Characterizing U.S. mothers with high human papillomavirus vaccine intent yet unvaccinated adolescents

Abstract

HPV vaccination rates remain suboptimal in the United States. While the current literature focuses on expressly hesitant parents, few studies have examined parents with “high intent”, or those indicating they definitely will vaccinate and have had the opportunity but not yet vaccinated their adolescents. Our objective was to differentiate characteristics of mothers with high intent from those who already vaccinated their adolescents using various socioeconomic, previous vaccine decision-making, and healthcare provider relationship-related variables. English-speaking mothers or female guardians of adolescents ages 11-14 years living in low HPV vaccine uptake states within the U.S. in September 2018 were recruited from a national survey panel as part of a larger study. We assessed HPV vaccine status of their adolescents and categorized respondents into two categories: Already Vaccinated and High Intent. We assessed differences using a multivariable logistic regression model. Among 2,406 mothers, 18% reported high intent vs. 82% already having vaccinated. Mothers with high intent were more likely to identify as non-Hispanic White (p=0.01), to have a younger adolescent (p<0.001), and to report not receiving a provider HPV vaccination recommendation (p<0.001). Mothers who estimated that half/more (vs. less) of their child’s friends have received/will receive the vaccine had higher odds of already vaccinating (p<0.001). Our findings suggest that clinicians may be able to improve HPV vaccination uptake within their practices by giving repeated, high-quality recommendations to parents of children who are not yet vaccinated. Additionally, these findings indicate perceived social norms may play a large role in on-time vaccine uptake. Reassuring hesitant parents that most parents accept the vaccine may also improve uptake in clinical practice.

Introduction

Human papillomavirus (HPV) vaccination is effective in preventing 90% of cervical cancer,¹ reducing the risk of HPV infections that are a major cause of 70% of oropharyngeal cancers,² and preventing HPV infections associated with about 5% of all cancers worldwide.³ Evidence shows that effective immunization programs in the U.S. since 2006 for females and 2011 for males have reduced the incidence of cervical cancer for females,⁴ reduced HPV-associated oral infections among vaccinated young adults,⁵ and contributed to herd immunity against oral infections with high-risk HPV strains among the unvaccinated.⁶ Given the strong cancer prevention benefits, the Centers for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices (ACIP) recommends routine immunization with the HPV vaccine series for U.S. adolescents starting at ages 9-10 to protect against HPV-related cancers.^7,8 However, coverage rates among U.S. adolescents lag compared to all other routinely recommended adolescent vaccines.^7,9 In 2021, only 61.7% of 13–17 year-olds completed the series, with slightly more up-to-date girls (63.8%) than boys (59.8%).⁹ Additionally, the COVID-19 pandemic further exacerbated this deficit, with declining routine childhood immunization rates leading to over 150,000 missed HPV vaccine doses.^10,11

To achieve maximum cancer prevention benefits by increasing immunization coverage, interventionists and clinicians need a better understanding of why coverage lags compared to other adolescent vaccines. Several factors are associated with increased or decreased HPV vaccination uptake, including a healthcare provider (HCP) recommendation and parental hesitancy.^12–16 Specifically, a strong HCP recommendation is associated with series initiation and completion regardless of adolescent age or gender, highlighting the importance of HCPs in improving national HPV vaccination coverage.^17,18 Studies have found that hesitant parents with concerns are less likely to refuse or delay if they receive a strong HCP recommendation and are more likely to accept the vaccine at a subsequent visit if they do delay vaccination after receiving a strong HCP recommendation at the initial visit.¹⁹

While hesitant parents who expressly refuse or delay HPV vaccines have been extensively studied in terms of reasons for vaccine hesitancy and interventions to change their intent,¹³ less is known about parents who report no concerns or hesitancy, indicate intent to vaccinate, but have not yet vaccinated their age-eligible children despite having opportunities. This gap between vaccine willingness or intent and uptake has been documented globally, but it is unknown how these high intent parents differ from parents who have already vaccinated their children with regards to having received a HCP recommendation, the strength of that recommendation, their vaccination attitudes, social norms and beliefs, and sociodemographic characteristics. Studying these factors are important because they can indicate where best to intervene to nudge parents into accepting HPV vaccines. The Theory of Reasoned Action and Theory of Planned Behavior posit that intention is a central determinant of a behavior.²⁰ However, as these behaviorally hesitant parents show high intention without action, we believe is important to further probe their behavioral beliefs, normative beliefs, and control beliefs to ultimately better understand and link their intentions with action.²⁰ Therefore, the objective of our study was to examine self-reported differences in vaccination attitudes, social influences, and HCP relationships among a sample of mothers who indicated high intent to vaccinate but had not yet vaccinated vs. those who had already vaccinated their 11–14-year-old child against HPV.

Methods

Study Design and Recruitment

Using a cross-sectional study design, we sampled a subset of participants recruited from a larger randomized controlled trial conducted in September 2018. Participants consisted of mothers or female guardians (hereinafter “mothers”) of adolescents ages 11-14 years old who either already vaccinated their adolescent or had high intent to vaccinate. This age group of adolescents was chosen because at the time of study recruitment the ACIP recommendation’s considered vaccination at ages 11-12 to be “on-time” or routine, and if adolescents got vaccinated before they reached fifteen years of age, they would only need two doses.²¹ Therefore, we wanted to focus on the 11-14 years age group to ensure vaccination when it was most effective. Inclusion criteria were English-speaking mothers of adolescents ages 11-14 years living in low HPV vaccine uptake states. “Low uptake states” were defined as the 27 states with the lowest HPV vaccine series initiation rates (≥1 doses) for children 13–17 years of age, as reported by the 2017 National Immunization Survey-Teen (Appendix A)²² Further details about the recruitment process are provided in our previous work (Appendix A).^23,24 Our study was ruled exempt by the Indiana University’s Institutional Review Board. After completing informed consent, mothers answered a series of questions on a Qualtrics questionnaire. See Appendix B for the detailed questionnaire.

Outcome

Already Vaccinated.

We assessed the child’s HPV vaccine status by asking, “How many shots of the HPV vaccine has your child had? It’s also called the human papillomavirus vaccine, Gardasil, or Gardasil 9.” Responses included: None, 1 shot, 2 shots, and At least one shot but I don’t know how many. We categorized 1+ doses as “Already Vaccinated.”

High Intent.

