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HPV vaccine acceptability was examined as part of a cohort study of HPV infection among adult males.
Between July 2004 and June 2007, 445 adult males aged ≥18 years were enrolled primarily from a university-based population. A structured questionnaire addressed HPV vaccine awareness, attitudes, and intention to be vaccinated.
Overall, 69% of men reported that they were likely or very likely to be vaccinated against HPV if a prophylactic vaccine were available. Men most frequently cited side effects (69%), efficacy (65%), and safety (63%) as the major factors that would influence their decision to be vaccinated against HPV. Issues of vaccine costs and efficacy were important considerations for men of vaccine-eligible ages (18–26 years).
Men who cited cost as a major factor in their HPV vaccine decisions and those indicating cost as a potential barrier had greater intention to be vaccinated. Heterosexual men had less intention to be vaccinated compared to men who have sex with men.
Acceptability of HPV vaccination among males is generally high. Costs and sexual history may influence vaccine utilization.
Human papillomavirus (HPV) is the primary causal agent of cervical cancer and also plays an etiologic role in malignancies of the vagina, vulva, anus, penis, oral cavity and oropharynx.1 Two prophylactic HPV vaccines have been developed and are available internationally. The quadrivalent vaccine against HPV 6, 11, 16, and 18 has been available in the United States since June 2006 when it was approved for use in females ages 9–26 years for the prevention of cervical cancer and anogenital warts.2 In 2009, a bivalent vaccine against HPV 16 and 18 was approved in the U.S. for females of the same age group for the prevention of cervical cancer. Also in 2009, the quadrivalent vaccine was approved for use in the U.S. for the prevention of anogential warts in males ages 9–26. (http://www.cdc.gov/vaccines/recs/provisional/downloads/hpv-vac-dec2009-508.pdf)
Vaccine acceptability among parents will be a critical determinant of HPV vaccine usage among boys and adolescent males. Acceptability of the vaccine among young adult men themselves will influence its usage in this age group. While HPV vaccine attitudes have been examined in females and in parents, only a few such studies have included adult males.3–5 Among Dutch college students, acceptance of HPV vaccination was greater among women than men and among younger than older individuals.3 In a sample of U.S. men, vaccine acceptance was greater among men with a higher education, those engaging in sexual and non-sexual high-risk behaviors, and men with a greater knowledge of HPV.4 In the present study, we examined HPV vaccine awareness, attitudes, and intent to be vaccinated in a cohort of U.S. adult men of a wide age range who were participating in a study of HPV infection. This study spanned a period both before and after availability of the first HPV vaccine approved for use in females in the U.S. and prior to approval of vaccine use in U.S. males.
Between July 2004 and June 2007, 445 adult males aged 18–79 were enrolled. Table 1 summarizes the characteristics of the study population and the responses to vaccine-related questions. The study population was largely ≤26 years (62%), U.S.-born (82%), White (58%), unmarried (84%), sexually active heterosexual (80%) men. The majority were college students (66%) and 21% reported a history of a sexually transmitted infection (STI). The background of study participants was generally comparable relative to the date of enrollment before and after June 2006 when the quadrivalent vaccine was approved for use in U.S. females. An exception was sexual orientation: MSM consisted of a larger proportion of study participants enrolled before (24%) than after (15%) vaccine approval (p = 0.04). MSM were also substantially older than heterosexual study participants (77% vs. 27% >26 years, p<0.0001).
Overall, a total of 16% of men reported ever hearing about the HPV vaccine (Table 1). Vaccine awareness varied with date of enrollment. Among men enrolled in the study prior to June 1, 2006, only 7% had heard of the vaccine compared to 31% of men enrolled after that date (p<0.0001). Sixty-nine percent of men reported that they were likely or very likely to be vaccinated against HPV should it become available, and 31% responded that they were unlikely or very unlikely to be vaccinated. There were no differences in the intention to be vaccinated between the time periods before and after June 1, 2006.
The major issues men wanted information on before making a decision to be vaccinated were side effects (69%,), efficacy (65%), and safety (63%) (Table 1). Men enrolled in the study after June 1, 2006 cited vaccine side effects more frequently than those enrolled prior to vaccine approval (75% vs. 66%, p = 0.05). Men indicated cost as the predominant potential barrier that would prevent men from getting the HPV vaccine (73%). Other reported reasons were not thinking that the vaccine would work (35%) and having to go to the clinic for 3 shots over 6 months (27%). Twenty–four percent of respondents cited other reason(s). The majority of these self-described other reasons were related to vaccine safety (data not shown).
Responses to HPV vaccination questions were compared by groups age-eligible (18–26 years) and age-ineligible (>26 years) for vaccination. There were no differences in vaccine awareness or intent to be vaccinated by age group. Compared to those older than 26 years, younger men more frequently cited how well the vaccine works (58% vs. 69%, p= 0.02) and vaccine costs (35% vs. 52%, p<0.001) and less frequently indicated vaccine safety (70% vs. 59%, p=0.02) and health care provider recommendation (25% vs. 17%, p=0.04) as considerations in making a decision to be vaccinated. The vaccine schedule requiring 3 shots over 6 months was more frequently reported to be a potential barrier to vaccination among men ≤26 years (31%) compared to men >26 years (22%) (p=0.05). Younger men also more frequently reported time off from work or school as potential barriers (19%) than men >26 years (11%) (p=0.03).
