Adherence to national and international vaccine information sources and future pandemic preparedness among Iranian adults in the post-COVID-19 era

Abstract

Background

The effectiveness of public health efforts and vaccination campaigns depends on the level of trust that the population has, which in turn depends on the population’s confidence in health information sources and organizations. This study aims to assess post-pandemic compliance with vaccine information sources and their influence on future pandemic preparedness in Iran and to identify the underlying factors related to adherence.

Methods

This cross-sectional study was conducted using an online questionnaire among Iranian adults in 2024. The instrument used in this study was rooted in the Health Belief Model and the 3 C Model of Vaccine Hesitancy, and was developed according to previous literature, objectives of the study, and inputs from experts in this field. Validity and reliability of the questionnaire were further evaluated using face, content and construct validity, and Cronbach’s alpha. We applied multiple linear regression to identify independent predictors of compliance with national and international vaccination guidelines and future pandemic preparedness.

Results

Among 457 Iranian adults who participated in our study, approximately 75% reported favorable attitudes toward adherence to vaccination guidelines and pandemic preparedness. Mean adherence scores were higher for international (4.06 ± 0.76) than for national (3.81 ± 0.81) vaccination guidelines. Multiple linear regression revealed that trust in health authorities, favorable vaccine perceptions, and self-efficacy were the strongest predictors of adherence to both national and international vaccination guidelines. Notably, trust in national health authorities was negatively associated with adherence to international vaccination guidelines (B: -0.137, 95% CI: -0.198 -0.076). In addition, individuals with a personal or family history of COVID-19 scored significantly higher in adherence to international vaccination guidelines by an average of 0.31 points (95% CI: 0.11–0.51).

Conclusions

Enhancing vaccine perceptions, trust in health organizations, and self-efficacy improves public compliance and pandemic preparedness.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-025-24161-6.

Background

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which emerged in late 2019, rapidly led to a global outbreak and showed significant unpreparedness in health systems [1]. Throughout this period, individuals relied heavily on health organizations and government agencies for accurate information, guidance, and interventions to mitigate the spread of the virus [2–4]. However, the effectiveness of public health measures and vaccination campaigns is dependent on the level of trust that the population has in these sources [4]. The erosion of trust presents a significant barrier to effective pandemic response efforts, induces negative attitudes towards other immunization programs, such as seasonal influenza vaccine or routine childhood vaccinations, and threatens future public health preparedness initiatives [5, 6]. For instance, in the United States (US), routine childhood vaccination coverage among kindergartners has dropped by 3% over three consecutive years compared to pre-pandemic levels [7]. More than two hundred thousand kindergarteners were unvaccinated for MMR, posing an increased risk for outbreaks of vaccine-preventable diseases such as measles and mumps [7–9]. This concern has already manifested in measles outbreaks in Washington and New York City in 2023, which cost millions of dollars to contain [10].

A survey by the Kaiser Family Foundation in the US indicated a significant decline in trust in the Centers for Disease Control and Prevention (CDC), federal institutions, and the US Food and Drug Administration (FDA) among the US general population during the pandemic [5]. Based on previous literature, vaccine hesitancy is often rooted in a lack of trust in health authorities and misinformation about vaccine safety [11]. In Iran, there have been significant challenges associated with mistrust in pandemic information sources and a lack of transparency as well [12]. Additionally, misinformation, disinformation, and politicization of public health measures have fueled distrust among the population [12, 13]. In a qualitative study on barriers to vaccine acceptance among the general population in Iran during the pandemic, interviews showed that the insufficient social trust in healthcare system officials, distrust in the effectiveness of the vaccines, and vaccine safety concerns were the main challenges addressed by the study groups [14].

Understanding the dynamics of trust and mistrust in the context of pandemics is essential for developing effective communication strategies, public health interventions, and policy measures. By developing a validated and reliable survey instrument, this study aimed to assess the level of trust among Iranian adults, investigate its impact on adherence to vaccination guidelines and future pandemic preparedness, and identify underlying factors related to nonadherence.

