Acceptance of Booster COVID-19 Vaccine and Its Association with Components of Vaccination Readiness in the General Population: A Cross-Sectional Survey for Starting Booster Dose in Japan

Global disparities in COVID-19 vaccine booster dose (VBD) acceptance and hesitancy: An updated narrative review

The global deployment of COVID-19 vaccine booster dose (VBD) has been recognized as a promising therapeutic alliance to provide repeated immunity against the arrival of new variants. Despite scientific evidence supports the effectiveness of periodic doses, COVID-19 vaccine booster reluctance continues to thrive. This narrative review aimed to examine global COVID-19 vaccine booster dose (VBD) acceptance and summarize an up-to-date assessment of potential antecedents associated with VBD acceptance. A comprehensive search was performed in several reputable databases such as Medline (via PubMed), Scopus, Google scholar, and Web of Science from June 10th, 2023, to August 1st, 2023. All relevant descriptive and observational studies on COVID-19 VBD acceptance and hesitancy were included in this review. A total of fifty-eight (58) studies were included, with Asia representing the highest count with thirty-one (53%) studies, Europe with eleven (19 %), the United States with nine (16 %), and other regions (Africa and multi-ethnic) with seven (12 %). Worldwide, the pooled COVID-19 VBD acceptance rate was 77.09 % (95 % CI: 76.28-78.18), VBD willingness (n) = 164189, and the total sample (N) = 212,990. The highest and the lowest VBD acceptance rate was reported in Europe and American regions, respectively, 85.38 % (95 % CI: 85.02-85.73, (n) = 32,047, (N = 37,533) vs. 66.92 % (95 % CI: 66.56-67.4), (n) = 29335, (N) = 43,832. However, Asia and multi-ethnic areas reported moderately high VBD acceptance rate 79.13 % (95 % CI: 78.77-79.23, (n) = 93,994, (N) = 11,8779) and 72.16 % (95 % CI: 71.13-72.93, (n) = 9276, (N) = 12,853), respectively. The most common and key antecedents of COVID-19 VBD acceptance and hesitancy across the countries were "equal safety", "efficacy", "effectiveness", "post-vaccination side effects", "community protection" "family protection", "risk-benefit ratio", "booster necessity", "trust", and "variants control". Disparities in the uptake of COVID-19 VBD were observed globally, with the highest rates found in Europe, and the lowest rates in American regions. Multiple potential antecedents including safety, efficacy, and post-vaccination side effects were associated with VBD acceptance and hesitancy.

Are the 7C psychological antecedents associated with COVID-19 vaccine behaviours beyond intentions? A cross-sectional study on at-least-one-dose and up-to-date vaccination status, and uptake speed among adults in France

BACKGROUND

Widely documented psychological antecedents of vaccination are confidence in vaccines, complacency, convenience, calculation, collective responsibility (5C model) with the recent addition of confidence in the wider system and social conformism. While the capacity of these seven antecedents (7C) to explain variance in COVID-19 vaccine intentions has been previously documented, we study whether these factors also are associated with vaccine behaviours, beyond intentions.

METHODS

From February to June 2022, we recruited a sample of adults in France, including persons with notified recent SARS-CoV-2 infection, along with relatives and randomly selected non-infected persons. Participants completed self-administered questionnaires assessing COVID-19 vaccination history and the 7C antecedents. We defined vaccination behaviours as three outcomes: at-least-one-dose vaccine status by 2022 (N = 49,019), up-to-date vaccination status (N = 46,566), and uptake speed of first dose (N = 25,998). We conducted multivariable logistic regressions and Cox models.

RESULTS

Among the 49,019 participants, 95.0% reported receipt of at least one dose and 89.8% were up to date with recommendations. All 7C antecedents were significantly associated with the outcomes, although effects were weaker for up-to-date vaccination status and uptake speed. The strongest effects (most vs. least vaccine-favourable attitude level, at-least-one-dose vaccination status) were observed for collective responsibility (OR: 14.44; 95%CI: 10.72-19.45), calculation (OR: 10.29; 95%CI: 7.53-14.05), and confidence in the wider system (OR: 8.94; 95%CI: 6.51-12.27).

CONCLUSION

This study demonstrates that the 7C not only explain vaccine intention, but also vaccine behaviours, and underpins the importance of developing vaccine promotion strategies considering the 7C antecedents.

