Managing HPV: A New Era in Patient Care – HPV Prevention

(Published June 2009)

The two primary means for preventing the transmission of HPV and subsequent infection are minimizing exposure, by reducing the number of sexual partners and using condoms, and vaccination.

Minimizing Exposure

The number of sexual partners has been shown to be the most constant predictor of HPV infection.¹ In fact, the number of partners is proportional to the risk of acquiring the infection.^2-4 According to the Centers for Disease Control and Prevention, with the exception of abstaining from all genital contact, long-term mutually monogamous relationships are the most effective behavioral approach to HPV prevention.⁵ For women who are not in long-term mutually monogamous relationships, reducing the number of sex partners is likely to reduce the chance of acquiring HPV infection.¹

Condom use does not completely prevent transmission of HPV, because the virus is spread via skin contact, not body fluids.¹ However, condoms appear to decrease the risk of transmission. A 2003 study documented that consistent condom use by their partners reduced the risk of HPV infection in female university students (adjusted hazard ratio = 0.3).⁶ Figure 4 illustrates the rate of HPV infection by frequency of condom use by partner in this study. Condom use also has been associated with higher rates of CIN regression and clearance of HPV infection in women, as well as regression of HPV-associated penile lesions in men.^7,8

Vaccination

A quadrivalent vaccine for HPV 6, 11, 16, and 18, (Gardasil™) which is manufactured by Merck, was approved for marketing in the United States by the FDA in June of 2006. Soon after its approval, the Advisory Committee on Immunization Practices (ACIP), which is an advisory committee of the Centers for Disease Control and Prevention, released recommendations for vaccination using the HPV vaccine. In November of 2006 the HPV quadrivalent vaccine was included in the Vaccines for Children Program, a federally funded vaccine program that provides vaccines for free to both children and adolescents through age 18 who are uninsured or underinsured.

GlaxoSmithKline has developed a bivalent vaccine (Cervarix™) for HPV 16 and 18, which is currently undergoing FDA review for approval. A comparison of the two vaccines is shown in Table 6.

Frequently Asked Questions About the HPV Vaccine^1,9

• What is the target age for the vaccine? According to ACIP recommendations, the target age is 11 to 12 years old for routine vaccination of females, although the series can be started as young as age 9 years.
• What about missed vaccines? Does it make sense for 24-year-olds to be vaccinated? “Catch-up” vaccines are recommended for females age 13 to 26 who were not previously vaccinated or who did not complete the full series. Vaccinating a 24-year-old woman does make sense. Even if she is already sexually active, she may not yet have been exposed to all four of the HPV types against which the vaccine offers protection.
• Who should not receive the vaccine? According to ACIP recommendations, the HPV vaccine should not be administered to:
  • Pregnant women. The quadrivalent vaccine is designated as Pregnancy Category B; its use has not been associated with adverse outcomes of pregnancy or adverse events to the developing fetus. However, because data on vaccination in pregnancy are limited, it is recommended that vaccination be postponed until after delivery.
  • Individuals with moderate or severe acute illnesses (although it can be administered to individuals with minor acute illnesses, such as diarrhea or mild upper respiratory infection).
  • Individuals with a history of immediate hypersensitivity to any vaccine component or to yeast.

The vaccine CAN be administered to immunocompromised individuals; however, efficacy might be less than that in immunocompetent individuals.

• How does previous HPV exposure affect the effectiveness of the vaccine? The vaccine is not effective at preventing HPV infection and related disease for HPV types to which an individual has already been exposed. However, in clinical studies to evaluate the quadrivalent vaccine, 74 percent of HPV positive participants had evidence of exposure at entry to just one of the four HPV types against which the vaccine offers protection. The vaccine is effective at preventing HPV-related disease associated with HPV types that have not yet infected an individual.
• Should I test for HPV before vaccination? Pap testing and screening for HPV DNA are not needed before vaccination. Few women have been exposed to all four HPV types present in the quadrivalent vaccine, making pretesting irrelevant.
• My patients don’t understand why they need to continue cervical cancer screening after vaccination. What should I tell them? It is important for females who receive the HPV vaccine to continue with regular cervical cancer screening for three reasons:
  • The vaccine does not protect against all of the HPV types that cause cervical cancer.
  • An individual may be at risk for HPV-related disease due to infection with a high-risk HPV type before vaccination.
  • An individual who does not complete the vaccine series may not receive the full benefits of the vaccine, and thus be at risk for HPV-related disease.
  • The vaccine is not 100% effective at preventing infection with the 4 HPV types, thus another reason to continue screening for cervical cancer.
• Do the vaccines provide cross-protection to other HPV types? There is some preliminary evidence that the bivalent and quadrivalent vaccines may provide protection against other HPV types. A 2006 clinical trial of the bivalent vaccine found significantly lower rates of infection with HPV types 31 and 45, which it does not target.¹⁰ The clinical relevance of these data is not yet known. In the quadrivalent vaccine, there was a significant decrease in persistent infection with type 31 as well as CIN-1 and CIN-2,3 associated with type 31.¹¹
• Is the type of adjuvant a clinically important difference between the bivalent and quadrivalent vaccines? The adjuvant present in the bivalent vaccine increases immunity in animal studies.¹³ The clinical relevance of these data is not yet known.
• Does the quadrivalent vaccine provide protection against external genital warts? Yes. In a combined analysis of three clinical trials, the efficacy of the quadrivalent vaccine was 98.9 percent against EGW that were associated with HPV types 6, 11, 16, or 18.
• What about the use of the vaccine in males? The vaccine is not FDA approved for males at this time, but Merck’s efficacy studies indicate the vaccine is 90.4% effective at preventing HPV 6,11,16,18 related EGW and 85.6% effective at preventing persistent infection with HPV 6,11,16,18 in men who are vaccinated. In men who have sex with men (MSM) the vaccine is 79% effective at preventing EGW and 94.4% effective at preventing persistent infection with HPV 6, 11, 16, & 18. These studies don’t address whether vaccinating men prevents HPV infection in their sex partners.¹²
• Does the HPV vaccine help treat existing disease? No. The HPV vaccine is not effective against existing disease, including existing HPV infection, cervical cytological abnormalities, or external genital warts.
• How safe is the HPV Vaccine? The CDC has been monitoring the safety of Merck’s vaccine since it went on the market in 2006. As of the end of 2008 23 million doses of Gardasil had been administered, and there had been 11,916 adverse events reported, 6% of which were classified as serious. The CDC has investigated these and has not found evidence that they are caused by the vaccine. The CDC continues to recommend that girls be vaccinated.¹³