Methods

This cross-sectional study was conducted among the Iranian population from September to November 2024 after obtaining approval from the Institutional Review Board of Shiraz University of Medical Sciences (IR.SUMS.MED.REC.1403.430). All subjects were assured of the confidentiality of their responses, and an online consent form was provided at the beginning of the survey. In addition, they were informed about the study design and objectives before completing the questionnaire.

Study participants and sample size determination

The study population consisted of participants who were aged 18 years or older, (2) resided in Iran, and (3) had access to online platforms (Telegram, WhatsApp, and Instagram); participation in the study was voluntary. Individuals with nationalities other than Iranian were excluded from our study. The required sample size for this study was determined using Cochran’s formula [15], reaching a minimum of 289 individuals, based on the assumptions of a 95% confidence level (Z = 1.96), a 5% margin of error, and an estimated mistrust prevalence of 25% drawn from previous studies [5, 16].

Questionnaire dissemination

The questionnaire was created using two online survey platforms, Google Forms and Porsline. These platforms allowed for easy distribution and data collection, ensuring accessibility for participants across Iran. The survey link was disseminated through online social media platforms (Telegram, WhatsApp, and Instagram) to reach a wide audience. Data collection was conducted over one month during October and November 2024.

Survey development process and structure

The initial phase involved the identification of key constructs based on a thorough literature review [17–21] and the study objectives. Items were generated to represent each construct adequately by reviewing existing validated questionnaires [17, 18] and incorporating feedback from experts in the field of community medicine.

The questionnaire was structured into three sections:

•  Background Information: This section assessed sociodemographic characteristics of the participants, including age, gender, educational level, work in healthcare systems or not, marital status, occupational status, history of COVID-19 in themselves or their relatives, history of their relatives’ death due to COVID-19, and history of SARS-CoV-2 vaccine uptake.

• Psychological factors: The initial version of this section included 26 items across six dimensions, each theoretically structured around established models of the Health Belief Model [22] and 3 C Model of Vaccine Hesitancy [23]. Specifically, COVID-19 Vaccine Attitude (4 items) and General Vaccine Attitude (5 items) reflect perceived benefits and perceived barriers within the HBM. Trust in Health Information Sources (4 items), Trust in National Health Authorities (5 items), and Trust in International Health Authorities (5 items) align with the confidence domain within the 3 C Model of Vaccine Hesitancy, addressing factors such as source credibility, institutional trust, and reliability. Lastly, self-efficacy (3 items) corresponds to both the HBM construct of perceived self-efficacy and the complacency component of the 3 C Model, capturing individuals’ confidence in their ability to act on health-related decisions. Two academic faculty members assessed the face validity of the items to ensure clarity. Responses were assessed using a 5-point Likert scale ranging from 1 (“strongly disagree”) to 5 (“strongly agree”). However, following pilot testing, two items were excluded from the final version of the instrument, as detailed in the subsequent sections. Each dimension score was calculated by averaging the scores of its constituent items based on the participants’ responses.

• Outcomes: This section measured the level of adherence to national and international vaccination guidelines and future pandemic preparedness. It assessed the participants’ intent to follow health measure guidelines and adhere to adult and children vaccination recommendations/guidelines issued by national and international health authorities. Responses were measured using a 5-point Likert scale ranging from 1 (“strongly disagree”) to 5 (“strongly agree”). The eight outcome items were grouped into two composite scores − (1) adherence to national vaccination guidelines and pandemic preparedness, and (2) adherence to international vaccination guidelines and pandemic preparedness - by averaging the scores of the corresponding four items in each category.

Completion of the questionnaires required approximately 5 to 10 min. The questionnaire, both Farsi and English versions, along with the construct dimensions, are included in the Supplementary Material.

Survey instrument validity and reliability

A panel of 12 experts with extensive experience in community medicine was recruited to evaluate the relevance and comprehensiveness of the items in the second section of our survey tool. Each expert assessed the items using the Content Validity Ratio (CVR) and Content Validity Index (CVI) methodologies [24–26]. Based on the CVR and CVI analysis [Supplementary Table 2], one item in the Self-efficacy dimension (CVR = −1; CVI = 0) was omitted and replaced based on expert recommendations. In addition, suggestions from the panel were incorporated to refine the wording of the item for improved clarity and relevance.

