Journal of Womens Health, Issues and Care ISSN: 2325-9795

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Research Article, J Womens Health Issues Care Vol: 3 Issue: 6

Nuances in Inoculation: Protecting Positive Attitudes toward the HPV Vaccine & the Practice of Vaccinating Children

Norman C. H. Wong1* and Kylie J. Harrison2
1Department of Communication, University of Oklahoma, USA
2Center for Curriculum, Learning, Technology, and Institutional Assessment, Mid-America Christian University, USA
Corresponding author : Norman C. H. Wong
Department of Communication at the University of Oklahoma, 610 Elm Avenue, Norman OK 73019
E-mail: [email protected]
Received: July 15, 2014 Accepted: October 19, 2014 Published: October 23, 2014
Citation: Wong NCH, Harrison KJ (2014) Nuances in Inoculation: Protecting Positive Attitudes toward the HPV Vaccine & the Practice of Vaccinating Children. J Womens Health, Issues Care 3:6. doi:10.4172/2325-9795.1000170

Abstract

Nuances in Inoculation: Protecting Positive Attitudes toward the HPV Vaccine & the Practice of Vaccinating Children

This study examined the use of two different inoculation messages in conferring resistance to persuasive messages attacking vaccinations. A three-phase experiment involving 212 participants was conducted to determine if young women who held positive attitudes toward the HPV vaccine/practice of vaccinating children could be inoculated against messages attacking the HPV vaccine/ practice of vaccinating children.

