In this longitudinal study, predictors of HPV vaccine initiation among adolescent girls differed from those suggested by HPV vaccine acceptability studies conducted primarily before vaccine licensure.10
Many health belief model constructs that we expected would be associated with uptake were not. Instead, key predictors of initiation included anticipated regret if their daughters got HPV that the vaccine could have prevented as well as not being a born-again Christian. While many studies have examined interest in a hypothetical HPV vaccine or cross-sectional correlates of vaccine initiation,10–13,19
this study adds important new information on predictors over time.
Over two years after HPV vaccine became available to the public, only about one in three eligible girls in an area with elevated cervical cancer rates had initiated the vaccine. This vaccine uptake is similar to that found in other US studies from the same time period.7
It is also similar to coverage for another adolescent vaccine (tetanus, diphtheria, acellular pertussis vaccine) about two years after its introduction in the US (30% in 2007).18,7
Our findings suggest missed opportunities to increase HPV vaccine uptake, including a large percentage of daughters who had been seen by their doctors but had not received an HPV vaccine recommendation, and two thirds of parents who intended to vaccinate their daughters but had not followed through with these plans a year later. One positive finding was parents’ report that most girls who had received the vaccine were on schedule to receive their next dose or had received all three doses.
In contrast to what we previously found in cross-sectional analyses of our baseline data on uptake11
and in our systematic review of acceptability,10,12
HPV vaccine initiation was not longitudinally associated with key health belief model constructs (perceived risk, perceived severity, and physician recommendation as a cue to action). The small and not statistically significant associations with risk beliefs were within the range we observed in our previous meta-analysis of vaccine use among adults.27
However, the observed associations were much smaller than associations with anticipated regret from not vaccinating. While the special predictive power of anticipated regret from not
vaccinating mirrors the findings of Weinstein and colleagues,29
we additionally show that anticipated regret from vaccinating
, at least with respect to sexual disinhibition, played essentially no role in vaccine decisions. This finding may be due to the different outcomes (cervical disease versus sexual disinhibition), or it may reflect different beliefs about harms caused by action and inaction.30
Doctor’s recommendation predicted reported HPV vaccine initiation in bivariate analyses, which is consistent with previous findings that doctors are uniquely credible and persuasive on issues related to medical care.25,26
The non-significant multivariate association may underestimate the importance of doctors’ recommendations, because our longitudinal analyses evaluated vaccine initiation over time according to doctors’ recommendations assessed at the baseline interview. As analyses only included those not yet vaccinated at baseline, daughters with doctor’s recommendations were those who had gotten a recommendation before baseline, but had not acted on it, and thus were perhaps less likely to be vaccinated later. Physicians could play a larger role in encouraging HPV vaccine initiation by adolescent girls and in providing information about the vaccine to parents.
Uptake was lower among parents who said they needed more information about the vaccine. Messages from doctors or other respected professionals that focus on helping parents who already plan to act and reducing perceived barriers may be especially effective in increasing HPV vaccine uptake. Conversations about consequences of vaccination, such as potential side effects, may be better redirected to focus on the consequences of not vaccinating (e.g., anticipated regret). Simply imagining–and anticipating–regretting a future in which their daughters had HPV was a powerful motivator for parents.
Born-again Christian parents in our study were half as likely as other parents to get their daughters HPV vaccine. This especially concerning, given that as many as 34% of the US population identify themselves in this way.20
A study in California found that born-again and evangelical Christian parents were less likely than other parents to prefer to vaccinate their daughters before age 13 than at older ages,21
but the study did not address the more fundamental question of willingness to get the vaccine at all or vaccine uptake. Our findings suggest public health programs to increase HPV vaccine uptake should make special efforts to reach born-again Christian parents.
Importantly, we found no differences in vaccine initiation by race, urbanicity, or age group. Equivalent but low uptake by whites and blacks will maintain, but not reduce, that U.S. black women’s sharply higher risk of dying from cervical cancer1
. Given the current low rates of vaccine uptake in the US, additional efforts should focus in ensuring that HPV vaccine uptake is high across all groups, but these efforts should also especially focus on those at highest risk. We previously reported higher uptake among older teens in analyses of our baseline data.22
The different findings might reflect a previous desire to catch older teens up to recommended vaccine guidelines or parents now being more comfortable with recommendations to vaccinate younger adolescent girls. Because HPV vaccine is likely to be most effective if given before adolescent girls initiate sexual activity, it may even be preferable to have higher rates of uptake for younger aged adolescent girls.
Study strengths include a diverse, population-based sample of parents from high-risk areas. The study’s longitudinal design is also a strength, although we cannot completely rule out confounding by unmeasured variables. Limitations include the use of parent self-report to assess HPV vaccination of their female daughters. While studies have not yet examined accuracy of self-reported HPV vaccine initiation, adults’ self-report of having received influenza vaccine is reasonably sensitive and specific.23,24
The generalizability of the findings to other populations is not yet known.
HPV vaccine research is important in groups at highest risk for cervical cancer, including African Americans and Latinas who have high cervical cancer mortality rates and people living in rural areas with diminished access to care. Our study’s findings lay the foundation for interventions designed to increase vaccine uptake in these and likely other populations. Furthermore, interventions will increasingly need to focus on demographic groups with low rates of vaccinating their daughters against HPV.