Then, a pilot test was conducted in September 2024 on a sample of 71 individuals to ensure the clarity and cultural appropriateness of the questionnaire. We provided them with information about the pilot test, including its purpose and the importance of their comments, and collected their feedback through open-ended questions, asking participants to comment on any issues they encountered. The Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy was 0.733, indicating a good fit for factor analysis [27]. Using principal components analysis (PCA), we performed exploratory factor analysis (EFA) to extract the factors with eigenvalues greater than 1. Data reduction yielded a six-factor solution with the cumulative extraction sums of squared loadings explaining 75.08% of the total variance. Item Q10 from the original questionnaire failed to load appropriately onto its corresponding dimension, with absolute factor loading below 0.4 and was excluded. In addition, all factors except factor 2 demonstrated satisfactory internal consistency. Factor 2 initially had a Cronbach’s alpha of 0.401, which improved substantially to 0.670 after excluding item Q5.

In the final dataset, collected from the general Iranian adult population following revisions to the questionnaire in the pilot test, we reevaluated construct validity and reliability for our instrument. With a KMO value of 0.925 and a significant Bartlett’s test of sphericity, our dataset underwent data reduction, which revealed a cumulative extraction sum of squared loadings of 75.41%. All items were grouped according to the conceptualized factor structure. The overall Cronbach’s alpha for the psychometric section was 0.931, suggesting excellent internal consistency. Supplementary Table 3 presents the rotated factor loadings along with internal consistency coefficients for each factor.

In the next step, we conducted confirmatory factor analysis (CFA) on the same dataset to preliminarily validate the final model derived from the EFA. The model fit indexes were as follows: χ²/df = 5.241, CFI = 0.873, TLI = 0.852 and RMSEA = 0.096. While these values fall slightly outside the conventional thresholds for excellent model fit, they are generally considered tolerable in the context of applied public health and behavioral research [28–30]. Detailed CFA results, including unstandardized regression weights, covariances, and the path diagram, are provided in Supplementary Material.

Statistical analysis

We used SPSS statistical software version 16.0 (IBM Corporation, Armonk, NY, USA) and IBM Amos version 24.0 (SPSS Inc., Chicago, IL, USA) for data management and statistical analyses. Continuous variables were described using means and standard deviations (SD). Categorical variables were summarized using frequencies and percentages. For data analysis, we applied an independent t-test, one-way ANOVA, Mann–Whitney U test, and Kruskal–Wallis test, as appropriate. We also conducted multiple linear regression with a stepwise entry method to identify independent predictors of adherence to national and international vaccination guidelines. Model assumptions, including linearity, homoscedasticity, multicollinearity, independence of errors, and normal distribution of errors, were checked and found to be met, as summarized in Supplementary Table 4 [31]. A p-value < 0.05 was considered statistically significant.

Results

Characteristics of the participants

A total of 457 individuals participated in the study, with a mean age of 47.73 years (± 12.53) and a median age of 48 (interquartile range: 38–57). Among participants, 246 (53.8%) were female. Most participants (77.2%) were married and had a Master’s degree or higher level of education (63.0%). Most participants were employed (68.9%) or were retired (16.6%); 212 individuals (46.4%) reported working as healthcare professionals. Almost all participants (94.7%) had experienced COVID-19 in family, friends, or themselves, and nearly half of them (47.9%) had witnessed COVID-19-associated mortality in family or close friends. In addition, 449 participants (98.2%) had received at least one dose of the COVID-19 vaccine, with the majority (71.7%) being up to date with their COVID-19 vaccination status, including having received booster doses.

