Parents' confidence in recommended childhood vaccinations: Extending the assessment, expanding the context

ABSTRACT

There has been significant and growing interest in vaccine hesitancy and confidence in the United States as well as across the globe. While studies have used confidence measures, few studies have provided in-depth assessments and no studies have assessed parents' confidence in vaccines in relationship to other frequently recommended health-related products for young children. This study used a nationally representative sample of 1000 US parents to identify confidence levels for recommended vaccinations, antibiotics, over-the-counter (OTC) medicines, and vitamins for children. The analyses examined associations between confidence ratings, vaccination behaviors and intentions, and trust in healthcare provider, along with associations between confidence ratings and use of the other health-related products. Parents' confidence in vaccines was relatively high and high relative to antibiotics, OTC medicines and vitamins. For all 4 health-related products examined, past product experience and knowledge of bad or adverse outcomes negatively impacted parents' confidence levels. Confidence levels were associated with both trust in advice from their child's healthcare provider and acceptance of healthcare provider recommendations. Parents in some groups, such as those with lower income and education levels, were more likely to have less confidence not just in vaccines, but also in antibiotics and OTC medicines for children. Overall, the findings extend understanding of vaccine confidence, including by placing it into a broader context.

KEYWORDS:

• parental confidence
• vaccine acceptance
• vaccine beliefs and attitudes
• vaccine communication
• Vaccine confidence
• vaccine hesitancy

Introduction

Coverage rates in the United States for recommended childhood vaccinations were at or near historical highs according to the 2014 National Immunization Survey,¹ but recent studies suggest more parents are choosing to delay or decline recommended vaccines or utilize non-recommended vaccination schedules.^2-6 One in 5 US pediatricians and family physicians surveyed by Kempe et al. reported at least 10% of parents made a request to spread out vaccines, with 23% of providers reporting this was an increase from the previous year.² Evidence also indicates an increase in non-medical vaccine exemptions,^7-8 that some states and communities have relatively high rates of non-medical exemptions^4-5,7,9 and that lower vaccination rates foster vaccine preventable disease outbreaks.^10-11

While economic and structural factors affect receipt of recommended childhood immunizations,^12-14 vaccine-related confidence is believed to play a significant and perhaps growing role in parents' vaccine decision making and behavior.^15-19 In 2013, such concern prompted the Assistant Secretary for Health to ask the National Vaccine Advisory Committee (NVAC) to assess how confidence affects childhood vaccination in the US²⁰ Also in 2013, the World Health Organization's (WHO) Strategic Advisory Group of Experts (SAGE) Working Group on Vaccine Hesitancy identified confidence as one of 3 domains related to vaccine hesitancy (with convenience and complacency being the other 2).^21-22 Vaccine hesitancy was recognized as occurring when an individual or parent delays or refuses to accept a recommended vaccine that is otherwise accessible and available.²² Both the SAGE and NVAC working groups conceptualized confidence in terms of trust, including how much people trust the recommended vaccine, the providers responsible for administering it, and/or the entities involved in vaccine licensure and vaccination recommendations.^20-21 While trust is an important component of confidence, published studies to date that have directly assessed confidence have generally employed broader measures (e.g., “How confident are you in the safety of routine childhood vaccines?”) that can encompass concern (or lack thereof) and/or faith (e.g., that one will benefit and/or experience no harm from a vaccine) as well as trust.^23-26

The recognition of confidence as an important or influential concept extends beyond these recent reports. Salmon et al.²⁷ noted that parental acceptance of vaccines “requires confidence,” while Gilkey et al.²⁸ stated “parents' confidence in vaccines is critical to the success of national immunization programs.” More broadly, it has been long recognized that trust often plays a central role in medical decision making, with an individual or patients' degree of trust affecting willingness to seek care, adherence to treatment recommendations, and acceptance of recommended treatment.^29-30 In the cases of vaccines and vaccination, McCauley et al.²⁴ found that among parents who indicated they followed vaccine recommendations, 63.1% reported being “very confident” and 35.5% reported being “somewhat” confident in the safety of childhood vaccines, while among parents not following vaccine recommendations, 25.8% reported being “very confident,” 51.0% reported being “somewhat” confident, and 14.2% were “not very confident.” More recently, Weiner et al.'s²³ survey of 200 first-time expectant mothers who were in their second or third trimester of pregnancy found those planning to comply with the recommended immunization schedule for their infants had the highest levels of confidence in vaccine effectiveness, value and safety compared to mothers who were planning to delay or decline some recommended vaccines or who were unsure of their immunization plans.

In the focus on vaccine hesitancy, there has been much concern that parents' confidence in recommended childhood vaccines as well as the recommended immunization schedule is declining. Black and Rappuoli (2010),³¹ along with Larson et al. (2012)¹⁵ posited that public confidence in vaccines not only was declining but was perhaps reaching a crisis state, while Dube et al. (2013)³² stated “lack of confidence in vaccines is now considered a threat to vaccination programs.” In contrast, the few published studies that have sought to directly assess parents' vaccine-related confidence levels suggest that, at least in the US, parent perceptions tend to be positive. Overall, for instance, Weiner et al.'s²³ survey of 200 first-time expectant mothers who were in their second or third trimester of pregnancy found 81.4% were confident in the effectiveness of routine childhood vaccines, 78.4% were confident in the value of routine childhood vaccines, and 73.5% were confident in the safety of routine childhood vaccines. Similarly, a 2010 survey of 376 parents of children younger than 6 y old found 72% of parents were “confident” in the safety of recommended childhood vaccines, with slightly more parents expressing confidence in the effectiveness of vaccines (78%) and the benefits of vaccines (77%).²⁵

While the limited efforts to assess parents' vaccine-related confidence have been helpful – with many finding an association between confidence, trust, and doubt ratings and vaccine safety-related perceptions^24-28,33-38– studies that extend the scope of the assessments and expand the context in which confidence is examined are lacking. Studies to date have assessed associations with demographic characteristics, vaccine safety beliefs, and vaccine-related behaviors,^33-38 but relatively little is known about parents' confidence in vaccines versus their confidence in the recommended immunization schedule or potential associations between vaccination confidence ratings, parents' previous vaccine-related experiences and their trust in the advice they receive from their child's health care provider. It is possible parents may be more or less confident in vaccines than in the recommended schedule (which imposes a structure and often involves multiple vaccinations) or that direct or indirect experiences with adverse vaccine reactions would affect parents' vaccine-related confidence. It is likely, for instance, parents who perceive their child experienced a bad reaction to a vaccine would have less vaccine-related confidence.

