HPV Vaccine: Good News, Bad News

Gardasil is highly effective at protecting women from precancerous lesion caused by HPVs (human papillomavirus) which cause most cervical cancers as well as most cases of genital warfare.

Two large, multi-country clinical trials have revealed this to be the positive news. However, the not-so good news is that among 15 to 26 year-old females who have been sexually exposed for at least one year -- many of which already have HPV infections -- this vaccine was far less effective in protecting them against potentially dangerous cervical lesions.

Nearly 5,500 16-24-year-old women were enrolled in the FUTURE I trial. More than 12,000 females aged 15-26 were enrolled in the FUTURE II study. The New England Journal of Medicine published three-year findings from the two trials in its May 10, 2010 issue.

Gardasil helps protect against HPV, which is most commonly spread during sexual activity. Although HPV infection is more common in women who have just started sexual activity, most HPV cases will never progress to cancer. The best age to receive the vaccine before you turn 13 is the ideal time.

Gardasil has been approved by the FDA for use in children aged 9 to 26, and added to the CDC's childhood vaccine schedule. While many states have been considering making HPV vaccine mandatory for school attendance in the public sector, all measures still allow parents to choose not to.

In the current studies, the vaccine looked very safe -- and very effective, says FUTURE II investigator Kevin Ault, MD, associate professor of gynecology and obstetrics at Atlanta's Emory University.

Ault informs WebMD, "The vaccine’s efficacy was the greatest news." It was 100% effective against precancerous lesion and genital warts in FUTURE I. In FUTURE II, 98% of it protected against precancerous, high-grade cervical lesions.

Different experts, different opinions

Ault's numbers reflect the vaccine's effectiveness against the four HPV strains included in the vaccine -- including cervical-cancer-causing HPV-16 and HPV-18.

These are just two HPV types that have been linked to cervical cancer. An editorial accompanying the studies notes that overall, the vaccine was no more than 20% effective in protecting women against high-grade precancerous lesions.

Karen Smith McCune MD, co-author of this editorial, says that it gives us a good idea about what we can expect when vaccinating an entire generation of children aged 15 to 26 years old regardless of their sexual history. The overall population showed a modest reduction in precancer rates when compared to the placebo group. There were 17% less cases in the vaccinated group versus the placebo. The most serious precancer is grade 3. There's no evidence of a significant decrease in the number of vaccinated mothers.

Smith-McCune works as associate professor of Obstetrics and Gynecology at University of California San Francisco. Smith-McCune is also the mother to two daughters.

"I don't want my daughters to be vaccinated, because it is proven that regular Pap screening reduces their chance of getting pap-stimulated," she states. The safety and efficacy data are not available for 11- and 12-year-olds. There is no long-term evidence of any vaccine's effectiveness.

Smith-McCune's gynecologist Brian Slomovitz MD of Weill Cornell Medical Center, New York disagrees. According to Slomovitz, even with regular Pap screening many women in their twenties will need to have cervical precancerous lesions treated -- which could lead into pregnancy complications.

Slomovitz told WebMD that cervical precancers and genital warts were a major problem. The ultimate benefit of HPV vaccination is the reduction in cervical cancer deaths. However, it's also useful for preventing cervical lesion and genital warts.

Slomovitz agrees to Ault.

"These studies are further proof that what we recommended last year was a good idea: This vaccine should be given to women age 9 to 26," he says.

Smith-McCune believes that there are still too many questions regarding the HPV vaccine for her to recommend mass vaccinations of young women and girls.

She says, "It's important to balance the urgency of vaccination of girls with the reality that cervical cancer in America isn't an urgent emergency." It is wonderful to see any improvement that can lower the chance of cervical cancer in women. There isn't enough evidence to back that up yet. The studies are ongoing. The impact of the vaccine on precancers and cervical cancer is something we still have much to learn."