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Abstract

Introduction:

Pneumonia is a leading cause of mortality worldwide, with Streptococcus pneumoniae being the most common cause. Older adults are particularly at risk. However, vaccination rates in Thailand remain low.

Objective:

This study aims to examine the prevalence of vaccine refusal and its association with factors outlined in the 5C model (Confidence, Complacency, Constraints, Calculation, and Collective Responsibility) among older patients with morbidities.

Setting:

Study was conducted at outpatient clinic of the Department of Family Medicine, Chiang Mai University.

Methods:

An observational cross-sectional study. The data was collected via a self-administered questionnaire including demographic data, questionnaire in 5C model, and intention to received pneumococcal vaccine. Comparison of characteristic between vaccine refuser and non-refuser was performed by using Chi-square or a T-test. To explore the association between factors in 5C model and vaccine refusal, multiple logistic regression was performed with an adjustment for confounders.

Results:

From a total of 150 participants, the mean age was 69.8 ± 5.6 years old. Most of the patients were female (60.7%). The study found that 18% of the participants refused the pneumococcal vaccine. After adjusted for the confounders, the lower collective responsibility and confidence were significantly associated with vaccine refusal (Odds ratio 0.22 (95% confidence interval [CI] 0.06-0.74, P = .015) and Odds ratio 0.43 (95% CI 0.20-0.89, P = .024), respectively.

Conclusion:

Strategies to enhance confidence and address complacency about vaccines are essential for improving pneumococcal vaccination coverage. This insight can be used as a guideline and policies can be formulated which are aimed at reducing pneumococcal vaccine refusal in the older adults by enhancing communication about the benefits, efficacy, and risks of vaccines.

Graphical Abstract

Keywords

pneumococcal vaccine elderly older adult prevention pneumonia

Introduction

Pneumonia remains a leading cause of mortality worldwide. In 2019, the incidence of pneumonia in Thailand was 388 per 100 000 populations while the mortality rate was 0.26 per 100 000 populations.¹ Streptococcus pneumoniae, also known as pneumococcus, is the most common cause of community-acquired pneumonia and was responsible for approximately 2.3 million deaths globally.² The elderly and individuals with conditions such as coronary heart disease, diabetes, lung disease, and cancer are particularly at risk, experiencing higher morbidity and mortality rates.³ Thailand has also now entered an aged society, with the older population currently making up 20% of the total population. This proportion is expected to rise to 28% over the next decade.⁴ Consequently, various strategies have been proposed to improve health outcomes for older adults, including vaccination, regular visiting to a dentist, and exercise.^5,6

Vaccination plays a critical role in prevention, with studies supporting the effectiveness of the pneumococcal vaccine in preventing pneumococcal pneumonia.^7
-10 The elderly are a key demographic for receiving the pneumococcal vaccine to prevent infection, reduce disease severity, and mitigate potential complications.^11,12 In Thailand, 2 types of pneumococcal vaccines are available for adults: the 23-valent pneumococcal polysaccharide vaccine (PPV23) and the 13-valent pneumococcal conjugate vaccine (PCV13). These vaccines are recommended for older adults according to the Thai guidelines for adult vaccination.¹³ Both the government and private health sectors conduct numerous campaigns and health promotion activities to raise awareness and increase the vaccination rate.^14,15 However, current vaccination rates for pneumococcal disease remain low. Among patients over 65 years of age, the pneumococcal vaccine coverage rate is <20%. Additionally, a study on vaccine coverage rates among Thai type 2 diabetic patients from 2010 to 2018 revealed a high rate of vaccine refusal.¹⁴

Refusal of vaccines to prevent pneumococcal infection is increasing, leading to a decrease in vaccine coverage rates.¹⁶ Data from the US Centers for Disease Control and Prevention indicates that current global vaccine coverage rates among the elderly remain suboptimal.¹⁷ Additionally, the outbreak of COVID-19 has further reduced these rates.¹⁸ This decline has various negative effects, such as longer hospital stays and increased medical expenses.¹⁹ Furthermore, individuals with chronic conditions, such as pulmonary disease, are experiencing more frequent exacerbations and requiring hospitalization more often.²⁰ Various factors influencing vaccine refusal have been identified, including gender, age, socioeconomic status, education level, income, presence of congenital diseases, and health insurance coverage.^21
-23 According to the principles of the 5C model, the factors contributing to vaccine hesitancy are as follows: Confidence, Complacency, Constraints, Calculation, and Collective Responsibility.²⁴ Understanding the causes and factors leading to vaccine refusal are crucial for planning and setting operational guidelines to achieve comprehensive and effective vaccination coverage. Therefore, this study aims to examine the prevalence of vaccine refusal and its association with the factors outlined in the 5C model among older patients. The findings would provide essential information and guidelines for health promotion and prevention in the elderly population.