Also missing is context. The few studies to date that have used confidence measures have only encompassed vaccines; they have not asked parents about their confidence in other health or medical-related products that are often recommended and provided to young children. Thus, while studies have documented antibiotic, over-the-counter medicine (OTC), and vitamin use by parents with young children and examined parents' beliefs regarding those types of products,^39-45 the concept of “confidence” has not been applied in those domains. While recommended childhood vaccines are distinct in that they are designed to prevent an unknown future harm and unique in that mandates are often used to foster compliance, it would be helpful to know if parents have greater or less confidence for vaccines than for antibiotics, OTC medicines, or vitamins for children. One would expect parents' confidence in recommended childhood vaccinations to be higher than for other child health-related products because of the very high safety and efficacy standards that vaccines are held to, but it may very well be the case that vaccine hesitancy has brought about relatively low levels of vaccine-related confidence. It would also be helpful to know if there is a confidence-related gap between recommended childhood vaccines and other health-related products for children, where the gap is and how large it may be. The value and need for antibiotics to treat disease, the discretionary nature of OTC medicines, or vitamins association with being “natural,” mean each product category has the potential to be differentially perceived when it comes to parent confidence assessments. In addition, the study undertaken here examined whether confidence is related to delaying or declining use of other health-related products for children and whether the correlates of confidence are similar or different across the examined health product categories. An Internet-based survey of a nationally representative sample of 1,000 parents of children 5 y old and younger was conducted from November 3, 2014, to December 1, 2014, in this extension and expansion of the application of the confidence concept.

Results

A national survey research firm (YouGov) interviewed 1054 respondents who were then matched down to a sample of 1000 to produce the final dataset. The response rate, calculated using the American Association for Public Opinion Research (AAPOR) formula for response rate 3, was 36.3%, while the survey completion rate was 90%.⁴⁶ AAPOR is the leading professional organization for public opinion and survey research and provides guidelines for the calculation of response rates in survey work⁴⁷ (for an overview of the formula please refer to reference 46). The respondents represented a demographically diverse group (Table 1). Just over half were White/Caucasian, while 23% were Hispanic, and 13% were Black. A quarter had a bachelors' degree or higher for highest educational level, 29% were high school graduates and 12% indicated less than high school education. For 74%, a pediatrician was the child's primary health care provider, for 21% it was a family physician.

Table 1. Survey respondents' demographic characteristics (N = 1000).

Variable	%
Gender
Male	46.0
Female	54.0
Age
18–24	15.9
25–30	25.4
31–35	23.8
36–40	14.2
41 and older	20.5
Race
White/ Caucasian	54.5
Hispanic	23.6
Black or African American	12.9
Asian	4.0
Other	5.1
Marital status
Married or Partnered	76.4
Divorced or Separated	7.8
Single	15.8
Highest education
Advanced degree	10.0
Four-year degree	17.7
Two-year degree	10.0
Some college or technical school	21.7
High school or GED	28.9
Less than high school	11.7
Occupational status
Employed full-time	46.3
Employed part-time	10.7
Unemployed	10.6
Stay-at-home parent	23.1
Student	3.4
Other	6.0
Annual income
Less than $29,999	35.8
$30,000-$59,9999	26.3
$60,000-$99,999	19.5
More than $100,000	10.0
Prefer not to say	7.6
Number of children make healthcare decisions for
1	37.7
2	34.7
3	18.5
4 or more	9.0

Vaccination and receipt of other health-related products

As shown in Table 2, 74.8% of children had received all recommended vaccinations to date, while 20.6% received “some” and 4.6% had received “none.” The highest compliance rates were among parents who were White, college-educated, and had household incomes greater than $30K per year. Parents most likely to indicate their child received some but not all recommended vaccinations were more likely to be Black or Hispanic, have some college or high school or less education, and household incomes of $30K a year or less (p's < .05). There were no significant differences based on race, education or income in the percentage of parents reporting that their child had received none of the recommended vaccines.

Table 2. Children's vaccine, antibiotic, over-the-counter medicine and vitamin behaviors based on race, education and income levels.

