A Systematic Review On Sociodemographic, Financial And Psychological Factors Associated With COVID-19 Vaccine Booster Hesitancy Among Adult Population Part 2

Psychological Factors

Most respondents expressing VBH believed that vaccines would evoke negative side effects or harm as per Mohamed Lounis et al. [24], Marine Paridans et al. [40], Neil G Bennett et al. [20], Makoto Yoshida et al. (57.7% concerned about adverse effects) [41], Dehua Hu et al. [37], and Gede Benny Setia Wirawan et al. [21]. Similarly, Petros Galanis et al. [16] found that possible short (29%) and long-term side effects (46.8%) were the main reasons for VBH or a new COVID-19 vaccine. On the other hand, Thin Mon Kyaw et al. [30] found that respondents were neutrally (36.0%) worried about serious adverse reactions after vaccination.

VBH was inversely correlated to trust in science as shown by Massimiliano Baratucci et al. [42]. 

With the severe impact of the epidemic, vaccines are considered to be one of the most important means to help us survive the crisis. As the vaccines become more widely available, many people worry about whether their side effects will affect their immunity. The relationship between vaccine side effects and immunity is very weak.

Vaccine treatment options have become increasingly popular over the past few years. Vaccines can prevent many diseases, such as measles, rabies, and so on. Vaccines stimulate the human body to different degrees according to the time, dose, and route of vaccination, forming various reactions, most of which are short-term adverse reactions and side effects, including symptoms at the vaccine site (redness, pain, etc.) Myalgia, headache, fever, joint pain, etc.).

However, these side effects do not mean that vaccines for the above diseases are affecting your immunity. On the contrary, vaccines help to strengthen and improve the body's immunity, especially for those who lack immunity and are susceptible to infection. Vaccines can improve two specific aspects of immunity: antigen sensitization and immune memory.

Antigens are part of a vaccine, usually a fragment of a microorganism. It activates the body's immune system, causing it to produce antibodies to fight off future infections. After vaccination, the body produces a subsequent antibody response sufficient to protect it from the disease. These follow-up reactions often include mild discomfort or side effects, but they do not offset the improved immunity.

Another vaccine-related factor is immune memory. Immunological memory refers to that when the human body is exposed to a specific pathogen or its part, the body responds quickly and powerfully to the 'invader' based on antigen recognition. This immune memory allows the immune system to quickly respond to any future infection, which is why most adults are protected from many prevalent viruses and infections.

In short, the relationship between vaccine side effects and immunity does exist. However, this relationship is weak, and strict quality control and careful monitoring during vaccine production and administration ensured that side effects and complications were minimized. On the contrary, we can say with certainty that vaccines will help strengthen our immunity and protect us from many diseases. Therefore, we should believe in the power of science, get vaccinated, protect ourselves, protect others, and fight the epidemic together. It can be seen that we need to improve immunity. Cistanche can significantly improve immunity, because Cistanche is rich in a variety of antioxidant substances, such as vitamin C, vitamin C, carotenoids, etc. These ingredients can scavenge free radicals, reduce oxidative stress, and improve immunity. immune system resistance.

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People who believed in conspiracy theories expressed greater VBH, according to Elias Kowalski et al. [30] and Neil G Bennett et al. [20]. Asians exhibited greater confidence in science than whites, which correlated with higher odds (OR = 8.73) of accepting the vaccine booster. Black respondents scored much lower on the mean trust in science scale than all other racial/ethnic groups as reported by Ryan C. Lee et al. [38].

34.7% believed that vaccinations were unnecessary because the COVID-19 outbreak in China was under control, as illustrated by Chenyuan Qin et al. [14]. Mohamed Abouzid et al. [18] reported that participants believed booster doses were superfluous (14.3%, n = 436). Likewise, Kevin Y. K. Tan et al. [35], Stephen R Neely [43] (29%), and Petros Galanis et al. [16] (19.4%) supported the above findings. Some believed they took the previous dose only a while ago and the next dose was unnecessary (24.6%). As per Walid Al Qareem et al. [44], this was the most cited reason for VBH [44]. Another common reason for VBH was the unavailability of recommendations (10.5%) for the booster dose after the initial COVID-19 shot, as Lai et al. [45] reported.

Chenyuan Qin et al. [11] showed that 30.2% believed that one to two doses were enough, supported by Mohamed Lounis et al. [24]. Likewise, 25% of Makoto Yoshida et al.’s [41] study believed that additional doses were unnecessary. Sameh Attia et al. [34] reported that those who received one dose of the COVID-19 vaccine expressed substantially higher VBH (62.2%) than those who received two or three doses (91.2% and 98.3%, respectively; p < 0.001) [33]. Martin S Hagger et al. [46] and Kyra’s model for predicting VBH demonstrated that the social cognition construct has a major role in VBH, which also depends on people’s attitudes and subject norms.