Keywords: Inoculation; HPV vaccine; Children

Keywords

Inoculation; HPV vaccine; Children

Introduction

Inoculation theory [1-6] offers a compelling theoretical framework for thwarting influence attempts through the induction of resistance to persuasion [7,8]. The combined function of motivating individuals to protect their attitudes by revealing the vulnerability of that attitude to attacks and equipping them with arguments to respond to counterattitudinal challenges have been credited as the active ingredients in the inoculation process [1,7,8]. Simply put, when individuals are informed they will encounter arguments that challenge their views on an issue, “a response analogous to inoculating with a weakened virus a person who has been raised in a germ-free environment would be expected to stimulate the person’s belief defenses, thus making him or her better able to resist the subsequent massive exposure” (p.184). Inoculation triggers threat, which in turn motivates counterarguing, and as a result, the person becomes more resistant to influence attempts.
Inoculation is a strong metaphor for the resistance process and the use of inoculation treatments has been shown to be an effective strategy at promoting resistance to influence in many persuasion contexts. Extant research has documented clear support for the inoculation strategy in political campaigns [9,10], advertising and public relations campaigns [11], credit card vendors [12], deceptive stealth campaigns by corporate front-groups [13] underage and binge drinking [14,15] and tobacco use [16,17]. Some of the consistent outcomes that have been found related to inoculation are that perceived attitudinal threat and counterarguing output are elicited at higher levels in inoculated versus control participants [18-20]. Inoculation treatments have also been found to enhance elicited issue involvement [13,18,19].
Specifically within the health context, inoculation treatments have been used to confer resistance to negative health behaviors and to protect positive attitudes about healthy behaviors from declining over time. Pfau, et al. [17] conducted a study to look at whether inoculation treatments could help confer resistance to smoking initiation among adolescents who held negative attitudes toward smoking. It was found that inoculation treatments successfully helped to protect the negative attitudes adolescents had about smoking from declining at both year 1 following the administration of the inoculation pretreatment [16] and year 2 [17].
Godbold, et al. applied inoculation treatments to help confer resistance to peer pressure among adolescents to discourage alcohol use. Specifically, sixth graders who were non-drinkers were inoculated against drinking with a normative inoculation message (compared to an informational or control message). Results found that those who received a normative inoculation message reported lower estimates of peer acceptance of alcohol and experienced less attitude change (i.e., remained negative about alcohol) than those who received the informational message or the control message [14].
Goldberg, et al. [21] tested an intervention to reduce alcohol use among adolescents by forewarning them about the persuasive tactics advertisers use to get them to drink alcohol and how to recognize and cope with social pressures to use alcohol. The goal was to inoculate these individuals to confer resistance to persuasive attempts to get them to use alcohol. Results found that compared to those who did not receive the inoculation, those who did reported more negative attitudes toward alcohol advertising and advertisers, greater knowledge of persuasive tactics, and better ability to cope with social pressure situations involving alcohol [21].
In the present study, inoculation theory will be tested in two vaccination contexts, specifically looking at the Human Papillomavirus (HPV) vaccine and the practice of vaccinating children. These two contexts were selected because both issues are likely to be moderately involving for young women (i.e., HPV mainly affects women, and childhood vaccination decisions are often made by the mother), and are topics that are vulnerable to attack due to the controversy surrounding the safety and efficacy of the HPV vaccine (e.g., reports of severe side effects) and the alleged link between the practice of vaccinating children and their development of autism and other neurological disorders. It has been argued that issue involvement plays an important role in the inoculation process such that topics that are moderately involving benefits the most from inoculation messages [7,13]. To date, inoculation theory has not been tested as a framework with either the topic of HPV vaccinations or childhood vaccinations.
The debate surrounding the safety of the HPV vaccine specifically and the practice of vaccinations more broadly provide excellent applied contexts in which to test the nuances of inoculation theory [1-6]. On the one hand, news stories that call into question the safety of the HPV vaccine or the practice of vaccinating children via the telling of emotionally traumatic stories may lower young women’s positive attitudes toward both the HPV vaccine and the idea of vaccinating children, and may also reduce their intentions to get the HPV vaccine or to support having their children receive all their recommended vaccinations in the future. These news stories essentially serve as counterattitudinal attack messages for young women with preexisting positive attitudes toward both the HPV vaccine and the practice of vaccinating children against diseases. On the other hand, messages from the CDC and other health professionals designed to bolster people’s confidence in the safety of the HPV vaccine and the practice of getting children vaccinated in general (i.e., to prevent the onset of a variety of conditions such as measles, rubella, and influenza), and that show how vaccination benefits far outweigh the risks of not getting vaccinated may serve as an effective inoculation protecting their positive attitudes from attacks by triggering counter-arguing processes. Taken together, both sets of messages can be used to conduct an applied test of inoculation theory. It is worth noting that unlike previous inoculation studies, the present research seeks to test the power of inoculation messages that occur more naturally in the mass media environment to confer resistance to influence as opposed to those that are crafted by researchers. Based on previous inoculation studies, it is expected that individuals who receive the inoculation treatment (compared to those that do not) will experience greater attitudinal threat, become more involved with the topic, engage in greater counterarguing, exhibit less decline in vaccination attitudes following exposure to a counterattitudinal attack message, perceive vaccines more positively in terms of their safety and efficacy, and report higher vaccination intentions.