		Race (%)			Education (%)				Income (%)
Action	Overall (%)	White	Black	Hispanic	High school or less	Some college	College degree	Post-grad. Degree	Less than $30K	$30K to $69,999	Greater than $70K
N	1000	545	129	236	406	217	277	100	358	328	314
Vaccine Behaviors
Has your youngest child received all, some or none of the recommended vaccines to date?
None	4.6	4.1^a	5.1^a	6.8^a	5.9^a	6.2^a	2.2^a	2.0^a	3.5^a	6.1^a	4.0^a
Some	20.6	16.6^a	26.3^a,b	27.5^b	22.6^a	24.2^a	19.1^a,b	9.2^b	28.4^a	16.2^b	16.3^b
All	74.8	79.3^a	68.6^a,b	65.8^b	71.5^a	69.7^a	78.7^a,b	88.8^b	68.0^a	77.7^b	79.7^b
Have you ever delayed having your child or children get a recommended vaccine for reasons other than illness or allergy? By delayed we mean put off, but ultimately ended up having it done.
No	69.5	73.0^a	75.6^a,b	62.9^b	67.7^a	71.1^a	69.5^a	72.9^a	63.7^a	70.5^a,b	74.7^b
Unsure	7.2	3.3^a	11.8^b	13.1^b	9.9^a	7.6^a,b	5.3^a,b	1.0^b	9.1^a	6.4^a	6.0^a
Yes	23.3	23.8^a	12.6^b	23.9^a,b	22.5^a	21.3^a	25.2^a	26.0^a	27.1^a	23.1^a	19.3^a
Have you ever decided not to have your child or children get a recommended vaccine for reasons other than illness or allergy?
No	74.2	81.0^a	67.8^b	60.6^b	70.0^a	72.2^a,b	79.6^b	79.2^a,b	71.4^a	74.4^a	77.2^a
Unsure	6.1	1.0^a	13.9^b	14.8^b	10.3^a	5.3^a,b	2.2^b	3.1^a,b	6.8^a	7.0^a	4.0^a
Yes	19.7	18.0^a	18.3^a	24.5^a	19.7^a	22.5^a	18.2^a	17.7^a	21.7^a	18.5^a	18.8^a
Do you plan or intend to have your child or children get all of the remaining recommended vaccines?
No	10.5	10.2^a	6.8^a	14.5^a	10.7^a	9.5^a	12.3^a	7.1^a	10.7^a	10.5^a	10.0^a
Unsure	12.8	8.8^a	26.5^b	16.4^a	15.1^a,b	17.1^b	8.9^a	6.1^a,b	15.0^a	12.1^a	11.0^a
Yes	76.7	81.0^a	66.7^b	69.1^b	74.2^a	73.3^a	78.8^a	86.7^a	74.2^a	77.4^a	79.0^a
Antibiotics Behaviors
Has your youngest child been given an antibiotic to treat an illness?
No	34.7	38.6^a	31.7^a,b	23.6^b	32.0^a	38.2^a	35.9^a	34.7^a	28.4^a	41.2^b	35.0^a,b
Unsure	5.5	3.3^a	7.5^a,b	10.0^b	7.3^a	4.7^a,b	5.0^a,b	0.0^b	5.1^a	5.1^a	5.8^a
Yes	59.8	58.1^a	60.8^a	66.4^a	60.7^a	57.1^a	59.2^a	65.3^a	66.5^a	53.7^b	59.2^a,b
Have you ever delayed having your child or children get a recommended antibiotic for reasons other than allergy?
No	81.1	86.0^a	77.4^a,b	72.0^b	78.1^a	78.8^a	82.5^a,b	93.5^b	78.2^a	81.7^a	83.9^a
Unsure	7.4	3.9^a	13.9^b	10.7^b	11.6^a	5.7^a,b	4.5^b	2.2^b	7.9^a	7.6^a	6.6^a
Yes	11.5	10.1^a	8.7^a,b	17.3^b	10.2^a,b	15.5^b	13.0^a,b	4.3^a	13.9^a	10.7^a	9.5^a
Have you ever decided not to have your child or children get a recommended antibiotic for reasons other than allergy?
No	82.0	87.6^a	85.3^a	65.9^b	76.7^a	81.8^a,b	85.5^b	92.5^b	79.0^a	81.6^a	85.8^a
Unsure	5.5	3.5^a	4.3^a,b	11.1^b	8.2^a	6.6^a,b	2.0^b	1.1^a,b	5.6^a	5.8^a	5.1^a
Yes	12.5	8.9^a	10.3^a	23.1^b	15.1^a	11.6^a	12.4^a	6.5^a	15.4^a	12.6^a	9.1^a
If your child will was ill, and your physician recommended an antibiotic, would you have your child take the antibiotic?
No	12.1	6.1^a	27.4^b	17.5^b	14.0^a	9.3^a	11.6^a	12.6^a	18.0^a	9.4^b	8.5^b
Unsure	13.4	12.3^a	11.1^a	16.6^a	14.3^a	17.2^a	10.5^a	8.4^a	8.7^a	17.4^b	14.2^a,b
Yes	74.5	81.6^a	61.5^b	65.9^b	71.7^a	73.5^a	77.9^a	78.9^a	73.3^a	73.2^a	77.3^a
Over-the-counter medicines Behaviors
Has your youngest child been given an over-the-counter medicine or drug to treat an illness?
No	19.1	18.4^a	17.4^a	20.7^a	18.6^a	21.2^a	19.3^a	15.1^a	21.4^a	16.5^a	19.2^a
Unsure	5.2	2.1^a	6.6^a,b	12.2^b	10.1^a	2.8^b	2.2^b	0.0^b	8.0^a	4.4^a,b	3.0^b
Yes	75.8	79.5^a	76.0^a,b	67.1^b	71.4^a	75.9^a,b	78.4^a,b	84.9^b	70.6^a	79.1^b	77.8^a,b
Have you ever delayed having your child or children get a recommended over-the-counter medicine for reasons other than allergy?
No	76.5	81.0^a	80.2^a	62.8^b	72.8^a	74.3^a,b	79.8^a,b	86.2^b	74.4^a	74.6^a	80.5^a
Unsure	7.6	4.0^a	6.9^a	17.5^b	13.5^a	5.3^b	2.7^b	3.2^b	9.1^a	7.9^a	5.8^a
Yes	15.9	15.1^a	12.9^a	19.7^a	13.7^a	20.4^a	17.4^a	10.6^a	16.5^a	17.5^a	13.7^a
Have you ever decided not to have your child or children get a recommended over-the-counter medicine for reasons other than allergy?
No	76.0	80.9^a	71.6^a,b	66.5^b	74.7^a	71.6^a	79.9^a	81.5^a	73.7^a	74.9^a	80.5^a
Unsure	6.7	3.2^a	10.3^b	14.0^b	11.1^a	4.8^a,b	2.7^b	5.4^a,b	6.7^a	7.0^a	6.2^a
Yes	17.3	16.0^a	18.1^a	19.5^a	14.2^a	23.6^b	17.4^a,b	13.0^a,b	19.6^a	18.1^a	13.4^a
If your child was ill and your child's doctor recommended an over-the-counter medicine, would you have your child take the medicine?
No	16.1	10.4^a	23.5^b	20.1^b	18.5^a	10.9^a	16.1^a	17.5^a	18.8^a	14.2^a	14.8^a
Unsure	11.4	10.6^a	9.2^a	16.4^a	10.5^a	15.6^a	12.4^a	5.2^a	7.6^a	15.5^b	11.8^a,b
Yes	72.4	79.0^a	67.2^b	63.6^b	71.0^a	73.5^a	71.5^a	77.3^a	73.6^a	70.3^a	73.4^a
Children's vitamins Behaviors
Has your youngest child been given a children's vitamin?
No	33.5	36.3^a	33.1^a	29.1^a	31.1^a	39.2^a	34.3^a	28.1^a	32.2^a	36.1^a	32.2^a
Unsure	3.7	1.9^a	5.0^a,b	6.4^b	5.1^a	4.2^a	1.9^a	1.0^a	5.1^a	3.8^a	2.3^a
Yes	62.8	61.8^a	62.0^a	64.5^a	63.8^a	56.6^a	63.8^a	70.8^a	62.7^a	60.1^a	65.4^a
Have you ever hesitated having your child or children take a vitamin for reasons other than allergy?
No	78.8	84.0^a	76.5^a,b	67.0^b	73.3^a	78.7^a,b	83.5^b	86.0^a,b	70.4^a	80.0^b	87.6^c
Unsure	6.8	2.9^a	5.2^a	16.3^b	12.0^a	5.1^b	1.6^b	4.3^a,b	10.2^a	5.6^a,b	4.0^b
Yes	14.4	13.1^a	18.3^a	16.7^a	14.8^a	16.2^a	15.0^a	9.7^a	19.4^a	14.4^a,b	8.4^b
Have you ever decided not to have your child or children take a vitamin for reasons other than allergy?
No	78.3	83.8^a	72.0b,c	66.7c	75.6^a	71.4^a	85.0^b	83.5^a,b	71.8^a	79.5^a,b	84.6^b
Unsure	6.4	2.0^a	12.7^b	13.4^b	10.8^a	5.0^a,b	2.4^b	4.1^a,b	7.4^a	7.3^a	4.3^a
Yes	15.3	14.2^a	15.3^a	19.9^a	13.6^a	23.6^b	12.6^a	12.4^a,b	20.9^a	13.2^b	11.1^b
Do you plan or intend to have your child take recommended vitamins in the future?
No	18.9	18.8^a	21.7^a	19.5^a	21.5^a	10.7^b	25.8^a	7.2^b	21.2^a	21.0^a	14.0^a
Unsure	17.1	17.2^a	14.8^a	19.1^a	15.5^a	22.3^a	15.5^a	17.5^a	16.4^a	17.8^a	17.4^a
Yes	64.1	64.0^a	63.5^a	61.4^a	62.9^a,b	67.0^a,b	58.7^b	75.3^a	62.4^a	61.2^a	68.6^a

Notes: (1) Comparisons are made across columns by row and grouping (e.g., all possible comparisons are made between 4.1, 5.1, and 6.8 in our first row of results comparing vaccine behaviors by race).

