**1. Introduction**

Today, people may find a lot of di fferent information regarding public health online. Research studies have shown that online sources represent a well-established and important site of health-related information seeking behavior [1,2], and, moreover, have a significant role in shaping health behaviors [3]. For example, one in three adults in the United States tries to diagnose a medical condition online [4]. Online sources have thus become the primary source of information in the 21st century, which is especially present in the field of medicine and public health. Through online information, almost everyone has access to numerous information with just few clicks. In other words, online media represent a critical factor of influence toward attitudes in di fferent areas, which is why the proper use of this form of communication also plays an important role in improvement of public health. However, online sources also contain misinformation that may negatively a ffect attitudes and behavior and, as such, may have extremely harmful e ffects on public health [5]. In addition, health misinformation, which is against established medical understanding [6], may be widely distributed in order to reach a large population in a short time in the digital age [7]. This is extremely important because previous studies have shown that many parents mostly receive vaccination information through online sources [8].

Although vaccination is considered to be the most e ffective and cost-e ffective way of preventing the contraction of an infectious disease [9,10], there are numerous controversies about vaccines. First of all, it is important to point out that vaccination is recognized as an integral part of public health policies and each country implements vaccination requirements in order to achieve satisfactory vaccination coverage. Avoidance of vaccination by parents directly leads to a lower vaccination rate among their children, increasing the social risk of infection [11]. In line with the above, a large number of previous studies have focused on the benefits of vaccinating children [12,13], which further positively reflects on strengthening trust in vaccines. Thus, researchers in many countries have emphasized the cost-e ffectiveness of vaccination in preventing disease [14–16] and this issue is especially important in less developed countries. Despite the trend of increasing vaccination rates around the world, many factors may influence the formation of negative attitudes, especially in developing countries, such as the countries of the Western Balkans region. Namely, these countries, most often, have a lower level of development of the health system and public health policy, which further reflects the influence of online media on the formation of attitudes and level of trust in vaccines, which is one of the motives of this research. This problem is faced not only by developing countries but also by developed countries. The issues related to vaccines are increasingly politicized today. An international study on attitudes towards vaccination has shown that, although overall confidence in vaccines is positive, it is the lowest in the European region [17].

Although there is a certain number of studies on trust in vaccines [18–20], it is often pointed out that there is a lack of such research, especially in less developed countries, which is why this issue continues to cause a lot of controversy. Namely, despite the scientific consensus that vaccines are safe and e ffective, there are still unconfirmed claims that doubt their safety [21]. In line with the above, some research studies show that public confidence in vaccines is increasingly lost, and there are more and more people who are beginning to question the safety of vaccines, changing the recommended vaccination schemes, or even rejecting vaccination [22–24]. This problem is especially pointed out when it comes to less developed countries, such as most of the countries of the Western Balkans. In recent years, vaccines have been "notorious" in these countries. This especially refers to the measles-mumps-rubella (MMR) vaccine because of its potential association with autism [25]. This creates a dilemma among parents whether to vaccinate their children or not, not only when it comes to this but also to other vaccines. The confirmation for this statement is the fact that there is a large number of cases that the pediatrician informed the health inspector that the parents refused to

vaccinate or revaccinate the child. In order to increase the number of vaccinated children, the countries of the Western Balkans often prescribe penalties. Thus, for example, parents in Montenegro, although in a dilemma, are obliged to vaccinate their children against ten infectious diseases, and, if they do not do so, they must pay a fine which is prescribed by the Law on Protection of the Population from Infectious Diseases [26]. However, there is another indirect sanction for parents who do not vaccinate their children. Namely, an unvaccinated child cannot be enrolled in a kinder garden or school, and the parents should provide medical certificates in order to confirm that the child is vaccinated. However, according to the latest data of the Institute of Public Health from the February 2020, 8000 children in Montenegro of ages from three to five did not receive mandatory vaccines [27]. In the past two years, the Directorate for Inspection A ffairs has filed over 177 misdemeanor charges against parents who did not vaccinate their children according to the compulsory immunization calendar, while courts imposed 150 fines worth of 15,000 euros in total while the other 27 parents received a reprimand [28]. The situation is similar in other countries of the Western Balkans, especially in Serbia and Bosnia and Herzegovina, which are included in this research. All this leads to the conclusion that a large number of parents have a dilemma about vaccination and that they have distrust in vaccines, which is why they often do the research about vaccines for themselves in order to make a decision. Distrust in vaccines served as one of the motives for this study.

