ONE OF THE MOST successful public health strategies is vaccination. However, there are factors that limit vaccine implementation including pragmatic issues such as cost, inconvenience and inertia,1,2 and attitudes and beliefs of professionals and individuals.3-6 Attitudinal issues may be of particular concern for vaccines for sexually transmitted diseases (STDs), given the social stigma associated with sexually transmitted infections.7 Understanding the potential attitudinal barriers is timely because there is extensive ongoing research to develop vaccines against STDs.8,9
Previous work examining attitudes regarding vaccine acceptance has drawn from social psychological theories of health behavior (e.g., Theory of Reasoned Action, Health Belief Model, Protection Motivation Theory).5,6,10 These studies and models have demonstrated that important aspects to consider include: perceived severity, perceived susceptibility, barriers, and social influence. Adolescents are prime candidates for STD vaccination; therefore, one needs to incorporate a developmental perspective. This includes the role of parents as significant others and the adolescents' perceptions of social norms reflected by universal versus high-risk vaccination strategies.10 The focus was on college students' anticipated acceptance of, rejection of, or uncertainty regarding vaccination against genital herpes.
Methods
Subjects
Subjects (n = 518) were recruited from an undergraduate psychology class at an urban university to complete anonymously a questionnaire regarding a potential genital herpes vaccine. Of these subjects, 511 were aware that genital herpes is an STD and 489 knew that genital herpes can cause recurrent infections. The subjects received research credit for their participation. The study was approved by the Institutional Review Boards of the University of Cincinnati and Children's Hospital Medical Center.
Measures and Procedures
Vaccine acceptance was measured by having the subjects respond to the following question: "If a genital herpes vaccine is made available to you, do you think you will decide to get the vaccine?" The subjects' options for responses were "Yes," "No," and "Not sure."
Predictors of vaccine acceptance included aspects of health behavior theories (perceived susceptibility to acquiring genital herpes, the perceived psychological severity of acquiring genital herpes, barriers to genital herpes vaccine acceptance, and influence of normative perceptions of genital herpes vaccination). Normative perceptions regarding genital herpes vaccination included social influence and beliefs about vaccine strategies (i.e., which groups of people should receive a genital herpes vaccine).
Perceived susceptibility was measured by the subjects' perception of the percentage chance they thought they had of getting genital herpes sometime in their life (choices were 0-5%, 6-25%, 26-50%, and >50%). Perceived psychological severity was measured by asking the subjects to choose one of the following choices describing what they would think if they acquired genital herpes (i.e., "It was no big deal," "I was a bad person," "I had bad luck," "I made a mistake"). They were asked to choose, from a five-point Likert scale, their reactions should they acquire genital herpes. The responses ranged from "Worst thing that could happen" to "OK, not upset at all." Barriers were assessed by asking the subjects to rate on a three-point Likert scale ("a lot," "a little," "not at all") whether a factor would discourage them from getting the vaccine. Factors that discourage someone were: having to pay for the vaccine, fear of getting genital herpes as a result of the vaccine, fear that the vaccine would not work, having to get a shot, and fear of someone thinking poorly of them for getting a genital herpes vaccination. Three of the factors also were asked in the opposite direction, i.e., would low cost, belief that vaccines are safe, or shots not bothering them foster vaccine acceptance. Normative perceptions were measured by a rating of their perceptions of how significant others (parents, partners, and health professionals) would feel if the subject received a genital herpes vaccine. Finally, subjects endorsed whether the following groups should receive the genital herpes vaccine: everyone, all adolescents and teenagers, all adults, homosexuals, all people who have sexual intercourse, people who have had many sexual partners, people with a partner with genital herpes, and people who have had an STD.
Statistical Analysis
Data analyses were conducted by means of the SAS system for personal computers (SAS, Cary, NC).11 The subjects completed the questionnaire independently in large groups. As a result, missing data exist occasionally. When the missing data exceeded 4% of the sample (i.e., 21 subjects), the amount of data missing is noted. Descriptive statistics, analysis of contingency tables, and logistic regressions were used as appropriate.
The analyses were run separately to compare those college students who said they would not get the vaccine against those who said they would, and to compare those who were unsure about getting the vaccine against those who would get the vaccine. This strategy was used because it was presumed that there may be different issues involved in rejecting a genital herpes vaccine than in being unsure. Two layers of analyses were performed. The first layer used logistic regression analyses to determine which of the independent variables within each aspect of health behavior theory (severity, susceptibility, barriers, normative perceptions) predicted vaccine acceptance. Statistically significant independent variables were then entered into one of the two common models involving Yes/No vaccine acceptance or Yes/Not sure vaccine acceptance.