Intent to be vaccinated was examined with and without adjustment for age and date of enrollment (Table 2). Vaccination intent did not differ by enrollment date, age, race, education level, birthplace, marital status, age of initial sexual activity, number of female sexual partners, circumcision status, substance use history, female partner's Pap smear history, self-reported STI history, or genital HPV DNA status (unknown to the individual at the time of the interview).
There were some differences by sexual orientation and practices. Sixty-eight percent of heterosexual men intended to be vaccinated compared to 75% of MSM (adjusted OR 0.54, 95% CI 0.30–0.97). Among heterosexual men, 59% of men who engaged in male oral-female anal contact intended to be vaccinated compared to 72% of those who did not engage in this type of sexual contact (adjusted OR 0.57, 95% CI 0.35–0.93). Similarly, men with history of male hand-female anal contact had less intention to be vaccinated than those who did not (61% vs. 73%, respectively, adjusted OR 0.60, 95% CI 0.40–0.92).
Men indicating cost as a major factor in HPV vaccination decisions had greater intention to be vaccinated compared to men who did not (74% vs. 65%, respectively, adjusted OR 1.53, 95% CI 1.01–2.33). Similarly, men who reported cost as a potential barrier to vaccination had greater intention to be vaccinated (73% vs. 60%, respectively, adjusted OR 1.76, 95% CI 1.12–2.74). Men citing the opinion of their sexual partner as a major factor in their vaccination decision had less intention to be vaccinated compared to those who did not (42% vs. 71%, respectively, adjusted OR 0.30, 95% 0.13–0.69). Men who indicated that the vaccine schedule of three-shots over 6 months as a potential barrier to vaccination had less intention to be vaccinated than those who did not (61% vs. 72%, respectively, adjusted OR 0.57, 95% CI 0.37–0.89).
We examined the acceptability of HPV vaccination—including vaccine awareness, attitudes, and intention to be vaccinated—in an exclusively adult male population. Our study spanned a period immediately before and after approval of the use of the quadrivalent HPV vaccine for U.S. females in June 2006 and prior to the approval of vaccine use in males in 2009. Awareness of HPV vaccination was substantially higher among participants enrolled after June 2006. This increased awareness is consistent with heightened local and national media attention in the U.S. which followed the availability of the vaccine. Overall, a large majority of men reported that they were likely or very likely to be vaccinated against HPV. Interestingly, the proportion of men indicating their intention to be vaccinated was comparable before and after the quadrivalent vaccine first became available for women. This may reflect the limited influence of female-targeted media and advertisements on males.
In 2009, the quadrivalent HPV vaccine was approved for use in the U.S. for the prevention of anogential warts in males ages 9–26. It is possible that HPV vaccine uptake in young men may be particularly challenging given a recent national study that found that HPV vaccine uptake in women ages 18–26 in the U.S. was far lower than that of females 13–17 years.6 We were able to compare willingness to be vaccinated against HPV among adult men age-eligible and not age-eligible for vaccination. Interestingly, while concerns about HPV vaccine efficacy, safety, costs, as well as the influence of health care providers varied by age, we observed no differences in the intention to be vaccinated between men ≤26 and >26 years.
Vaccine side effects were the most important factor that men indicated would influence their HPV vaccination decisions. A greater proportion of men enrolled in our study after vaccine approval were concerned about side effects compared to those enrolled earlier. This may also be attributed to increased media attention-- both favorable and unfavorable-- following vaccine approval. Vaccine safety was another important consideration in a man's decision to be vaccinated although men >26 years were more concerned about vaccine safety than those ≤26. Vaccine efficacy was also a major issue in vaccination decisions but was more of a concern among younger men. Efficacy is an important predictor of HPV vaccine acceptability among adult females and parents.7
Cost was the most important potential barrier to vaccination although no specific vaccine cost information was provided to study participants. Men ≤ 26 years more frequently indicated cost as a consideration in their decision to be vaccinated. It is likely that younger men represent a more uninsured and underinsured population with fewer financial resources. Other practical issues which may be related to income and economic stability-- time off from school or work and the 3-visit vaccine schedule-- were also considered to be greater potential barriers among young men. Interestingly, both men who cited cost as a major consideration in the decision to be vaccinated and those indicating cost as a potential barrier to vaccination had greater intention to be vaccinated. Cost was also found to be an independent predictor of HPV vaccine acceptability among U.S. male college students.5
Heterosexual men had less intention to be vaccinated than MSM. MSM were older and were more likely to be early enrollees in the study. Earlier enrollment may be attributed to greater interest in participating in research focused on sexual health due to perceived sexual risk. Nonetheless, the association of sexual orientation with intention to be vaccinated was observed when adjustment was made for both age and enrollment date.