The mean score for adherence to national vaccination guidelines and pandemic preparedness was 3.81 (± 0.81), while the mean score for adherence to international guidelines was 4.06 (± 0.76), both measured on a 5-point Likert scale ranging from strongly disagree (1) to strongly agree (5). Figure 1 shows the distribution of responses across adherence levels to national and international vaccination guidelines. While both outcomes demonstrated a high proportion of agreement (mean composite score 3–5), adherence to international guidelines showed a relatively higher proportion of strong agreement (mean scores 4–5), indicating a generally more favorable attitude.

Fig. 1.

Distribution of participants’ adherence scores to national and international vaccination guidelines

Univariate analysis revealed that married participants with higher education levels, healthcare professionals, and those who had received more doses of the COVID-19 vaccine had significantly higher scores in their adherence to national vaccination guidelines and pandemic preparedness. On the other hand, adherence to international vaccination guidelines and pandemic preparedness composite score was markedly higher in females, participants with higher levels of education, those with personal or family history of SARS-CoV-2 infection, and healthcare workers (Table 1).

Table 1.

Sociodemographic and health characteristics of the participants associated with adherence to national and international vaccination guidelines and pandemic preparedness

	N = 457 Frequency (%)	Adherence to national vaccination guidelines and pandemic preparedness composite score (mean (± SD))	P-value	Adherence to international vaccination guidelines and pandemic preparedness composite score (mean (± SD))	P-value
Age (year)
18–39	123 (26.9)	3.65 ± 0.98	0.18	4.05 ± 0.85	0.07
40–59	255 (55.8)	3.86 ± 0.76		4.07 ± 0.75
> 60	79 (17.3)	3.90 ± 0.63		4.09 ± 0.64
Gender
Male	211 (46.2)	3.77 ± 0.80	0.19	3.98 ± 0.77	0.01
Female	246 (53.8)	3.85 ± 0.82		4.14 ± 0.75
Marital status
Unmarried	104 (22.8)	3.63 ± 0.96	0.02	4.09 ± 0.82	0.61
Married	353 (77.2)	3.86 ± 0.76		4.06 ± 0.75
Occupation
Employed	315 (68.9)	3.82 ± 0.82	0.22	4.10 ± 0.76	0.06
Housewife	25 (5.5)	3.50 ± 0.96		3.68 ± 1.10
Student	23 (5.0)	3.89 ± 0.87		4.29 ± 0.65
Unemployed	18 (3.9)	3.47 ± 1.06		4.05 ± 0.88
Retired	76 (16.6)	3.92 ± 0.58		3.96 ± 0.56
Educational level
Diploma or lower	25 (5.5)	3.78 ± 0.91	0.00	3.68 ± 0.90	0.00
Associate	19 (4.2)	3.42 ± 0.95		3.63 ± 0.91
Bachelor	125 (27.4)	3.59 ± 0.87		3.87 ± 0.85
Higher academic education	288 (63.0)	3.94 ± 0.74		4.21 ± 0.65
Healthcare worker
No	245 (53.6)	3.72 ± 0.82	0.00	3.93 ± 0.77	0.00
Yes	212 (46.4)	3.92 ± 0.79		4.21 ± 0.72
History of COVID-19 in family and friends or themselves
No	24 (5.3)	3.55 ± 1.16	0.43	3.62 ± 1.10	0.03
Yes	433 (94.7)	3.83 ± 0.79		4.09 ± 0.73
History of COVID-19 associated mortality in family and friends
No	238 (52.1)	3.82 ± 0.84	0.57	4.04 ± 0.79	0.61
Yes	219 (47.9)	3.80 ± 0.79		4.09 ± 0.74
COVID-19 vaccine doses received
Zero	8 (1.8)	2.81 ± 1.18	0.00	3.43 ± 1.13	0.00
One	10 (2.2)	3.15 ± 0.91		3.45 ± 1.03
Two	107 (23.4)	3.60 ± 0.88		3.91 ± 0.88
Three or more	332 (72.6)	3.93 ± 0.74		4.15 ± 0.68

