Merck’s HPV vaccine Gardasil was found to be effective in men as well, this time preventing genital warts, a sexually-transmitted problem that is embarrassing and uncomfortable though not life-threatening.

Gardasil got the Food and Drug Administration approval back in 2006. The vaccine is given to teenage girls and young women as protection against four strains of the human papillomavirus, two of which accounting for about 70 percent of cervical cancer cases. Last month, Gardasil received FDA approval for vulvar and vaginal cancers as well. These cancers affect more than 5,000 women annually in the United States.

The CDC currently recommends Gardasil for 11 and 12-year-old girls, because nearly none of them has begun their sex lives, and therefore they haven’t been exposed to the virus. For that reason, Gardasil will offer them maximum protection.

Now, the Merck study says Gardasil is effective in preventing genital warts in boys as well. The study involved about 4,000 males ages 16 to 26 from nearly 20 countries. It showed the vaccine was 90 percent effective in preventing genital warts, with only 15 cases of persistent infection in a vaccinated group of males as compared to 101 cases in a group that was given a fake vaccine.

“This is groundbreaking data. To demonstrate that Gardasil prevents infection and disease at a very high level in males - that's the other half of the world,” said Anna Giuliano, professor of medicine and epidemiology at University of South Florida, who co-authored the study.

The results of the study were presented Thursday at a medical conference in Europe.