Among mothers who reported that their child had received no doses of the HPV vaccine, we gave brief information about the adolescent immunization platform from the Centers for Disease Control and Prevention (CDC) (Appendix C). We then asked, “How likely are you to get your child the HPV vaccine sometime in the next 12 months?”:

1. “Definitely will”

2. “Not sure/I have questions or concerns.”

We categorized, “Definitely will as High Intent to vaccinate. Mothers who reported questions or concerns about the HPV vaccine were eligible for the clinical trial and excluded from the current study (Figure 1).

Figure 1. Study sample selection flow chart.

This diagram shows which patients from the larger randomized-controlled trial were included in these analyses. Participants who had not vaccinated their adolescents and did not have “high intent” to vaccinate were excluded from these analyses.

Exposures

Demographics.

Mothers reported their own and their child’s age, ethnicity, race, and insurance status. They self-reported their highest level of educational attainment, household income, household composition, and state of residence.

Reasons for Vaccination or High Intent.

Mothers could select multiple reasons why they already had (Already Vaccinated) or will vaccinate their child (High Intent) from the following: HCP recommendation (1), read or heard (2), belief in the effectiveness of vaccines and keep child up-to-date (3), protect my child from HPV and diseases it causes (4), and family members/friends’ recommendation (5).

We examined HCP recommendation (item 1) and family/friend recommendation separately (item 5). We created a composite variable summing positive responses items 2-4. Mothers who selected 0-1 of these three items were assigned a “Low” score for the Heard/Believe/Protect composite variable, while mothers who selected 2-3 of the items were assigned a “High” score.

Previous Vaccine History.

We assessed the child’s receipt of other vaccinations including influenza, tetanus (Td or Tdap), and meningococcal (MCV4/Menactra). We created a composite multilevel vaccine variable that indicated receipt status: (0) None of the recommended vaccines, (1) Tdap only, (2) Tdap and MCV4, or (3) Tdap, MCV4, and influenza. We also compared mothers who reported their child had received no other vaccines to those who reported their child had received 1+ vaccines.

HPV Vaccine Age.

Mothers were asked: How likely would you be to vaccinate at age 9 if provider recommended it? Responses were collected using a five-point Likert-type scale (Very Unlikely to Very Likely).

Perceived Social Norms.

We assessed mothers’ perceptions of social norms around HPV vaccine: How many of your child’s fiends do you think have received HPV vaccine, or may receive the vaccine in the next year? We compared mothers who estimated that most or all their child’s friends were vaccinated, to those who estimated that about half were, and to those who estimated that some or none of their child’s friends were vaccinated.

Adolescent Vaccine Confidence.

We used a validated short form of the Vaccine Confidence Scale using the four-item Benefits factor to assess general beliefs about vaccines (Appendix D).^25,26 Each item was rated on a five-point Likert-type scale from Strongly disagree (1) to Strongly agree (5). We averaged the composite score based on all measures, and mothers at or below the median were considered to have low vaccine confidence and those above the median were considered to have high vaccine confidence.

Relationship with HCP and Office Staff.

We asked mothers to rate their child’s HCP and office staff on trust, timeliness, helpfulness, remembering, and care on a 1-5 scale (1=Never, 2=Rarely, 3=Sometimes, 4=Often, 5=Always) using a series of nine items. In addition, we assessed the mother’s ease of access to their child’s HCP, including how frequently the mother needed to take off work to see the HCP and the length of time (minutes) to commute to the practice.

Provider Recommendation Quality.

Using a series of items regarding discussions about the HPV vaccine with the child’s provider, we created a composite variable indicating the provider’s recommendation quality like Gilkey, et. al. (None, Low, High) (Appendix B).^26,27 Mothers reported if they had ever received a HCP recommendation, if the recommendation was bundled with other vaccines, the strength of endorsement, if the recommendation included a cancer prevention message, and if the HCP recommended the child receive the vaccine at that visit. A “Low Quality Recommendation” was defined if mothers indicated “Yes” for none or one of the three: Strength of endorsement, cancer/prevention topics, recommended today, or if the HCP mentioned the teen should get the HPV vaccine. A “High Quality Recommendation” was defined if mothers indicated “Yes” for two or all three of the above. “No Recommendation” was defined if mothers indicated the child’s HCP did not discuss the HPV vaccine at a previous visit or if they did not answer the question. We also assessed the child’s age at which the HCP first discussed HPV vaccine.

Statistical Analysis

HCP and Staff Relationship Scale.

To assess the internal consistency of 1) HCP and office staff trust, timeliness, friendliness, and helpfulness and 2) HCP and office staff remembering and care (described in Exposures above), we conducted a principal factor analysis with oblique rotation to allow for correlation between factors to determine scale dimensionality.¹⁴ We fit and examined factor loadings for two-, three-, and all factor models. We also examined each item individually to determine if it loaded meaningfully on at least one factor, and discarded items with loadings of < 0.30 on all factors. Using this approach, we created composite scales for these two variable groups to assess associations with having already vaccinated.

Logistic Regression.

We modeled differences between High Intent and Already Vaccinated (outcome) groups using multivariable logistic regression model (α = 0.05). Variable selection was performed by determining bivariate associations using Pearson’s Chi² (χ²) tests between the outcome (HPV vaccination) with a variable selection threshold of p-value < 0.2 and performing stepwise backward elimination. All selected variables were checked for missingness (using a 5% maximum missing threshold) and collinearity (using a variance inflation factor threshold of less than 10).

Sensitivity Analyses

In a sensitivity analysis, we performed stratified multivariable logistic regression by child age at the survey date to assess for effect modification and found no evidence of significant effect modification by age (Appendix E). Separately, we restricted to mothers who reported their child’s HCPs had previously discussed HPV vaccine and compared differences between groups using χ² tests.

StataIC 14 and StataBE 17 were used for data analysis.

Results

Among 2,406 mothers, 437 (18.2%) indicated they had High Intent to get their 11–14-year-old child vaccinated with the HPV vaccine, and 1,969 (81.8%) indicated their child was Already Vaccinated (Table 1). High Intent mothers had younger children overall than Already Vaccinated mothers (41.9% of High Intent vs. 18.2% of Already Vaccinated had an 11-year-old child, p<0.001). Characteristics of the two groups can be viewed in Table 1.

Table 1.

