Messages for patient and family: You can let the family know that HPV vaccines have been in use for over a decade and studied in clinical trials for even longer. Further, HPV vaccine is strongly recommended by the major medical groups. The most recently released 9-valent vaccine protects against even more high-risk HPV types.

Background discussion: Several vaccines have been developed to help decrease risks and subsequent sequelae related to acquisition of HPV infection. The US Food and Drug Administration (FDA ) has approved the use of three HPV vaccines, which protect against two, four, or nine types of HPV. After FDA licensing and review of available studies, recent Advisory Committee on Immunization Practices’ (ACIP) vaccination guidelines (March 2015) reaffirmed the recommendations for vaccination of all males and females at ages 11–12 with catch-up for females aged 13–26 and males aged 13–21 [7]. The recommendations permit use in males and females as young as age 9 and males ages 22–26. However, it is important to note that the vaccine is specifically recommended in several special populations including cases of sexual abuse or assault (starting at age 9), catch-up vaccination through age 26 for men who have sex with men, and in both males and females who are immunocompromised [7, 8] (Table 2.2). All guidelines from major medical organizations agree with ACIP regarding the age group for routine immunization. In December 2016, the Centers for Disease Control and Prevention (CDC ) approved the use of a two-dose series for boys and girls initiating HPV vaccination prior to age 15; the three-dose series is still recommended for those who start HPV immunization between ages 15 through 26 [9].

Messages for patient and family: For maximum protection, the patient should complete the entire series of shots. You can also emphasize the recommendation of universal vaccination at ages 11–12, since, even if the patient is not exposed to HPV prior to marriage, younger adolescents achieve a better antibody response to the vaccine than older teens. It is important to emphasize that this is a cancer prevention vaccine against a virus that the vast majority of individuals will be exposed to from future sexual partners.

Background discussion: HPV vaccines were initially recommended as a three-dose series , with the minimum time between doses 1 and 2 being 4 weeks and between doses 2 and 3 being 12 weeks [2]. There must be a minimum of 24 weeks between doses 1 and 3. A two-dose series has been approved by the CDC for males and females beginning HPV vaccination before the age of 15, with doses given 6–12 months apart [9]. Completion of a vaccine series with the same type of HPV vaccine is ideal in order to be consistent with the vaccine research studies. However, in cases where the previous vaccine type is unknown or unavailable, ACIP recommends completing the series, with the available HPV vaccine, rather than restarting the entire three-dose series [7].

Completion of the vaccine series results in production of vaccine-type HPV antibodies, or seropositivity, in over 99% of healthy individuals, and the antibody response produced by the two-dose series is non-inferior to that of the three-dose series [9]. Antibody titers decrease in the first 2 years after vaccination but then tend to stabilize at levels which are significantly higher than those resulting from natural HPV infection [2]. Furthermore, HPV antibody responses are significantly higher in 9–15-year-olds compared to older adolescents and young adults, contributing to the recommendation to vaccinate all 11–12-year-olds [2, 7]. The antibody titers for the 9-valent vaccine are non-inferior to the quadrivalent vaccine [2].

In the HPV vaccine research studies, there was no identified lower threshold of antibody level below which an individual would not be protected from vaccine-related HPV types [2]. In practical terms, HPV antibody titers are not commercially available nor used in the clinical setting. We do know, however, that these vaccines are incredibly effective at preventing HPV-related disease [2] (Table 2.2). The protection from the bivalent and quadrivalent vaccines does not decrease even a decade after vaccination, as evidenced by the lack of breakthrough disease in 8–10-year follow-up studies [2]. Though HPV vaccines are most effective if given before a patient’s sexual debut, the vaccines can be used in patients who have been sexually active or even have evidence of current or past HPV infection. Individuals are unlikely to be infected with all vaccine-preventable types of HPV and will receive protection from the types to which they have not been exposed. It should also be noted that the vaccine is not therapeutic [2]. In other words, HPV vaccines do not treat disease but only can prevent disease.