Predictive factors of coronavirus disease (COVID-19) vaccination series completion: a one-year longitudinal web-based observational study in Japan

Introduction

Addresing vaccine hesitancy is considered an important goal in management of the COVID-19 pandemic. We sought to understand what factors influenced people, especially those initially hesitant, to receive two or more vaccine doses within a year of the vaccine's release.

Methods

We conducted longitudinal Web-based observational studies of 3,870 individuals. The surveys were conducted at four different time points: January 2021, June 2021, September 2021, and December 2021. In the baseline survey (January 2021), we assessed vaccination intention (i.e., "strongly agree" or "agree" [acceptance], "neutral" [not sure], and "disagree" or "strongly disagree" [hesitance]), and assumptions about coronavirus disease (COVID-19), COVID-19 vaccine, COVID-19-related health preventive behavior, and COVID-19 vaccine reliability. In subsequent surveys (December 2021), we assessed vaccination completion (i.e., ≥2 vaccinations). To investigate the relationship between predictors of COVID-19 vaccination completion, a multivariable logistic regression model was applied. Adjusted odds ratios (AORs) and 95% confidence intervals (CIs) were calculated while adjusting for gender, age, marital status, presence of children, household income category, and presence of diseases under treatment. In a stratified analysis, predictors were determined based on vaccination intention.

Results

Approximately 96, 87, and 72% of those who demonstrated acceptance, were not sure, or hesitated had been vaccinated after 1 year, respectively. Overall, significant factors associated with COVID-19 vaccine compliance included the influence of others close to the index participant (social norms) (AOR, 1.80; 95% CI, 1.56-2.08; p < 0.001), vaccine confidence (AOR, 1.39; 95% CI, 1.18-1.64; p < 0.001) and structural constraints (no time, inconvenient location of medical institutions, and other related factors) (AOR, 0.80; 95% CI, 0.70-0.91; p = 0.001). In the group of individuals classified as hesitant, significant factors associated with COVID-19 vaccine compliance included social norms (AOR, 2.43; 95% CI, 1.83-3.22; p < 0.001), confidence (AOR, 1.44; 95% CI, 1.10-1.88; p = 0.008), and knowledge (AOR, 0.69; 95% CI, 0.53-0.88; p = 0.003).

Discussion

We found that dissemination of accurate information about vaccines and a reduction in structural barriers to the extent possible enhanced vaccination rates. Once the need for vaccination becomes widespread, it becomes a social norm, and further improvements in these rates can then be anticipated. Our findings may help enhance vaccine uptake in the future.

General Vaccination Readiness in Japan: Results from the JASTIS 2023 Study

General vaccine hesitancy is a global concern. Clarifying general vaccination readiness and the psychological factors comprising it is important. Previous studies reported that Japan has one of the lowest vaccine confidence levels worldwide. However, the status of other psychological factors comprising general vaccination readiness in Japan remains unclear. Therefore, we aimed to clarify the status of seven psychological factors comprising general vaccination readiness and their patterns in Japan. This descriptive study utilized data from a large-scale nationwide internet survey (Japan Society and New Tobacco Internet Survey 2023 study, N = 31,037). Seven psychological factors were assessed using the 7C of vaccination readiness scale. Cluster analysis was performed using k-means++ clustering to clarify patterns. Of the seven factors, support for social monitoring of people refusing vaccination (e.g., vaccine passports) was very low among the participants. Cluster analysis showed that the participants' vaccination readiness could be classified into six patterns, of which the very low vaccination readiness cluster, with the lowest scores for most psychological factors, accounted for 11.1% and was more common among those aged 30-49 years (13.1-16.4%). Individuals in this cluster may refuse to receive recommended vaccines.

Estimation of cutoff score for the 7C of vaccination readiness scale

The 7C of the vaccination readiness scale provides a score to evaluate the willingness and readiness to get vaccinated (vaccination readiness). This cross-sectional study clarifies the cutoff vaccination readiness score to determine whether an individual is willing to be vaccinated. We conducted an online survey of 774 participants. The vaccination readiness scores for the full and short survey versions were calculated. The coronavirus disease 2019 vaccination status was used to determine whether the participant was willing to be vaccinated. Receiver operating characteristic curve analysis was performed using the Youden index. The Youden Index was at its maximum when the cutoff score was 4.02 for the full version (area under the curve [AUC]:0.94) and 4.07 for the short version (AUC:0.90). Vaccination readiness scores greater than 4 on both the full and short version may indicate a willingness to be vaccinated. This cutoff value facilitates the interpretation of the 7C scale results.