Respondent demographic characteristics by HPV vaccination vs. intent status. (N = 2,406)

	Already Vaccinated	High Intent	Pearson’s χ2 p-value
Total	1,969	437
Child Age (years)			< 0.001*
11	359 (18.2%)	183 (41.9%)
12	488 (24.8%)	118 (27.0%)
13	580 (29.5%)	77 (17.6%)
14	542 (27.5%)	59 (13.5%)
Child Sex (assigned at birth)			0.520
Male	917 (46.6%)	211 (48.3%)
Female	1,052 (53.4%)	226 (51.7%)
Mother Age (years)			0.650
21-25	9 (0.5%)	0 (0.0%)
26-30	135 (6.9%)	28 (6.5%)
31-35	454 (23.2%)	101 (23.3%)
36-40	533 (27.2%)	121 (27.9%)
41-45	381 (19.5%)	82 (18.9%)
46-50	229 (11.7%)	52 (12.0%)
51-55	115 (5.9%)	22 (5.1%)
56-60	57 (2.9%)	12 (2.8%)
61-65	23 (1.2%)	7 (1.6%)
66-70	16 (0.8%)	8 (1.8%)
71-75	4 (0.2%)	0 (0.0%)
Highest Level of Education (mother)			0.250
Less than high school	51 (2.6%)	15 (3.4%)
High school	439 (22.4%)	82 (18.8%)
Some college or vocational training	809 (41.3%)	178 (40.8%)
Bachelor’s degree or higher	662 (33.8%)	161 (36.9%)
Ethnicity and Race (mother, self-reported)			0.010*
Non-Hispanic White	1,284 (65.2%)	320 (73.2%)
Non-Hispanic Black	237 (12.0%)	37 (8.5%)
Hispanic	252 (12.8%)	41 (9.4%)
Asian, Other, Multiple	196 (10.0%)	39 (8.9%)
Annual Household Income			0.044*
Under $25,000	369 (18.8%)	67 (15.4%)
$25,000 to $49,999	492 (25.1%)	115 (26.4%)
$50,000-$74,999	404 (20.6%)	113 (25.9%)
$75,000-$99,999	297 (15.2%)	52 (11.9%)
$100,000 or above	397 (20.3%)	89 (20.4%)
Health Insurance Status			0.048*
Yes	1,779 (90.4%)	408 (93.4%)
No	190 (9.6%)	29 (6.6%)

^*denotes a significant p-value (α = 0.05)

Vaccine Beliefs, Previous Behavior, and Decision-Making

Proportionately more High Intent mothers had high vaccine confidence than Already Vaccinated mothers (56% vs. 49%, p=0.01). Additionally, more of the Already Vaccinated mothers reported that their child had received all other adolescent immunizations: Tdap, MCV4, and influenza (37.5% vs. 28.4%, p<0.001). When asked if they would vaccinate at age nine if a provider recommended it, 66% (n=1,576) of all mothers indicated that they were somewhat or very likely to do so, and there was no statistically significant difference between Already Vaccinated vs. High Intent mothers (p=0.052) (Table 2).

Table 2.

Responses to how likely mothers would be to vaccinate their children at age 9 if a provider recommended it.

Responses	High Intent (N = 437)	Already Vaccinated (N = 1,969)	Overall (N = 2,406)
Very Unlikely	43 (10%)	134 (7%)	177 (7%)
Somewhat Unlikely	81 (19%)	311 (16%)	392 (16%)
Neither	50 (11%)	211 (11%)	261 (11%)
Somewhat Likely	131 (30%)	613 (31%)	744 (31%)
Very Likely	132 (30%)	700 (36%)	832 (35%)

Pearson’s χ² p-value = 0.052

Vaccination Intention Reasons and Social Norms

There were group differences in reasons for vaccinating or intending to vaccinate between Already Vaccinated vs. High Intent mothers (Table 3). More Already Vaccinated mothers selected “My provider recommended it” as a reason to vaccinate compared to the High Intent mothers (73.7% vs. 50.3%, p<0.001). There were differences in their main source of information when multiple sources were selected: a higher proportion of Already Vaccinated (65.4%) vs. High Intent mothers (50.4%) indicated healthcare professionals as their main source of information (p<0.001). Regarding social norms, when asked how many of their adolescent’s friends had received HPV vaccine, or may receive the vaccine in the next year, more Already Vaccinated mothers indicated most or all of their adolescents’ friends had received or would receive the vaccine than the High Intent mothers (32.5% vs. 15.1%, respectively; p<0.001).

Table 3.

Common reasons cited for vaccination or high intent by surveyed mothers.

Vaccination or High Intention Reasons	High Intent (N = 437)		Already Vaccinated (N = 1,969)		Pearson’s χ2 p-value
	Count	Percentage	Count	Percentage
My provider recommended it.	220	50.3%	1,452	73.7%	< 0.001*
I read or heard about it.	168	38.4%	556	28.2%	< 0.001*
I believe in the effectiveness of vaccines and want to keep my child up to date.	256	58.6%	822	41.7%	< 0.001*
I want to protect my child from HPV and diseases caused by HPV.	312	71.4%	1,077	54.7%	< 0.001*
Family members or friends recommended it.	45	10.3%	126	6.4%	0.004*
Other/None of the above	14	3.2%	49	2.5%	0.397

^*denotes a significant p-value (α = 0.05)

Healthcare Encounters and Provider Relationships

When asked about their child’s age when their HCP first discussed the HPV vaccine, Already Vaccinated mothers reported their children were younger than High Intent mothers did (Table 4, p<0.001). Almost half (48.1%) of High Intent mothers said their provider “did not discuss” the HPV vaccine compared to 26.1% of Already Vaccinated mothers (p<0.001).

Table 4.

Differences in child age between mothers by vaccination vs. intent status.

Child age when provider first discussed HPV vaccine	Already Vaccinated	High Intent	Pearson’s χ2 p-value
10 years old or younger	289 (14.7%)	67 (15.3%)	< 0.001*
11-12 years	801 (40.7%)	126 (28.8%)
13-14 years	173 (8.8%)	21 (8.8%)
Not sure/I don’t remember	193 (9.8%)	13 (3.0%)
Did not discuss	513 (26.1%)	210 (48.1%)

^*denotes a significant p-value (α = 0.05)

Regarding HCP and office staff trust, timeliness, friendliness, helpfulness, remembering, and care, most mothers (64.7%) reported that they often or always trust their primary HCP, nurses, and other HCPs, and there were no significant group differences between mothers (p=0.9). These findings were similar for timeliness, friendliness, and helpfulness of HCPs and staff. Furthermore, 1,447 (60.1%) mothers reported their HCP and office staff often or always cared about the health of their adolescent and remembered them at visits with no significant group differences between mothers (p=0.8). We also found no differences with regards to ease of access to their HCP for either needing to take time off work (p=0.5) or length of commute to the HCP (p=0.9).