In a study by Chenyuan et al. [14], among 196 participants who expressed VBH, 58.4%, and 50.0% were unsure of the vaccine’s effectiveness and safety. This is also supported by Mohamed Abouzid et al. [18] (14.6% hesitant), Thin Mon Kyaw et al. [30], Piotr Rzymyski et al. [32] (22.4% hesitant), Xiaozhen Lai et al. [45], Abdul Moeed et al. [29], Marine Paridans et al. [40], Petros Galanis et al. [16], Lucio folcarelli et al. [47] (43.2% hesitant), Makoto Yoshida et al. [41] (19.2% hesitant), and Xiaozhen Lai et al. (10.2% hesitant due to efficacy concerns and 11.8% hesitant due to safety concerns) [45]. Stephen R Neely [43] showed that one in ten did not think immunization stopped the spread of COVID-19 (10.0%).

The marginal mean willingness to get a booster dose for preventing 50% symptomatic infection was only 0.49. A booster with 70% of the effect increased the marginal mean willingness to 0.59. For 90% success, the marginal mean willingness further increased to 0.73. Marginal means for all three degrees of efficacy differ from one another significantly, as portrayed by Shyam Raman et al. [39].

Infection

Lower stress levels generated by concerns of infection or becoming seriously ill also boosted VBH. A study in Pakistan by Abdul Moeed et al. [29] showed that VBH was related to COVID-19 being considered a seasonal flu (26.4%) and belief in natural immunity (22.9%). In Qin et al.’s [14] study, 14.4% believed they were healthy enough to fight COVID-19. This was also supported by Elise Paul et al. [22]. Yufang Sun et al. [48] reported that the main reason for VBH was the low perceived risk of infection with COVID-19. A US study by Stephen R Neely et al. reported that fewer than one in ten respondents were never concerned about COVID-19 (12.3%) [43]. Similarly, in a cross-sectional study by Petros Galanis et al. [16], 19.4% felt that they did not require any vaccine because they enjoyed adequate immunity to COVID-19.

Mohamed Abouzid et al. [18] found the lowest VBH among those who weren’t infected with COVID-19. Quite in contrast, Sameh Attia et al. [34] suggested that those with a history of infection (76.4%) expressed significantly (p < 0.01) greater VBH. Similarly, Carlos Izaias Sartorão-Filho et al. [49] showed that people infected with COVID-19 were 5.4 times more likely to express VBH. Moreover, Yufang Sun et al. [48] and Gede Benny Setia Wirawan et al. [21] suggested that rapid viral mutation and strain changes were reasons for VBH.

Vaccine

One of the major reasons for VBH was side effects associated with previous COVID-19 vaccine doses (10.3% of respondents), according to Mohamed Abouzid et al. [18]. Carlos Izaias Sartorão-Filho et al. [49] stated 4.7 times more VBH due to a history of side effects. Jairoun et al. [36]’s study showed 35.1% of participants expressing concern due to negative side effects, whereas 65.5% were worried about unforeseen side effects and 47.3% were hesitant due to general mistrust. The history of side effects being a reason for VBH was also supported by Stephen R Neely [43] and Sameh Attia et al. [33].

Studies by Tesfaye Yadete et al. [17], Ammar Abdulrahman Jairoun et al. [36], Xiaozhen Lai et al. [45], Mohamed Abouzid et al. [18] suggested that people who did not receive the first dose of COVID-19 vaccine and were not used to vaccination against influenza expressed greater VBH. Similarly, Sky Wei Chee Koh et al. [50] showed that those who were hesitant during their first dose expressed 3.66 times greater VBH.

A study by Khalid Alhasan et al. [51] in Saudi Arabia reported a lower preference for the AstraZeneca vaccine, whereas Mohamed Lounis et al. [24] found the most preferred COVID-19 vaccine to be Sinovac (33.3%), followed by Janssen (12.6%), AstraZenecaOxford (11.8%), and Pfizer-BioNTech (9.6%). However, in the US, Shyam Raman et al. [39] showed that marginal mean willingness was highest for Pfizer, followed by Moderna, and, finally, Johnson & Johnson. VBH due to preference of vaccine was also shown by Sameh Attia et al. [34] where 15.8% of participants wished to receive a different type of vaccine, of which some wanted the government to purchase a certain type such as BNT 16B2. mRNA-1273, AZD1222, and Ad26.COV2. S.

Social Media

Another factor identified was media consumption.

Gede Benny Setia Wirawan et al. [21] found that VBH was negatively correlated with trust in reliable information sources. However, print media’s influence was favorably linked to acceptance, while television’s influence was found to boost VBH.

