Introduction

Human papillomavirus (HPV) is the most prevalent sexually transmitted infection in the USA [1]. Persistent infection with high-risk HPV sub-types 16 and 18 is associated with 99.7 % of all cervical cancers [2]. Two HPV vaccines, the quadravalent HPV-4 (Gardasil, Merck, Whitehouse Station, NJ) [3] and the bivalent HPV-2 (Cervarix, GlaxoSmithKline, Philadelphia, PA) vaccine [4], are currently recommended by the Advisory Committee on Immunization Practices (ACIP) [5]. Current guidelines by the ACIP recommend routine vaccination of females aged 11 to 12 years and catch-up vaccination for females aged 13–26 years old [5]. Both HPV vaccines administered as a three-dose series have demonstrated between 70 and 95 % efficacy in reducing the rate of HPV-associated diseases [3, 4]. Despite the vaccine’s benefits, rates of vaccine uptake among eligible women in the USA have been low to moderate. Rates of receipt of ≥1, ≥2, and ≥3 doses of the vaccine among adolescent girls aged 13 to 17 years were approximately 54, 43, and 33 %, respectively, in 2012 [6]. Whereas, among females aged 18–26 years, initiation rates (receipt of ≥1 dose) range from 43 to 45 % [8–10], while completion rates (receipt of three doses) among those who start the series range from 13 to 58 % [11–13].

Racial/ethnic minorities are disproportionately affected by the burden of HPV-associated cervical cancer incidence and mortality [14], yet racial/ethnic disparities in uptake of the HPV vaccine continue to be reported. In studies of non-college women, some studies show black and Hispanic adolescent women have similar or even higher rates of initiating HPV vaccination than their white counterparts; however, nearly all studies show that black women are less likely to complete the series as compared to white women [12, 15–19]. Several factors have been associated with HPV vaccine uptake and could help explain any racial/ethnic disparities. These include factors such as sociodemographic characteristics, cost or lack of health insurance, provider recommendation, negative attitudes toward vaccination (e.g., concerns about side effects), lack of knowledge about HPV infection, and a woman’s perceived risk for HPV infection (e.g., a family or friends experience with a HPV-associated disease) [7, 12, 20–24]. Also, women who seek sexual health services such as Pap tests or prescription contraception (e.g., hormonal contraception) may be more proactive to their sexual health, engage in regular contact with healthcare services and therefore, more likely to be made aware of and receive HPV vaccination. Additionally, parental concerns that HPV vaccination may give young women a false sense of security and license for increased sexual activity may also influence HPV vaccination rates [7].

Female college students have demonstrated increased knowledge of HPV infection and vaccination as compared to a community sample of similar age [25] along with access to a college’s health care center that provides HPV vaccination. Whether racial/ethnic disparity in HPV vaccination persists in a sample of female college students has not been thoroughly described. As college women are exposed to known risk factors for HPV infection such as  early initiation of sexual activity and multiple sexual partners [20, 26], it is therefore important to continuously monitor the progress of HPV vaccine coverage and to delineate factors influencing vaccination. Therefore, the aims of this analysis were to (1) determine the rates of initiation and completion of the three-dose HPV vaccine series among a sample of college women, and (2) to determine the association of racial/ethnic status with vaccine initiation and completion.

Methods

Participant Recruitment

As part of a larger study related to oral HPV infection, participants for this study include a convenience sample of young women recruited from the campus of the University of Florida, a large US southeastern university. From April 2011 to September 2011, women were recruited within and around the university Student Health Care Center (SHCC). The sample included women seeking care at the center, as well as those just passing by, referred by friends, or responding to brochures or online advertisements about the study. Women were eligible to participate if they were at least 18 years of age and currently enrolled in a college course. Among women who inquired about the study and declined to participate, the primary reason for non-participation was lack of time. The study was approved by the institutional review boards at the University of Florida and the Moffitt Cancer Research Center. All participants provided written informed consent and received a $20 incentive.

Data Collection Procedure

Participants completed an anonymous 10–15 min web-based survey in a private room. Survey responses were entered directly by participants using a netbook computer.

