When a large American drug company announces that its genetically engineered vaccine was found one-hundred percent effective in preventing cervical cancer, people are bound to take notice. Especially when the study included more than ten-thousand sexually active young women.

After all, cancer of the cervix is the second-most-common cancer in women, with seventeen-thousand new cases each year.

In the final-stage study of the vaccine, called Gardasil, researchers found it blocks infection with two types of human papilloma [papp-ih-lo-mah] virus, or H-P-V. These sexually transmitted viruses together account for about seventy percent of cervical cancers.

Women who participated in the Gardasil study were all sixteen to twenty-six years old and virus-free. Half got three doses of the vaccine over six months, and half got dummy shots. Among those still virus-free after the six months, none who received the vaccine developed cervical cancer over a two-year follow-up period. This compares with twenty-one who got dummy shots. Scientists say this difference was unlikely due to chance alone.

A second analysis involving five-thousand-plus women showed that just one participant developed cervical cancer after receiving the vaccine treatment.

Both studies were funded by Merck and Company. Reporting at a recent meeting of the Infectious Diseases Society of America, the scientists said the key is getting women, teens and even girls in grammar school to take the vaccine before they become sexually active.

Merck plans to seek F-D-A approval to sell its vaccine for use by girls and young women sometime in 2006.