Healthcare/Non-Healthcare Staff

Fan Wu et al.’s [31] study showed that males and medical personnel expressed less VBH than females and non-medical employees. Sky Wei Chee Koh et al. [50] found that administrative healthcare workers expressed greater VBH than ancillary, medical, and nursing staff.

However, Mohamed Lounis et al. [24] demonstrated that healthcare professionals expressed greater VBH (p = 0.011) (45.9%) than non-medical professionals, which has been supported by Xiaoxiao Wang et al. [23].

Governmental Policy

Shyam Raman et al. [39], Kavita Batra et al. [19], Tesfaye Yadete et al. [17], and Neil G Bennett et al. [20] showed that Republicans expressed greater VBH than Democrats. Ruben Juarez et al. [52]’s study underlines lack of faith in official information and sources significantly aggravated VBH. However, Marine Paridans et al. [40] stated that hesitant groups in their study were not aligned with the vaccination plan.

Other factors associated with VBH were a lack of trust in the government, low compliance with COVID-19 government guidelines, and right-leaning political views.

4. Quality Assessment

The quality of the articles included in the review was thoroughly assessed. The quality of the results of the systematic review directly depends on the overall strength of the evidence collected. By utilizing the Critical Appraisal Skills Program (CASP) checklist, all articles selected for the review were of good quality, with definitive research ideas, appropriate aims, methodology, and findings. 

The only difficulty was to check for an association between the researcher and participant of the study followed by determining whether the ethical considerations were taken into account. Eight of the 10 questions of the CASP yielded a definitive ‘yes’ for each article, thereby leading us to conclude that all articles included in the systematic review were of high quality and highly reliable (Supplementary Data S2).

5. Discussion

This comprehensive systematic review provides an overview of the factors contributing to VBH. The review included a total of 42 studies representing 28 countries, with a predominant representation from the USA (N = 9), followed by China (N = 9), and three studies each from Germany and India. Most of the remaining countries were represented by only one study. Although the included studies represent countries from almost all continents, sub-Saharan Africa is underrepresented. From another perspective, around 17 studies were conducted in Asian countries while 10 were European studies. The remaining were conducted in North America (N = 10), the Middle East and North Africa (N = 6), and Latin America (N = 1).

Factors evaluated may be grouped under three main categories and a range of individual attributes. The three main categories are sociodemographic, financial, and psychological factors. Individual attributes are related mainly to the impact of social media, government policy, and perceptions toward vaccine efficacy and safety. Most studies have reported factors belonging to at least two groups of VBH determinants, indicating the need for customized interventions to target the modifiable factors contributing in every context.

There are very few studies conducted in India confined to VBH. However, considering the population of India and its unique demographics, multiple reasons for VBH were revealed in comparison to the vast majority of reasons cited commonly by people across the world. In one of the studies, the most frequently mentioned reasons for VBH were lack of vaccination slots, vaccine doses, or centers being too far. 

These reasons for VBH were uniquely limited to India. Similarly, believing COVID-19 doesn’t exist anymore, belonging to rural areas, or not knowing others tested positive for COVID-19 were other reasons cited primarily in India, which reflects the outstanding cultural diversity and demographic mass that characterizes the Indian population.

Meanwhile, among Japanese populations, VBH was positively correlated with younger age and influenced by perceptions of vaccine safety and efficacy [50]. The application of protection motivation theory among the Chinese population shows that VBH was associated with high perceived severity and response cost [31]. A Singapore study revealed that VBH was lower than first-dose hesitancy among healthcare workers. Those expressing first-dose hesitancy were more likely to express VBH [50]. Additionally, another study in Singapore reported VBH in about a third of the study population expressing lower threat perceptions, lower perceived benefits, and higher perceived concerns [32]. Therefore, it is essential to consider focused interventions to restrain VBH and facilitate vaccine-related health perceptions.

Furthermore, a large Chinese study (n = 6375) revealed a comprehensive list of demographic and psychosocial factors that mitigate VBH. Lower VBH is reported among younger age groups, females, recipients of higher education, those suffering fewer side effects with previous doses, those with higher perceived susceptibility, infection severity, and finally, a greater trust level in the authorities [53]. Thus VBH is multifactorial, with potentially modifiable factors with appropriate interventions. In addition to socio-psychological factors that lower VBH, trust in science can significantly elicit vaccination intention [42]. In a Malaysian study (n = 1010), lower VBH was associated with younger age, higher income, Chinese ethnicity, and fewer previous experiences of side effects [54]. Knowledge about and confidence in COVID-19 vaccines and trust in the government diminishes VBH among Middle Eastern migrants in Australia [55]. Reports from culturally diverse communities suggest the need for deploying tailored interventions that address separate, context-specific VBH determinants.