While it is clear that the inoculation strategy has been shown to be effective at promoting resistance to persuasion [8], Compton, et al. called for additional fine-tuning of the theory to determine if a single inoculation pretreatment can afford protection to multiple counterattitudinal attacks. Compton and Pfau have labeled this new line of inoculation inquiries the “blanket of protection” [7], however Parker, et al. [22] called this phenomenon the “umbrella of protection” (p. 9). This line of inquiry is the logical extension of the general immunizing effect discovered early in inoculation research. Specifically, in numerous empirical investigations the active pair of threat and counterarguments mitigates the “subsequent belief-weakening impact not only of strong forms of the same counterarguments but of alternate counterarguments as well” [5]. The general immunizing effect makes the application of inoculation much more efficacious because it is unlikely that all possible counterattitudinal challenges could be anticipated [22] and responded to in a single message.
The umbrella of protection simply takes the general immunizing effect a step further by advancing that not only can inoculation confer resistance to same and different counterattitudinal attacks on the same topic, the inoculation can also protect different but related topics (i.e., within the same content category). The general immunizing effect has been confirmed repeatedly by a multitude of tests of inoculation [9,10,12,13,18,20,23,24], and as a result, it is likely that the blanket of protection extends beyond just the specific attitude object in question to broader attitudes about the topic. In their study, Parker et al. [22] investigated whether or not a single inoculation focused on protecting young adults from unprotected sex (i.e., a risky behavior) would also work to help inoculate them against binge drinking (i.e., another risky behavior). Their results confirm a general immunizing effect whereby inoculating against risky a behavior such as unprotected sex was also effective at inoculating against binge drinking, a different but related topic [22]. The current study looks at whether an inoculation against attacks on the practice of vaccinating children would be effective at inoculating against attacks on a related, but different topic (i.e., getting the HPV vaccine). The HPV vaccine is one of several recommended vaccinations for young college adults, along with vaccinations to prevent meningitis, tetanus, and influenza [25]. Specifically, it is expected that inoculation treatments targeted for conferring resistance to attacks against the general practice of vaccinations will also confer resistance to attacks on getting the HPV vaccine. With the development of new vaccines occurring often, having a single inoculation message to counter potential attacks on different vaccines would make for a more efficient way to build resistance to persuasion among health consumers. Thus, the following set of hypotheses are posited to test both traditional inoculation theory as well as the recent extension of the umbrella of protection effect:
H1: Compared to those not receiving a HPV vaccine inoculation treatment, participants receiving the inoculation treatment will report greater perceived attitudinal threat, issue involvement, and counterarguing output related to the HPV vaccine.
H2: Compared to those not receiving a generalized vaccination inoculation treatment, participants receiving the inoculation treatment will report greater perceived attitudinal threat, issue involvement, and counterarguing output related to the practice of vaccinating children.
H3: Compared to those not receiving a HPV vaccine inoculation treatment, participants receiving the inoculation treatment will report more positive attitudes and greater perceptions of safety and efficacy toward the HPV vaccine, and higher intent to get the HPV vaccine in the next year.
H4: Compared to those not receiving a generalized vaccination inoculation treatment, participants receiving the inoculation treatment will report more positive attitudes and greater perceptions of safety and efficacy toward the practice of vaccinating children, and higher intent to vaccinate their children in the future.
H5: Compared to those receiving no HPV vaccine inoculation treatment, participants who receive the generalized inoculation treatment about the safety and efficacy of getting vaccinations will be more resistant to attacks on the safety and efficacy of getting the HPV vaccine.
The present research also seeks to determine whether inoculation against attack messages on the HPV vaccine can be used to protect people’s positive attitudes toward the general practice of vaccinating children from counter-attitudinal attacks. Simply put, would the refutational preemption of specific attacks against getting the HPV vaccine confer resistance to attacks on the practice of vaccinating children? Since this idea of a diffusion effect for an inoculation treatment (i.e., using preemptive refutations designed to protect a specific attitude object to protect general attitudes about the behavior category) has not been explored in previous inoculation studies, the following research question is posed:
RQ1: Can the HPV vaccine inoculation treatment confer resistance against an attack on the safety and efficacy of vaccinating children and how does this compare to no inoculation treatment?