Results
Demographics and Sexual History
The subjects (n = 518) had a mean age of 20 years (range, 17.7 to 32.2). They were 52% female, 86% white, 9% black, and 5% other ethnic backgrounds. Their class level was as follows: freshmen-47%, sophomore-34%, junior-13%, and senior-6%. With regard to dating status, 20% of the subjects were not dating, 27% were dating with no steady partner, 46% had one steady partner with whom they were not living, and 7% had a steady partner with whom they were living.
Of the 518 subjects, 416 (195 males and 221 females) were sexually experienced. Twenty-eight reported a history of STD. Thirty women reported a history of a pregnancy. The mean number of lifetime partners was 4.5, mode 1, median 3. Four of the subjects reported having had sex with a partner they knew had genital herpes and two subjects self-reported a history of genital herpes.
Vaccine Acceptance
When asked if they would be likely to get a vaccine for genital herpes, 100 (19%) subjects answered "No," 207 (40%) responded "Yes," and 211 (41%) said they were "Not sure."
Comparison of "Yes" Responders to "No" Responders
When comparing those who would accept a genital herpes vaccine to those who would not, there were no significant differences in age, race, gender, and class level. Those subjects who were dating without a steady partner (χ2 = 16.43, P < 0.01) were more likely to respond yes than those in other relationship categories. Those subjects who responded yes were more likely to be sexually experienced (χ2 = 10.3, P < 0.01). Those subjects with more lifetime partners also were more likely to accept a genital herpes vaccine (Wald χ2 = 5.0, P < 0.03). A history of an STD was unrelated to vaccine acceptance. When the significant variables were entered into a logistic regression with backward elimination, all three (sexual experience, number of lifetime partners, and dating status) remained significant (Wald χ2 = 5.9, P < 0.02; Wald χ2 = 5.2, P < 0.02; and Wald χ2 = 6.0, P < 0.01, respectively).
The percentage of subjects in each category of perceived susceptibility is presented in Table 1. Those subjects who believed they had a 0% to 5% chance of acquiring genital herpes were less likely to accept the vaccine than those who believed they had a 6% chance or greater of acquiring genital herpes (χ2 = 44.9, P < 0.01). With regard to perceived psychological severity, when asked about what they would think if they acquired genital herpes, most subjects (81%) endorsed that they would think they "made a mistake" (attribution). When asked how they would feel about acquiring genital herpes, 72% thought that it would be a major upset (reaction) (see Table 2). There were so few subjects who endorsed that it was "no big deal," "OK, not upset at all," and "slightly upset," that these subjects were dropped from contingency table analyses comparing the yes/no and yes/not sure responses. Chi-square analyses examining attribution and reaction did not reveal a significant difference in perceived severity between those subjects who would accept the vaccine and those who would not.
The discouraging and encouraging factors that were significant for the comparison of the yes/no and yes/not sure are presented in Table 3. The barriers were evaluated using contingency table analyses. Those who reported low cost (χ2 = 55.2, P < 0.01), a belief that vaccines were safe (χ2 = 24.7, P < 0.01), and that shots did not bother them (χ2 = 8.7, P < 0.01) were more likely to accept the vaccination.
In general, most college students believed that their health care providers would support vaccination (81%). With regard to parents, 61% believed that their parents would support vaccination, and 24% thought their parents would not care. Forty-six percent of the college students believed that their partners would support vaccination, and 25% thought the partners would not care. When these variables were entered into a logistic regression with a backward elimination, the variable that remained in the model was parents' feelings about vaccination. Those subjects who believed their parents would encourage vaccination were more likely to endorse acceptance of the genital herpes vaccine than those who believed their parents would discourage or would not care about their receiving the vaccine (Wald χ2 = 15.05, P < 0.01). Ninety-eight to 99% of respondents thought those who had an STD, those who have many sexual partners, and those with a partner with genital herpes should receive a genital herpes vaccine. Because of the limited variance, these items were not included in further analyses. Eighty-one percent of the college students thought that all people who had had sex should be vaccinated; 68% thought that all teens should be vaccinated; and 55% thought everyone should be vaccinated. College students who responded yes were more likely to believe that the following groups should receive a genital herpes vaccine: everyone (Wald χ2 = 17.3, P < 0.01), teens (Wald χ2 = 14.1, P < 0.01), and people who have had sex (Wald χ2 = 6.7, P < 0.01).