Predictors of adherence to national and international vaccination guidelines

Table 2 presents the results of adherence to national vaccination guidelines and pandemic preparedness regression model, outlining the unstandardized coefficients (B), standard errors (SE), standardized coefficients (β), 95% confidence intervals (CIs) for the B coefficients, and p-values for each predictor variable included in the analysis. The model was statistically significant (F (22, 434) = 27.150, p-value < 0.001, with an R² of 0.579 and an adjusted R² of 0.558). In this model, none of the sociodemographic variables demonstrated a statistically significant association with adherence to national vaccination guidelines and pandemic preparedness. However, several psychological factors showed strong and independent associations. Specifically, a one-point increase in Factor 2: General Vaccine Attitude, Factor 4: Trust in National Health Authorities, and Factor 6: Self-efficacy was associated with increases of 0.31 (95% CI: 0.21–0.42), 0.35 (95% CI: 0.28–0.42) and 0.1 (95% CI: 0.02–0.17) points, respectively, in the composite score of adherence to national vaccination guidelines.

Table 2.

Multivariable linear regression analysis for the factors influencing adherence to national vaccination guidelines and pandemic preparedness

Variables	B coefficient	Standard error	β coefficient	95% CI for B coefficient	P-value
Age	0.001	0.003	0.003	−0.005, 0.006	0.951
Gender (Ref: Male)
Female	0.080	0.056	0.049	−0.029, 0.189	0.151
Marital status (Ref: Unmarried)
Married	−0.037	0.072	−0.019	−0.178, 0.103	0.603
Occupation (Ref: Employed)
Housewife	−0.213	0.130	−0.059	−0.469	0.104
Student	−0.135	0.126	−0.036	−0.383, 0.113	0.286
Unemployed	0.034	0.142	0.008	−0.245, 0.312	0.813
Retired	−0.015	0.089	−0.007	−0.189, 0.160	0.868
Educational level (Ref: Diploma or lower)
Postgraduate	−0.190	0.169	−0.046	−0.522, 0.142	0.261
Bachelor	−0.213	0.123	−0.117	−0.455, 0.028	0.083
Higher academic education	−0.151	0.122	−0.089	−0.392, 0.089	0.217
Healthcare worker (Ref: No)	−0.045	0.063	−0.027	−0.169, 0.079	0.477
History of COVID-19 in family and friends or themselves (Ref: No)	0.203	0.118	0.055	−0.029, 0.435	0.087
History of COVID-19 associated mortality in family and friends (Ref: No)	−0.004	0.053	−0.003	−0.108, 0.099	0.933
COVID-19 vaccine doses received (Ref: Zero)
One	0.203	0.267	0.036	−0.321, 0.727	0.446
Two	0.006	0.210	0.003	−0.407, 0.419	0.977
Three or more	0.032	0.212	0.018	−0.385, 0.450	0.879
Factor 1: COVID-19 vaccine attitude	0.065	0.042	0.079	−0.017, 0.147	0.121
Factor 2: General vaccine attitude	0.316	0.053	0.293	0.212, 0.420	0.000***
Factor 3: Trust in health information sources	0.064	0.043	0.060	−0.020, 0.147	0.133
Factor 4: Trust in national health authorities	0.358	0.036	0.425	0.288, 0.428	0.000***
Factor 5: Trust in international health authorities	−0.017	0.039	−0.018	−0.093, 0.059	0.658
Factor 6: Self-efficacy	0.100	0.040	0.091	0.021, 0.178	0.013**