(2) Differences in superscripts represent differences that are significant at a p-value of .05. For example, there are no significant differences between 4.1^a, 5.1^a, and 6.8^a in our first row of results comparing vaccine behaviors by race, as illustrated by the superscript ‘a’ common to all values. However, there is a significant difference between 16.6^a and 27.5^b in the second row of results, as illustrated by the difference in superscripts. Specifically, 16.6% of White respondents reported that their child had received “some” of the recommended vaccines to date, a percentage that was significantly lower than the 27.5% of Hispanic respondents who reported their child had received “some” of the recommended vaccines to date. The value for black respondents (26.3^a,b) did not differ significantly from either 16.6^a or 27.5^b, as illustrated by the superscripts ‘a’ and ‘b’ for that value.

Table 2 shows that 59.8% had given their child an antibiotic, 75.8% had given an OTC medicine, and 62.8% had given a children's vitamin. Antibiotic administration was 75% for respondents whose youngest child was 3 y old or older vs. 46.1% for those with children 2 y old and younger, with OTC medicine (84.1%) and children's vitamin (76.7%) use also higher among these parents (vs. 67.9% and 49.5%, p's < .05).

Vaccine and other health-related product delay and declination

Table 2 shows that 23.3% of parents delayed a recommended vaccination, while 19.7% declined a recommended vaccination. Black parents and parents in households with the highest annual incomes were least likely to have delayed a recommended vaccination, while Black and Hispanic parents had the highest levels of uncertainty regarding vaccine refusal. Around 12% of parents had delayed receipt of a recommended antibiotic, with a similar percentage indicating they had declined a recommended antibiotic. Parents with college or greater education were least likely to delay or decline a recommended antibiotic, while Hispanic parents were most likely to have delayed or declined a recommended antibiotic. Around 16% of parents delayed a recommended OTC medicine and 17% had declined such a medication. Parents with a post graduate education were least likely to have delayed a recommended OTC medicine. About 15% of parents delayed a vitamin recommendation and 15% had decided not to have their child receive a recommended vitamin. Parents in households with the lowest annual incomes were most likely to delay or decline children's vitamins. Also of note was the finding that the proportion of parents who reported delaying or declining a recommended vaccination for their child differed significantly (i.e., was higher) from the proportion of parents who reported delaying or declining the administration of (1) an antibiotic, (2) an over-the-counter medicine, and (3) a children's vitamin. This pattern persisted for the items probing future intentions as well, although future vaccination and antibiotic use intentions did not significantly differ from one another.

Vaccination and other intentions

Seventy-seven percent of parents planned to have their child receive all recommended vaccines in the future, while 13% were unsure and 10% said “no.” The strongest vaccination intentions were among parents who were White and had a graduate education (Table 2). About 26% of Black parents, 16.4% of Hispanic parents, and about 16% of parents with some college or less education said they were “unsure” if their child or children would get all of the remaining recommended vaccines. Another 14.5% of Hispanic parents said they were not planning to have their child or children receive all the remaining recommended vaccines. Similar to vaccination intentions, about 75% of parents said if their child were ill they would have them take a recommended antibiotic or OTC medicine. Also similar to vaccines, Black and Hispanic parents had higher levels of uncertainty or likely refusal compared to White respondents. With respect to antibiotics, 27.4% of Black parents and 17.5% of Hispanic parents would decline a future recommended antibiotic (vs. 6.1% for White parents, p's < .001), and 23.5% of Black parents and 20.1% of Hispanic parents would decline a future recommended OTC medicine for their child (vs. 10.4% for White parents, p's < .001). Higher uncertainty and potential refusal levels also were associated with less formal education and lower household incomes for antibiotics, OTC medicines and vitamins. Overall, about 19% of parents planned to decline a future recommended vitamin, a percentage nearly twice as high as that for vaccines.

Confidence in vaccines, antibiotics, OTC medicines and children's vitamins

Vaccination confidence ratings averaged around a ‘7’ on a 0–10 scale for all but one item- the measure involving confidence that their child will not have a serious adverse reaction to a vaccine (Table 3). The average overall rating of 6.6 for this measure was half a point less than that for other confidence measures, and 13.5% of parents gave a 0–2 response (i.e., indicated little or no confidence) that their child would not have a bad or serious reaction to any of the recommended vaccines. Black parents, parents with post graduate education, and highest income parents had the highest levels of confidence for all measures, while parents with some college or less education had the lowest confidence levels. In addition, confidence ratings were similar for the immunization schedule and for the individual vaccines in the schedule.

Table 3. Confidence in vaccines, antibiotics, over-the-counter medicines and vitamins based on race, education and income levels.

