In the United States last year, more than 11,000 women developed cervical cancer and 3,600 women died of it. All of the cases were caused by HPV infections. In addition, some cases of five other kinds of cancer are also caused by HPV and could be prevented. The HPV vaccine, if given to girls or young women before exposure, offers virtually complete protection from infections by the two varieties of HPV that account for 70 percent of cases of cervical cancer in the U.S. Does blocking the infection actually prevent the development of cervical cancer? There is every reason to expect that it will, and it's already been shown to prevent certain precancerous conditions. But cancer develops slowly, and it's possible that vaccine immunity will fade. We won't know for sure until we've had time for long-term observations. But the likelihood seems so great that holding back seems to me horribly unfair to the many women who would die if we waited for perfect results.