Human papilloma virus, or HPV, is the most common sexually transmitted infection (STI) in the United States. According to the U.S. Centers for Disease Control and Prevention (CDC), there were an estimated 43 million HPV infections in 2018 — many of them in adolescents and young adults. HPV vaccines are crucial for preventing this condition among this age group and beyond. Because some types of HPV can lead to cervical cancer, as well as cancers of the oropharynx, vulva, vagina, penis and anus, prevention is important for patients of all genders.
HPV Vaccines Mark a Major Step in STI Prevention
HPV infections are transmitted mainly through skin-to-skin or skin-to-mucosa contact. Until the advent of an HPV vaccine, the only way for sexually active people to protect against the virus was through the use of condoms. However, this approach cannot offer total protection, since HPV is able to infect areas not covered by condoms. There is also a risk of patient-to-patient transmission of HPV from improperly cleaned medical equipment, specifically transvaginal ultrasound probes. Careful disinfection can help reduce this risk.
A new option for preventing the transmission of HPV arrived in 2006, when a vaccine first became available in the U.S. for cisgender adolescent girls and young adults. In 2009, the first HPV vaccine was approved for use in cisgender adolescent boys and young adults. These vaccines are bivalent and quadrivalent, protecting against two to four different types of HPV. HPV vaccines are developed based on a virus-like particle of the major papillomavirus capsid protein L1 and are considered noninfectious and nononcogenic. Numerous studies, such as one published in Human Vaccines and Immunotherapeutics, continue to confirm the safety of HPV vaccination.
Preventing Genital Warts and Cancer
The efficacy of vaccination for HPV is clear: A vaccine can prevent the most common and highest-risk types of HPV. In particular, the nonavalent vaccine Gardasil 9 has been shown to protect against roughly 90 percent of cervical cancers, according to research from the Official Publication of the College of Family Physicians of Canada. It also appears to significantly lower the incidence of HPV-involved vulvar cancer and vaginal cancer. Evidence suggests that Gardasil 9 can pass through the placenta, potentially protecting fetuses from some types of HPV.
A large 2019 meta-analysis of 60 million people from 14 high-income countries published in the Lancet highlights the impact of vaccination against HPV. The researchers found that vaccination significantly decreases the prevalence of genital HPV infections, anogenital warts and cervical intraepithelial neoplasia grade 2 or worse (CIN2+) in women, girls and boys. HPV16 and 18 — the most common types of the virus — decreased by 83 percent, while HPV31, 33 and 45 were reduced by 54 percent in adolescent girls. The prevalence of anogenital warts and CIN2+ decreased by 67 percent and 51 percent, respectively.
Addressing Roadblocks to HPV Protection
Despite their proven effectiveness, the adoption of HPV vaccines continues to lag, particularly among developing countries and among cisgender men. In general, HPV national programs cover only about 30 percent of the global target population, with the vaccination rates appearing in Australia, Denmark and Sweden. Only about 1 percent of female adolescents in low-income countries have received a full course of an HPV vaccine, according to research published in the journal Vaccines.
Because the majority of deaths from cervical cancer occur in low- and middle-income countries, increased public health measures are critical to improving vaccination rates. Estimates suggest that when combined with screening, HPV vaccines could prevent up to 97 percent of cervical cancer cases globally by 2100, according to a separate Lancet study.
While rates of HPV-related cancers are higher in cisgender women, cisgender men have a higher risk of oral HPV infection and certain HPV-related cancers. Female HPV vaccine coverage is less than 60 percent in most countries, the Vaccines research notes, indicating that heterosexual cisgender men may not enjoy herd immunity. Vaccination in adolescent boys and young men is just as important for protection against the virus.
Deciding Who Should Be Vaccinated and When
The CDC's HPV vaccine recommendations call for children to be vaccinated at age 11 or 12, although the vaccine can be administered to those as young as 9. Everyone should be vaccinated against HPV by age 26. The dosing schedule involves two to three doses, depending on age.
- Adolescents age 15 and younger receive two doses six to 12 months apart
- Adolescents and young adults ages 15 to 26 receive three doses: the second one or two months after the first and the third six months after that
Adolescents who receive two doses less than five months apart will require a third dose.
Although vaccination is less beneficial for sexually active adults age 27 and older — the majority of whom have already been exposed to HPV — some people between 27 and 45 may choose to be vaccinated after discussing it with their physician.
Recent research reported by the University of Washington suggests that a one-dose HPV vaccine could be highly effective, showing promise for vaccination efforts in low-income and resource-poor areas.
Finding Opportunities for Patient Education
OB/GYNs can help educate patients and their families about the importance of HPV prevention as well as regular screening for cervical cancer. This may involve dispelling common myths about the vaccines' safety and effectiveness and providing educational materials to the parents and caregivers of pediatric patients.
All patients, but especially those who are sexually active, should be screened for cervical cancer starting at age 21. The American College of Obstetricians and Gynecologists recommends that between ages 21 and 29, patients should have a Pap smear every three years. Patients ages 30 to 65 can have a Pap smear every three years, HPV testing every five years or a combination of a Pap smear and HPV testing every five years. Meanwhile, ultrasound is a cost-effective way to screen for cervical cancer and to stage and plan cancer treatment, if necessary.
The connection between STIs and cancer risk — especially oropharyngeal cancer — may not be obvious for gynecology patients. The HPV vaccine is a generally accessible way for OB/GYNs to offer their patients preventative care and promote lifelong reproductive health.