* p-value < 0.05, ** p-value < 0.01, *** p-value < 0.001

Table 3 highlights the predictors of adherence to international vaccination guidelines and pandemic preparedness. This multivariate linear regression model was statistically significant (F (22, 434) = 34.683, p-value < 0.001, with an R² of 0.614 and an adjusted R² of 0.637). Like the previous model, sociodemographic characteristics did not show statistically significant associations with the outcome. Notably, Factor 2: General Vaccine Attitude (β: 0.274, p-value < 0.001) and Factor 5: Trust in International Health Authorities (β: 0.572, p-value < 0.001) emerged as the strongest predictors of adherence with international vaccination guidelines among the participants. Individuals who reported a positive history of COVID-19 in their family and friends or themselves scored 0.31 (95% CI: 0.11–0.51) points higher on the composite adherence scale (range: 1–5) than those without such experiences. In addition, with every one-point increase in Factor 2: General Vaccine Attitude, Factor 5: Trust in International Health Authorities, and Factor 6: Self-efficacy scores, the average score of adherence to international vaccination guidelines and pandemic preparedness increased by 0.27 (95% CI: 0.18–0.36), 0.50 (95% CI: 0.43–0.56) and 0.08 (95% CI: 0.01–0.15). Conversely, Factor 4: Trust in National Health Authorities showed a negative association with the outcome (B = − 0.137, 95% CI: - −0.076), suggesting that higher trust in national authorities corresponded to lower adherence to international vaccination guidelines.

Table 3.

Multivariable linear regression analysis for the factors influencing adherence to international vaccination guidelines and pandemic preparedness

Variables	B coefficient	Standard error	β coefficient	95% CI for B coefficient	P-value
Age	0.001	0.002	0.023	−0.003, 0.006	0.560
Gender (Ref: Male)
Female	0.094	0.048	0.061	−0.001, 0.188	0.053
Marital status (Ref: Unmarried)
Married	−0.073	0.062	−0.040	−0.195, 0.049	0.241
Occupation (Ref: Employed)
Housewife	−0.015	0.113	−0.005	−0.238, 0.208	0.893
Student	−0.012	0.110	−0.003	−0.228, 0.204	0.913
Unemployed	0.036	0.124	0.009	−0.207, 0.279	0.771
Retired	−0.051	0.077	−0.025	−0.203, 0.101	0.511
Educational level (Ref: Diploma or lower)
Postgraduate	−0.046	0.147	−0.012	−0.334, 0.243	0.757
Bachelor	−0.066	0.107	−0.038	−0.276, 0.144	0.537
Higher academic education	−0.005	0.106	−0.003	−0.214, 0.204	0.963
Healthcare worker (Ref: No)	0.012	0.055	0.008	−0.096, 0.119	0.834
History of COVID-19 in family and friends or themselves (Ref: No)	0.312	0.103	0.091	0.111, 0.514	0.002**
History of COVID-19 associated mortality in family and friends (Ref: No)	0.011	0.046	0.007	−0.079, 0.101	0.810
COVID-19 vaccine doses received (Ref: Zero)
One	−0.124	0.232	−0.024	−0.580, 0.332	0.592
Two	−0.034	0.183	−0.019	−0.393, 0.325	0.852
Three or more	−0.065	0.185	−0.038	−0.428, 0.298	0.726
Factor 1: COVID-19 vaccine attitude	0.036	0.036	0.047	−0.035, 0.108	0.318
Factor 2: General vaccine attitude	0.278	0.046	0.274	0.187, 0.368	0.000***
Factor 3: Trust in health information sources	0.018	0.037	0.018	−0.055, 0.090	0.633
Factor 4: Trust in national health authorities	−0.137	0.031	−0.173	−0.198, −0.076	0.000***
Factor 5: Trust in international health authorities	0.502	0.034	0.572	0.436, 0.568	0.000***
Factor 6: Self-efficacy	0.086	0.035	0.085	0.018, 0.155	0.014**

* p-value < 0.05, ** p-value < 0.01, *** p-value < 0.001

Discussion

In this cross-sectional study, we assessed adherence to national and international immunization protocols among Iranian adults in the post-COVID-19 era. Overall, participants demonstrated generally favorable levels of compliance, with only about 25% of participants reporting unfavorable attitudes toward vaccination guideline adherence, indicated by a mean composite score below three. In addition, our findings revealed that trust in national and international health organizations, as well as attitudes and perceptions toward vaccination in general, were the strongest predictors of adherence and pandemic preparedness. Self-efficacy in evaluating public health information and distinguishing reliable sources was also found to be a significant associated factor with higher levels of adherence to both national and international vaccination guidelines.

