Of 2,146 hotline callers invited to complete the eligibility screener, only 18 refused (<1%). Of the remaining 2128 callers, 24.8% (n= 528) met eligibility criteria. The most common reason for ineligibility (97% of ineligible) was not being the caregiver for a girl between the ages of 9–18 years. Of those eligible, 93% (n=490) provided data. The majority (85%) of respondents were mothers of vaccine-eligible girls, with the remaining caregivers being grandmothers, stepmothers, aunts or older sisters. For simplicity, we refer to study participants as mothers for the remainder of this article.
Demographic characteristics of respondents and girls are shown in . The vast majority of participants were ethnic minorities (93%), immigrant women (88%) with low levels of income and education. Over half (52%) of participants were Latina; the remaining mothers were Chinese (20%), Korean (14%), African American (8%) or another race/ethnicity (7%; non-Hispanic white, multi-racial or from other Asian subgroups). Three-fourths of mothers were uninsured and daughters were mainly on public insurance (61%) or uninsured (26%). The average age of respondents was 44 years and that of daughters was 14 years.
Sample Characteristics (n=490)
HPV vaccine awareness and uptake
presents HPV vaccine awareness and uptake for the total sample and by race/ethnicity. Overall, 63% of respondents had heard of HPV and 61% had heard of the HPV vaccine, but statistically significant ethnic differences were observed. For example, 46% of Korean mothers were aware of HPV compared to about 65% of Latina, Chinese and African American mothers. In the total sample, 29% of mothers reported their daughter had initiated the vaccine (i.e., received at least one dose), including 33% of Latina mothers, 25% of Chinese, 24% of Korean, and 24% of African Americans mothers. Among all girls, 12% (n = 56) had completed the three dose regimen. No ethnic differences were observed in vaccine initiation or completion rates. Vaccine initiation rates were also examined among 13–17 year olds to allow comparisons with national data. In the total sample, 36% of girls in this age range had received at least one dose of the vaccine (data not in table).
HPV awareness, vaccine uptake and Health Behavior Framework constructs by race/ethnicity
Health Behavior Framework Constructs
also presents HBF factors that may be correlates of vaccine initiation: perceived severity of HPV, perceived HPV risk of daughter, and perceived effectiveness of the vaccine. Most mothers perceived their daughters’ risk for HPV to be the same or less than that of other girls their daughters’ age (84%). Perceived severity of HPV was generally high, with 87% of mothers agreeing that HPV would be a serious problem for their daughters. About one third of mothers (33%) believed the vaccine was very effective against HPV and another third gave a “don’t know” answer to this question. Statistically significant ethnic differences were observed only for perceived risk. Twenty percent of Latino and 11% of African American mothers thought their daughters were at greater risk for HPV compared to other girls, while not a single (0%) Chinese or Korean mother endorsed this category.
General Vaccine Attitudes and Opinions about School Mandates
Vaccine attitudes and opinions about school mandates for the vaccine differed by ethnicity (). The majority of mothers overall (92%) agreed that “immunization against disease is a good thing” but African American and Chinese mothers were less likely to endorse this statement compared to other groups. While mothers on average reported 13.9 years old was the youngest age acceptable for HPV vaccination (participants were told that the vaccine was approved for girls 9–26 and then asked at what age they thought the vaccine should be given), Chinese and Korean mothers on average believed their daughters should be vaccinated at older ages (15 years and 14.6 years respectively). Only 36% of respondents agreed that the HPV vaccine should be required for school entry and 53% of Koreans and 44% of Latinas were much more likely to supportive of mandates compared to 19% of African Americans and 16% of Chinese mothers.
Predicting Vaccine Initiations: Bivariate Analyses
The following were associated with greater odds of vaccine initiation () in bivariate analyses: Latina ethnicity, daughter having an usual source of care, older age of daughter, having heard of HPV, believing it is acceptable for the HPV vaccine to be given at younger ages, higher perceived severity of HPV, higher perceived HPV vaccine effectiveness, holding favorable vaccine attitudes, agreement with school mandates for the HPV vaccine and believing that the vaccine should be given at a younger versus older ages.
Bivariate and Multivariate Correlates of HPV Vaccine Initiation (Received ≥ 1 dose of HPV vaccine)
Predicting Vaccine Initiation: Multivariate Analyses
also presents results of multivariate logistic regression analyses to identify factors independently associated with HPV vaccine initiation. Variables included in the multivariate analyses were those found significant in bivariate associations (at p<0.05) and after taking into account issues of multicollinearity. Although not significantly associated with vaccination in bivariate analyses, respondent age and education were included in the model. Income was not included do to its correlation with education. A strong relationship between daughter’s insurance status and usual source of care was observed; therefore, only usual source of care was included in multivariate analyses.
The first multivariate model included: ethnicity (Latina vs. non-Latina), education level of respondent, age of respondent, heard of HPV, daughter’s usual source of care, daughter’s age, perceived vaccine effectiveness, perceived severity of HPV, general vaccine attitudes, agreement with HPV vaccine school mandates, and youngest acceptable age for HPV vaccination. The strongest independent predictor of vaccine initiation was having heard of HPV (OR 12.8; 95% CI: 6.01, 27.2), older age of daughter (OR 1.23, 95% CI: 1.11, 1.36) and belief that vaccination is acceptable at younger ages (OR 1.19, 95% CI: 1.09, 1.29). No other variables were associated with vaccine initiation in this model.
The second multivariate model omitted HPV awareness to determine whether additional factors might emerge after removing awareness and its very strong association with vaccine initiation (data not shown). Results of the second model were similar to the first, except that higher perceived vaccine effectiveness emerged as an additional variable associated with greater odds of vaccine initiation (OR 1.81, 95% CI: 1.03 3.20).
Barriers to uptake among unvaccinated girls by race/ethnicity
Barriers to vaccine uptake were assessed among mothers of unvaccinated girls (n=345; ). Two-thirds of these mothers (66%) reported needing more information about the vaccine before making a decision. Significant ethnic differences were observed, with 81% of Chinese, 66% of Korean, 64% of Latina, and 41% of African American mothers needing more information. The majority of women (74%), regardless of ethnicity, reported that they did not know where their daughter could get the vaccine.
Barriers to HPV vaccine uptake among unvaccinated girls by race/ethnicity
A sub-set of participants (N=164) were administered an additional module of the questionnaire to assess concerns about the vaccine’s potential impact on daughters’ fertility, future health, and sexual behavior (). These items were added to the survey near the end of the data collection period. No differences in demographic variables (e.g. mother’s race/ethnicity, marital status, income, education, age, years in the U.S., daughter’s age, insurance status) were observed between the early and late cohorts. Relatively few mothers expressed concerns that the HPV vaccine would cause fertility problems (17%), negatively affect their daughter’s health in the future (15%), or increase likelihood of sexual activity (13%). Ethnic differences were observed for concerns about future health problems and sexual behavior, but these estimates may be unstable given the very small sample sizes within ethnic groups.