Acceptance of COVID-19 vaccine booster dose among the people of Bangladesh: A cross-sectional study

Vaccine booster dose (VBD) provides a potential therapeutic alliance in preventing breakthrough infection and new variant's arrival while preserving long-lasting host immunity. This study aimed to analyze COVID-19 VBD willingness and identified the key determinants of VBD acceptance among the general people of Bangladesh. This survey-based study applied a quantitative research paradigm. A validated, anonymous, and multi-item questionnaire was adopted through a theoretical review of pertinent literature on the topic. Data were collected between August 2022─October 2022, and sampling was done randomly. A total of 704 individuals were invited via face-to-face interview approach; however, 13.8 % of them declined to give consent, which resulted in the participation of 607 potential respondents. The main outcome measure was COVID-19 VBD acceptance willingness. Binary logistic regression analysis was conducted to rationalize the study's objectives. The pooled COVID-19 booster vaccine acceptance rate was 70.0 % (95 % confidence Interval [CI]: 67─73) among Bangladeshi people. An analysis of binary logistic regression revealed that, out of 14 potential factors, "efficacy", "repeated immunity", "communication", and "trust" showed highly significant positive association (adjusted odds ratio [aOR ] = 2.151 95 % CI: 1.391─ 3.508, aOR = 2.033 95 % CI: 1.299─ 3.181, and aOR = 2.552 95 % CI: 1.557─4.183 respectively, p<0.01), and "equal safety", "risk-benefit ratio" and "community protection" had significant positive association (aOR = 1.739 95 % CI: 1.070─2.825, aOR = 1.712 95 % CI: 1.116─2.627, and aOR = 1.628 95 % CI: 1.395─0.998, p<0.05) with VBD acceptance. However, post-vaccination "side effects" showed significant negative (aOR = 0.393 95 % CI: 0.237─0.674, p<0.01) associations with VBD acceptance. The odds of accepting the COVID-19 vaccine booster was found 1.26, and it was found insignificant (p>0.05) in the Chi-squared test. Bangladeshi people expressed a moderately high level response to COVID-19 VBD acceptance. A positive attitude towards the COVID-19 VBD is an outcome of this study, regardless of the circumstances, as far as safety, efficacy, perceived health benefits, communication, trust, and community resistance are concerned. Post-vaccination side effects fear was the primary reason for booster dose skepticism as well as a barrier to administering booster shots. The confidence in COVID-19 VBD will be boosted when mass people are effectively communicated and vaccine's data become more available publicly.

Investigating the tendency to use COVID-19 vaccine booster dose in Iran

INTRODUCTION

Vaccine hesitancy is recognized as a significant public health threats, characterized by delays, refusals, or reluctance to accept vaccinations despite their availability. This study, aimed to investigate the willingness of Iranians to receive booster shots, refusal rate, and their preferred type of COVID-19 vaccine.

MATERIALS AND METHODS

This cross-sectional study was conducted over a month from August 23 to September 22, 2022 using an online questionnaire distributed through WhatsApp and Telegram online communities. The questionnaire assessed participants' intent to accept COVID-19 booster vaccination and had no exclusion criteria. Data analysis involved using SPSS version 16.0, with t-tests and chi-square tests used to assess the bivariate association of continuous and categorical variables. A multivariate logistic regression model was built to examine the association between Health Belief Model (HBM) tenets and COVID-19 vaccination intent. The Hosmer Lemeshow Goodness of Fit statistic was used to assess the model's fit, with a p-value > 0.05 indicating a good fit.

RESULTS

The survey was disseminated to 1041 adults and the findings revealed that 82.5% of participants expressed a desire to receive the booster dose. Participants who intended to be vaccinated were generally older (46.4 ± 10.9), mostly female (53.3%), single (78.9%), had received a flu vaccine (45.8%). The findings indicated that the HBM items, including perception of COVID-19 disease, perceived benefits of COVID-19 vaccines, COVID-19 safety/cost concerns, preference of COVID-19 vaccine alternatives, and prosocial norms for COVID-19 vaccination, received higher scores among individuals intending to be vaccinated compared to vaccine-hesitant individuals, with statistical significance (p < 0.05). However, the "COVID-19 risk-reduction habits" item had a higher score but did not reach statistical significance (p = 0.167).