In a final model, the significant variables (sexual experience, number of lifetime partners, dating status, perceived susceptibility, low cost, belief that vaccines are safe, not being bothered by shots, parents' feelings about vaccination, and the belief that the vaccine should be given to everyone, all teens, and those who have had sex) were entered into one common model to compare the yes/no answers. The final model included low cost (Wald χ2 = 18.04, P < 0.01), everybody should be vaccinated (Wald χ2 = 14.3, P < 0.01), all teens should be vaccinated (Wald χ2 = 8.0, P < 0.01), and those who had had sex should be vaccinated (Wald χ2 = 5.7, P < 0.02). The Somers' D = 0.78, number of concordant pairs was 85.2. College students were more likely to accept vaccination if it was low cost and if they endorsed a vaccination strategy of everyone, all teens, and those who had had sex.
Comparison of "Yes" Responders to "Not Sure" Responders
When comparing those who would accept a genital herpes vaccine to those who were unsure, there were no significant differences in age, race, gender, and class level. Those subjects who were not sexually experienced (χ2 = 6.1, P < 0.01) were more likely than those who were sexually experienced to report that they were unsure about receiving the vaccine. Dating status, number of lifetime partners, and STD history were insignificant in the yes/not sure comparison.
With regard to perceived susceptibility, those subjects who believed they had a 0% to 5% chance of acquiring genital herpes were more likely to be unsure of accepting the vaccine than those who believed they had a 6% chance or greater of acquiring genital herpes (χ2 = 18, P < 0.01).
Contingency table analyses revealed no significant differences in perceived severity between those subjects who would accept the vaccine and those who were uncertain about accepting the vaccine.
Those who responded not sure thought the following were barriers to accepting the vaccine: fear that one could get the disease from the vaccine (χ2 = 7, P < 0.03) and that the vaccine would not work (χ2 = 6.4, P < 0.04). Those who responded yes thought the following factors would encourage vaccine acceptance: low cost (χ2 = 22.3, P < 0.01) and belief that the vaccine would be safe (χ2 = 15.7, P < 0.01).
The college students' perceptions of the feelings of significant others was entered into a logistic regression. The variable that remained in the logistic regression was parents' feelings about vaccination. Those subjects who believed their parents would encourage vaccination were more likely to receive the genital herpes vaccine than those who believed their parents would discourage or would not care about the college student receiving the vaccine (Wald χ2 = 14.5, P < 0.01).
The variables regarding who should be vaccinated (everyone, those who had sex, all adults, all homosexuals, all teens) were entered into a logistic regression with a backward elimination to predict vaccine acceptance. The results indicated that those subjects who believed everyone (Wald χ2 = 14.1, P < 0.01) and all teens (Wald χ2 = 7.9, P < 0.01) should be vaccinated were more likely to respond yes rather than not sure.
In the final model the following variables were entered into a logistic regression with backward elimination: sexual experience, their chance of getting the disease, the belief that the vaccine would not work or that they could get the disease from the vaccine, low cost and belief that the vaccine would be safe, parents supporting vaccination, and beliefs that everyone or all teens should be vaccinated. The final model included concern that the vaccine would not work (Wald χ2 = 6.7, P < 0.01), low cost (Wald χ2 = 16.4, P < 0.01), everybody should be vaccinated (Wald χ2 = 12.3, P < 0.01), and all teens should be vaccinated (Wald χ2 = 8.3, P < 0.01). The Somers' D = 0.50, concordant pairs was 72%. College students were more likely to accept vaccination if it was low cost, if they did not believe that the vaccine would not work, and if they believed that everyone and all teens should be vaccinated.