Methods

Participants
Participants were 212 female students between the ages of 18- 26 (M =19.84, SD=1.47) who had not completed any of the HPV vaccinations (i.e., not received any of the 3 required doses). This was an important inclusion criterion given that we were interested in measuring women’s intent to get the HPV vaccine. Female students were recruited from introductory communication courses at a large Southwestern university. Participants were given course credit in exchange for their participation in the study.
Procedures
A secure on-line survey collector was used to collect the data for this three-phase study. During Phase 1 (initial screening), participants completed a brief survey to determine if they had favorable attitudes toward the HPV vaccine and/or the practice of vaccinating children. If the individuals did not have favorable attitudes toward either topic (i.e., they scored below the median on the attitudinal measures), they were thanked for their interest in the study and excused. Inoculation treatments in this study were designed to reinforce existing positive attitudes and therefore, individuals with negative attitudes toward both the HPV vaccine and the practice of vaccinating children were not appropriate for this study.
Prior to Phase 2, the attitude scores of the remaining participants were examined. Three pools of participants were created. For the first pool, those participants who scored above the median on attitudes toward the HPV vaccine only were randomly assigned to the HPV vaccine inoculation or the control condition (no inoculation). For the second pool, those participants who scored above the median on attitudes toward the practice of vaccinating children only were randomly assigned to the generalized vaccination inoculation or the control condition (no inoculation). Lastly, for the third pool, those participants who had favorable attitudes toward either topic were randomly assigned to 1 of 3 conditions (HPV vaccine inoculation, generalized vaccination inoculation, no inoculation). Within each pool, participants were given an arbitrary ID number (e.g., 001, 002, etc.) and for participant pools 1 and 2, every odd numbered participant was assigned to the inoculation condition, and every even numbered participant assigned to the control condition. For the last participant pool, beginning with a random starting point, every 2nd participant was assigned to the HPV vaccine inoculation, every 3rd participant was assigned to the generalized inoculation, and every 4th participant was assigned to receive no inoculation. There was a short delay (i.e., 2 days) between the administration of Phase 1 and Phase 2. Participants were emailed a link that directed them to the assigned experimental condition.
During Phase 2, participants were first asked to complete a set of pretest measures to reassess their attitudes toward the HPV vaccine/practice of vaccinating children along with their level of issue involvement, perceived safety and efficacy, and behavioral intentions regarding the HPV vaccine/practice of vaccinating children. Next, participants in the inoculation conditions were exposed to the threat manipulation that warned all participants that despite their positive opinions about either the HPV vaccine or the idea of vaccinating children, there was a real possibility that they would encounter arguments that attacked their position due to the controversy surrounding the safety and effectiveness of both the HPV vaccine (e.g., concerns of paralysis and death) and the practice of vaccinating children (e.g., concerns of autism and other neurological disorders). Following this, participants in the inoculation conditions watched one of two real news stories embedded in the online survey, which featured a physician discussing some concerns raised by the media, parents, and other interest groups about the HPV vaccine or the practice of vaccinations in general and their responses to these concerns, reassuring people that the HPV vaccine/practice of vaccinations in general are both safe and important. Participants in the control condition were not given the threat message nor did they watch any news stories about vaccinations. Finally, counterarguing output was assessed in which all participants were asked to generate both counterattitudinal arguments and responses to these counterattitudinal arguments regarding the HPV vaccine or the practice of vaccinating children. For both sets of arguments, they rated the strength of the arguments.
Prior to Phase 3, participants were randomly assigned to one of two attack message conditions: one attacking the safety and efficacy of the HPV vaccine and the other attacking the safety and efficacy of vaccinating children. Combined with their inoculation treatment condition, participants were randomly assigned to 1 of 6 experimental conditions: HPV vaccine inoculation-HPV vaccine attack, HPV vaccine inoculation-childhood vaccinations attack, generalized vaccinations inoculation-HPV vaccine attack, generalized vaccinations inoculation-childhood vaccinations attack, HPV vaccine attack only, or childhood vaccinations attack only). Random assignment of participants to condition was done via the online survey company that administered the study surveys. Approximately one week elapsed between Phase 2 and Phase 3. Participants were emailed a link that directed them to the appropriate experimental condition.
During Phase 3, participants first viewed the attack messages that included a news story attacking both the safety and efficacy of the HPV vaccine or the practice of vaccinating children and then completed posttest measures to assess attitudes, level of involvement, and perceived safety and efficacy related to the HPV vaccine/practice of vaccinating children. Additionally, participants were asked about their behavioral intentions to get the HPV vaccine in the next year or to get their children vaccinated in the future should they have any children.
Experimental materials
Inoculation messages: Two real news reports were selected for the inoculation messages. Official messages promoting the safety and efficacy of the HPV vaccine and the practice of vaccinations in general were adapted into the standard inoculation format which first emphasized the vulnerability of a viewer’s attitudes and the likelihood those vulnerable attitudes would be subsequently attacked in the future (see threat manipulation described below).