CONCLUSION

Factors such as lack of trust in the effectiveness of the vaccine, trust in specific vaccine manufacturers, and concerns about side effects of COVID-19 vaccine are among the most important factors. These findings have implications for national vaccination policies, emphasizing the need for policymakers in the health sector to address these factors as vital considerations to ensure the continuity of vaccination as one of the most important strategies for controlling the pandemic.

COVID-19 Vaccine Booster Hesitancy among Hispanic Adults: A Cross-Sectional Study from the Puerto Rico Community Engagement Alliance against COVID-19 Disparities (PR-CEAL)

Hispanic/Latino communities have suffered a disproportionate burden of the COVID-19 pandemic. Although Puerto Rico has one of the highest COVID-19 primary series vaccination rates nationwide, this estimate contrasts with the reported booster doses' low uptake. This study aimed to assess health belief correlates of COVID-19 vaccine booster uptake. Using a convenience sampling approach, the Puerto Rico-Community Engagement Alliance (PR-CEAL) conducted a cross-sectional study where 787 participants were recruited using online and in-person strategies between December 2021 and February 2022. Participants were adults 18 years or older, Spanish-speaking, and residents of Puerto Rico. The Health Belief Model was used to evaluate attitudes and beliefs. A total of 784 participants were used in this analysis. Adjusted Poisson regression models were used to estimate prevalence ratios (PR) and 95% confidence intervals (CI) of booster refusal. Overall, 22% of participants refused the vaccine booster or had not gotten it yet. Adjusted models showed that (i) participants who disagreed that getting the booster dose either made them feel less worried about COVID-19 or (ii) felt that the vaccine decreased their chances of getting COVID-19 presented higher booster-refusal prevalence ratios (PR = 4.20, 95% CI: 3.00, 5.90; PR = 3.70, 95% CI: 2.64, 5.18). Moreover, participants that (iii) reported having concerns for booster side effects [PR = 2.47; 95% CI = 1.73, 3.51], (iv) booster efficacy [PR = 2.50; 95% CI = 1.75, 3.58], and (v) booster safety [PR = 2.80; 95% CI = 1.96, 3.99] were significantly more likely to refuse the booster. In conclusion, booster vaccination refusal was associated with lower perceived vaccine benefits and greater barriers among adults in Puerto Rico. These results informed the development of PR-CEAL's targeted community outreach strategies and public health campaigns to increase booster vaccine uptake.

Public Knowledge About COVID-19 Booster Vaccines in Pakistan: A Study Conducted in a Tertiary Care Hospital in Karachi

The coronavirus disease 2019 (COVID-19) pandemic has deteriorated the healthcare system and economy worldwide. Globally, by making the primary vaccination against the coronavirus necessary, the surge in cases waned, but as the effects of this vaccination decreased after some time, to prevent another pandemic, vaccination was still necessary. As a result, receiving a COVID-19 booster shot can boost immunity against the coronavirus. This study aimed to assess knowledge of COVID-19 booster vaccines in Pakistan among the general public and understand the factors affecting the vaccination process in the state. In this cross-sectional study, non-probability convenience sampling was done. Its physical data collection was conducted in September 2022 in a tertiary care hospital in Karachi, Pakistan. Data were collected from 384 individuals who visited the hospital with consent before filling out the questionnaire. The mean age of respondents was 35.81 (standard deviation (SD) = ±13.006), and 98.7% of individuals were primarily vaccinated for COVID-19, but out of these, only 60.1% received the booster jab. The most commonly reported side effects of primary doses of COVID-19 and its booster were pain at the injection site, fatigue, and fever, but these effects did not appear to have as much of an impact on the vaccination process as education did. The results are evident that out of primarily vaccinated individuals against COVID-19, 40.16% are reluctant to receive its booster. Therefore, it is essential to create awareness among the masses about vaccination and its importance.

Attitudes and concerns regarding booster dose of COVID-19 vaccine among Egyptian patients with autoimmune and rheumatic diseases: a cross-sectional survey study

BACKGROUND

COVID-19 booster dose vaccination acceptance and actual vaccination behavior is not known among Egyptian individuals with autoimmune and rheumatic diseases (ARDs). The aim of this study was to investigate the acceptability of booster dose of the COVID-19 vaccine, as well as the factors that drive and inhibit that acceptance among Egyptian patients diagnosed with ARDs.