Heterosexual men who engaged in anal contact with females not involving intercourse had less intention to be vaccinated. Such sexual practices may be perceived as low risk behaviors with respect to STI exposure. Consistent with these findings, in a study of U.S. men, HPV vaccine acceptance was greater among men engaging in sexual high-risk behaviors.4 Sexual activity and perceived susceptibility to HPV infection were found to be independent predictors of HPV vaccine acceptability among male heterosexual college students.5 Perceived risk of HPV infection is also a predictor of vaccine acceptability among U.S. adult females and parents.7, 8 Interestingly, men who cited the importance of the opinion of their sexual partners in their vaccine decisions had less intention to be vaccinated.
The major focus of the cohort was to examine the epidemiology and natural history of HPV infection in adult men. It was not intended to provide an assessment of HPV vaccine acceptability in the general population of men in Hawaii. For this reason, a number of limitations must be considered in the interpretation of the results.
Our evaluation did not address knowledge or awareness of HPV among study participants. Men participating in this study may not represent the general population of adult men with respect to a priori knowledge of HPV and HPV vaccination or sexual risk behaviors and other practices that may influence attitudes towards vaccination. Rather, our study population may reflect men who are more motivated to be vaccinated against HPV. Given their participation in a study of HPV, the men in our study may have been more knowledgeable about HPV than the general population of U.S. men. Acceptance of HPV vaccination was observed to be greater among men with more knowledge of HPV.4
Given the nature of this study, participants were likely not representative of the general U.S. male population with respect to risk of sexually transmitted infections. Indeed, over 20% of participants reported a history of one or more STIs. Accordingly, the level of interest in HPV vaccination in this high-risk population may be more than that observed in other men.
In our population of sexually active men, a proportion are likely previously infected with one or more HPV types covered by the quadrivalent vaccine and would therefore not fully benefit from prophylactic vaccination. Indeed, in a previous analysis, HPV DNA was detected in the external genitals of over half of men in this cohort.9
The present evaluation identified a number of factors influencing HPV vaccine acceptability among adult males. Our study population included young men who fall within the age groups for whom the quadrivalent vaccination was recently approved in the U.S.. Acceptability will be critical to population coverage in this age group and its long-term effect on reducing HPV-associated disease among men, and, possibly, in their sexual partners.
This natural history cohort was established to evaluate HPV infection in men.9, 10 The study was approved by the Committee on Human Studies of the University of Hawaii and written, informed consent was obtained from all study subjects. Study participants were primarily recruited from a university-based population in Hawaii. The study was promoted through campus flyers, newspaper advertisements, and invitations sent to the e-mail addresses of enrolled male undergraduate and graduate students. The study was also promoted on a limited basis through general public venues. Eligible men were 18 years and older and English-speaking with no history of blood-clotting disorders (blood was collected for serologic testing). Study visits were conducted at the University of Hawaii's University Health Services and the Cancer Research Center of Hawaii. All participants received monetary compensation for their time and transportation. HPV status was unknown to the study participant at the time of the interview. HPV DNA testing methods and results are detailed elsewhere.9, 10
A comprehensive, structured questionnaire was administered by a trained interviewer at study enrollment. The questionnaire queried demographic information and medical, sexual and reproductive history. Of the 56 questions included in the questionnaire, four multiple-choice questions addressed HPV vaccine awareness, attitudes, and intention to be vaccinated: (1) “Have you ever heard of a vaccine for HPV (human papillomavirus)?” Yes/No; (2) “How likely is it that you would get a vaccine that prevents some HPV infections? Very unlikely/unlikely/likely/very likely; (3) “What would you want to know about the HPV vaccine before you made a decision to get the vaccine? Check the boxes for the 3 most important things you would want to know.”; and (4) “What do you think would prevent or stop you from getting the HPV vaccine? Check 2 boxes only.” For question 3, a list of 11 choices were listed including “Other (describe)”; for question 4, a list of 8 choices were listed including “Other”. Questions about general HPV knowledge or awareness of HPV were not included.
All analyses were conducted using SAS (version 9). Associations between factors and categorical responses to questions were examined using chi-square tests. The relationship of factors with the likelihood of vaccination (likely or very likely versus very unlikely or unlikely) was evaluated using unconditional logistic regression to calculate odds ratios and 95% confidence intervals. Odds ratios were adjusted for age as a continuous variable and enrollment as a categorical variable (before or after June 1, 2006).
We extend our gratitude to the staff of the Cancer Research Center of the University of Hawaii (UH) and the UH University Health Services.
Financial support: Centers of Biomedical Research Excellence Program (award P20 RR018727 from the National Center for Research Resources, National Institutes of Health).
Disclosures: B. Hernandez has previously received consultation and research funds from the Merck Corporation, manufacturer of the quadrivalent HPV vaccine, Gardasil. The research funds were for a project unrelated to the study described in this manuscript.