Methods

Study Design

This is an observational cross-sectional study using a self-administered questionnaire. The study was reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement.²⁵

Setting

The study was conducted at the outpatient clinic of the Department of Family Medicine, Chiang Mai University. Approximately 150 patients receive health services at this clinic each week. Over 90% of patients visit were older patients with chronic diseases who requires pneumococcal vaccination according to Thai vaccination guideline.¹³

Participants

Participants were randomly sampled from the patients who visited the outpatient clinic of the Department of Family Medicine, Chiang Mai University, between July and December 2023. The inclusion criteria were the patients who being 60 years old or over and being able to communicate and make decisions independently. The patients with the following health issues would be excluded: dementia or mild cognitive impairment (as diagnosed previously or having a history of Thai Mental State Examination score <23.²⁶ or Montreal Cognitive Assessment score <25²⁷), depression (as diagnosed previously or having a history of positive Patient Health Questionnaire-2 (PHQ-2)²⁸ result), having contraindications for receiving the pneumococcal vaccine, or in a condition of completely dependent status (defined as having an Activity of Daily Living score <5²⁹), and those who are unable to respond to questionnaires even with assistance.

Sample Size

We included 150 study participants, following the 5C model with 10 participants per factor for a total of 15 questions, as recommended by Kyriazos et al.³⁰ Additionally, based on previous study³¹ using the infinite population proportion calculation, this sample size was estimated to achieve a statistical power of over 90% to detect the proportion of vaccine refusal.

Data Collection

The data collection was done by patient self-administered questionnaire. The questionnaire had been developed by the researchers to measure outcomes according to the predetermined objectives. It was divided into 3 sections.

Section 1: General characteristics of participants based on factors affecting vaccination in the previous studies,^22,31 include: age, sex, living status, smoking status, alcohol consumption, underlying diseases, education levels, monthly incomes, health benefit schemes, and drug allergy history.

Section 2: Vaccine hesitancy questionnaire indicated by 5C model has been translated to Thai from the study by Betsch et al.²⁴ This questionnaire had been validated with permission from the author for translation into Thai for research and educational purposes. The 5C model includes (1) Confidence: Trust in the efficacy and safety of vaccines; (2) Complacency: Perception that the risk of vaccine-preventable diseases is low, leading to the belief that vaccination is unnecessary; (3) Constraints: Barriers related to physical readiness, financial ability, geographic access, language comprehension, health literacy, and access to immunization services; (4) Calculation: Thoroughly searching for information and weighing the risks of infection versus vaccination; and (5) Collective Responsibility: Willingness to protect others by vaccinating oneself to create herd immunity. The questionnaire consists of the total 15 items by subdividing into 5 subgroups of 3 questions each. Each subgroup measures factors of vaccine hesitancy according to the 5C model. The items can be responded to with the instruction, “Please evaluate how much you disagree or agree with the following statements,” and is assigned a 7-point Likert scale as follows: 1 = strongly disagree, 2 = moderately disagree, 3 = slightly disagree, 4 = neutral, 5 = slightly agree, 6 = moderately agree, and 7 = strongly agree.

Section 3: This section addressed participants’ decisions regarding pneumococcal vaccination, with response options including “refused,” “unsure,” or “yes.”

Data Analysis

Based on the results from questionnaire section 3, we categorized patients into 2 groups: (1) those who refused vaccination (Refuser), and (2) those who did not refuse vaccination (yes and unsure to vaccination; Non-refuser). For the descriptive analysis, the categorical variables were characterized using frequency and percentage. The continuous variables were described as mean and standard deviation (SD). To examine the correlation between general characteristics and vaccine refusal, we used Chi-square and T-test for categorical and continuous data, respectively. To investigate the difference in the decision on vaccination between refusers and non-refusers, a T-test was used on the 5C model scores.