METHODS

This interview-based, cross-sectional analytical study was carried out on ARD patients from 20 July to 20 November 2022. A questionnaire was created to assess sociodemographic and clinical data, as well as COVID-19 vaccination status and the intention to receive a COVID-19 vaccine booster dose, perception of health benefits of it in addition to the perceived barriers and/or concerns.

RESULTS

A total of 248 ARD patients were included, with a mean age of 39.8 years (SD = 13.2), and 92.3% were females. Among them, 53.6% were resistant to the COVID-19 booster dose, whereas 31.9% were acceptant and 14.5% were hesitant. Those who were administering corticosteroids and hydroxychloroquine shown significantly greater booster hesitancy and resistance (p = 0.010 and 0.004, respectively). The primary motivation for taking a booster dose among the acceptant group was own volition (92%). Most acceptants believed that booster dose can prevent serious infection (98.7%) and community spread (96.2%). Among the hesitant and resistant groups, the main concerns for booster dose were fear about its major adverse effects (57.4%) and long-term impact (45.6%).

CONCLUSIONS

There is a low acceptability rate of booster dose of COVID-19 vaccine among Egyptian patients with ARD diseases. Public health workers and policymakers need to make sure that all ARD patients get clear messages about accepting the COVID-19 booster dose.

Patterns of HPV vaccine hesitancy among catch-up generations in Japan: A descriptive study

BACKGROUND

Cervical cancer is a preventable disease caused by human papillomavirus (HPV). The HPV vaccine uptake in Japan has been slow since the Ministry of Health, Labour and Welfare suspended the recommendation for proactive HPV vaccination in 2013. In April 2022, Japan initiated catch-up vaccinations for women who missed the opportunity to receive the HPV vaccine. However, as of September 2022, very few women had received catch-up vaccination, raising concerns about vaccine hesitancy in the target population. It is necessary to understand the thinking and motivation of the target population to develop effective strategies to improve vaccination rates. Therefore, using cluster analysis, this study aimed to clarify the pattern of HPV vaccine hesitancy among the catch-up generations in Japan.

METHODS

This descriptive study was based on an Internet survey completed by 3,790 women in Japan aged over 18 years who were eligible for catch-up vaccination and had not yet received an HPV vaccine. Participants were asked about their intention and thinking about the HPV vaccine and descriptive norms on vaccination intention. Cluster analysis using k-means clustering was performed to clarify these patterns.

RESULTS

Cluster analysis revealed three hesitancy patterns: acceptance, neutral and refusal. The acceptance group, with high intention, comprised 28.2% of the participants, and students and a high-income level mainly dominated this group. The refusal group, with negative thinking and low intention, accounted for 20.1% and was more prevalent among workers and the unemployed. The neutral group, with neutral thinking and intention, accounted for 51.6%. The perceived effect of descriptive norms on vaccination intention was large in the acceptance group but small in the refusal group.

CONCLUSION

HPV vaccine awareness promotion strategies must be based on the characteristics of each group and the different distributions of sociodemographic factors.

Assessing COVID-19 Vaccine Booster Hesitancy Using the Modified 5C Scale in Zhejiang Province, China: A Cross-Sectional Study

Following the rollout of a booster campaign to promote immunity against COVID-19 in China, this study aimed to assess booster hesitancy among adults who were fully vaccinated with primary doses across Zhejiang Province. Firstly, the modified 5C scale developed by a German research team was assessed for reliability and validity via a pre-survey in Zhejiang Province. Then, a 30-item questionnaire was established to conduct online and offline surveys during 10 November to 15 December 2021. Demographic characteristics and information on previous vaccination experience, vaccine type of primary doses, attitudes towards booster doses and awareness of SARS-CoV-2 infection were collected. Chi-square tests, pairwise comparison and multivariate logistic regression were performed in data analysis. In total, 4039 valid questionnaires were analyzed, with booster hesitancy of 14.81%. Dissatisfaction with previous vaccination experience of primary doses (ORs = 1.771~8.025), less confidence in COVID-19 vaccines (OR = 3.511, 95%CI: 2.874~4.310), younger age compared to the elderly aged 51-60 years old (2.382, 1.274~4.545), lower education level (ORs = 1.707~2.100), weaker awareness of social responsibility of prevention and control of COVID-19 (1.587, 1.353~1.859), inconvenience of booster vaccination (1.539, 1.302~1.821), complacency regarding vaccine efficacy as well as self-health status (1.224, 1.056~1.415) and excessive trade-offs before vaccination (1.184, 1.005~1.398) were positively associated with booster hesitancy. Therefore, intelligent means should be strengthened to optimize vaccination services. More influential experts and other significant figures should be supported to promote timely evidence-based information via various media platforms to reduce public hesitancy and increase booster uptake.