Discussion
Vaccines are a cost-effective disease prevention strategy.12,13 For sexually transmitted infections, such as genital herpes, vaccines have the potential of preventing disease or reducing its severity, and decreasing spread to susceptible persons.14,15 A recent study by Zimet et al. examined potential predictors of genital herpes vaccine acceptance in 321 subjects participating in Phase III clinical trials of an experimental herpes simplex virus 2 (HSV-2) vaccine.5 The results of their study showed that for this unique population, attitudinal and behavioral factors influenced acceptance of a hypothetical genital herpes vaccine. These authors thought that psychosocial issues could be more important with regard to acceptance of a genital herpes vaccine among selected populations who were not involved in genital herpes research. As with other vaccines, there are two potential approaches to STD vaccine usage (i.e., universal vs. selected). For a genital herpes vaccine, selected populations may include sexual partners of persons known to have genital herpes, those with high-risk sexual behaviors, adolescents, college students, and those in military service. To extend the work of Zimet et al., we investigated psychosocial factors that may influence acceptance of a genital herpes vaccine among college students.
In our study, among 518 college students, less than 20% indicated they would not accept vaccination against genital herpes. The remainder was equally divided among those who would accept the vaccine and those who were unsure.
Demographic factors that did not appear to influence vaccine acceptance included age, race, gender, and class level. With regard to sexual history variables, those willing to accept vaccination with a genital herpes vaccine were more likely to be dating without a steady partner, be sexually experienced, and have more lifetime partners.
With regard to risk factors, a history of an STD was unrelated to vaccine acceptance; however, the number reporting an STD history was small (n = 28), as was the number of subjects who had a partner with genital herpes (n = 4). When perceived susceptibility was evaluated, those who believed they were at low risk of acquiring genital herpes were unlikely to accept a genital herpes vaccine. This would suggest that educating students regarding risk of acquiring genital herpes may be an important component of programs to promote vaccination.
These college students were influenced by vaccine cost. Financial resources can affect access to vaccines.1 Some students endorsed concerns that the vaccine may not work, may be unsafe, or that they could acquire genital herpes from the vaccine. Health education programs need to address directly these concerns to facilitate vaccine acceptance. One important aspect of educational campaigns will be to ensure the trust of the public in health care provider's recommendations regarding vaccines and their efficacy and side effects. Care providers must find accurate ways of promoting vaccination and presenting efficacy data in everyday language.
Although parental attitudes did not stay in the final models, these college students were influenced by their perception of their parents' attitudes. Similar influences were noted in a study examining hepatitis B virus (HBV) vaccine acceptance among younger adolescents.10 The young people in this study may be legal adults; however, their parents remain an important source of influence even regarding STD prevention.
Consistent with a previous study on HBV vaccination, we found that students who endorsed that everyone should be vaccinated were more likely to accept genital herpes vaccination.10 This suggests that acceptance of a genital herpes vaccine will be facilitated by a public health policy that recommends universal genital herpes vaccination. In considering universal vaccination for genital herpes, it will be necessary to determine the appropriate age when vaccination should be initiated. Possibilities include infancy, preadolescence, or adolescence. Early vaccination with an HSV vaccine may be considered for two reasons. First, the vaccine may protect against nongenital HSV infections such as herpes gingivostomatitis or herpes keratitis.16 Second, HSV-2 seroprevalence studies indicate that a substantial number of adolescents acquire HSV-2 infection within the first few years of becoming sexually active, thus suggesting the need to target populations not yet sexually active.17-19
Because most people follow health care provider recommendations regarding vaccines,10-20 it will be important that providers support vaccination for genital herpes. Unfortunately, in some circles, issues relating to sexually transmitted infections engender many negative reactions that may impede optimal STD vaccine implementation.5,7 Health care providers' support will be critical, but support is unlikely to happen if they anticipate negative reactions from patients or parents.
It is unlikely that any genital herpes vaccine in development will be able to completely protect all vaccine recipients against genital HSV infection. However, vaccines may be able to prevent symptomatic genital herpes disease, diminish latency, reduce subsequent recurrent infections, and possibly reduce the spread to susceptible persons.14-16 The extent to which HSV vaccines protect the individual against disease but not against infection may influence public health decisions regarding how these vaccines will be used and could impact vaccine acceptance. To facilitate vaccine acceptance among health care providers and the public, it will be important to develop educational programs that clearly convey what can be realistically expected of genital herpes vaccines.
This study represents an examination of Midwestern college students' attitudes about genital herpes vaccination. Most of the subjects in the study were white. Additional studies with other college populations should be conducted to confirm the generalizability of these results. In addition, studies need to be conducted of parents of young teens to determine the acceptability of an HSV vaccine among that population. That few college students in this study would reject entirely vaccination against genital herpes suggests that with appropriate education, wide-spread vaccination of this population can be accomplished.
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