Multivariable Logistic Regression Model

In the multivariable logistic regression model, mothers who reported their HCP recommended the vaccine (vs. did not select as an option) had 2.38 times higher odds of having already vaccinated [1.87-3.04] (Table 5). Their odds of having already vaccinated were 2.49 times higher (95% CI: 1.93-3.22) if they reported receiving a high-quality HCP recommendation vs. no recommendation. In addition, mothers who reported perceiving that most or all their child’s friends (vs. some or none) received or may receive the HPV vaccine within the next year had almost three times higher odds of already vaccinating (OR: 2.95 [2.17-4.01]). Children who did not have insurance had lower odds of having already been vaccinated (OR: 0.61 [0.38-0.96]) (Table 5). Finally, increasing child age was associated with higher odds of vaccinating, with mothers of 14-year-olds having 4.57 times the odds of already vaccinating (95% CI 3.24-6.46) as compared to mothers of 11-year-olds.

Table 5.

Results of the multivariable logistic regression model for already receiving HPV vaccination (n = 2,406).

Variables	Adjusted Odds Ratio (aOR)	95% Confidence Interval [aORs]		P-value
No Health Insurance	0.618	0.394	0.968	0.036*
Child Age (Reference: 11 years old)
12 years old	1.986	1.481	2.664	< 0.001*
13 years old	3.707	2.688	5.114	< 0.001*
14 years old	4.574	3.237	6.463	< 0.001*
Mother Race + Ethnicity (Reference: Non-Hispanic White)
NH Black	1.312	0.876	1.966	0.188
Hispanic	1.559	1.054	2.304	0.026*
Asian, Other, Multiple	1.186	0.792	1.776	0.408
How many of your child’s friends do you think have received HPV vaccine, or may receive the vaccine in the next year? (Reference: None/Some)
About half	2.194	1.612	2.986	< 0.001*
Most/All	2.947	2.168	4.005	< 0.001*
Vaccine Confidence Scale (Reference:Low (at or below median VCS)) Above Median VCS	0.758	0.597	0.963	0.024*
Received other vaccines (Reference: Received none)
One or more	1.337	1.052	1.699	0.017*
Provider Recommendation Quality (Reference: No recommendation)
Low Quality Recommendation	1.175	0.823	1.677	0.374
High Quality Recommendation	2.491	1.925	3.224	< 0.001*
Reasons for Intent or Already Vaccinated
My provider recommended it.	2.387	1.874	3.041	< 0.001*
Heard, Belief, and Protect Composite (Reference: Low Score) High Score 1	0. 466	0.364	0.595	< 0.001*
Family members or friends recommended it.	0.578	0.384	0.869	0.008*

^*Denotes significant p-value (α = 0.05)

In sensitivity analyses, controlling for adolescent age, the odds of mothers already vaccinating their adolescent were more than three times as high when a HCP had discussed the HPV vaccine at a previous visit (OR: 3.27 [2.54-4.21]; p<0.001) (Appendix E). Furthermore, among the subset of mothers whose provider had previously discussed the HPV vaccine, a significantly higher proportion of Already Vaccinated mothers reported receiving a high-quality recommendation compared to High Intent mothers (84.3% vs 72.5%, respectively, p<0.001).

Discussion

In this survey of mothers who highly intend vs. already vaccinated their child against HPV, we assessed why some parents choose to delay despite expressing high intent to get the HPV vaccine for their children and provide areas for intervention focus. Our findings reiterated the critical role of the HCP recommendation in vaccination uptake. Our results are consistent with prior literature, as the odds of already being vaccinated were over twice as high when mothers reported a HCP recommendation as the reason for vaccinating their child. ^14,18 Although the role of the HCP recommendation has been well-documented,²⁸ evidence suggests that the type and frequency with which parents receive HCP recommendations continues to vary in the U S. A national survey of physicians found that although they mostly self-reported “strongly” recommending the HPV vaccine, the strength of their recommendation was higher for older adolescents and uptake varied with the type of the recommendation, with a presumptive recommendation style being associated with the highest uptake.²⁹ With regards to HCP recommendation quality, our results provide more nuanced insights. Although mothers who rated recommendation quality as “Low” vs. no recommendation were still trending toward more likely to be already vaccinated, our sensitivity analyses showed a significant gap between the Already Vaccinated vs. High Intent mothers on the recommendation quality, with more already vaccinated mothers receiving a high-quality recommendation. The importance of this provider recommendation continues to be critical today because although the COVID-19 pandemic led to a decline in childhood vaccinations,^10,11 it also brought more public attention to vaccines. Subsequently, providers are better educated about counseling patients to get vaccines, and more resources are available for them to do so. Previous work underscores that providers remain the primary trusted source of vaccine information,^30,31 and this trust can be leverage to make strong HPV vaccine recommendations as well.

Furthermore, mothers in the study indicated that they were likely to vaccinate at age nine if they received a provider recommendation. Although CDC’s ACIP currently recommends that the HPV vaccine can be given starting at nine years of age, their routine recommendation states starting the series at age 11-12 years.²¹ However, a systematic review of factors influencing completion of multi-dose vaccine schedules in adolescents specifically found that adherence to multiple doses is higher if the series is started in early adolescence, as early as age nine compared to later in adolescence.³² In addition, the American Cancer Society, the American Academy of Pediatrics, and the National HPV Vaccination Roundtable all support starting the HPV series at nine years of age for numerous reasons including that starting at age nine provides more time for series completion, increases vaccination rates, and consequently, increases the numbers of cancers prevented.³³ Given that our results show that this would be highly acceptable to mothers, this further highlights the clinical importance for HCPs to provide a recommendation for HPV vaccination to all eligible patients at the age nine and ten well visits, to improve the strength and quality of that recommendation, and use every future opportunity to reinforce the recommendation. This finding also supports national organizations like CDC’s ACIP more strongly recommending HPV vaccine series initiation at age nine.

Our analyses also revealed important differences between these two groups of mothers that may be useful for tailored interventions and clinical programs. Mothers with high intent had younger children and a larger proportion identified as non-Hispanic White. In addition, their children were less likely to be insured. These findings are consistent with existing literature: mothers with younger children are more likely to be high intent as they will have had fewer opportunities for their child to receive for the HPV vaccine after becoming age-eligible.^17,34 Previous vaccine behaviors, such as vaccinating against Tdap, MCV4, and influenza, were also associated with vaccinating against HPV, potentially indicating that high intent mothers are not only behaviorally hesitant with HPV vaccine, but may have hesitancy and delay extending to other vaccines. More research is needed to determine if these high intent mothers are more likely to be covertly hesitant around HPV vaccine, specifically, and vaccines in general.