One message was specifically designed to inoculate against attacks on the safety and efficacy of getting the HPV vaccine and one message was designed to inoculate against attacks on the safety and efficacy of the practice of vaccinations in general. Both messages comprised of detailed media interviews with medical doctors who first talked about the concerns that they have heard raised by both parents and other interest groups regarding either the HPV vaccine (e.g., unsafe, causes severe side effects, can be fatal) or the practice of vaccinations in general (e.g., it causes severe adverse reactions or fatalities, vaccines are not properly tested, they are unnecessary), then responded to these claims by providing reassurance of the safety and efficacy of getting the HPV vaccine (e.g., very few adverse reactions to the HPV vaccine have been reported among millions of doses given, HPV vaccine is approved by the FDA and endorsed by the CDC, and HPV vaccine shown to prevent HPV infections in scientific studies) or the practice of vaccinations in general (e.g., vaccines would never be put on the market if they are unsafe and ineffective, side effects occur with all medications, severe adverse reactions are rare and isolated incidents, and vaccinations save lives).
Threat manipulation: To manipulate threat in the inoculation conditions, participants read a short message designed to warn them of a potential attack on their positive attitudes toward either getting the HPV vaccine or the practice of vaccinating children. Specifically, participants read a message that said, “Despite your positive attitude and feelings toward (the HPV vaccine/the practice of vaccinating children), there exists out there many reports and stories by the media and various interest groups aimed at attacking your attitude and feelings on this issue, and there is a real possibility that you will come into contact with these arguments in the near future, some of which are so persuasive that they may cause you to question your attitude and feelings toward (getting the HPV vaccine/supporting the practice of vaccinating children against diseases).” This threat message was modeled after those used in past inoculation studies [15,26].
Attack messages: Real news reports were selected as the two attack messages to be used in this study. The clips were taken from a search online and featured a combination of both national news reports (e.g., CBS news) and local news report (e.g., the authors’ local CBS affiliate station). Specifically, safety concerns about the HPV vaccine were highlighted in two news reports, one focused on a summary of national cases where young women reported paralysis, experiences of severe pain, or death after getting the HPV vaccine, and the other focused on a local case where a young girl was diagnosed with a serious chronic health condition (i.e., autoimmune disease) after receiving the HPV vaccine from her family doctor.
Two news reports were also used to raise safety concerns about the practice of vaccinating children against diseases. A local news report was presented where a young girl featured in the story was diagnosed with autism after receiving her series of childhood vaccinations from her physician. Her mother directly attributed the cause of the disorder to the vaccinations, saying that her behavior only changed after receiving the vaccinations at the doctor’s office. For the national news report, a CBS story featured several parents talking about how their children developed a neurological disorder or became autistic after receiving vaccinations at the doctor’s office, two of the parents featured were medical doctors themselves.
Measures
Attitude toward vaccinations: In order to assess attitudes about vaccinations, Burgoon, et al. [27] attitude instrument consisting of six 7-interval bipolar adjective pairs was employed. The statement: “Your overall attitude toward (g etting the HPV vaccine/children getting vaccinations) is that it is” was followed by six adjective pairs: negative/ positive, wrong/right, foolish/wise, good/bad, unfavorable/favorable, and unacceptable/acceptable (Burgoon et al., 1978). Both attitudes toward getting the HPV vaccine and children getting vaccinations were assessed. Reliability of the attitude scale was very good for participants’ attitudes toward getting the HPV vaccine during both the pretest (M=5.44, SD =1.41, α=.96) and the posttest (M=4.34, SD= 1.53, α=.97). Participants’ attitudes toward children getting vaccinations were also very reliable both during the pretests (M=5.67, SD =1.36, α=.97) and the posttest (M=4.57, SD =1.53, α=.98).
Personal issue involvement: In order to assess participant involvement with the HPV vaccination issue or the topic of childhood vaccinations, Zaichkowsky’s [28] Personal Involvement Inventory, a 7-point bipolar adjective scale used in previous inoculation studies was employed. Six adjective pairs followed the question of “How important is the issue of (HPV vaccines/childhood vaccinations) to you?”: means nothing/means a lot, unimportant/important, of no concern/ of much concern, doesn’t matter/matters to me, and insignificant/significant, irrelevant/relevant. The reliability of the Personal Involvement Inventory on the importance of the HPV vaccination issue was very good both for the pretest (M=4.93, SD =1.59, α=.97) and the posttest (M=4.53, SD =1.45, α=.97). The reliability of the Personal Involvement Inventory on the issue of childhood vaccinations was also very good for the pretest (M=5.47, SD =1.38, α=.97) and the posttest (M=3.72, SD =2.08, α=.97).