		Race				Education				Income
Confidence Items	Mean	White	Black	Hispanic	p-value	High school or less	Some college	College degree	Post-grad. degree	p-value	Less than $30K	$30K to $69,999	Greater than $70K	p-value
N	1000	545	129	236		406	217	277	100		358	328	314
How confident are you in each of the following statements:
Vaccine Confidence – Schedule
1. The recommended childhood vaccination schedule is safe.	7.1	7.0	7.7	6.9	.026	6.9	6.8	7.1	8.3	.000	6.8	7.0	7.4	.032
2. The overall recommended childhood vaccination schedule will protect my child from all the diseases and illnesses.	7.0	6.9	7.6	6.9	.019	6.8	6.6	7.2	8.2	.000	6.8	7.1	7.3	.032
3. My child's overall health will benefit from getting all the recommended vaccines.	7.2	7.3	7.5	7.0	.142	7.0	7.0	7.34	8.4	.000	6.9	7.3	7.6	.008
Vaccine Confidence – Individual Vaccines
1. My child won't have a bad or serious adverse reaction to any of the recommended vaccines.	6.6	6.5	7.2	6.5	.053	6.4	6.6	6.6	7.6	.001	6.4	6.6	6.9	.048
2. Each of the recommended vaccines is effective in protecting my child from disease and illness.	7.1	7.1	7.4	6.9	.343	6.9	6.9	7.2	8.1	.000	6.9	7.1	7.4	.044
3. My child's overall health benefits from each one of the vaccines in the recommended childhood vaccination schedule.	7.0	7.0	7.3	6.9	.321	6.8	6.8	7.2	8.1	.000	6.7	7.0	7.4	.011
Antibiotics Confidence
1. My child won't have a bad or serious adverse reaction to a recommended children's antibiotic.	6.6	6.6	7.2	6.4	.004	6.4	6.2	6.9	7.7	.000	6.3	6.7	7.0	.000
2. A recommended children's antibiotic will successfully treat the illness or disease.	7.1	7.1	7.6	6.8	.004	6.9	7.0	7.2	7.9	.000	6.8	7.1	7.4	.010
3. My child's overall health will benefit from taking a recommended children's antibiotic.	6.8	6.8	7.4	6.7	.017	6.7	6.6	6.9	7.6	.002	6.7	6.8	7.0	.231
Over-the-counter (OTC) medicines Confidence
1. My child won't have a bad or serious adverse reaction to an over-the-counter medicine or drug for children.	6.8	6.7	7.1	6.9	.185	6.5	6.6	7.1	7.6	.000	6.4	7.0	7.2	.000
2. Over-the-counter medicines and drugs for children will successfully treat the illness or disease.	6.3	6.1	6.7	6.6	.002	6.3	6.1	6.5	6.8	.089	6.0	6.5	6.5	.007
3. My child's overall health will benefit from taking over-the-counter medicines or drugs for children.	6.4	6.1	7.0	6.5	.001	6.1	6.1	6.7	6.8	.002	6.0	6.5	6.7	.001
Children's vitamins Confidence
1. My child won't have a bad or serious reaction to a children's vitamin.	7.3	7.4	7.3	7.1	.189	6.9	7.3	7.6	7.8	.001	6.6	7.7	7.7	.000
2. Children's vitamins will successfully protect my child from illness or disease.	5.8	5.5	6.4	6.3	.000	5.9	5.6	5.9	5.8	.590	5.8	5.8	5.9	.859
3. My child's overall health will benefit from taking children's vitamins.	6.7	6.6	7.2	6.7	.038	6.7	6.7	6.8	6.7	.989	6.5	6.9	7.0	.018

Parents' confidence level that a recommended antibiotic would successfully treat an illness was similar to those for vaccines and for the immunization schedule protecting their child from illnesses and diseases (Table 3). Again, confidence ratings were typically highest among parents with post graduate education, Black parents, and those with the highest household incomes and generally lowest among those with some college or less. Confidence in vaccine and antibiotic effectiveness was higher than for OTC medicines and vitamins (7.1 vs. 6.3 vs. 5.8, p's < .05). The lowest confidence rating was for children's vitamins' ability to provide protection from illness or disease, but parents had high confidence their child would not have a bad reaction to vitamins, with that belief highest among higher income and education parents.

Confidence ratings and receipt, delay, declination, and future intentions

Table 4 shows parents who reported their child had received all recommended vaccinations to date had the highest confidence ratings for the immunization schedule and the individual vaccines in the schedule. Their ratings ranged from 7.1 to 8.0 compared to a range of 3.5 to 4.0 for parents who said their child had received none of the recommended vaccinations to date, and a range of 5.1 to 5.6 for those whose children had received some recommended vaccinations to date (p's < .001). Parents who intended to comply with future vaccination recommendations also had much higher confidence ratings than parents who were unsure or not planning to have their child receive future recommended vaccinations. Table 4 shows many similar patterns, though not as large, differences with respect to children's antibiotics, OTC medicine, and vitamin receipt. Parents whose children had received an antibiotic, OTC medicine, or vitamin had the highest confidence levels, while parents who their child had not received these things had the lowest levels. However, the results related to future intentions were quite different, with parents planning to comply or decline future recommendations often having similar confidence levels and parents who were unsure having the lowest ratings.

Table 4. Confidence in vaccines, antibiotics, over-the-counter medicines and vitamins for children based on behaviors in those areas.

	Child received recommended vaccines to date?				Delayed?				Declined?				Future Intentions?
Confidence Items	None	Some	All	p-value	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value
N	310	34	586		704	61	130		704	58	138		173	158	593
How confident are you in each of the following statements:
Vaccine Confidence – Schedule
1. The recommended childhood vaccination schedule is safe.	3.7	5.1	7.8	.000	7.6	7.0	5.8	.000	7.6	6.0	5.4	.000	4.5	5.3	7.8	.000
2. The overall recommended childhood vaccination schedule will protect my child from all the diseases and illnesses.	3.8	5.4	7.7	.000	7.5	6.8	6.1	.000	7.5	6.0	5.6	.000	4.9	5.4	7.7	.000
3. My child's overall health will benefit from getting all the recommended vaccines.	3.5	5.5	8.0	.000	7.7	7.1	6.2	.000	7.8	5.9	5.6	.000	4.5	5.5	8.0	.000
Vaccine Confidence – Individual Vaccines
1. My child won't have a bad or serious adverse reaction to any of the recommended vaccines.	3.6	5.6	7.1	.000	6.9	6.6	6.1	.000	7.0	5.8	5.7	.000	4.1	5.7	7.2	.000
2. Each of the recommended vaccines is effective in protecting my child from disease and illness.	4.0	5.6	7.7	.000	7.5	6.7	6.6	.000	7.6	6.1	5.8	.000	4.8	5.4	7.8	.000
3. My child's overall health benefits from each one of the vaccines in the recommended childhood vaccination schedule.	3.6	5.4	7.7	.000	7.5	6.8	6.2	.000	7.5	6.2	5.6	.000	4.4	5.5	7.8	.000
N	43	195	706		644	67	219		685	56	184		98	119	714
	Child received antibiotic?				Delayed?				Declined?				Future Intentions?
Antibiotics Confidence	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value
1. My child won't have a bad or serious adverse reaction to a recommended children's antibiotic.	6.5	6.9	6.7	.230	6.9	6.1	6.2	.003	6.9	6.1	5.8	.000	6.7	5.4	6.9	.000
2. A recommended children's antibiotic will successfully treat the illness or disease.	6.7	7.0	7.4	.000	7.4	6.3	6.6	.000	7.4	6.7	6.1	.000	6.6	5.7	7.4	.000
3. My child's overall health will benefit from taking a recommended children's antibiotic.	6.4	6.7	7.1	.000	7.1	6.1	6.2	.000	7.1	6.2	5.8	.000	6.4	5.0	7.2	.000
N	318	50	556		714	66	103		724	48	113		113	123	694
	Child received OTC medicine?				Delayed?				Declined?				Future Intentions?
Over-the-counter (OTC) medicines Confidence	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value
1. My child won't have a bad or serious adverse reaction to an over-the-counter medicine or drug for children.	6.3	6.1	7.0	.000	7.0	5.8	6.7	.000	7.0	6.3	6.6	.027	6.9	5.4	7.1	.000
2. Over-the-counter medicines and drugs for children will successfully treat the illness or disease.	5.6	6.0	6.5	.000	6.5	5.9	6.8	.002	6.5	6.1	5.7	.000	6.6	4.7	6.5	.000
3. My child's overall health will benefit from taking over-the-counter medicines or drugs for children.	5.4	5.8	6.7	.000	6.6	6.0	5.7	.000	6.6	6.0	5.7	.000	6.6	4.6	6.6	.000
N	176	49	711		700	69	147		693	61	157		147	107	672
	Child received children's vitamin?				Delayed?				Declined?				Future Intentions?
Children's vitamins Confidence	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value
1. My child won't have a bad or serious reaction to a children's vitamin.	6.8	7.0	7.6	.000	7.7	6.1	6.5	.000	7.5	6.5	6.9	.001	7.0	6.5	7.7	.000
2. Children's vitamins will successfully protect my child from illness or disease.	4.7	6.6	6.3	.000	6.1	6.2	5.0	.000	6.0	6.1	5.3	.021	5.0	4.8	6.4	.000
3. My child's overall health will benefit from taking children's vitamins.	5.6	6.8	7.4	.000	7.2	6.4	5.4	.000	7.0	6.3	6.0	.000	5.5	5.5	7.5	.000