Our findings suggest that social norms, specifically mothers’ perceptions of how many of the adolescents’ friends are vaccinated against HPV, play a role in the decision to vaccinate. Mothers who perceived that more of their child’s friends were or would be vaccinated had higher odds of having vaccinated themselves. Previous studies show that parents who ask for opinions from trustworthy sources beyond providers, such as family and friends, as a way of assessing social acceptance are more likely to increase intent to vaccinate their children.³⁵ These findings suggests that people ranging from close family to peers influence mothers’ vaccine acceptance. The upsurge of misinformation on social media regarding vaccination in recent years will need to be combatted to decrease mothers’ exposure to vaccine myths in their social networks.^36–38 Additionally, mother-child communication about sexual health-related topics is associated with HPV-series initiation; therefore, emphasis on social norms may be critical to vaccine decision-making.^39,40 Previous findings that parental beliefs about the social acceptability of vaccination has been associated with intent to vaccinate, as confirmed by our results, also supports the importance of social norms, and suggests that parents align themselves with the expectations of their peer groups.^41,42

We also found insurance status to be an indicator of vaccine delay. Mothers who reported their child did not have health insurance had much lower odds of already vaccinating. Given that HPV vaccines are fully covered for both private and public insurance options under the Affordable Care Act,⁴³ this may relate to other socioeconomic factors that impact access. Future policy work focused on boosting self-efficacy in accessing vaccination through efforts that address structural barriers to HPV vaccination such as lack of insurance and subsequent cost may help to reduce delay among parents with high intent to vaccinate and improve equity in HPV vaccine uptake. If not addressed, innovations to improve provider recommendations may inadvertently drive greater disproportionality in vaccine uptake, since populations that are uninsured or underinsured are unlikely to vaccinate regardless of the strength and quality of a HCP recommendation. These disparities could be further exacerbated in the context of the COVID-19 pandemic, where pediatric and adolescent routine vaccination up-to-date rates significantly declined compared to pre-2020 levels.^10,11

Strengths and Limitations

Our study has several strengths and limitations. One limitation of our study is that over 80% of mothers had already vaccinated their adolescents against HPV. Thus, there is a relatively small proportion of mothers who delayed HPV vaccination while still indicating high intent to vaccinate. While the number of high intent mother was proportionately small, we believe that this sample size allowed for adequate representation of states with low HPV vaccine uptake for hypothesis generation for future interventions. This study also did not link high intent with reasons for delay or eventual vaccine uptake. Our study is strengthened by its focus on mothers in states with lower HPV vaccine uptake, and its focus on an understudied population of mothers who express high intent to vaccinate but delay.

Conclusion

This novel research provides insight into differences between mothers who have already vaccinated their children against HPV versus behaviorally hesitant mothers who intend to vaccinate but have delayed, a previously understudied comparison. We found that social norms, such as the perception of only some of their adolescent’s friends are vaccinated, may contribute to parental delay among mothers with high intent to vaccinate. Healthcare provider recommendations remain crucial to vaccine acceptance. Furthermore, lack of insurance is a key individual-level barrier to vaccination which needs to be addressed when planning interventions to increase uptake to prevent exacerbation of inequities, particularly as the Affordable Care Act assures access to all recommended childhood vaccines regardless of insurance status. Future studies should follow up with mothers with high intent to link their intentions with vaccine uptake and plan interventions around maternal concerns. Understanding how vaccination beliefs, social norms, and provider relationships can link intention to action is critical now in our cancer prevention efforts to increase low up-to-date rates due to the COVID-19 pandemic.

Highlights.

• The strength and quality of a provider HPV vaccine recommendation matters for vaccine acceptance.

• Providers should give mothers a strong HPV vaccine recommendation starting at the age 9 well visit.

• Social norms (child’s friends being vaccinated) influence maternal HPV vaccine decisions.

• Lack of health insurance for their child is a barrier for maternal HPV vaccine acceptance.

Abbreviations

HPV

Human papillomavirus

HCP

Healthcare providers

CDC

Centers for Disease Control and Prevention

Td

Tetanus toxoid

Tdap

Tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis

MCV4

Meningococcal conjugate vaccine

Appendix A. Detailed trial recruitment information.

Data were collected as part of a larger, randomized controlled trial (Clinical Trial Registration: NCT03628885) in September 2018. Participants were recruited from a national survey panel maintained by Survey Sampling International (SSI; now named Dynata), and email invitations for the online Qualtrics survey were sent to members of SSI’s U.S.-based panel who met inclusion criteria. Previous research has shown that mothers are the major health-care decision-makers for their children, especially regarding sex-related conversations and decisions.^34,44,45 This survey focused on mothers/female guardians to maximize the number of participants who primarily or jointly were the decision-maker for their child’s immunizations. States that participants were recruited from included: Alabama, Alaska, Arizona, Arkansas, Florida, Georgia, Idaho, Illinois, Indiana, Kansas, Kentucky, Mississippi, Missouri, Montana, Nevada, New Jersey, New Mexico, North Carolina, Ohio, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, West Virginia, and Wyoming.

Appendix B.

Questionnaire administered to all participants.

