Dr. Rachel Katzenellenbogen, Adolescent Medicine physician at Seattle Children’s, addresses questions about the HPV vaccine for girls and boys.
Thank you to Dr. Wendy Sue Swanson, a pediatrician at The Everett Clinic in Mill Creek, a member of Seattle Children’s medical staff and executive director of Digital Health, and author of the Seattle Mama Doc blog, for submitting these questions.
Recommendations for HPV vaccine administration have undergone many changes since the original ACIP (Advisory Committee on Immunization Practices) recommendation to only administer to girls. Can you tell us about those shifts, including recommendations to vaccinate boys?
In 2006, ACIP recommended vaccinating girls against HPV and in 2008 added a recommendation for boys.
There are three HPV vaccines currently available for children ages 9 to 26. The bivalent vaccine, which is approved for girls, protects against two high-risk HPV types that are associated with about 70% of cervical cancers as well as other anogenital cancers and head and neck cancers.
The quadrivalent vaccine, approved for girls and boys, includes two more low-risk HPV types associated with 90% of genital warts. The 9-valent vaccine, which has just been recommended for use in girls and boys, protects against five additional high-risk HPV types and can replace the quadrivalent vaccine once available.
Since we’ve been giving the vaccine to girls for over eight years, what do we know about durability and what data is there to support it? Do you think we’ll need to continue to “boost” girls’ and boys’ immune systems through adulthood to maintain ongoing protection?
Several studies have followed the women who participated in the initial clinical trial that led to FDA approval of the quadrivalent vaccine. Those women have not developed infections from the four HPV types they were vaccinated against.
Other studies have looked at the peak of antibody titers in younger women and men who have been vaccinated against HPV. Those titers have leveled out and remained high over time, meaning there is likely long-lived protection.
At this time, there’s no recommendation to boost because there has been no evidence that the antibody levels drop below a certain point that would require a boost.
What concerns do you have about the HPV vaccine?
My only concern is that people need to be vaccinated before they engage in sexual activity. So, delays in getting vaccinated are what put people at risk. These vaccines are safe and give great protection from infection.
What are the real side effects of the vaccine and how do you weigh them against the benefits?
The most common side effect is swelling or irritation at the vaccination site. Headache, fever and fatigue can also occur. All other significant adverse effects, like ovarian failure, have not been validated in large studies. Syncope is a concern that’s been reported, so the recommendation is for teenagers to sit during the vaccination and for 15 minutes after so they don’t feel faint.
Any of these side effects are significantly outweighed by the benefits of avoiding the development of cancer or genital warts associated with HPV.
What concerns do you have about teens and families who decide to “wait until later” to immunize? Can you explain the science behind the immunogenicity of the vaccine – is it more effective at producing a robust response in younger girls and boys than older girls and boys?
In studies looking at antibody responses, researchers found that response is best for girls and boys ages 9 to 11. Since the younger you are, the better the antibody response, I don’t see any significant benefit in waiting.
75% of us have evidence of a current or prior HPV infection if you screen from adolescence to adulthood in the United States, so this is an extraordinarily common infection. My concern about parents who decide to wait until later is that it will be too late to protect their child.
The CDC and AAP recommend talking about the HPV vaccine as an anti-cancer vaccine. In your experience, what messages are most compelling to build trust with teens and parents who may have concerns about the vaccine?
When talking about this vaccine, it is important to know that it is safe and effective in protecting people from developing several types of cancer and genital warts. Not everyone gets cancer, but most people get HPV. If you remove HPV from the equation, you remove the risk of cervical cancer, other anogenital cancers, and some head and neck cancers.
Why do you think we’ve had such a hard time getting all teens the entire vaccine series? What suggestions do you have to help improve this vaccine rate – what can pediatricians do to help?
Once kids are school-age, parents have less of a reason to take their child to the doctor and receive vaccinations beyond annual flu vaccinations. I think pediatricians can normalize that this is part of the recommended vaccines for kids, and the earlier you do it, the better its efficacy will be. You can vaccinate girls and boys as young as age 9, but we typically bundle the HPV vaccine at the 11- or 12-year-old visit.