Confidence, bad reactions, and vaccine preventable disease knowledge

About 24% of parents said they knew of someone who had a bad reaction to a vaccine, with 65.8% saying “no” and 10.7% unsure. In response to a separate question, 13.4% said a child of theirs had experienced a bad reaction to a vaccine, with 8% unsure. Parents with a high school or less education and the lowest annual incomes were most likely to know of someone who had a bad reaction to a vaccine as well as to believe they had a child who experienced a bad reaction. Overall, about 25% of parents reported knowing of someone who had a vaccine-preventable disease.

One third of parents knew of someone who had a bad reaction to an antibiotic, and 14.4% had a child who had a bad reaction. White parents were twice more likely than Black or Hispanic parents to say they knew of someone who had a bad reaction to an antibiotic but most likely to say none of their children had such an experience. For OTC medicines, 16.7% knew of someone who had a bad reaction, and 7% said a child of theirs had a bad reaction. Personal experience was higher for Hispanic and Black parents, and Hispanic parents were most likely to know someone who had a bad reaction to an OTC medicine. For vitamins, 8.7% knew of someone who had a bad reaction, and 5.3% said a child of theirs had a bad reaction.

As Table 5 shows, knowledge and personal experience of bad or adverse events was generally associated with lower confidence ratings. For all products, including vaccines, confidence ratings were highest among parents who did not know of anyone who experienced a bad reaction or who did not have such an experience with a child of their own. In addition, being uncertain about whether their child had experienced a bad reaction or whether they knew of anyone who had experienced a bad reaction to a vaccine, antibiotic, OTC medicine or vitamin was often associated with the lowest confidence ratings. This was particularly true for vaccines relative to the other health-related products. As Table 5 also shows, the impact of knowing of someone who had a bad reaction was greatest for vaccines relative to the other products (e.g., usually about a 2 point decline in confidence ratings vs. a 1 point decline for antibiotics and OTC medicines and a less than 1 point decline for vitamins). Conversely, knowing of someone who had a vaccine-preventable disease had no association with confidence ratings.

Table 5. Confidence in vaccines, antibiotics, over-the-counter medicines and vitamins for children based on adverse reaction experience.

	Any of your children ever had a bad reaction to a vaccine?				Know of anyone who has had a bad reaction to a vaccine?				Know of anyone who has had a vaccine-preventable disease?
Confidence Items	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value
N	731	73	126		617	100	222		579	125	233
How confident are you in each of the following statements:
Vaccine Confidence – Schedule
1. The recommended childhood vaccination schedule is safe.	7.4	5.8	6.4	.000	7.7	6.7	5.5	.000	7.1	7.2	6.9	.558
2. The overall recommended childhood vaccination schedule will protect my child from all the diseases and illnesses.	7.3	5.5	6.5	.000	7.6	6.5	5.7	.000	7.2	7.0	6.8	.134
3. My child's overall health will benefit from getting all the recommended vaccines.	7.6	5.7	6.6	.000	7.8	6.6	6.0	.000	7.3	7.5	7.1	.283
Vaccine Confidence – Individual Vaccines	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value
1. My child won't have a bad or serious adverse reaction to any of the recommended vaccines.	6.9	5.6	6.1	.000	7.1	6.3	5.5	.000	6.7	6.8	6.3	.127
2. Each of the recommended vaccines is effective in protecting my child from disease and illness.	7.4	5.9	6.6	.000	7.6	6.7	6.0	.000	7.2	7.3	7.0	.445
3. My child's overall health benefits from each one of the vaccines in the recommended childhood vaccination schedule.	7.3	5.9	6.4	.000	7.5	6.8	5.8	.000	7.1	7.2	6.8	.286
	Any of your children ever had a bad reaction to an antibiotic?				Know of anyone who has had a bad reaction to an antibiotic?
Antibiotics Confidence	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value
N	680	53	125		529	87	305
1. My child won't have a bad or serious adverse reaction to a recommended children's antibiotic.	7.0	6.7	5.6	.000	7.1	6.2	6.0	.000
2. A recommended children's antibiotic will successfully treat the illness or disease.	7.4	6.7	6.7	.000	7.4	6.6	6.8	.000
3. My child's overall health will benefit from taking a recommended children's antibiotic.	7.1	6.4	6.5	.005	7.2	6.1	6.4	.000
	Any of your children ever had a bad reaction to an OTC medication?				Know of anyone who has had a bad reaction to an OTC medication?
Over-the-counter (OTC) medicines Confidence	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value
N	788	63	64		695	76	155
1. My child won't have a bad or serious adverse reaction to an over-the-counter medicine or drug for children.	7.0	6.1	6.4	.003	7.1	6.2	6.2	.000
2. Over-the-counter medicines and drugs for children will successfully treat the illness or disease.	6.4	6.1	6.3	.586	6.6	5.7	5.6	.000
3. My child's overall health will benefit from taking over-the-counter medicines or drugs for children.	6.5	6.1	5.8	.037	6.7	5.8	5.4	.000
	Any of your children ever had a bad reaction to a vitamin?				Know of anyone who has had a bad reaction to a vitamin
Children's vitamins Confidence	No	Unsure	Yes	p-value	No	Unsure	Yes	p-value
N	793	60	48		787	59	81
1. My child won't have a bad or serious reaction to a children's vitamin.	7.5	5.9	7.3	.000	7.5	6.5	6.7	.001
2. Children's vitamins will successfully protect my child from illness or disease.	5.9	6.0	6.8	.067	5.9	5.6	6.0	.637
3. My child's overall health will benefit from taking children's vitamins.	6.9	6.0	7.2	.012	6.9	5.7	6.4	.000

Confidence ratings and trust in health care provider advice

Overall, about 70% of parents “agreed” or “strongly agreed” they trusted the advice they received about vaccines from their child's health care provider, with similar results for antibiotics (71.5%), OTC medicines (71%), and children's vitamins (71%). For all 4 product categories, there was a strong association between trusting advice and confidence ratings. For vaccines, parents' average ratings for all 6 vaccine confidence measures were around 8.0 among parents with high trust in their child's health care providers' advice, 5.8 for those with medium trust, and around 4.0 for parents who indicated they did not trust the health care providers' advice (p's < .001). Similar patterns were found for trust in child's health care provider's antibiotic advice and antibiotic confidence (e.g., averages around 7.5 among high trust parents, 6.0 for medium trust, and 4.3 among low trust), OTC medicine advice and confidence ratings (e.g., 7.0 vs. 5.7 vs. 4.2), and vitamins (7.0 vs. 6.0 vs 5.0) (p's < .001).