Item	Response options
How many 11-to 14-year-old children do you have?	1, 2, 3, 4, 5, 6, 7, 10 or more
According to the answer you provided, you have [INSERT] children ages 11 to 14. Please think about the one who most recently had a birthday when you answer the questions in this survey. According to the answer you provided, you have one child ages 11 to 14. Please think about this child when you answer the questions in this survey.
To help the survey work better, please give a name that you would like us to use for your child. (This information is only for the survey. You can give initials or a nickname —whatever you will remember.)
Is [TEEN] …	1 = Male 2 = Female 3= Other (born female, now male) (Note missing n=12)
You indicated “other” when asked about the gender of your child, so we’d like to just gather a little more information. First, what was [TEEN]’s biological sex at birth?	1=Female 2 = Male
Second, what is the preferred gender pronoun for [TEEN]?	1 = “He” 2 = “She”
How old is [TEEN]?	1 = 11 years old 2 = 12 years old 3 = 13 years old 4 = 14 years old 5=10 years or younger 6=15 years or older
In your household, who is the main person who makes decisions about [TEEN]’s health care?	1 = You 2 = Your spouse or partner 3 = You and your spouse/partner share equally in the decision-making 4=Someone else
Now we would like to ask vour oninion about vaccines given to nreteens and teenagers under the age of 18. Please tell us how much you disagree or agree with the following statements.
Vaccines are necessary to protect the health of teenagers.	1 = Strongly disagree 2 = Somewhat disagree 3 = Neither disagree or agree 4 = Somewhat agree 5 = Strongly agree
Vaccines do a good job in preventing the diseases they are intended to prevent.	1 = Strongly disagree 2 = Somewhat disagree 3 = Neither disagree or agree 4 = Somewhat agree 5 = Strongly agree
Vaccines are safe.	1 = Strongly disagree 2 = Somewhat disagree 3 = Neither disagree or agree 4 = Somewhat agree 5 = Strongly agree
If I do not vaccinate my teenager, he or she may get a disease such as meningitis.	1 = Strongly disagree 2 = Somewhat disagree 3 = Neither disagree or agree 4 = Somewhat agree 5 = Strongly agree
Now we will ask about [TEEN]’s health care, including vaccines [HE/SHE] may have gotten.
Did [TEEN] receive the flu vaccine this most reason flu season?	1 = Yes 2 = No 3 = Not sure/Don’t know
Has [TEEN] ever received a tetanus booster shot? There are two main types of tetanus booster shots: Td and Tdap.	1 = Yes 2 = No 3 = Not sure/Don’t know
Has [TEEN] ever received a meningitis (meningococcal) vaccine? It’s also called Menactra.	1 = Yes 2 = No 3 = Not sure/Don’t know
How many shots of the HPV vaccine has [TEEN] had? It’s also called the human papillomavirus vaccine, Gardasil, or Gardasil 9.	1 = None 1 = 1 shot 2 = 2 shots 3 = At least one shot but I don’t know how many
Item	Response options
Now we’d like to ask you some questions about your perspectives on the HPV vaccine specifically. How likely are you to get [TEEN] the HPV vaccine sometime in the next 12 months? Would you say you …	1 = Definitely will 2 = Not sure / I have questions or concerns
Please select all reasons [TEEN] mav not receive HPV vaccine in the next 12 months:	1 = I need more information about the vaccine 2 = My child is too young 3 = I am concerned about the long-tenn effects of the vaccine 4 = My child’s health care provider did not recomnend it or said my child could wait 5 = The vaccine is not required for school 6 = Other / none of the above
Please select the MAIN reason [TEEN] mav not receive HPV vaccine in the next 12 months:	1 = I need more information about the vaccine 2 = My child is too young 3 = I am concerned about the long-tenn effects of the vaccine 4 = My child’s health care provider did not recoimnend it or said my child could wait 5 = The vaccine is not required for school 6 = Other / none of the above (please explain):
Item	Response options
The next questions are about [TEEN]’s health care.
Please select ALL reasons [TEEN] will likely receive the HPV vaccine in the next 12 months. OR Please select ALL reasons [TEEN] received the HPV vaccine.	1 = My provider recoimnended it 2 = I read or heard about it 3 = I believe in the effectiveness of vaccines and want to keep my child up to date 4 = I want to protect my child from HPV and diseases caused by HPV 5 = Family members or friends recoimnended it 6 = Other/None of the above (please explain):
Where have you gotten information about HPV vaccine? Select all that apply.	1=Social media 2=Google search 3=Television 4=Family/Friends 5=School or other parents 6=Healthcare professionals 7=Other (Fill in blank ____)
Of the sources of information you selected, what would you say has been your main source of information? Select one.	[Populate from above]
Other than a healthcare provider, please select all people you’ve had conversations with about the HPV vaccine [SELECT ALL THAT APPLY]	1 = Family members 2 = Friends 3 = Other parents 4 = Classmates/ friends of [TEEN] 5 = Co-workers 6 = Social network contacts 7 = Other [Fill in blank ___] 8 = None of the above
Other than a healthcare provider, please select the person who has had the most influence in your decision to get the HPV vaccine for [TEEN] [Response options carried forward from those selected in D60]	1 = Family members 2 = Friends 3 = Other parents 4 = Classmates/ friends of [TEEN] 5= Co-workers 6 = Social network contacts 7 = Other [Fill in blank ___] 8 =None of the above
How many of [TEEN]’s friends do you think have received HPV vaccine, or may receive the vaccine in the next year? Give your best estimate.	1=None 2=Some 3=About half 4=Most 5= All
Now we’d like to learn a little more about [TEEN]’s primary care provider (doctor, nurse practitioner, or physician assistant), the clinic, and the clinic staff.
[TEEN]’s providers office uses an computer charting system (electronic medical record).	1=Yes 2=No 3=Not sure
[TEEN]’s provider’s office provides appointment reminders	1= Yes 2=No
How are the appointment reminders given? Check all that apply	1 = Phone 2 = Email 3 = Text message 4 =Social Media 5 = Online Patient portal 6 = Appointment reminder card 7 = Postcard or mailed letter 8 = Other (Please explain):
The next questions are about [TEEN]’s healthcare provider and their office staff
I trust [TEEN]’s primary healthcare provider (doctor, nurse practitioner, or physician assistant).	1 = Never 2 = Rarely 3 = Sometimes 4 = Often 5 = Always
I trust the nurses and other providers who work alongside [TEEN]’s primary provider.	1 = Never 2 = Rarely 3 = Sometimes 4 = Often 5 = Always
[TEEN]’s healthcare provider is on time to the appointment	1 = Never 2 = Rarely 3 = Sometimes 4 = Often 5 = Always
The office staff are friendly and helpful.	1 = Never 2 = Rarely 3 = Sometimes 4 = Often 5 = Always
When I call the [TEEN]’s healthcare provider’s office, I get the help I need.	1 = Never 2 = Rarely 3 = Sometimes 4 = Often 5 = Always
Continue to think about [TEEN]’s healthcare provider and the office staff as you answer this next set of questions
[TEEN]’s healthcare provider remembers [him/her] at each visit.	1 = Never 2 = Rarely 3 = Sometimes 4 = Often 5 = Always
[TEEN]’s provider cares about [him/her] and wants what is best for [his/her] health.	1 = Never 2 = Rarely 3 = Sometimes 4 = Often 5 = Always