US data indicate that VBH is higher among those who distrust vaccine efficacy or the government. On the other hand, VBH was lower among those who regularly took their seasonal flu vaccine or feared potential job losses [20]. Moreover, another study among healthcare workers in the US underlined that their primary motivation for booster doses was impelled by their desire to protect themselves and others. Meanwhile, the study highlighted vaccine-related safety concerns and misinformation, amplified by race-related medical mistrust and a lack of proper communication, which become significant determinants of VBH [56]. Therefore, interventions or campaigns that neutralize VBH should focus on major safety concerns and overcome barriers to trust and communication between different races. A Latin American study underpinned that VBH is positively correlated with low education, living in a town, food insecurity, depressive symptoms, and a previous COVID-19 infection. VBH was negatively correlated with being female and having anxiety symptoms [57].

A Polish study found that VBH was higher among those who experienced side effects after previous doses, expressed safety concerns, and did not perceive the need for further vaccination. Lower VBH was reported among older adults, obese women, people with chronic diseases, and those who had previous influenza vaccine experiences [32]. Moreover, a study from Italy showed that VBH was more likely among those with unpleasant experiences after previous vaccination, lack of close family or friends infected by COVID-19, and a dearth of official information from government authorities. Furthermore, a large study (n = 22,139) in the UK has highlighted that approximately 4% were uncertain and another 4% expressed VBH. The uncertainty or unwillingness was greater among those who had the same attitude towards the first dose: younger, healthier, low education, disadvantaged socio-economics, low perceived susceptibility, and low compliance to government-imposed COVID-19 restrictions [47].

Many reports have confirmed the multifactorial nature of vaccine hesitancy, necessitating multifaceted, tailored interventions that address all potentially modifiable factors [49]. Indeed, customized education, proper communication on perceived risks and benefits, and strategic legislation might help reduce VBH among HC workers [50]. Interestingly, a series of ten cross-sectional studies in Hong Kong (n = 7411) revealed that factors associated with VBH change over time, mandating the need to update and adjust vaccine promotion strategies in the community [58]. Any intervention to increase booster vaccine uptake should not overlook previous experiences following the first two doses. Unaddressed adverse experiences after primary doses can consistently impact VBH even among healthcare workers [59]. Previous research shows that vaccine-related side effects vary across age groups, gender, and recipients of different vaccines [60]. These differences add another dimension when considering interventions to counter VBH, where the above groups should be carefully assessed and counseled accordingly.

Evaluating these articles demonstrated that the major factors for VBH were in the domain of trust deficit in the vaccine, its efficacy, science, or policy. In a vastly populated country like India, despite multiple government schemes for vaccination, such as HarGharDastak or 75 days of free vaccination (in connection with the 75th year of Independence), these schemes must reach the public. We need to understand the level of awareness of these schemes among the common multitude. This review aims to facilitate the spread of awareness and bridge the communication gap between science and the people.

6. Conclusions

In our study, we found strong evidence suggesting age, gender, lack of trust in science, and concerns about safety and efficacy as major determinants for VBH. Among other factors, employment status, infection with COVID-19, fear of side effects, and governmental policies were identified. Identifying these factors can help shape interventions that improve the vaccination strategy. Targeted intermediation based on specific reasons for VBH can facilitate purposeful interventions. As the main message of this systematic review, we propose a thorough evaluation of factors that potentially affect hesitancy, followed by appropriate communication at both individual and community levels about the benefits of booster doses and the risk of losing immunity through their neglect.

supplementary Materials:

The following supporting information can be downloaded at https: //www.mdpi.com/article/10.3390/vaccines11030623/s1, Supplementary Data S1: Data extracted from the included articles; Supplementary Data S2: The quality of each included article was assessed through the Critical Appraisal Skills Program (CASP) checklist.

Author Contributions:

Conceptualization, S.A. (Shruti Ayyalasomayajula), A.D. and M.S.K.; Data retrieval, S.A. (Shruti Ayyalasomayajula), A.D., M.S.K., S.A.T. and S.A. (Suhaj Abdulsalim); validation, M.H.E., S.S., and M.S.K.; formal analysis, M.S.K., S.A. (Shruti Ayyalasomayajula), A.D. and S.A. (Suhaj Abdulsalim); writing—original draft preparation, M.S.K., S.A. (Shruti Ayyalasomayajula), and A.D.; writing—review and editing, S.A. (Suhaj Abdulsalim), S.A.T., S.S., M.K.U. and M.H.E.; visualization, M.S.K.; supervision, M.S.K., S.A. (Suhaj Abdulsalim) and M.K.U. All authors have read and agreed to the published version of the manuscript.

Funding:

The researchers would like to thank the Deanship of Scientific Research, Qassim University, Saudi Arabia for funding the publication of this project.

Institutional Review Board Statement:

Not applicable.

Informed Consent Statement:

Not applicable.

Data Availability Statement:

Not applicable.

Conflicts of Interest:

The authors declare no conflict of interest.

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