Multivariate analyses

Regression analyses were used to determine the most significant predictors of confidence ratings and behaviors when all predictor variables were included in the same statistical model. Education emerged as the most consistent positive predictor of confidence for each health-related product. In turn, confidence was the most important factor when it came to predicting parents' delay, declination, and future intention behaviors. Higher confidence levels were associated with a decreased tendency to delay or decline a given recommendation as well as with higher future use intentions. Non-White respondents were more likely than White respondents to report negative future intentions to vaccinate and follow future antibiotic and OTC medicine recommendations. Trust in the advice of the child's health care provider also emerged as a powerful ad consistent predictor of confidence ratings, past vaccination behavior, and future vaccination intentions. Specifically, trust was associated with higher confidence ratings across all 4 product categories, a lower likelihood of having delayed or declined a recommended health product, and a greater intention to comply with future recommendations.

Discussion

While recent US measles and pertussis outbreaks, along with evidence of increasing vaccination delays and refusals, have led some to conclude that a crisis of public confidence exists regarding vaccines,³¹ the results from this study are more reassuring, particularly with respect to parents of young children. Similar to other published studies, most parents of young children had fairly high confidence levels with respect to value, effectiveness, and safety^23-26,28 – and in this case, for both the recommended immunization schedule and the individual vaccines encompassed by the schedule. Notably, there was not a confidence gap between recommended childhood vaccines and the other examined products. Instead, parents' vaccine-related confidence ratings were as high, and usually higher, than for other health-related products for children that also are often recommended by healthcare providers and used by parents. This was the case even with vaccinations being associated with the highest likelihood of both delay and declination. In addition, the 2 other health-related products with the greatest use discretion – OTC medicines and vitamins—had nearly comparable rates of delay and refusal. In line with a recent continuum put forward by Gowda and Dempsey,⁴⁸ compliance with the recommended schedule and lack of negative experience were associated with the highest vaccination confidence ratings, while the lowest confidence ratings were found among parents who had declined recommended vaccinations as well as those who reported personal experience or knowledge of a bad adverse reaction.

Along with finding consistent associations between confidence ratings and parent vaccination behaviors, the findings extend previous research in 2 other ways. First, they suggest parents' confidence levels do not appear to differ significantly when it comes to vaccines versus the overall immunization schedule. Both received similar ratings, with the pattern of results being generally the same across demographic groups. The primary place a confidence difference may exist involves their expectations regarding the likelihood of a bad or serious vaccine adverse reaction, where there is a modest decrease in confidence ratings (though to levels similar for those found with antibiotics and OTC medicines). This suggests that there is an association between parents' beliefs or expectations regarding bad or serious adverse reactions and confidence levels (e.g., those who believe bad or adverse reactions are likely will lower safety-related confidence ratings). If so, safety-related vaccine (or health-related product) confidence measures may be a helpful way to assess the effectiveness of efforts designed to positively influence safety-related beliefs and expectations.

Second, not only do the results provide additional evidence that safety is related to confidence, they indicate that both knowledge of and direct experience with bad or serious vaccine reactions negatively affects confidence. Notably, knowing of someone had a stronger association with confidence levels than direct experience. This suggests that vaccine adverse event information or stories from friends or the media may involve outcomes that are more severe than those experienced by the vast majority of parents. Healthcare providers need to be mindful that parents' actual experiences with vaccine reactions can affect confidence levels and intentions, but indirectly acquired information is also likely and may have more influence. It may thus be helpful to either surface what parents have heard regarding adverse events or proactively provide information on how rarely severe reactions happen. In addition, the results obtained here suggest this also applies to impacting or affecting parents' confidence in antibiotics, OTC medicines and vitamins. Conversely, even though a quarter of the respondents indicated they knew of someone who had a vaccine preventable disease, that knowledge did not appear to affect vaccine-level confidence levels. It may be that the cases parents were aware of did not involve severe disease, involved illnesses that resolved without apparent lasting harm (e.g., influenza, chickenpox, measles), or were perceived as being successfully medically treatable. This is thus an area in need of additional research.

Expanding the context of the confidence concept beyond vaccines and vaccination provided additional helpful insights. First, it provided perspective. The overall results, for instance, suggest that when it comes to parents' perceptions of health-related products for children, high confidence is represented by ratings of ‘7–8’ on a ‘0–10’ scale rather than 9s or 10s. Very few parents had complete or absolute confidence in recommended vaccines, antibiotics, OTC medicines or vitamins. Rather, most respondents appeared to recognize that these health-related products for children have limits when it comes to safety, effectiveness, and benefits. It is likely unrealistic to expect most parents to indicate they have absolute confidence, and likely unproductive to pursue confidence building strategies that seek to achieve such a goal. Rather, the results from this and other studies suggest a better strategy would be to increase the percentage of parents who are confident or very confident in the safety, effectiveness, and benefits of vaccination (e.g., give 7s or 8s on a 0–10 scale). At present, this and recent research suggests 25–35% of parents have modest or relatively weak confidence levels (e.g., 6s or lower) when it comes to recommended childhood vaccines.

Second, the results provide context for interpreting vaccination delay and refusal. The finding that about 25% of parents have not followed the recommended schedule to date is in line with recently published studies, which have found 13–27% of parents of young children delaying recommended vaccinations and 6–16% declining recommended vaccinations. The findings here, however, indicate these estimates are generally higher than those for antibiotics but similar to those for OTC medicines. In addition, given the similar overall average confidence levels for vaccines and antibiotics, the results suggest that some parents who had high vaccine-related confidence ratings have delayed and/or declined recommended vaccinations. Indeed, subsequent analyses revealed that between 16–20% of high vaccine confidence parents (i.e., those scoring 8–10 on a given confidence item) reported delaying a vaccine and between 13–16% of these parents reported declining a recommended vaccine.