Psychological determinants of COVID-19 vaccine acceptance: A comparison between immigrants and the host population in Japan

This study explored the differences in COVID-19 vaccination readiness based on the 7C model and its association with vaccine acceptance among foreign-born immigrants, Japan-born immigrants, and locals in Japan. A cross-sectional survey was conducted in October 2021 (n = 3,690). Our results show that COVID-19 vaccination readiness, acceptance, and their relationship differ according to migratory status and nativity. Immigrant participants reported higher general vaccination readiness and acceptability for vaccination against COVID-19 than the Japanese participants, but had lower vaccination coverage, particularly among those born in Japan. The psychological determinants of Japan-born immigrants were more similar to those of Japanese participants than those of foreign-born immigrants. The effects of confidence, complacency, and constraints on COVID-19 vaccine acceptance were strong among all three groups. However, the role of collective responsibility and conspiracy varied by migratory status. This study highlighted the importance of culturally tailored interventions in vaccine delivery to immigrants.

The Relationship between Daily Behavior Changes and Vaccine Attitudes at the Early Stage of the COVID-19 Pandemic among Japanese People from Different Demographics: A Retrospective and Exploratory Examination Using a Free-Response Survey

This study investigated how daily behaviors of Japanese people changed during the early stages of the COVID-19 pandemic and whether the change was mediated by demographics. It also examined whether the magnitude of behavior change in a demographic group is related to their attitudes towards the COVID-19 vaccine. 301 Japanese responded to an online survey in February 2021, in which they first wrote some activities they frequently performed before the virus outbreak and then wrote about activities in their current life. The number of gathered answers were 1858 for 'before' and 1668 for 'after', and they were grouped into 19 behavior categories. Overall, behaviors such as traveling, eating out, and shopping were much less frequently described in the 'after' condition; while housework, food delivery, and pandemic prevention were mentioned more. However, the change pattern was significantly influenced by demographics of age, gender, having children or not, and household income. Especially women, younger generations, and people without children showed the greatest extent of behavior change compared with the other demographic cohorts. These groups were reported to be vaccine-hesitant in the literature. This study suggests that individuals with hesitant attitudes towards vaccines are more willing to change their behaviors to control viral transmission.

Drivers of and Barriers to COVID-19 Vaccine Booster Dose Acceptance in Indonesia

Obtaining a booster dose of coronavirus disease 2019 (COVID-19) vaccine is required to maintain the protective level of neutralizing antibodies and therefore herd immunity in the community, and the success of booster dose programs depends on public acceptance. The aim of this study was to determine the acceptance of a booster dose of COVID-19 vaccine and its drivers and barriers in Indonesia. A cross-sectional survey was conducted in the provinces of Indonesia between 1 and 15 August 2022. Individuals who completed the primary series of the COVID-19 vaccine were asked about their acceptance of a booster dose. Those who refused the booster dose were questioned about their reasons. A logistic regression was used to determine the determinants associated with rejection of a booster dose of COVID-19 vaccine. A total of 2935 respondents were included in the final analysis. With no information on the efficacy and safety of the COVID-19 vaccine, 95% of respondents agreed to receive a booster dose if it were provided for free by the government. This acceptance was reduced to only 50.3% if the vaccine had a 75% efficacy with a 20% chance of side effects. The adjusted logistic regression analysis indicated that there were eight factors associated with the rejection of the booster dose: age, marital status, religion, occupation, type of the first two vaccines received, knowledge regarding the importance of the booster dose, belief that natural immunity is sufficient to prevent COVID-19 and disbelief in the effectiveness of the booster dose. In conclusion, the hesitancy toward booster doses in Indonesia is influenced by some intrinsic factors such as lack of knowledge on the benefits of the booster dose, worries regarding the unexpected side effects and concerns about the halal status of the provided vaccines and extrinsic determinants such as the effectiveness and safety of the vaccine. These findings suggest the need for more campaigns and promotions regarding the booster dose benefits to increase its acceptance.