To explore the impact of factors in the 5C model on vaccine refusal, we employed multiple logistic regression, incorporating factors from the 5C model and adjusted for confounding factors, age, sex, living status, education levels, monthly income, health benefit schemes, and having multimorbidity status. All analyses were conducted using STATA version 17.

Result

Demographic Characteristics and the Tendency to Refuse Vaccination

There were 150 eligible participants. Figure 1 shows the study flow diagram. The majority of patients were female (60.7%). The average age was 69.8 ± 5.6 years old. More than half of the study patients were aged 60 to 69 years old (53.3%). Most of patients lived with their partners (72.0%), finished primary school as their education level (43.3%), and had a maximum income ranging from 10 000 to 20 000 baht per month (36.7%). Also, most of the study patients never smoked (69.3%) and never drank alcohol (53.3%). Most patients had high blood pressure (81.3%), were members of the Government medical service schemes (87.3%) and had no allergy to drugs or vaccines (86.7%). Table 1 shows the general characteristics of participants.

Figure 1.

Study flow diagram.

Table 1.

General Characteristics of Participants.

Characteristic (N = 150)	N (%)	Pneumococcal vaccinated decision
		Refuser	Non-refuser	P-value
		n (%)	n (%)	P-value
Total		27 (18)	123 (82)
Sex
Male	59 (39.3)	11 (39.0)	48 (40.7)	.869
Female	91 (60.7)	16 (59.2)	67 (60.9)
Age (years old)
Mean ± SD (range)	69.8 ± 5.6 (60-89)	69.56 ± 3.84	69.84 ± 5.88	.812
Living status
Civil union	108 (72.0)	23 (85.2)	85 (69.1)	.162
Widowed	23 (15.3)	1 (3.7)	22 (17.9)
Single	12 (8.0)	1 (3.7)	11 (8.9)
Others	7 (4.7)	2 (7.4)	5 (4.1)
Education level
Primary school	65 (43.3)	13 (48.2)	52 (42.3)	.947
Secondary school	42 (28.0)	7 (25.9)	35 (28.5)
College/University and more	42 (28.0)	7 (25.9)	35 (28.5)
Monthly income (Bath)
Less than 5000	11 (7.3)	1 (3.7)	10 (8.1)	.245
5000-10 000	42 (28.0)	4 (14.8)	38 (30.9)
10 000-20 000	55 (36.7)	13 (48.2)	42 (34.2)
More than 20 000	42 (28.0)	9 (33.3)	33 (26.8)
Smoking status
Current smoker	1 (0.7)	0	1 (0.81)	.776
Never smoker	104 (69.3)	20 (74.1)	84 (68.3)
Past smoker	45 (30.0)	7 (25.9)	38 (30.9)
Alcohol intake
Current drinker	21 (14.0)	5 (18.5)	16 (13.0)	.215
Never drinker	80 (53.3)	17 (62.9)	63 (51.2)
Past drinker	49 (32.7)	5 (18.5)	44 (35.8)
Underlying disease
Essential hypertension	117 (78.0)	19 (16.2)	98 (83.8)	.291
Diabetes mellitus	42 (28.0)	5 (11.9)	37 (88.1)	.226
Hyperlipidemia	122 (81.3)	21 (17.2)	101 (82.8)	.601
Osteoporosis	16 (10.7)	2 (12.5)	14 (87.5)	.545
Others	5 (3.3)	1 (20.0)	4 (80.0)	.906
Multimorbidity	114 (76.0)	16 (14.1)	98 (85.9)	.024
Health benefit schemes
Government enterprise officer	131 (87.3)	25 (92.6)	106 (86.2)	.661
Universal coverage scheme	10 (6.7)	1 (3.7)	9 (7.3)
Pay yourself	9 (6.0)	1 (3.7)	8 (6.5)
Drug allergy
No allergy	130 (86.7)	21 (77.8)	109 (88.6)	.133
Having drug allergy	20 (13.3)	6 (22.2)	14 (11.4)

Abbreviation: SD, standard deviation.

Regarding the prevalence of vaccine refusal, there were 27 refusers (18.0%) and 123 non-refusers (82.0%). The number of patients with multimorbidity between refuser (14.1%) and non-refuser (85.9%) groups shows a statistically significant difference (P = .024).