The results also provide insights into potential correlates of high and low confidence levels. Demographically, confidence in recommended vaccines, antibiotics, OTC medicines and vitamins for children tended to be highest among Black parents and parents with the highest levels of education and income. Conversely, confidence ratings were generally lowest among Hispanic parents and those with the lowest levels of education and income. In addition, parents with less confidence in vaccination-related recommendations had less confidence in recommended antibiotics and OTC medicines. This suggests some parents' hesitancy or lack of confidence extends beyond vaccinations into other domains of mainstream medicine. It would be helpful for future research to explore this in greater depth.

The findings with respect to vaccine confidence, behaviors, and intentions and respondents' demographic characteristics also serve as an important reminder that relationships and associations often vary across studies. While it is often the case that vaccine hesitancy is found among higher educated, higher income households, the research to date appears to be more equivocal.^6,19,49 Some studies have found that higher educated, higher income White parents are more hesitant about recommended childhood vaccines.^5,26,33,50 Other studies, however, suggest vaccine hesitancy, delay, and/or refusal are more common among groups that have less formal education, lower household incomes, or less access to healthcare.^9,12 This study's results are in line with studies that have found Black parents more likely to have vaccine-related concerns, Hispanic parents more likely than other parents to believe that vaccines cause autism, Black parents more likely to have ever refused a vaccine recommended by their child's physician, and those with high school or less formal education to be most interested in alternative vaccination schedules.^51,52 While this study found higher formal education and higher household income associated with greater vaccine confidence, this finding highlights the need for continued examination of when and why demographic characteristics relate to vaccine hesitancy, confidence, and acceptance.

The results also extend understanding of the important role that health care providers play when it comes to achieving compliance with vaccination recommendations. Here, the findings indicated that trust in the advice from a health care provider was highly related to confidence in the value, effectiveness, and safety of recommended vaccines. In addition, these results suggest the influence of trust on confidence may be greater in the domain of vaccines compared to antibiotics, OTC medicines and vitamins. The 10% of parents who indicated they did not trust the advice of their child's health care provider about vaccines had confidence ratings that were half of those for parents' who trusted health care provider advice and much lower intentions to comply with future vaccination recommendations. While this highlights the importance of establishing trust, it also reaffirms that parents who have doubts about the value, safety, and/or effectiveness of recommended childhood vaccines have beliefs and convictions that impede efforts to establish or build trust.

Finally, the results affirm the value of efforts to monitor and build parent confidence in routinely recommended health-related products for children, including vaccines. As illustrated here, parents vary in their confidence assessments. There are demographic, trust, and other factors associated with confidence levels, and healthcare providers would likely benefit from more parents having greater confidence in their recommendations, particularly if that mitigates delays and refusals. Future research is also important given this study is unable to discern what produced parents' confidence levels nor able to assess casual relationships. It is not possible to know which happened first – parents' confidence level or the recommendation encounter. More studies are also needed to identify and assess interventions to build confidence, including ones that encompass strengthening trust in health care provider advice. The findings here suggest lower SES parents, Hispanic parents, and parents with direct experience or knowledge of “bad reactions” need particular attention. Many had lower confidence levels, with those lower levels associated with delays and refusals in utilizing products that can improve children's health.

Limitations

There are 2 limitations to note with respect to this study. One, this study used an Internet-based panel designed to produce representative population estimates. However, this approach is relatively new compared to surveys that have used random digit dialing or probability-based population sampling. It is possible that use of a probability-based sampling method would obtain different results. However, the demographic profile of the respondents in this study were well matched to the latest US Census data and studies that have compared different polling methods have supported the ability of Internet panel approaches to produce valid and generalizable results.⁵³

A second limitation is the use of self-report items to measure parents' compliance with the recommended childhood immunization schedule and to assess whether their children had received recommended antibiotics, over-the-counter medicines, and vitamins. Self-reporting is the most simple and inexpensive way to assess compliance, but it is susceptible to forgetting and recall bias. In the case of this survey, for instance, 4.6% of parents reported their child had received none of the recommended vaccinations to date, which is higher than the estimated 1.0% consistently found by the CDC's National Immunization Surveys. The higher estimate may be the result of differences in the sampling method (i.e., random digit dialing vs. Internet panel), recall bias, and/or, differences in the sample populations. The NIS surveys, for instance, involve parents of children 18–35 months old while this study included parents who had children 5 y old and younger, and thus included those with children under 18 months of age. It may be that the inclusion of parents of very young children results in a higher estimate of non-vaccination because these parents have not faced as many vaccination visits/opportunities and/or because daycare and school entry requirements are not as tangible.

Methods

A leading research firm, YouGov, was used to field an Internet survey of a nationally representative sample of 1000 parents of children 5 y old or younger between November 3 and December 1, 2014. YouGov employs stratified sampling designed to produce representative population estimates that are analogous to those from probability telephone or mail surveys.⁴⁹ YouGov interviewed 1054 respondents who were then matched down to a sample of 1000 to produce the final data set. Respondents were matched on gender, age, and race to a sampling frame constructed using the 2012 National Health Interview Survey. Parents with more than one child were asked to use their youngest child as the frame of reference. The survey assessed both compliance with the US recommended childhood vaccination schedule to date and intention to comply with future vaccinations. Equivalent questions were used to assess past and potential future use of children's antibiotics, OTC medicines, and vitamins. In line with other published studies, the survey assessed delay or declination for reasons other than illness or allergy. For each product category, parents were also asked if they had a bad reaction experience “outside of general soreness, fever, redness, or swelling at the injection site” and whether they had knowledge of anyone who had experienced a bad reaction “outside of general soreness, fever, redness, or swelling at the injection site.” In addition, respondents were asked if they knew of anyone who had a vaccine-preventable disease. Parents were also asked to indicate their level of agreement with statements related to their level of trust in the advice they received about vaccines, antibiotics, OTC medicines, and children's vitamins from their child's doctor or health care provider.

The study used 3 items to assess parents' confidence that 1) their child's overall health would benefit from the recommended item; 2) their child will not have a bad reaction to the recommended item (i.e., safety); and 3) the recommended item would be effective for protection, treatment or prevention. The vaccine confidence measures and measurement approach was based on previously published studies in order to provide a basis for comparing and interpreting the results of this survey. Weiner et al.²³ and Kennedy et al.,²⁵ for example, used similar items that assessed parents' confidence in vaccine effectiveness, benefits and safety. As Table 3 illustrates, vaccine-related confidence was assessed for the recommended vaccination schedule and in terms of the individual vaccines.

Statistical analyses included cross tabulations, ANOVAs, and multiple regression, with demographic, behavior/use and intentions, and bad event experiences and perceptions being the variables of interest.

Abbreviations

NVAC	=	National Vaccine Advisory Committee
OTC medicine	=	over the counter medicine
SAGE	=	Strategic Advisory Group of Experts
US	=	United States

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Funding

Funding for this research was provided by the Grady College of Journalism and Mass Communication at the University of Georgia.