Our study indicates the critical role of public trust in health organizations that shapes health-related behaviors. Participants who expressed greater confidence in the pandemic response and management strategies, vaccine guidance, and overall disease prevention effectiveness of both national and international health organizations were more likely to comply with public health protocols, adhere to adult and children vaccination instructions issued by national and international health authorities, and encourage others to do so. Similarly, a survey on various sources of pandemic information found that trust in public healthcare systems and healthcare providers was the strongest independent predictor of vaccination intention in the United Kingdom (UK) [3]. Another study by Jamison et al., in 2019, found that mistrust in government and health agencies was significantly associated with lower vaccination rates for both influenza and childhood vaccines in the US. Most participants considered pharmaceutical companies as profit-driven. The study emphasized that transparent communication and community engagement are crucial for rebuilding trust [32].

Interestingly, our participants showed relatively stronger trust in international health authorities and higher adherence to their vaccination guidelines. Specifically, the mean score for Factor 5: Trust in International Health Authorities was 3.69 ± 0.87, while Factor 4: Trust in National Health Authorities was lower at 3.02 ± 0.97. Likewise, adherence to international vaccination guidelines (4.06 ± 0.76) exceeded that of national guidelines (3.81 ± 0.81). Furthermore, a higher score on the trust in national health authorities subscale was negatively associated with adherence to international vaccination protocols (B = −0.137), possibly suggesting a discordance in public health messaging by policymakers. This discrepancy may reflect the public’s critical response to the government’s handling of the pandemic, especially the politicization of the COVID-19 vaccination process. For instance, the Pfizer-BioNTech vaccine was explicitly banned in Iran, and skepticism toward Western-produced vaccines was publicly voiced by health officials, national media outlets, and even select academic institutions. Notably, several open letters, signed by university faculty members, and statements from high-ranking officials questioned the safety and intent behind vaccines developed in the US and UK [12, 33, 34]. This is reflected in the markedly low mean score (2.60 ± 1.13) for the item assessing confidence in vaccine recommendations from national TV programs (Q11, Factor 3).

To delve deeper, participants also reported substantially lower confidence in the government’s overall handling of the COVID-19 pandemic (2.60 ± 1.12) compared to international efforts (3.61 ± 1.01). Iran’s COVID-19 vaccine rollout faced multiple challenges, including limited early access to approved international vaccines, lack of transparency in the licensing of domestic vaccines by the Iran Food and Drug Administration, and delays caused by prioritization of domestic production over timely imports [35–37]. As illustrated in Supplementary Fig. 2, which shows daily per capita vaccine administration based on publicly available global data (Our World in Data), Iran experienced a markedly slower and more delayed vaccine uptake compared to other countries in the Middle East, including Turkey, Saudi Arabia, and the United Arab Emirates [38]. For example, by April 2021, Turkey, as a neighboring country with comparable population size and cultural dynamics, had administered over 20 million more vaccine doses than Iran [36]. These disparities likely contributed to diminished public trust in national institutions and increased reliance on international health authorities, which are perceived as more neutral and reliable sources of information and guidance.

Of note, the consequences of eroded trust extend far beyond individual decision-making. They can weaken public health efforts and even reverse long-standing progress. For example, in Samoa, a measles outbreak in 2019 resulted in over 80 deaths, primarily among children. The outbreak was accentuated by low vaccination rates due to public mistrust following a medical vaccination error and the spread of anti-vaccine misinformation [39]. Furthermore, a comprehensive study across 22 African countries found that higher levels of institutional mistrust were significantly associated with lower child vaccination rates. Specifically, a one SD increase in mistrust correlated with a 10% increase in the likelihood of a child not receiving any basic vaccines [40]. Collectively, this consistent observation across different settings underscores the universality of trust as a critical determinant of vaccine-related behavior and public health compliance.