References:

1. Centers for Disease Control and Prevention. HPV and HPV Vaccine: Information for Providers. Available at: www.cdc.gov/std/hpv/hpv-vacc-hcp-3-pages.pdf. Accessed January 10, 2008.
2. Ho GY, Bierman R, Beardsley L, Chang CJ, Burk RD. Natural history of cervicovaginal papillomavirus infection as measured by repeated DNA testing in adolescent and young women. N Engl J Med. 1998;338(7):423-8.
3. Winer RL, Lee S-K, Hughes JP, Adam DE, Kiviat NB, Koutsky LA. Genital human papillomavirus infection: incidence and risk factors in a cohort of female university students. Am J Epidemiol. 2003;157:218-26.
4. Sellors JW, Karwalajtys TL, Kaczorowski J, Mahony JB, Lytwyn A, Chong S, et al. Incidence, clearance and predictors of human papillomavirus infection in women. Can Med Assoc J. 2003;168(4):421-5.
5. Ley C, Bauer HM, Reingold A, Schiffman MH, Chambers JC, Tashiro CJ, et al. Determinants of human genital papillomavirus infection in young women. J Natl Cancer Inst. 1991 Jul 17;83(14):997-1003.
6. Winer RL, Hughes JP, Feng Q, O’Reilly S, Kiviat NB, Holmes KK, et al. Condom use and the risk of genital human papillomavirus infection in young women. N Engl J Med. 2006;354(25):2645-54.
7. Bleeker MCG, Hogewoning CJA, Voorhorst FJ, van den Brule AJ, Snijders PJ, Starink TM, et al. Condom use promotes regression of human papillomavirus associated penile lesions in male sexual partners of women with cervical intraepithelial neoplasia. Int J Cancer. 2003;107:804-10.
8. Hogewoning CJ, Bleeker MC, van den Brule AJ, Voorhorst FJ, Snijders PJ, Berkhof J, et al. Condom use promotes regression of cervical intraepithelial neoplasia and clearance of human papillomavirus: a randomized clinical trial. Int J Cancer. 2003;107:811-6.
9. Markowitz LE, Dunne EF, Saraiya M, Lawson HW, Chesson H, Unger ER; Centers for Disease Control and Prevention; Advisory Committee on Immunization Practices. Quadrivalent Human Papillomavirus Vaccine: Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR. 2007;56(RR-2):1-24.
10. Harper DM, Ranco EL, Wheeler CM, Moscicki AB, Romanowski B, Roteli-Marins CM, et al. Sustained efficacy up to 4.5 years of a bivalent L1 virus-like particle vaccine against human papillomavirus types 16 and 18: follow-up from a randomised control trial. Lancet. 2006;367(9518):1247-55.
11. Brown DR, Kjaer SK, Sigurdsson K, Iversen OE, Hernandez-Avila M, Wheeler CM, et al. The impact of quadrivalent human papillomavirus (HPV; types 6, 11, 16, and 18) L1 virus-like particle vaccine on infection and disease due to oncogenic nonvaccine HPV types in generally HPV-naive women aged 16-26 years. J Infect Dis. 2009 Apr 1;199(7):926-35.
12. Centers for Disease Control and Prevention. GARDASIL^® Update: Male Efficacy & Safety. Available at: www.cdc.gov/vaccines/recs/acip/downloads/mtg-slides-feb09/10-3-hpv.pdf. Accessed May 5, 2009.
13. Centers for Disease Control and Prevention. Reports of Health Concerns Following HPV Vaccination. Available at: www.cdc.gov/vaccinesafety/vaers/gardasil.htm. Accessed May 5, 2009.
14. Garland SM, Hernandez-Avila M, Wheeler CM, Perez G, Harper DM, Leodolter S, et al. Quadrivalent vaccine against human papillomavirus to prevent anogenital diseases. N Engl J Med. 2007;356(19):1928-43.
15. Pedersen C, Petaja T, Strauss G, Rumke HC, Poder A, Richardus JH, et al. Immunization of early adolescent females with human papillomavirus type 16 and 18 L1 virus-like particle vaccine containing AS04 adjuvant. J Adolesc Health. 2007;40:564-71.
16. Paavonen J, Jenkins D, Bosch FX, Naud P, Salmerón J, Wheeler CM, et at. Efficacy of a prophylactic adjuvanted bivalent L1 virus-like-particle vaccine against infection with human papillomavirus types 16 and 18 in young women: an interim analysis of a phase III double-blind, randomised controlled trial. Lancet. 2007 Jun 30;369(9580):2161-70.
17. Sasagawa T, Tani M, Basha W, et al. A human papillomavirus type 16 vaccine by oral delivery of L1 protein. Virus Res. 2005;110(1-2):81-90.