Reduced prevalence of vulvar HPV16/18 infection among women who received the HPV16/18 bivalent vaccine: a nested analysis within the Costa Rica Vaccine Trial.
BACKGROUND
Vaccine efficacy (VE) against vulvar human papillomavirus (HPV) infection has not been reported and data regarding its epidemiology are sparse.


METHODS
Women (n = 5404) age 22-29 present at the 4-year study visit of the Costa Rica Vaccine Trial provided vulvar and cervical samples. A subset (n = 1044) was tested for HPV DNA (SPF10/LiPA25 version 1). VE against 1-time detection of vulvar HPV16/18 among HPV vaccinated versus unvaccinated women was calculated and compared to the cervix. Prevalence of and risk factors for HPV were evaluated in the control arm (n = 536).


RESULTS
Vulvar HPV16/18 VE (54.1%; 95% confidence interval [CI], 4.9%-79.1%) was comparable to cervix (45.8%; 95% CI, 6.4%-69.4%). Vulvar and cervical HPV16 prevalence within the control arm was 3.0% and 4.7%, respectively. Independent risk factors for vulvar HPV were similar to cervix and included: age (adjusted odds ratio [aOR] 0.5 [95% CI, .3-.9] ≥28 vs 22-23]); marital status (aOR 2.3 [95% CI, 1.5-3.5] single vs married/living-as-married); and number of sexual partners (aOR 3.6 [95% CI, 1.9-7.0] ≥6 vs 1).


CONCLUSIONS
In this intention-to-treat analysis, VE against vulvar and cervical HPV16/18 were comparable 4 years following vaccination. Risk factors for HPV were similar by anatomic site.


CLINICAL TRIALS REGISTRATION
NCT00128661.
['Lang Kuhs|Krystle A|KA|', 'Gonzalez|Paula|P|', 'Rodriguez|Ana Cecilia|AC|', 'van Doorn|Leen-Jan|LJ|', 'Schiffman|Mark|M|', 'Struijk|Linda|L|', 'Chen|Sabrina|S|', 'Quint|Wim|W|', 'Lowy|Douglas R|DR|', 'Porras|Carolina|C|', 'DelVecchio|Corey|C|', 'Jimenez|Silvia|S|', 'Safaeian|Mahboobeh|M|', 'Schiller|John T|JT|', 'Wacholder|Sholom|S|', 'Herrero|Rolando|R|', 'Hildesheim|Allan|A|', 'Kreimer|Aimée R|AR|', '|||']
D000293:Adolescent D000328:Adult D002584:Cervix Uteri D003364:Costa Rica D004279:DNA, Viral D005260:Female D052162:Human papillomavirus 16 D052161:Human papillomavirus 18 D006801:Humans D030361:Papillomavirus Infections D053918:Papillomavirus Vaccines D015995:Prevalence D012307:Risk Factors D014844:Vulva D014845:Vulvar Diseases D055815:Young Adult
Costa Rica HPV HPV vaccine vulvar human papillomavirus vaccine