Measures

The primary outcome measure “HPV vaccination status” was assessed with the following question: “How many HPV vaccine shots have you received in your lifetime (Cervarix or Gardasil)? (0, 1, 2, or 3). In this analysis, we defined HPV vaccine initiation as receipt of any (n ≥ 1) HPV vaccine dose and vaccine completion as receipt of all three doses. Participants who reported “0” number of shots in the vaccine question were defined as unvaccinated. Participants with missing data or who answered “don’t know” to the HPV vaccination question (n = 68) were excluded from the analysis yielding a final study sample of 835 college women aged 18–26 years. There were no significant differences in the distribution of the sociodemographic variables, and all other covariates between those included in the final analytic sample and those that were excluded (data not shown).

Participant’s sociodemographic characteristics, sexual behavior, gynecological health care utilization, and perceptions of risk for HPV-associated diseases were assessed for their association with HPV vaccination and for possible inclusion in multivariable analysis. A single question was used to ask participants to describe their racial/ethnic status. We categorized racial/ethnic status as white, black, Hispanic, Asian, and other. Age was dichotomized to 18–20 versus 21–26 years. Participants’ relationship status was categorized as single, in a relationship, and other.

Sexual behavior was measured as number of vaginal sex partners in the past year, which was an ordinal variable categorized as none, 1–2, or 3+ partners. We included variables to assess gynecological health care utilization. Participants were asked whether they had ever received a Pap test, dichotomized as yes versus no, and to indicate through a check list which contraceptive methods they had used in the past year. Hormonal contraception which must be prescribed by a healthcare provider was dichotomized as yes versus no. The survey included items related to perceptions of risk of HPV-associated diseases in which participants were asked whether they ever had a physician or health care provider diagnosis of an abnormal Pap smear/colposcopy/biopsy, genital warts, or genital HPV, and whether they had a family history of head and/or neck cancer.

Data Analysis

We compared sociodemographic characteristics, sexual behaviors, gynecological health care utilization, and perceived risk of HPV infection by racial/ethnic status using chi-square or Fishers exact test. Similar methods were used to determine bivariate associations of factors associated with HPV vaccination. Covariates with p values at or below 0.2 were included in a multivariable analysis. We used log-binomial regression models to calculate crude and adjusted prevalence ratios with 95 % confidence intervals [27]. All data analyses were conducted using SAS version 9.3 (Cary, NC).

Results

Sample Characteristics

The final study sample included 835 college women aged 18–26 years. Approximately, half of the female college students in this sample self-identified as white (51 %), followed by black (16.5 %), Hispanic (13.8 %), Asian (8.3 %), and other (9.9 %). Table 1 displays the sociodemographic, sexual behavior, gynecological health care utilization, and perceptions of risk of HPV-associated disease by racial/ethnic status. The results show that there were several significant differences across racial/ethnic groups for several variables related to sociodemographic characteristics, sexual behavior, and gynecological health care utilization (Table 1).

Table 1 Sociodemographic characteristics, sexual behaviors, sexual health care utilization, and perceptions of risk, by racial/ethnic status
Full size table

HPV Vaccine Coverage

Table 2 displays the HPV vaccination status of the study sample by racial/ethnic groups. Overall, 53 % of the study participants had initiated the vaccine (receipt of at least one dose); of these, 70 % had received all three doses. The rates of initiating the HPV vaccine were similar between whites and Hispanics (57 and 57 %, respectively) and higher than all other racial groups (blacks: 42 %, Asians: 51 %, other: 47 %). Whites had the highest completion rate, whereas blacks had the lowest (whites: 78 %, blacks: 45 %, Hispanics: 66 %, Asians: 65 %, other: 69 %).

