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Gardasil Study - Most Young HIV-Positive Women Still Negative for Key HPV Genotypes
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2nd International Workshop on HIV & Women. January 9-10, 2012, Bethesda, Maryland
Mark Mascolini
Most of 99 young HIV-positive women getting their first human papillomavirus (HPV) vaccine dose were negative for high-risk HPV genotypes, a result supporting HPV vaccination for HIV-positive women [1]. A separate analysis found that a fair proportion of these women mistakenly believed they would have a lower risk of non-HPV sexually transmitted infections (STIs) after vaccination.
HPV, the most frequently transmitted sexual pathogen in the United States, can lead to cervical, vaginal, anal, and other cancers. The CDC recommends HPV vaccination for 11- and 12-year-old girls and for 13- to 26-year-old women who have not been vaccinated or have not completed the 3-shot series [2].
A clinical trial conducted through the Adolescent Medicine Trials Network for HIV/AIDS Interventions (ATN) is addressing several questions in young HIV-positive women who will get three doses of the Gardasil vaccine, which is designed to protect against four high-risk HPV genotypes: 6, 11, 16, and 18. This phase 2, open-label, multicenter trial enrolled 16- to 23-year-old HIV-positive women who will receive the three doses over 24 weeks and have 24 weeks of follow-up after that.
Study participants must be behaviorally infected with HIV and can be either antiretroviral-naive or have a viral load below 400 copies after being treated for at least 6 months. The trial excludes women who received one or more doses of any HPV vaccine, who had anogenital warts or cervical intraepithelial neoplasia 2 or 3, and who are pregnant or substance dependent. Study participants cannot have an active opportunistic infection or serious bacterial infection.
The 99 women average 21.4 years in age, 80% are non-Hispanic black, 16% are Hispanic, and 4% are non-Hispanic white. While 86% entered the trial with a CD4 count at or above 350, 40% had a viral load under 400 copies, 17% had 400 to 999 copies, 31% had 1000 to 9999 copies, and 11% had 10,000 copies or more. Whereas 30% of study participants had 0 to 5 lifetime male sex partners, 32% had 6 to 10 and 38% had more than 10. One quarter of these young women (28%) had vaginal sex more than 10 times in the past 90 days, and 36% had vaginal sex 2 to 10 times in the past 90 days. As a group, study participants correctly answered 49% of questions about HPV and vaccines.
Researchers tested cervicovaginal swabs for 41 HPV types when women came for their first vaccination. Three quarters of women tested positive for any HPV type, while 15% were positive for types 16 and/or 18, and 18% were positive for types 6, 11, 16, and/or 18 (the types covered in the vaccine). Slightly more than half of these women (53.5%) tested positive for 1 or more high-risk HPV types, and 69% of women who tested positive for any type were positive for 2 or more types (average 3.1 HPV genotypes, range 1 to 9). Of the four genotypes covered in the Gardasil vaccine, positivity rates were generally low: 2% for type 6, 1% for type 11, 12% for type 16, and 5% for type 18.
Multivariate analysis identified four factors independently associated with positivity for high-risk HPV, at the following adjusted odds ratios (AOR) (and 95% confidence intervals):
-- Non-Hispanic black (versus Hispanic): AOR 5.10 (1.36 to 19.1)
-- HIV load at or above 400 copies: AOR 2.86 (1.12 to 7.31)
-- 6 or more vaginal sex episodes in last 90 days (vs 0): AOR 6.00 (1.54 to 23.5)
-- 1 to 5 vaginal sex episodes in last 90 days (vs 0): AOR 6.83 (1.66 to 28.1)
The researchers suggested that the relatively high prevalence of any HPV or HPV-16 or 18 compared with the general population supports current advice to target 11- and 12-year-old girls for vaccination, before they are likely to begin sexual intercourse. But because the "vast majority" of these young HIV-positive women remained negative for these HPV types before vaccination, the investigators argued, young HIV-positive women should be vaccinated.
The trial team suggested that the association between higher HIV load and high-risk HPV raises the question whether improved HIV control--either through antiretroviral therapy or immune-mediated host mechanisms--could prevent HPV infection.
At their first vaccination appointment, study participants answered three questions about risk after vaccination:
1. After getting vaccination against HPV, I am less worried about getting HPV.
2. After getting vaccination against HPV, I am less worried about getting an STI other than HPV.
3. After getting vaccination against HPV, I feel that condom use during sex is less necessary.
With a possible high score of 50 for each question, mean scores were 19.5 for question 1 (indicating that most women correctly believed they would have a lower HPV risk after vaccination), 31.2 for question 2 (indicating that most women correctly believed they would not have a lower risk of another STI after vaccination), and 43.1 for question 3 (indicating that a large majority of women believed they still had to practice safer sex).
The researchers noted that answers to questions 1 and 2 indicate that perceptions about HPV and STI risk after vaccination are appropriate. But the relatively high proportion of women who thought they would have a lower risk of other STIs after vaccination "suggests more effective individual educational interventions or public health initiatives are needed." The finding that most young women believed safer sex remains important after HPV vaccination, the researchers proposed, should reassure clinicians and parents about recommending vaccination.
References
1. Kahn J. HPV vaccination in HIV-infected young women: risk perceptions, HPV epidemiology, and immune response. 2nd International Workshop on HIV & Women. January 9-10, 2012, Bethesda, Maryland. Invited lecture.
2. CDC. HPV vaccine information for young women--fact sheet. http://www.cdc.gov/std/hpv/stdfact-hpv-vaccine-young-women.htm
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