The Vaccination Hesitancy Based on the 5C Model

Table 2 shows the score summation of the 5C model on refusers and non-refusers of vaccination. In both groups, the calculation has the highest score (6.68 ± 0.54), followed by confidence (5.87 ± 0.88) and collective responsibility (4.36 ± 2.36). The vaccine refusers had significantly lower mean scores in confidence and collective responsibility, while having higher complacency, compared to those non-refusers (P < .001, .012, and .009, respectively).

Table 2.

Classification 5C Scale Score Summation.

5C scale and questionnaire items	Score summation (0-7) (mean ± SD)	Refuser (mean ± SD)	Non-refuser (mean ± SD)	P-value
Confidence	(5.87 ± 0.88)	5.47 ± 0.81	5.95 ± 0.63	<.001
1. I am completely confident that vaccines are safe.	5.98 ± 0.85	5.59 ± 1.12	6.07 ± 0.75	.008
2. Vaccinations are effective.	5.85 ± 0.90	5.41 ± 0.75	5.95 ± 0.91	.004
3. Regarding vaccines, I am confident that public authorities decide in the best interest of the community.	5.76 ± 0.88	5.40 ± 0.93	5.84 ± 0.85	.021
Complacency	(2.18 ± 1.26)	2.60 ± 0.97	2.08 ± 0.96	.012
4. Vaccination is unnecessary because vaccine preventable diseases are not common anymore.	2.43 ± 1.32	2.59 ± 1.05	2.39 ± 0.12	.489
5. My immune system is so strong, it also protects me against diseases.	2.04 ± 1.20	2.56 ± 1.28	1.93 ± 1.15	.013
6. Vaccine-preventable diseases are not so severe that I should get vaccinated.	2.05 ± 1.22	2.67 ± 1.36	1.92 ± 1.15	.004
Constraints	(1.45 ± 0.99)	1.54 ± 0.61	1.42 ± 0.70	.433
8. For me, it is inconvenient to receive vaccinations.	1.73 ± 1.12	1.93 ± 1.41	1.69 ± 1.04	.323
9. Visiting the doctor’s makes me feel uncomfortable; this keeps me from getting vaccinated.	1.10 ± 0.47	1.11 ± 0.32	1.09 ± 0.50	.894
Calculation	(6.68 ± 0.54)	6.74 ± 0.40	6.67 ± 0.49	.498
10. When I think about getting vaccinated, I weigh benefits and risks to make the best decision possible.	6.63 ± 0.55	6.59 ± 0.57	6.64 ± 0.54	.671
11. For each and every vaccination, I closely consider whether it is useful for me.	6.70 ± 0.50	6.81 ± 0.39	6.67 ± 0.52	.190
12. It is important for me to fully understand the topic of vaccination, before I get vaccinated.	6.72 ± 0.58	6.81 ± 0.39	6.69 ± 0.61	.351
Collective responsibility	(4.36 ± 2.36)	4.15 ± 0.39	4.41 ± 0.48	.009
13. When everyone is vaccinated, I don’t have to get vaccinated, too.	1.49 ± 0.97	1.78 ± 0.89	1.43 ± 0.98	.092
14. I get vaccinated because I can also protect people with a weaker immune system.	4.90 ± 1.12	4.48 ± 0.84	4.99 ± 1.16	.032
15. Vaccination is a collective action to prevent the spread of diseases.	6.70 ± 0.66	6.19 ± 0.87	6.81 ± 0.55	.000

Abbreviation: SD, standard deviation.

The Factors Impacting Vaccine Refusal

To investigate the factors impacting vaccine refusal, we used multiple logistic regression. We found that the lower collective responsibility and confidence were significantly associated with vaccine refusal (Odds ratio 0.22 (95% CI 0.06-0.74, P = .015) and Odds ratio 0.43 (95% CI 0.20-0.89, P = .024), respectively (Figure 2).

Figure 2.

Correlation of 5C model and characteristic in refuser pneumococcal vaccine.

Discussion

The objective of this study was to study the prevalence of pneumococcal vaccine refusal and the factors related to disfavor among elderly patients. The study found that those who refused to receive the vaccine were 18.0%, and those who did not refuse were 82.0%. Patients with multimorbidity were significantly less likely to refuse vaccination, with no significant differences found in other factors. Regarding the factors according to the 5C model, the study revealed that those vaccine refusers had significantly lower mean scores in confidence and collective responsibility, while having higher complacency, compared to those non-refusers. After adjusting for confounding factors, age, sex, living status, educational levels, monthly incomes, health benefit schemes, and the presence of multiple chronic diseases, it was found that collective responsibility and confidence were significantly related to vaccine refusal. Individuals with greater collective responsibility and higher confidence are less likely to refuse the pneumococcal vaccination.

