In late 2014, the US Food and Drug Administration approved a 9-valent human papillomavirus vaccine. In early 2015, the Advisory Committee on Immunization Practices made the recommendation that it be offered as one of the available HPV vaccines this country. The vaccine, made by Merck, is known commercially as Gardasil 9 and generically as Human Papillomavirus 9-valent Vaccine, Recombinant (9vHPV).
This change in the vaccine will make HPV vaccination more broadly effective; 9vHPV protects against HPV strains that cause 90% of cervical cancers – as compared with the quadrivalent vaccine, whose two oncogenic strains account for approximately 68% of cervical cancers in the United States. Moreover, the new vaccine may provide protection to subgroups of women who are more vulnerable to HPV types not in the bivalent and quadrivalent vaccines.
A 2013 poster based on a study in a Duke University-affiliated clinic presented the finding that African American women with abnormal Pap smears were two times less likely to be infected with HPV 16 and 18 than Caucasian women (HPV 16 and 18 are the two oncogenic genotypes of HPV in bivalent and quadrivalent HPV vaccines). The researchers also found that in African American women with high-grade lesions, HPV types 31, 45, 51, and 66 were most the most common oncogenic types found. Of those types, 31 and 45 are in the new nine-valent vaccine.
The significance of these findings needs to be explored, but several hypotheses for the difference in incidence of HPV types have been offered. One is that African American women in the study population may have different types of exposures, or that persistence of HPV types or resistance to infection with certain HPV types may be different in different populations. Some commenters have noted, though, that what truly matters is not which HPV types are associated with precancerous lesions — which may resolve on their own — but distribution of HPV types in invasive cervical cancer. The latter may not have significant population differences.
In any case, the effect of the 9-valent HPV vaccine on global cervical cancer rates could be enormous; as Serrano et al. (2013) state, high global coverage with this vaccine “… would provide a higher impact [on rates of invasive cervical cancer] than any screening programme has ever produced in the very best scenarios.”
As for now, the ACIP recommends vaccination with any available HPV vaccine for girls and young women. So, for example, a girl could have two doses of the three-dose series as bi- or quadrivalent vaccine and complete the series with the nine-valent vaccine. Boys and young men, who are not recommended to receive the bivalent vaccine, can similarly complete a series once begun with either the quadrivalent or nine-valent vaccine. ACIP does note, however, that the effectiveness of one dose of nine-valent vaccine has not been determined.
A clinical trial is ongoing to study alternative dosing schedules for 9vHPV. Recommendations are likely to change as the nine-valent vaccine becomes more widely available and when the aforementioned trial is completed.
Mulcahy N. Vaccines do not cover most HPV types that infect black women. Medscape Medical News: Oncology. October 28, 2013. http://www.medscape.com/viewarticle/813365
Petrosky E, et al. Use of 9-valent human papillomavirus (HPV) vaccine: Updated HPV vaccination recommendations of the Advisory Committee on Immunization Practices. MMWR March 27, 2015; 64;11:300-304. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6411a3.htm
Serrano B, Alemany L, Tous S, Bruni L, Clifford GM, Weiss T, Beach FX, de Sanjose S. Potential impact of a nine-valent vaccine in human papillomavirus related cervical disease. Infectious Agents and Cancer. 2013;7:38 http://www.infectagentscancer.com/content/7/1/38
Vidal AC, et al. HPV genotype distribution and cervical intraepithelial neoplasia in African American and white women living in the southeastern United States. Poster presented at Twelfth Annual AACR International Conference on Frontiers in Cancer Prevention Research; Oct 27-30, 2013; National Harbor, MD. http://cancerpreventionresearch.aacrjournals.org/content/6/11_Supplement/PR01.abstract