So, in many countries, health experts state that there is a trend of mistrust when it comes to vaccines, and thus a refusal to use them. The World Health Organization (WHO) has included this trend in one of the 10 threats to world health in 2019 [29]. At the same time, it should have in mind that a number of studies highlight the negative aspects of vaccination, which are very often the result of media influence. A health scare, or panic created by the media in relation to health issues, has been shown to increase people's need for information and for people to begin to question traditional sources of information as trustworthy [30]. Furthermore, research shows that vaccination rates vary depending on the use of the mass media [31], especially online media, which is the dominant form of communication in most countries. In line with the above, some studies have shown that more and more parents are searching for vaccination information on various online sources [8].

As previously pointed out, online media are a critical factor of influence on the formation of attitudes in many areas of modern society, which is why their proper use plays an important role in increasing trust in vaccines, and thus improving public health. Online media include various forms, such as medical websites, social networks, portals, blogs, forums, etc., and research shows that some of them like social media have the capacity to influence and shape public opinion regarding vaccination in a viral manner—both positively and negatively [32]. In this context, it is extremely important to analyze online media as a part of marketing communication and social marketing, which also has an important role in the improvement of public health. Namely, social marketing is an approach used to develop activities aimed at changing or maintaining people's behavior for the benefit of individuals and society as a whole. Social marketing, through its various forms and strategies, plays a significant role in the field of medicine and public health [33]. In this way, social marketing influences parents' attitudes and better understanding of online media and marketing communications and decision makers as an important factor in strengthening trust in vaccines and improving public health. More specifically, it is very important that both parents and decision-makers understand social marketing, as well as to understand how particular forms of marketing communication, such as online media, influence perceptions, and attitudes about vaccination of children [31], which is one of the motives of this research. This is because, as mentioned above, despite the existence of numerous studies that explain the benefits of vaccination, there are still many conflicting views on pro-vaccine and anti-vaccine [34], especially having in mind more intensive use of online media and marketing campaigns in modern age. Research studies show that anti-vaccine articles are more likely to be shared, commented on, and reacted to online than pro-vaccine messages [35]. Online anti-vaccine messages may lead parents to question the safety of vaccine, distrust health professionals, and seek non-medical vaccine exemptions [36,37]. Regarding this matter, several studies have been conducted in order to

analyze how online information influence parents' attitudes and decisions about vaccination. Some studies have focused on specific vaccines, while others have been general [8]. According to one of the studies, "the most recent statistics available show 16% of seekers searched online for vaccination information and 70% say what they found affected by their treatment decisions" [38].

In line with the above, research studies around the world show that media exposure may significantly facilitate a change in parents' behavior [21,39], which is especially important when it comes to using online media. This would contribute to the strengthening of trust in vaccines, as well as to the improvement of public health, through adequate online communication and various forms of social marketing. It should have in mind that, in addition to the positive effects, online media may also use groups to ge<sup>t</sup> people to oppose vaccination, raising skepticism about the scientific evidences regarding the risks and benefits of vaccines [40]. Online media, especially web pages against vaccination, are widely spread on Internet [41] and, in many countries, may be more compelling sources of information than vaccination sources [42]. People have been shown to be more responsive to personal stories than statistics [43], which means that online vaccine sources and their personal stories may create a stronger emotional response for readers than official health online sites with statistics and arguments.

Thus, media in general and specially the online media, have significantly contributed to widespread public distrust of vaccines in many countries around the world [44], and countries in our region are no exception. In fact, the dissemination of negative information about immunizations has been increased by the progress of certain forms of online resources, such as individual social networks (Facebook and Twitter) [44,45]. Since 2013, the World Economic Forum has cited mass digital misinformation among the major threats to our society [46]. Recent studies emphasize that the spread of misinformation is the result of a paradigm shift in content consumption caused by the advent of social media. In fact, the platforms of particular forms of online media, such as Facebook or Twitter, have created a direct path for users to produce and consume content, changing the way people inform themselves [32,47,48] and form attitudes. It is often discussed that online media, and especially social media, have important role in creating hesitancy [10] and fear in parents and encouraging them to avoid vaccination. Many of these fears come from information that parents find online and many of these sources not only propagate unproven claims regarding vaccines but may also undermine the physician-family relationship by challenging parents' trust in the medical professionals [49].