Our findings held key policy implications. Despite including a diverse range of sociodemographic variables in our regression models, none remained independently associated with adherence to either national or international vaccination guidelines. This suggests dynamic modifiable constructs, such as vaccine perceptions, trust in health authorities, and self-efficacy, are more influential on health-related behaviors. Public health policies should, therefore, prioritize strategies that improve trust and enhance individuals’ capacity to evaluate health information. In a large population-based study in Germany, self-efficacy was found to be the strongest predictor of comprehensive health literacy, a core element in health promotion [41]. Previous studies have also demonstrated that discernment abilities are linked to reduced susceptibility to health misinformation [42]. Policymakers and educators can promote self-efficacy through a variety of interventions, including self-management programs, telehealth services, mobile applications, and social media [43]. In addition, integrating scientific critical thinking into educational curricula, teaching how to verify sources of health-related information and how to refrain from sharing unreliable information, and promoting media literacy are essential steps toward a more health-literate and resilient society. By targeting these modifiable factors, policymakers can better support informed decision-making and improve compliance with future vaccination campaigns and emergency preparedness efforts.

This study has several strengths and limitations that warrant consideration. By developing a validated and reliable instrument, we assessed a relevant and timely topic in the post-COVID-19 era. In addition, the application of multiple linear regression models with satisfactory model fit helped us identify independent predictors of adherence to vaccination protocols. However, despite efforts to recruit a diverse sample, the predominance of well-educated individuals and healthcare workers may limit the generalizability of our findings to other subgroups within the Iranian population. This overrepresentation may be due to the fact that the current research topic is more closely aligned with their professional experiences and areas of interest. Moreover, reliance on online platforms for survey dissemination may exclude individuals without reliable internet access or adequate digital literacy, potentially underrepresenting older adults or those in rural areas. Another limitation of this study is the use of the same dataset for both EFA and CFA. Furthermore, the reported model fit indices from the CFA indicate a mediocre fit, highlighting the need for further improvements before broader application of the survey in future studies.

Conclusion

In conclusion, this study explored public perceptions of vaccination, levels of trust in national and internal health organizations, and adherence to their vaccination guidelines. Favorable attitudes toward vaccination in general, trust in health authorities, and self-efficacy emerged as significant determinants of adherence and pandemic preparedness among our participants. In addition, while the overall compliance to vaccination protocols and pandemic preparedness was generally positive, our participants demonstrated a relatively more enthusiasm about international vaccination guidelines. Our findings underscore the need for health policymakers to promote trust, health literacy and self-efficacy to improve public engagement with future vaccination efforts and foster pandemic preparedness.

Abbreviations

CDC

Centers for Disease Control and Prevention

CFA

Confirmatory factor analysis

CI

Confidence interval

COVID-19

Coronavirus disease 2019

CVI

Content Validity Index

CVR

Content Validity Ratio

EFA

Exploratory factor analysis

FDA

Food and Drug Administration

PCA

Principal components analysis

SARS-CoV-2

Severe acute respiratory syndrome

SD

Standard deviation

UK

United Kingdom

US

United States

Authors’ contributions

MA, ET and NH conceptualized and supervised this project. MA, NM, AA, ET and SZ contributed in designing study and questionnaire. AA and AS carried out data collection and entry. NM, SM and AS helped in data analyzing and interpretation. SM and SZ were major contributors in writing the manuscript. All authors critically reviewed and approved the final manuscript.

Funding

The Vice-Chancellor for Research at Shiraz University of Medical Sciences supported this study with the code of 30913. The funding source helped investigators in questionnaire dissemination and targeted advertisements.

Data availability

The dataset supporting the findings of this study would be shared upon reasonable request to the corresponding author.

Declarations

Ethics approval and consent to participate

Approval for this study was granted by the Institutional Review Board of Shiraz University of Medical Sciences (IR.SUMS.MED.REC.1403.430), ensuring adherence to ethical standards and guidelines. The study was conducted in accordance with the principles of the Declaration of Helsinki and its subsequent amendments. Before participation, all individuals were informed about the study design and objectives, were assured of the confidentiality of their responses, and were made aware of their right to withdraw at any time. Informed consent was obtained through an online consent form presented at the beginning of the survey.

Consent for publication

Informed consent for publication of the study findings in accordance with ethical guidelines was provided at the beginning of the questionnaire and obtained from our participants.

Competing interests

The authors declare no competing interests.