The staff at [TEEN]’s healthcare provider’s office remembers [him/her] at each visit.	1 = Never 2 = Rarely 3 = Sometimes 4 = Often 5 = Always
The staff at [TEEN]’s provider’s office cares about [him/her] and wants what is best for [his/her] health.	1 = Never 2 = Rarely 3 = Sometimes 4 = Often 5 = Always
For the next questions, continue to think about [TEEN]’s primary healthcare provider.
Did [TEEN]’s provider discuss HPV vaccine with you at a previous visit?	1 = Yes 2 = No 3 = Not sure/ don’t remember
At the first visit [TEEN]’s healthcare provider brought up HPV vaccine, about how old was [TEEN]? [DISPLAY ONLY IF D200=1]	1 = 10 years old or younger 2 = 11 years old 3 = 12 years old 4 = 13 years old 5 = 14 years old 6 = Not sure/ don’t remember
Did the provider discuss HPV vaccine along with other shots [TEEN] was due for, or did he/she discuss HPV vaccine separately? [DISPLAY ONLY IF D200=1 AND A160 >1]	1 = Discussed with other shots 2 = Discussed separately from other shots 3 = [TEEN] was not due for other shots 4 =Not sure/don’t remember
[IF A160 > 0 then show, otherwise skip] Where did [TEEN] receive [his/her] first HPV shot?	1 = Provider’s office 2 = Emergency room 3 = Health Department 4 = Elementary/Middle/High school 5 = Pharmacy or Drag store 6 = Other clinic or health center (please explain): 7 = Other/none of the above (please explain):
Did [TEEN] receive any of the following vaccines at the same visit as the HPV shot? Select all that apply	1 = Tetanus booster 2 = Meningitis vaccine 3 = Flu shot 4 = None of these 5 = Not sure
How important did the provider say the HPV vaccine was for [TEEN]?	1 = Not important 2 = Somewhat important 3 = Very important 4 = Did not discuss
What did the provider say the HPV vaccine could prevent? Select all that apply.	1 = HPV infection 2=Cervical cancer 3 = Other cancers 4 = Genital warts 5 = None of these 6 = Not sure/ don’t remember
Did the provider tell you [TEEN] should get the HPV vaccine?	1 = No 2 = Yes
When did the provider tell you [TEEN] should get the HPV vaccine?	1 = At the visit that is was first discussed 2 = At a later visit 3 = The provider gave me a choice about when to get it 4 = The provider didn’t say when to get it
Did the provider give you the opportunity to ask questions about the HPV vaccine?	1 = Yes 2 = No 3=Not sure/don’t remember
Did the provider give you the opportunity to ask questions about all the shots your child was receiving at that visit?	1 = Yes 2 = No 3=Not sure/don’t remember
How satisfied were you with the way [TEEN]’s primary healthcare provider answered your questions?	1 = Very unsatisfied 2 = Somewhat unsatisfied 3 = Neither satisfied nor dissatisfied 4 = Somewhat satisfied 5 = Very satisfied 6 = I didn’t ask any questions
HPV vaccine is approved for children ages 9 and older. If [TEEN]’s primary healthcare provider had recoimnended that your child get the first HPV shot at age 9, how likely would you have been to follow this recomnendation?	1 = Very unlikely 2 = Somewhat unlikely 3 = Neither 4 = Somewhat likely 5 = Very likely
How likely is it that [TEEN] will receive another HPV shot in the next 12 months? Would you say …	1 = Very unlikely 2 = Somewhat unlikely 3= Neither 4 = Somewhat likely 5 = Very likely
Item	Response options
The last set of questions on this survey will help us understand more about [TEEN]’s general background and experiences in the healthcare system.
Did [TEEN] have an 11-12 year old physical exam or general check-up?	1 = Yes 2 = No 3 = I don’t know / not sure
How old was [TEEN] at [his/her] last physical exam or general check-up? Please do not include visits for medical treatment or illnesses.	1 = 7 years or younger 2 = 8 years old 3 = 9 years old 4 = 10 years old 5 = 11 years old 6 = 12 years old 7 = 13 years old 8 = 14 years old
During the past 12 months, how many times has [TEEN] seen a doctor or other health care professional at a provider’s office, a clinic, or some other place? Do not include times [TEEN] was hospitalized overnight, visits to hospital emergency rooms, home visits, dental visits or phone calls with the clinic staff.	1 = None 2 = 1 3 = 2-3 4 = 4-5 5 = 5+
For the following statement, indicate how frequently this happens: I must take time off work to take [TEEN] to the doctor or healthcare provider.	1 = Never 2 = Rarely 3 = Sometimes 4 = Often 5 = Always
How long is the commute to [TEEN]’s healthcare provider’s office?	1 = Less than 10 minutes 2= Between 10-30 minutes 3 = Between 30-60 minutes 4 = More than an hour
[TEEN] dreads going to the doctor or healthcare provider.	1 = Never 2 = Rarely 3 = Sometimes 4 = Often 5 = Always
[TEEN] dreads getting shots.	1 = Never 2 = Rarely 3 = Sometimes 4 = Often 5 = Always
Is [TEEN] Hispanic or Latino/Latina?	1 = No 2 = Yes
What is [TEEN]’s race? (Check all that apply.)	1 = White 2 = Black or African American 3 = Asian 4 = Native Hawaiian or Pacific Islander 5 = American Indian or Alaska Native 6 = Other, please specify: [open ended]
Does [TEEN] have any form of health insurance? This could include private insurance or government plans like Medicaid.	1=No 2=Yes
Do you have other children who have received any number of doses (1,2, or 3) the HPV vaccine?	1=Yes 2=No 3=Not applicable
How old was your other child/children when he/she received his/her first shot of HPV vaccine? If you have more than one child who has received the vaccine, please think of the child with the most recent birthday. [Display if E150=1 otherwise skip]	1=Ages 9-10 2=Ages 11-12 3=Ages 13-14 4=Ages 14-15 5=Ages 16-17 6=Ages 18 or older
The next few auestions are about your background.
What is the highest level of formal education you completed?	1 = Less than high school 2 = High school 3 = Some college or vocational training 4 = Bachelor’s degree or higher
How old are you?	1=21-25 years old 2=25-30 3=31-35 4=36-40 5=41-45 6=46-50 7=51-55 8=56-60 9=61-65 10=66-70 11=70-75 12=76 or older
Have you received HPV vaccine?	1 = Yes 2 = No
How many doses of the HPV vaccine have you received? [DISPLAY if E130=1 otherwise skip]	1 = 1 2 =2 3 = 3 or more 4 = At least one shot, but I don’t know how many
What is your gender?	1 = Male 2 = Female 3 = Other
What is your annual household income?	1 = Under $25,000 2 = $25,000 to $49,999 3 = $50,000 to $74,999 3 = $75,000 to $99,999 4 = $100,000 or above
How many adults ages 18 and older live in your household?	1 = 1 2 = 2 3 = 3 or more
How many children under age 18 live in your household?	1 = 1 2 = 2 3 = 3 4 = 4 5 = 5 6 = 6 or more
What is your state of residence?	1=Alabama 2=Alaska 3=Arizona 4=Arkansas 5=California 6=Colorado 7=Connecticut 8=Delaware 9=District of Columbia 10=Florida 11=Georgia 12=Hawaii 13=Idaho 14=Illinois 15=Indiana 16=Iowa 17=Kansas 18=Kentucky 19=Louisiana 20=Maine 21=Maryland 22=Massachusetts 23=Michigan 24=Minnesota 25=Mississippi 26=Missouri 27=Montana 28=Nebraska 29=Nevada 30=New Hampshire 31=New Jersey 32=New Mexico 33=New York 34=North Carolina 35=North Dakota 36=Ohio 37=Oklahoma 38=Oregon 39=Pennsylvania 40=Puerto Rico 41=Rhode Island 42=South Carolina 43=South Dakota 44=Tennessee 45=Texas 46=Utah 47=Vermont 48=Virginia 49=Washington 50=West Virginia 51=Wisconsin 52=Wyoming 53=I do not reside in the United States
Are you Hispanic or Latino[a]?	1 = No 2 = Yes
What is your race? (check all that apply)	1 = White 2 = Black or African American 3 = Asian 4 = Native Hawaiian or Pacific Islander 5 = American Indian or Alaska Native 6 = Other, please specify: [open ended]

