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HPV Vaccine May Need a Redesign Due to Changes in Circulating Strains

OCT 22, 2016 | MICHAEL R. PAGE, PHARMD, RPH
Recommendations from the Advisory Committee on Immunization Practices (ACIP) in February 2015 advise use of the 9-valent human papillomavirus (HPV) vaccine as part of a routine vaccination schedule at the age of 11 or 12 years. When children are not vaccinated at that age, the vaccine may be administered in females aged 13 to 26 years, and in males aged 13 to 21 years.1,2
 
Although ACIP recommends use of the 9-valent vaccine, bivalent and quadrivalent versions of the vaccine are also available. All available HPV vaccines offer protection against 2 strains that are responsible for most cases of cervical cancer that involve HPV (strains 16 and 18). Of all cervical cancers, 51% are associated with strain 16, and 16% of are associated with strain 18. The remainder are associated with other HPV strains and additional risk factors.1,2
 
Although the HPV vaccine was used by a minority (32%) of females aged 13 to 17 years in 2010, by 2014, a reduction in the prevalence of HPV strains contained in the vaccine were observed in adolescent girls.1,2
 
At the present time, existing protection offered by bivalent, quadrivalent, and 9-valent HPV vaccines may help prevent the majority of cervical cancer cases. However, additional circulating strains of HPV (eg, 31, 33, 45, 52, and 58) are implicated in approximately 1 in 10 additional cases of cervical cancer, and these strains may eventually become more common.1,2
 
In a study published in the journal Emerging Infectious Diseases, researchers analyzed the effect of HPV vaccination on circulating strains of HPV by analyzing literature before and after the vaccine became available.3
 
Researchers collected data from 13,886 girls and women aged 19 years and younger, and from 23,340 women aged 20 to 24 years. Changes in strain prevalence indicate that the existing 9-valent vaccines may offer some protection against an additional high-risk strain that is not included in the vaccine (strain 31), potentially due to antigenic similarities with other strains. There was little evidence of reductions in strains 33 and 45, however.3
 
Less encouragingly, researchers observed slight increases in the prevalence of infection with strains 39 and 52, as well as 2 potential high-risk strains: 53 and 73.3
 
Although the HPV vaccine may offer some protection against rarer high-risk forms of HPV, it is possible that strains of HPV not covered by existing HPV vaccines will eventually become more common, potentially supplanting the existing high-risk strains, necessitating development of new vaccines against HPV.3

References
1. Petrosky E, Bocchini JA Jr, Hariri S, et al. Use of 9-valent human papillomavirus (HPV) vaccine: updated HPV vaccination recommendations of the advisory committee on immunization practices. MMWR Morb Mortal Wkly Rep. 2015;64(11):300-304.
2. Markowitz LE, Dunne EF, Saraiya M, et al. Human papillomavirus vaccination: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep. 2014;63(RR05):1-30.
3. Mesher D, Soldan K, Lehtinen M, et al. Population-level effects of human papillomavirus vaccination programs on infections with nonvaccine genotypes. Emerg Infect Dis. 2016;22(10):1732-1740.
 
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