Perceived vaccination safety: Five items were included in the pretest and posttest in order to assess participants’ perceptions of the safety of the HPV vaccine and the practice of vaccinating children. Items were adapted from measures used in a previous study that looked at HPV vaccination safety [29]. A sample item includes: How concerned are you about the negative side effects that may occur to (you/your child) if (you/your child) received (the HPV vaccine/their vaccinations)? Participants responded by indicating on a 7-point scale from (1) “not at all concerned” to (7) “very concerned.” The reliability of participants’ perceived safety measure for getting the HPV vaccine was good both for the pretest (M=3.72, SD =1.38, α=.87) and the posttest (M=3.67, SD =1.44, α=.90). Similarly, the reliability of participants’ perceived safety measure for children receiving their vaccinations was very good for the pretest (M=3.95, SD =1.51, α=.90) and posttest (M=3.69, SD =1.54, α=.93).
Perceived vaccination efficacy: Four items were included in the pretest and posttest in order to assess participants’ perceptions of the efficacy of the Gardasil HPV vaccine and children getting vaccinated. Items were adapted from measures used in a previous study that looked at HPV vaccination effectiveness [29]. A sample item includes: How effective do you feel the (HPV vaccine/practice of vaccinating children) is in protecting (people against HPV/them against diseases)? Participants responded by indicating on a scale of 1-7 whether they believed the vaccination to be “not at all effective” to “very effective.” The reliability for the measure of participants’ perceptions of the efficacy of the Gardasil HPV vaccine in preventing HPV-related diseases was very good both for the pretest (M=4.98, SD =1.20, =.94) and posttest (M=4.67, SD =1.36, α=.96). The reliability for the measure of participants’ efficacy perceptions about childhood vaccinations for preventing diseases were also high both at the pretest (M=5.61, SD =1.02, α=.93) and posttest (M=5.02, SD =1.35, α=.95).
Behavioral intention: In order to assess behavioral intention to get the HPV vaccine or to get their children vaccinated in the future, three items were used. A sample item inclu des, “How seriously will you consider getting (the HPV vaccine in the next year/your children all of their recommended vaccinations in the future should you have any)?” on a 7-point scale from “not at all” to “very seriously.” The reliability for the measure of participant’s intentions to get the HPV vaccine in the next year was very good both in the pretest (M=4.16, SD =2.07, α=.98) and posttest (M=3.72, SD =2.08, α=.94). Similarly, the reliability of the measure on behavioral intention of the participants to get their children all their recommended vaccinations in the future was also very good both for the pretest (M=5.98, SD =1.31, α=.97) and posttest (M=5.18, SD =1.73, α=.95).
Manipulation checks
Threat: In order to assess attitudinal threat, bipolar adjective pairs used in earlier inoculation studies were employed. Participants were asked to rate on a 7-point scale the extent to which the possibility of having their attitudes toward the HPV vaccine/practice of vaccinating children attacked to be: safe/dangerous, unintimidating/intimidating, nonthreatening/threatening, not harmful/harmful, and not risky/ risky [13,26]. The reliability of the threat measure was very good (M=3.83, SD=1.59, α=.95). Higher scores reflected greater perceived attitudinal threat.
Counterarguing output: To measure counterarguing, participants were asked to use a thought-listing procedure [30]. First, participants were asked to identify as many possible (up to 10) persuasive arguments (i.e., counterattitudinal arguments) that opposed their favorable view of the HPV vaccine or the practice of vaccinating children. Participants were then asked to list as many as possible responses (up to 10) to these counterattitudinal arguments. This two-step procedure has been used in previous inoculation studies [23,24]. Next, participants were directed to evaluate the strength of the counterattitudinal arguments and their responses to the counterattitudinal arguments using a 7-point rating system, with 7 being a very strong argument and 1 being a very weak argument, employed by Pfau, et al. [13]. Combining both sets of information, overall counterarguing output regarding the HPV vaccine and the practice of vaccinating children were calculated using the following formula developed and used by Pfau, et al. [13]: (Total # of counterattitudinal arguments x strength of counterattitudinal arguments) – (total # of responses to counterattitudinal arguments x strength of responses to counterattitudinal arguments). Using the formula, the larger the negative number, the greater the amount of counterarguing output.
Data analyses
Two Multivariate Analyses of Covariances (MANCOVAs) were used to test for traditional inoculation effects (i.e., matching of inoculation and attack messages) as well as to test the two alternative pathways of the inoculation process (i.e., umbrella of protection effect, diffusion effect). For one of the MANCOVAs, the outcome measures were all related to the HPV vaccine (e.g., Phase 2 perceived attitudinal threat and counterarguing output for the HPV vaccine; Phase 3 attitudes and involvement toward the HPV vaccine, perceived safety and efficacy of the HPV vaccine, and intentions to get the HPV vaccine in the next year). HPV vaccine attack-focused conditions (i.e., HPV vaccine inoculation-HPV vaccine attack, generalized vaccination inoculation-HPV vaccine attack, and HPV vaccine attack only) served as the independent factor.
For the other MANCOVA, the outcome measures were all related to the practice of vaccinating children (e.g., Phase 2 perceived attitudinal threat and counterarguing output for the practice of vaccinating children; Phase 3 attitudes and involvement toward childhood vaccinations, perceived safety and efficacy of vaccinating children, and intentions to have their children receive all recommended vaccinations in the future). Childhood vaccination attack-focused conditions (i.e., HPV vaccine inoculation-childhood vaccination attack, generalized vaccination inoculation-childhood vaccination attack, and childhood vaccination attack only) served as the independent factor.
Pretest measures (i.e., Phase 2) of attitudes and involvement, perceived safety and efficacy, and behavioral intentions related to both the HPV vaccine and the practice of vaccinating children were used as covariates in the MANCOVA analyses. This was done to increase our confidence that changes in the dependent variable occurred due to changes in the independent variable.