On the other hand, many parents from many countries who have decided not to vaccinate their children have done their own (online) research. Research studies show that parents seeking for information about vaccine risk will find more online sources that are against the vaccine, compared to parents seeking information about the benefits of vaccines [50]. This means that it is likely that parents who are worried about vaccination will find online sources to confirm their fears. So, today the information is widely spread through different forms of online marketing especially social media and networks. For example, a quick Facebook search provided more anti-vaccination groups from around the world. Anti-vaccine content exists in many of the vaccine-related top Google search results [42,51]. By doing a Google search on the key term "vaccine refusal", 3,340,000 results could be found [8]. It may be concluded that despite all the advantages of vaccination, there is still a strong resistance in form of anti-vaccine movements, which are on the one side the result of mistrust, and on the other of the strong influence of the media. It is important to emphasize that vaccine-related misinformation, which is often spread via the Internet by vaccine groups [51], may be the most commonly distributed health-related misinformation [52].

Relying on the results of previous research and the observed literary gap, the authors wanted to conduct a study that would target the impact of online media on parents' attitudes towards vaccination of children, as well as the impact of other characteristics (gender, age, country of origin, etc.), in order to direct social marketing activities to strengthening trust in vaccines, thus improving public health. So, in order to discover, identify and understand the relationship between online media and parents' attitudes toward children's vaccination, especially from the country of respondents' origin (Montenegro, Serbia, and Bosnia and Herzegovina), this paper tends to fill the gap compared to previous studies. Therefore, the aim of the paper was to investigate the level of influence that online media, as a form of marketing communication, have on the formation of parents' attitudes toward the vaccination of children, that is trust in vaccines in analyzed countries of the Western Balkans region, as well as a role of social marketing in strengthening trust in vaccines and improvement of public health.

The paper is organized into five sections. Following the abstract, in the first section, a review of the results of previous research regarding the vaccination and online media was made, as well as the literature overview in which the motive for this research was found. This section contains an analysis of key aspects of vaccination, arguments pro and against vaccines, vaccines trust, the role of online media, and the importance of social media in strengthening trust in vaccines, as well as the influence of the country development on these questions. This segmen<sup>t</sup> also refers to materials and methods and includes a description of research methodology, i.e., data collection and simple, measures and instrument validation. The next part presents the results of research, while the fourth part represents the discussion of the results. Finally, the paper concludes with concluding remarks, a review of the implications, and recommendations for future research studies.

#### **2. Hypotheses Development, Materials, and Methods**

Based on the relevant literature and using data obtained from empirical research in three countries: Montenegro, Serbia, and Bosnia and Herzegovina, several hypotheses were developed in order to investigate the relationship between the analyzed variables and parents' attitudes toward vaccination of children, especially from the aspect of online media.

As previously noted, existing research supports the thesis that some of the demographic characteristics may be important in forming parents' attitudes toward vaccination of children. Thus, for example, Brown et al. [53] emphasize the gender and age of parents, while Anderberg et al. [54] point out that decisions about vaccinating children significantly depend on the level of education of parents, because a higher level of education is translated into a higher awareness or the information being perceived di fferently. Similarly, Walsh et al. [55] relate the age and education of parents. Furthermore, the aim of some research in this area is to determine the extent to which parents' attitudes towards immunization a ffect coverage (number of vaccinated children) and to assess the level of parents' knowledge about immunization [56]. In addition, a number of these studies highlight the country's level of development as an impact factor, and these studies do not analyze this. In addition, the adequate application of social marketing may influence the change of behavior [57], i.e., it may influence the strengthening of trust, considering the previously mentioned characteristics when creating marketing communication strategies. Thus, the results of previous studies point out that gender, age of parents and their education, as well as knowledge about immunization, may be mentioned as important influencing factors, which the authors wanted to investigate in this research. In accordance with the above, the following hypotheses have been defined:

#### **Hypothesis 1 (H1).** *Identified characteristics of respondents have a significant e*ff*ect on attitudes toward children's vaccination, which reflects on the level of trust in vaccines.*

On the other hand, previous literature suggests that the online media today represent the crucial factor of influence on formation of attitudes in di fferent areas, and that is why their proper use has important role in strengthening trust in vaccines and improvement of public health. Di fferent forms of online marketing may have positive and negative influence [32]. Under the influence of online media, conflicting views on pro-vaccine and anti-vaccine may often be heard [34]. Thus, anti-vaccine articles are more likely to be shared, commented on, and reacted to online than pro-vaccine messages [11]. It is indisputable that media exposure influences the change of parental behavior [21,39]. Hence, the concept of social marketing has more importance and, through various forms and strategies, it plays a significant role in the field of medicine and public health [33]. Thus, in the context of the research topic, online media may be considered as a segmen<sup>t</sup> of social marketing, which plays an important role in improving public health. Namely, online media and other forms of marketing communication may have an impact on perceptions and attitudes toward vaccination of children [31], which encourages the importance of social marketing in order to improve public health. In accordance with the above, the following hypotheses have been defined:

**Hypothesis 2 (H2).** *Online media have a significant impact on parents' attitudes toward children's vaccination, which encourages the importance of adequate implementation of social marketing in the function of improving public health.*

In addition to demographic characteristics and the influence of online media, the authors wanted to analyze other factors that may be relevant, and which, in interaction with other factors, may have a strong influence on the formation of parents' attitudes toward vaccination. According to this, the authors noted that the level of country's development and policy, i.e., the measures that countries take in terms of vaccination may have a significant impact on the formation of attitudes. In this sense, a significant number of countries are trying to develop motivational measures, and we often talk about the obligation to vaccinate and penal policy in case of refusal [58]. For example, despite the implementation of vaccination regulations in Poland, as in other European Union countries, the final decision on vaccination of children is made by their parents or legal guardians [59]. On the other side, experience in the countries of our region shows that developed countries, such as Croatia and Slovenia, have similar policies, while, in countries with lower levels of development, such as Montenegro, Serbia, Bosnia and Herzegovina, there is a stricter vaccination policy, which includes high penalties and provisions in case of refusal of vaccination. In that sense, understanding the attitudes and opinions of parents toward vaccination is essential for planning and undertaking extensive and properly directed educational actions in order to prevent their indecision. Taking these measures, supported by an adequate social marketing strategy, may lead to a strengthening of trust in vaccines, as well as an improvement of public health. Starting from the fact that the countries in which the research was conducted belong to less developed countries, which have relatively similar legislation, people's habits, and that all three countries tend to harmonize public health policies in accordance with European standards, the third hypothesis was formulated:

#### **Hypothesis 3 (H3).** *There is no significant di*ff*erence in parents' attitudes toward children's in the analyzed countries regarding to the impact of online media.*

The conceptual model, based on the defined hypotheses in given in the figure below (Figure 1). Having in mind motives and goals of the research, the defined hypotheses, results of previously published research, as well as evaluations of theoretical models, the authors developed a form of a questionnaire. The questionnaire was prepared and distributed to 3031 parents in three countries (Montenegro, Serbia, and Bosnia and Herzegovina). Namely, in cooperation with preschool institutions (kindergartens) and parents' associations, the questionnaire was transmitted online (via mailing lists and viber groups) in order to ensure the highest possible representativeness of the sample. The poll lasted for 30 days, and 1593 fully filled in polls were returned, giving the answer rate of 52.55%. This can be considered a high response rate, which is explained by the actuality of the topic itself and the parents' interest to participate in the research. The survey was undertaken in the first quarter of 2020. The questionnaire identified 20 questions, and, for the purpose of analyze of results of the survey, according to identified criteria, 3 variables were defined. The pilot survey, which tended to examine the validity of the content of the questionnaire, was conducted in Montenegro by 15 parents. Based on their suggestions, the final form of the questionnaire was created.

**Figure 1.** Conceptual model of research. **Source:** Authors.

Cronbach's alpha was used to test the reliability of the study. The calculated values of Cronbach's Alpha are at a satisfactory level and are 0.892 (the Cronbach's alpha values adhered to the suggested minimum value of 0.6), which means that the data are suitable for further analysis [60,61]. We processed the collected data in the SPSS program (Statistics 20) and, during the analysis, we used descriptive statistics, the ANOVA test, the eta coefficient and logistic regression. Analysis of variance (ANOVA) is an analytical model for testing the significance of differences [62,63]. The advantage of this method is that the model considers all the variables, as well as their interaction. Analysis of variance is essentially a special mathematical and statistical procedure that allows testing the significance of the difference between arithmetic means from three or more samples, and within that testing the influence of one or more factors on the variability of a tested numerical feature. Furthermore, in order to further examine the importance of a certain way of using online media to form attitudes, i.e., parents' trust in vaccines, eta-coefficient was used. The Likert scale was treated as an interval scale by placing neither in the place of neutral or moderately [64]. It is obvious that the data itself divide into two categories were the parametric tests is applicable. If the Likert scale data are treated as interval scale data, then the ANOVA test can be used. If the Likert scale data are from 1–5 with equal intervals then the midpoint already exists at 3 [65]. Therefore, the Likert scale is the same as the interval scale, with the difference in the labeling. A Likert scale, finally, label does not create any difference in the data distance since the codes are the same so the usage of parametric tests will ge<sup>t</sup> the best results [66].

On the other hand, logistic regression was used in order to obtain a more precise answer to the question of the relationship between the demographic characteristics of the respondents and their attitude towards vaccines based on information from online media. Logistic regression is the most commonly used in order to rank the relative importance of independent variables and to quantify the effect of their interaction [67]. The results of the research are given below.
