Gardasil came on the market last year for preventing infection with two strains of human papillomavirus (HPV), 16 and 18, that are responsible for up to 70% of all cervical cancers, and HPV 6 and 11, which account for 90% of genital warts.
The new study, which involved about 11,000 young women aged 15 to 26, shows that the vaccine is also 38% effective against 10 additional HPV types, which are responsible for an additional 20% of cervical cancers.
“The new study shows that Gardasil affords an extra degree of protection for young women,” says researcher Darren R. Brown, MD, professor of medicine, microbiology and immunology at the Indiana University School of Medicine in Indianapolis.
Gardasil Guards Against 10 More HPV Strains
Brown’s previous research, presented at a major cancer meeting earlier this year, showed that Gardasil continues to offer nearly 100% protection against HPV types 16 and 18 five years following administration.
The new study, presented here at a meeting of the American Society for Microbiology, shows that the vaccine also:
- Is 38% effective against 10 additional strains of HPV that cause cervical cancer
- Provides 45% protection against persistent infection from types 45 and 31, two other HPV strains linked to cervical cancer
- Is 62% effective in preventing serious precancerous lesions from those two strains
Brown says that it’s not a surprise that the vaccine offers protection against additional types of HPV, as they are all close cousins.
“They’re related genetically, so you would expect some, but not complete, protection against additional subtypes, which is what we found," he tells WebMD.
The Cervical Cancer Debate
The vaccine has been the center of hot debate since it came on the market, with proponents calling for routine vaccination of young women and critics charging that the vaccine promotes promiscuity and denies parents of their rights.
The CDC recommends the HPV vaccine for all 11- and 12-year-old girls, but it can be given as young as age 9. The vaccine is also recommended for girls and women aged 13 through 26 who have not been previously vaccinated or completed the vaccine series.
Texas is the first and only state to mandate the vaccine.
Brown says he thinks the new findings will propel more parents to get their teenaged girls vaccinated.
But even if you are vaccinated, it’s still imperative to get regular checkups and Pap tests to look for any signs of precancerous lesions or cancer, he stresses.
‘Important Information for Women’
Scott M. Hammer, MD, chief of the division of infectious diseases at Columbia University in New York City and chairman of the committee that chose which studies to highlight at the meeting, says, “This is really important information for women.
"We knew this vaccine was safe and effective for HPV types 6, 11, 16, and 18, but we didn't know if it worked beyond that.
“The new study offers strong support that Gardasil is about 35% to 40% effective in preventing infection with other types of human papillomavirus that cause cervical cancer,” he tells WebMD.
More than 11,000 new cases of invasive cervical cancer will be diagnosed in 2007, with more than 3,600 deaths, according to the American Cancer Society.
The study was sponsored by Gardasil maker Merck & Co. Inc.