The cervical cancer vaccine is nearly 100 percent effective against the two types of the human papillomavirus responsible for most cases of cervical cancer, according to a study published today in the New England Journal of Medicine.

Researchers at more than a dozen international medical centers evaluated the effect of the vaccine, marketed under the brand name Gardasil, on four types of HPV in more than 12,000 women ages 15 to 26 in 13 countries for nearly three years.

The vaccine was about 98 percent effective in preventing the two types of HPV — 16 and 18 — which cause about 70 percent of all cases of cervical cancer.

Cervical cancer is the second most common cause of cancer deaths in women worldwide, resulting in nearly half a million diagnoses and 240,000 deaths each year.

Ten women in the U.S. die from the disease every day, according to Kevin Ault MD, associate professor of obstetrics and gynecology at Emory University School of Medicine, and one of the study authors.

"The two main things to emphasize are the vaccine efficacy and the safety," Ault said in a statement from Emory University. "These clinical trials have consistent efficacy around 98 percent. And severe reactions to the vaccine appear to be rare."

According to estimates from the Centers for Disease Control and Prevention, HPV is the most common STD in the U.S. with more than 20 million men and women infected, and more than six million new infections are reported each year.

"Nearly all sexually active people are going to get exposed to the virus sometime during their lives," said Ault.

Gardasil was approved by the U.S. Food and Drug Administration last year for use in females ages 9 to 26.

"The goal of the study was to see if we could prevent precancerous cases and we were 98 percent effective," Ault said.