's all right to go ahead and have sex. I got the vaccine so I'm not going to get cervical cancer 20 to 40 years from now." The reality is that young girls may choose to have sex no matter what we adults think. Why not protect them now from a disease that could kill them?

Though I have mixed feelings about mandatory vaccination with Gardasil, I would surely advise it for every girl before puberty. Once an infection occurs, it is too late to provide this protection against cervical cancer.