Table 2 Unadjusted and adjusted prevalence ratios of HPV vaccine initiation and completion
Full size table

HPV Vaccine Initiation

Table 2 shows results from the unadjusted and adjusted prevalence ratios of HPV vaccine initiation. After adjusting for age and hormonal contraception use in the past year, the prevalence of HPV vaccine initiation was significantly lower among blacks (aPR = 0.80, 95 % CI = 0.65, 0.99; Table 2) than whites. Asides from Hispanics, who had similar prevalence rates as compared to whites (aPR = 1.00, 95 % CI = 0.85, 1.18), the prevalence for vaccine initiation among all other racial/ethnic groups were lower than their white counterparts, although these associations were not statistically significant.

HPV Vaccine Completion

In unadjusted analysis, blacks had significantly lower rates of HPV vaccine completion (aPR = 0.58, 95 % CI = 0.43, 0.77) than whites. All other racial/ethnic groups also had lower rates of completion than white women but not statistically significant. In adjusted analyses that controlled for hormonal contraception use in the past year, the prevalence of HPV vaccine completion remained significantly lower for blacks (aPR = 0.64, 95 % CI = 0.48, 0.84) than whites. All other racial/ethnic groups had lower but non-significant HPV vaccine completion rates as compared to white women.

Discussion

The findings from this analysis indicate that female college students in this sample had modest rates of HPV vaccine initiation (53 %), whereas, among those who initiated, completion rate was relatively high (70 %). The rates reported in this study are slightly higher than those reported in previous studies of women aged 18–26 years old which have ranged from 25 to 50 % for initiation [8, 22, 28–31] and 2 to 53 % for completion [8, 15, 25, 31, 32], with one study reporting a completion rate of 70 % [25].

In our multivariable models, we found younger-aged college women to report significantly higher prevalence of initiating HPV vaccination. This likely reflects increased healthcare provider recommendation for HPV vaccine as well as the eligibility of this age group for the vaccine for children program (VFC), which provides free vaccines for children and adolescents through 18 years of age who are uninsured. Our finding shows that past year hormonal contraception use is predictive of HPV vaccine initiation. This finding is not surprising, as women who seek sexual health promotion services may be more concerned about their sexual health and more likely to seek other sexual health preventive services including HPV vaccination. In this analysis, black women had significantly lower prevalence rates of initiating and completing the HPV vaccine, while no other racial/ethnic group had initiation or completion rates that were significantly different from whites. We are aware of only one study that has investigated racial/ethnic differences in HPV vaccine uptake in college women. Bednarczyk et al. [33] found that black women were 33 % less likely to have initiated the HPV vaccination as compared to white women; however, data for completion rate among racial/ethnic group was not reported. Of note in the present analysis is the relatively higher number of single relationship status and lower number of past year vaginal sex partners among black women than other racial/ethnic groups. Therefore, it is possible that black women in this study may have perceived themselves to be at lower risk for an HPV infection and not likely to benefit from receiving the HPV vaccine. Additionally, black women in this analysis reported lower rates of past year hormonal contraception use and Pap tests as compared to most racial/ethnic groups. It is also possible that the black women in this sample may have been less proactive to sexual health, less inclined to seek sexual health preventive services, and thus have missed opportunities to be made aware of and receive HPV vaccine.

The findings from this analysis should be interpreted cautiously. Firstly, this was a cross-sectional analysis, and therefore we are unable to make any inferences about causality. Secondly, for our primary outcome measure, we relied on self-reported HPV vaccination status, and there is a potential for some reporting bias in our estimates of HPV vaccination uptake. In one study, adolescent girls aged 14–17 years were more likely to underestimate than to overestimate their HPV vaccine uptake [34], and therefore, there is a possibility that the actual HPV vaccination rate may be higher. Also, we did not account for other important factors including socioeconomic status and cultural health beliefs about HPV vaccination which could have influenced the propensity to get vaccinated. Thirdly, since our study was from a single university, our results may not be generalizable to all college students.

Despite these limitations, our analyses provide a 5-year update on rates of initiation and completion of the HPV vaccine in a sample of college women. Our findings suggest that racial/ethnic disparity in HPV vaccination persists even among female college students, specifically in black women. Although the completion rates are encouraging, our analysis suggest that more targeted intervention for HPV vaccination may be needed among minority women.