Results

A breakdown of the demographics for the participants by experimental condition is provided in Table 1. A summary of the means and standard deviations for the pretest measures are provided in Table 2. All of the omnibus results were followed by univariate tests where significant results were found. Planned comparisons were conducted to test specific hypotheses.
Table 1: Breakdown of Demographics by Experimental Condition.
Table 2: Means and Standard Deviations for Pretest Measures.
Preliminary analyses
The first manipulation check was performed on the level of perceived attitudinal threat generated by the inoculation messages. For the inoculation messages to work, they need to be able to elicit high levels of attitudinal threat among those receiving the inoculation so that they feel their positive attitudes toward the HPV vaccine/ practice of vaccinating children are vulnerable to attack in the near future. An independent samples t-test was performed on the data set with inoculation condition (present/absent) as the independent variable and perceived attitudinal threat as the dependent measure. On average, participants who received an inoculation treatment (either for the HPV vaccine or practice of vaccinations in general) reported feeling greater Phase 2 attitudinal threat (M=4.09, SD=1.47, n=141) than those who received no inoculation treatment during Phase 2 of the study (M=3.32, SD=1.71, n=71), t(210)=3.38, p<.01, η2=.05.
The second manipulation check was performed to determine whether the inoculation was properly manipulated and whether it yields findings consistent with past inoculation research. If successfully manipulated, those who received an inoculation message should report significantly greater counterarguing output compared to those who received no inoculation message. An independent samples t-test was conducted with inoculation condition (present/ absent) as the independent variable and total counterarguing output (i.e., collapsed across both the HPV vaccine/practice of vaccinating children conditions) as the dependent measure. Those who received an inoculation treatment (either for the HPV vaccine or the practice of vaccinating children) reported greater overall Phase 2 counterarguing output (M=-7.37, SD=8.92, n=141) than those who received no inoculation treatment during Phase 2 of the study. (M=- 2.55, SD=5.37, n=71), t(210)=4.18, p<.001, η2=.08.
Main analyses
To test the three study hypotheses and answer the research question posed, two MANCOVAs were performed on the data set (described above). For the MANCOVA that focused on outcomes related to the HPV vaccine, Phase 2 (i.e., pretest) measures of perceived efficacy of the HPV vaccine, F(6, 97)=5.68, p<.001, Pillai-Bartlett’s V=.27, and HPV vaccine intention, F(6, 97)=5.52, p<.01, Pillai-Bartlett’s V=.25 were significant covariates. These were controlled for in all analyses related to HPV vaccine outcomes.
For the MANCOVA that focused on outcomes related to practice of vaccinating children, Phase 2 (i.e., pretest) measures of involvement with the issue of childhood vaccinations, F(6, 89)=4.51, p<.001, Pillai-Bartlett’s V=.25, perceived safety of vaccinating children, F(6, 89)=2.89, p<.05, Pillai-Bartlett’s V=.17, and intention to vaccinate their children in the future, F(6, 89)=2.91, p<.05, Pillai-Bartlett’s V=.12 were all significant covariates. These were all controlled for in analyses related to outcomes regarding the practice of vaccinating children.
HPV Vaccine-related outcomes
Hypothesis 1: It was predicted that those who received the HPV vaccine inoculation message would report greater attitudinal threat, issue involvement and counterarguing output related to the HPV vaccine compared to those not receiving the inoculation. This prediction was partially supported. Planned comparisons examining control (no inoculation) and HPV vaccine inoculation condition means indicated that inoculated participants experienced: greater attitudinal threat, F(1, 72)=21.35, p<.001, η2=.23; and greater counterarguing output, F(1, 72)=7.08, p<.05, η2=.09. However, there was no significant difference in terms of elicited issue involvement between the two groups, F(1, 72)=1.33, p=.25. Means are displayed in Table 3.
Table 3: Dependent Measures as a Function of Experimental Conditions for HPV Vaccine-Related Outcomes.
Hypothesis 3. It was predicted compared to those not receiving a HPV vaccine inoculation message, participants receiving the inoculation will report more positive attitudes and perceptions of safety and efficacy toward the HPV vaccine, and higher intentions to get the HPV vaccine in the next year. This prediction was supported. Planned comparisons examining control and HPV vaccine inoculation condition means revealed that inoculated participants reported: more positive attitudes toward the HPV vaccine, F(1, 72)=11.74, p<.01, η2=.14, greater perceptions of HPV vaccine safety, F(1, 72)=18.73, p<.001, η2=.21, HPV vaccine efficacy, F(1, 72)=4.70, p<.05, η2=.06, and greater intent to get the HPV vaccine, F(1, 72)=11.86, p<.01, η2=.14. Means are shown in Table 3.
Hypothesis 5. It was predicted that compared to those receiving no HPV vaccine inoculation message, participants inoculated about the safety and efficacy of receiving vaccinations in general will be more resistant to attacks on the safety and efficacy of getting the HPV vaccine. This was a test of the “umbrella of protection” effect and it was partially supported. Planned comparisons examining means between the control group and the generalized vaccination inoculation-HPV vaccine attack condition revealed that those inoculated against attacks on the safety and efficacy of receiving vaccinations in general reported: more positive attitudes toward the HPV vaccine, F(1, 71)=12.42, p<.01, η2=.15, greater perceptions of HPV vaccine safety, F(1, 71)=13.04, p<.01, η2=.16, intent to get the HPV vaccine, F(1, 71)=15.25, p<.001, η2=.18 and more counterarguing related to the HPV vaccine, F(1, 71)=9.34, p<.01, η2=.12. However, the generalized vaccination inoculation condition did not differ from the control group in terms of perceived HPV vaccine efficacy, F(1, 71)=2.43, p=.12. Means are reported in Table 3.
Practice of vaccinating children-related outcomes
Omnibus results. Practice of vaccinating children attack-focused condition was found to have a significant main effect on childhood vaccinations outcomes, Pillai-Bartlett’s V=.43, F(14, 178)=3.49, p<.001, partial η2=.22. The univariate test for childhood vaccinations attack-focused condition revealed significant effects on: Phase 2 perceived attitudinal threat, F(2, 94)=14.64, p<.001, η2=.23; Phase 3 perceived safety of vaccinating children, F(2, 94)=4.04, p<.05, η2=.06; Phase 3 intent to get their future child vaccinated, F(2, 94)=6.61, p<.05, η2=.04; and Phase 2 counterarguing output related to the practice of vaccinating children, F(2, 94)=4.78, p<.05, η2=.09.
Hypothesis 2. It was predicted that compared to those not receiving a generalized vaccination inoculation treatment, those who were inoculated would report greater perceived attitudinal threat, issue involvement, and counterarguing output related to practice of vaccinating children. This prediction was partly supported. Planned comparisons examining control (no inoculation) and generalized vaccination inoculation condition means revealed that inoculated participants did report experiencing greater attitudinal threat, F(1, 65)=16.21, p<.001, η2=.20, and more counterarguing output related to the practice of vaccinating children, F(1, 65)=7.02, p<.05, η2=.10, but not elicited issue involvement with the topic of childhood vaccinations, F(1, 65)=0.21, p=.65,. Means are displayed in Table 4.
Table 4: Dependent Measures as a Function of Experimental Conditions for the Practice of Vaccinating Children-Related Outcomes.
Hypothesis 4. It was expected that participants who received the generalized vaccinations inoculation message would report more positive attitudes and greater perceptions of safety and efficacy toward the practice of vaccinating children, and also higher intentions to get their children vaccinated in the future. This prediction was supported. Planned comparisons examining control and generalized vaccination inoculation condition means indicated that inoculated participants had: more positive attitudes toward the practice of vaccinating children, F(1, 65)=7.07, p<.05, η2=.10, higher perceptions of safety about vaccinating children, F(1, 65)=11.32, p<.01, η2=.15, efficacy regarding childhood vaccinations, F(1, 65)=5.48, p<.05, η2=.08, and greater intent to vaccinate their children in the future, F(1, 65)=7.68, p<.01, η2=.11. Means are found in Table 4.
Research question one. An inquiry was made regarding whether a diffusion effect could occur whereby an inoculation treatment for attitudes toward a specific topic (i.e., the HPV vaccine) could confer resistance to attacks on generalized attitudes about the topic (the practice of vaccinations in general). Planned comparisons examining the means between the control group and the HPV vaccine inoculation-childhood vaccination attack condition indicated that inoculated participants did not report: greater attitudes toward the practice of vaccinating children, F(1, 65)=1.48, p=.23, higher perceptions of safety about vaccinating children, F(1, 65)=3.40, p=.05, efficacy of childhood vaccinations, F(1, 65)=2.28, p=.14, or intent to get their children vaccinated in the future, F(1, 65)=3.33, p=.07. Thus, the current study finds no empirical support for the “diffusion effect” of inoculation. However, inspection of the means suggest that compared to controls, those who were inoculated with the HPV vaccine inoculation message did enact some resistance to counterattitudinal attacks on the practice of vaccinating children. Means are reported in Table 4.