Appendix C. Informational Prompt that mothers of unvaccinated children received.

There are four vaccines recommended for preteens:

• Meningococcal Conjugate Vaccine

  Protects against some of the bacteria that can cause meningitis.

• HPV Vaccine

  Protects against HPV infection and HPV cancers.

• Tdap Vaccine

  Protects against tetanus, diphtheria and pertussis (whopping cough).

• Flu Vaccine

  Protects against the most common strains of flu each year.

Preteens, like people of any age, may experience mild side effects from vaccination. The most common side effects are redness and soreness where they get the shot in the arm. Some people, including preteens, might faint after getting a shot. Staying seated and being observed for a few minutes after receiving a shot can help.

The vaccines recommended for preteens can prevent very serious diseases including meningitis and HPV cancers. You can help protect your preteen from these preventable diseases by getting the vaccines recommended for them when they are 11 or 12 years old.

We recommend you talk to your child’s health care provider for more information about these vaccines.

Source: CDC, 2017

Appendix D. Vaccine Confidence Scale validated 4-items Benefits factor.

Vaccine Confidence Scale Items – Benefits Factor (Gilkey et. al., 2014, 2016)

1. Vaccines are necessary to protect the health of teenagers. (Benefit construct: Protect)

2. Vaccines do a good job in preventing the diseases they are intended to prevent. (Benefit construct: Prevent)

3. Vaccines are safe. (Benefit construct: Safe)

4. If I do not vaccinate my teenager, he or she may get a disease such as meningitis. (Benefit construct: Disease)

Appendix E.

Adjusted Multivariable Logistic Regression Model Stratified by Child Age.

Variables	11 years old				12 years old				13 years old				14 years old
	aOR	p-value	[95% CI]	aOR	p-value	[95% CI]	aOR	p-value	[95% CI]	aOR	p-value	[95% CI]
No Health Insurance	0.301	0.007*	0.127	0.715	1.301	0.470	0.637	2.657	0.76	0.597	0.275	2.102	0.295	0.108	0.067	1.308
Mother Race + Ethnicity (Reference: Non-Hispanic White)
NH Black	0.887	0.711	0.469	1.675	1.313	0.518	0.575	3.001	2.168	0.165	0.727	6.462	1.877	0.267	0.617	5.711
Hispanic	1.211	0.542	0.655	2.241	1.996	0.058	0.978	4.075	1.465	0.454	0.539	3.981	2.494	0.153	0.711	8.745
Asian, Other, Multiple	1.171	0.685	0.546	2.508	1.96	0.115	0.849	4.528	0.804	0.603	0.354	1.828	0.937	0.883	0.393	2.23
How many of your child’s friends do you think have received HPV vaccine, or may receive the vaccine in the next year? (Reference: None/Some)
About half	1.773	0.035*	1.043	3.014	2.531	0.002*	1.407	4.553	2.014	0.034*	1.055	3.842	4.025	0.006*	1.502	10.785
Most/All	2.505	<0.001*	1.521	4.126	2.994	<0.001*	1.663	5.392	5.747	<0.001*	2.361	13.99	2.332	0.021*	1.136	4.79
Vaccine Confidence Scale (Reference: Low (at or below median VCS)) Above Median VCS	0.699	0.096	0.458	1.065	0.917	0.705	0.584	1.439	0.613	0.078	0.355	1.057	0.798	0.454	0.443	1.44
Received other vaccines (Reference: Received none)
One or more	1.533	0.043*	1.014	2.318	1.155	0.541	0.728	1.834	0.967	0.905	0.555	1.684	1.868	0.037*	1.039	3.361
Provider Recommendation Quality (Reference: No recommendation)
Low Quality Recommendation	1.569	0.176	0.816	3.017	1.091	0.804	0.548	2.174	0.984	0.966	0.466	2.076	1.028	0.946	0.455	2.323
High Quality Recommendation	2.307	<0.001*	1.48	3.597	2.188	0.002*	1.337	3.582	3.821	<0.001*	2.114	6.907	2.376	0.009*	1.238	4.558
Reasons for Intent or Already Vaccinated
My provider recommended it.	2.405	<0.001*	1.582	3.657	2.925	<0.001*	1.818	4.708	1.659	0.071	0.958	2.873	2.742	0.001*	1.526	4.926
Heard, Belief, and Protect Composite (Reference: Low Score) High Score 1	0.468	<0.001*	0.306	0.714	0.302	<0.001*	0.186	0.491	0.451	0.004*	0.262	0.776	0.766	0.398	0.412	1.423
Family members or friends recommended it.	0.263	<0.001*	0.124	0.557	0.805	0.585	0.369	1.754	0.685	0.454	0.255	1.844	1.118	0.851	0.35	3.567

aOR = adjusted odds ratio

CI = confidence interval

^*Denotes significant p-value (α = 0.05)