Discussion

This study sought to further enhance our understanding of the inoculation process for conferring resistance to influence by testing two alternative pathways for the inoculation process, an umbrella of protection effect (i.e., using an inoculation for a generalized attitude to protect against attitudinal attacks on a specific attitude toward a given topic) and a diffusion effect (i.e., using an inoculation for a specific attitude to protect against attitudinal attacks on a generalized attitude toward a given topic). The investigation also looked at the impact inoculation had on both traditional inoculation outcomes (e.g., attitudes, counterarguing, issue involvement) as well as more nuanced outcomes (e.g., perceived safety and efficacy, intentions) related to vaccinations.
Hypotheses 1 to hypotheses 4 examined traditional inoculation pathways, whereby there was a match between the issues on which individuals were inoculated on and the counterattitudinal attack message they received. With regards to traditional inoculation outcomes, the results revealed that inoculation treatments elicited greater perceived attitudinal threat and counterarguing, but not issue involvement. These findings are somewhat consistent with previous inoculation studies but do confirm the instrumental role of attitudinal threat [5,18-20] in motivating resistance. One possible explanation for why the inoculation treatments in this study did not elicit greater issue involvement as has generally been the case in previous inoculation research [18-20] may be due to the fact that the inoculation treatments weren’t designed to bolster issue involvement as part of the experimental manipulation.
In terms of more nuanced outcomes, the results indicated that inoculation treatments were also somewhat effective at protecting individuals’ initial perceptions of safety and behavioral intentions regarding vaccinations from attacks aimed at negatively altering those perceptions. The results showed that inoculation confers resistance to protect more than just a person’s attitudes but also other cognitions as well. In particular, the results revealed that participants who received the inoculation treatments reported significantly higher intentions to get the HPV/have their children vaccinated in the future than those who did not receive the inoculation treatments. This implies that inoculating against negative messages about vaccinations may be an effective strategy to help to bolster vaccination rates.
Hypothesis 5 examined the umbrella of protection effect that some inoculation scholars have argued could occur [15,31] in which a generalized inoculation treatment can motivate people to generate an arsenal of counterarguments able to withstand a variety of different attacks on the person’s beliefs regarding multiple topics (e.g., getting the HPV vaccine, getting the H1N1 vaccine, getting the meningitis vaccine, or getting my children vaccinated) that are all connected within a broad content domain (getting vaccinations). The results did find support for an “umbrella of protection” effect in that individual who received a generalized inoculation to confer resistance to attacks on their beliefs about the practice of vaccinations in general also had their beliefs about the HPV vaccine protected from counter attitudinal attacks.
Interestingly, a diffusion effect was not found in that an inoculation treatment designed to confer resistance against attacks on the HPV vaccine did not protect people’s beliefs from an attack on the practice of vaccinating children. One potential explanation for not finding support for this effect may be that we did not examine outcomes related to the practice of vaccinations in general. Instead, we only looked at outcomes related to the practice of vaccinating children, which is a different topic. It may be the case that inoculating people against attacks on the HPV vaccine could also protect people’s attitudes toward the idea of getting other vaccinations as well. This is a limitation of the current study that could be addressed in future research.
Another limitation of this study was that counterarguing output was not assessed following the counterattitudinal attack message. It may be that when faced with a message that directly challenged people’s beliefs about vaccinations (either the HPV vaccine or the practice of vaccinating children), that threat alone motivated a defensive response whereby people more strongly clung to their initial attitudes and beliefs as opposed to being impacted by the inoculation treatment. Measuring counterarguing output after exposing the participants to the attack messages would have provided us with a stronger indicator that the inoculation treatments was responsible for conferring resistance to influence.
A final limitation of this study was that we only looked at how a generalized inoculation treatment protected attitudes toward only one specific vaccine (i.e., the HPV vaccine), but not attitudes toward other vaccines that could be attacked via different arguments (e.g., the H1N1 vaccine, the meningitis vaccine, etc.). To more accurately test for the “umbrella of protection” effect of inoculation, it would be important to look at whether we can replicate the results of this study examining people’s attitudes toward other vaccines. Could a generalized inoculation message about the safety and efficacy of getting vaccinations in general be enough to thwart off counterattitudinal attacks on multiple vaccines? This remains an empirical question that should be explored in future studies. Currently, we have only preliminary evidence to suggest that this can work.

Practical Implications

The results of this study provide two important implications for public health communicators and practitioners. First, inoculation may be a very useful strategy to help people maintain the positive health beliefs and cognitions, as well as behaviors, that public health communicators elicit in their target audiences via their health campaign messages over time, able to withstand negative influences promoting unhealthy practices (e.g., negative health advertising). If individuals can be forewarned that their positive beliefs about healthy lifestyle behaviors could be challenged, and provided with refutational responses in advance, health consumers may become more resistant to advertisements that endorse unhealthy behaviors (e.g., alcohol ads) or try to persuade people into thinking unhealthy products are healthy (e.g., fructose corn syrup is as healthy as cane sugar). One way that this could be done would be for public health educators to enact counter-marketing advertisements similar to the ads used in the Truth campaigns to warn adolescents of the deceptive marketing practices that the tobacco industry will use to try to get them to initiate smoking behaviors. The ads provide adolescents with the false claims they will likely hear from tobacco companies and offer counterarguments in the form of different truth messages that debunk the false claims.
Secondly, this study demonstrated that an inoculation message designed to protect a person’s generalized attitude toward a topic or behavior may be able to provide a “blanket of protection” for a person’s attitudes toward multiple topics that all fall within the same broad content domain. From a utility standpoint, this would make it easier for public health communicators and practitioners to protect people’s attitudes toward a variety of disease prevention behaviors (e.g., mammogram, colonoscopy, Pap smears) within a specific domain (e.g., cancer screenings) using a single generalized inoculation message from multiple counterattitudinal attacks. Specifically, an inoculation message can be created to protect people’s positive attitudes about taking health precautions.

Conclusion

Overall, this study provided a nuanced test of the inoculation theory to further our understanding of the resistance process. While some insight has been gained in terms of finding empirical support for an “umbrella of protection” or “blanket of protection” metaphor of the inoculation process, more research is yet to be done to explore other nuanced aspects of the inoculation process. A few recent studies have explored the role of affect in inoculation [26,32] in terms of whether or not affective inoculation treatments are as effective as cognitive inoculation treatments in conferring resistance to influence. Future research could test whether affective-laden inoculation treatments works better than cognitive inoculation treatments in conferring resistance to affective-laden attack messages.
Additionally, inoculation research has also explored the possibility of relying on word-of-mouth and interpersonal communication as the modality of inoculation treatments. One venue for future research may be to examine whether inoculation can be conferred via passive exposure to word-of-mouth inoculation treatments as opposed to being actively targeted with an inoculation message. This would also have practical implications for health communicators interested in diffusing inoculation effects among a mass audience via the use of social networks.

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