Our findings align with a study conducted in middle-income countries, which identified 2 key enablers of vaccine implementation: the presence of strong primary healthcare systems and established policy processes for vaccine decision-making.³² These results are also consistent with research on the 5C factors influencing COVID-19 vaccination decisions in United States with the lowest vaccination rates. In that study, confidence and collective responsibility were found to be the most significant factors.³³ Similarly, a study by King et al³⁴ revealed that confidence, complacency, and collective responsibility were the primary factors associated with COVID-19 vaccination. Among Métis Nation of Ontario citizens, research by Rancher et al³³ also found that confidence and collective responsibility were more critical to the decision to receive the COVID-19 vaccine than other factors. Currently, media coverage on various aspects of vaccines is insufficient, making it difficult for people to access and understand the information.³⁵ Health professionals and related parties should focus on expanded health communications and promote effective informational materials about vaccine safety and benefits for both patients and the community. Additionally, creating an environment that facilitates access to vaccine communication between service providers and recipients at both the community and government policy levels is crucial.^36,37 These efforts will help increase confidence, trust, and collective responsibility, thereby promoting greater vaccine acceptance.^34,38,39 In the United States, the National Vaccine Advisory Committee has established the Vaccine Confidence Working Group Membership to enhance vaccine confidence and collective responsibility.⁴⁰

Collective responsibility and confidence have gained more attention globally due to the COVID-19 pandemic and growing concerns over vaccine hesitancy. Collective responsibility is a key predictor of vaccine acceptance, as people recognize the importance of immunization programs for community health,⁴¹ especially in public health crises.⁴² During the COVID-19 pandemic, the focus on community health and shared responsibility highlighted how individual vaccine choices impact others. Confidence in vaccine efficacy and safety also plays a crucial role in promoting vaccine acceptance; strong confidence in COVID-19 vaccines has significantly boosted vaccination rates.⁴³ Although the pandemic initially heightened vaccine hesitancy in some areas, targeted health communication strategies have helped to rebuild public trust in vaccines.⁴⁴ When people feel assured of vaccine safety and efficacy, they are more likely to engage in communal health practices, such as immunization.

However, the other 3 factors—complacency, constraints, and calculation of benefits and disadvantages—were not found to be related to vaccine refusal. The lack of impact from complacency may be because most patients are unaware of information about pneumonia caused by pneumococcus and the associated dangers that comes with it.³⁶ Constraints often stem from access and cost issues related to receiving the vaccine, which is common in developing countries, including Thailand.⁴⁵ For the pneumococcal vaccine, patients are required to pay for the cost themselves.¹⁴ The calculation of benefits and disadvantages may be influenced by fears or concerns about potential side effects of vaccines⁴⁶ and may depend on the patient’s health status or morbidities.³³ Previous studies have shown that patients with multimorbidity are more likely to get vaccinated^47,48 as these patients are generally at higher risk of severe outcomes if they contract any type of infection.^49
-51

In our study, non-refuser group includes individuals willing to accept or uncertain about the vaccine but still exhibiting varying degrees of hesitancy. This hesitation could be affected by factors like healthcare costs, including doctor consultations and vaccine expenses, which may deter some non-refusers from vaccination.⁵² Thailand has a larger population that is hesitant rather than outright refusing, influenced by cultural beliefs and misinformation, highlighting the need for targeted health promotion efforts.⁵³ Additionally, the survey may have favored urban participants with greater digital access, potentially skewing results toward those more informed about health issues.⁵² Comprehensive strategies are essential to bridge the gap between vaccine willingness and actual uptake, ultimately improving public health outcomes. In addition, the survey’s structure could have educational effects on participants, as the process of completing the questionnaire may provide them with information about the importance of vaccination and the risks associated with their health conditions, potentially increasing their willingness to accept the vaccine.^54,55 While the survey may have included a significant number of non-refusers, the underlying hesitancy among patients could still affect their actual vaccination decisions.⁴¹

The results of this study can support the development of guidelines for enhancing health promotion among older adults. This is particularly in promoting vaccination to prevent pneumococcal infection through advice from healthcare providers or providing vaccine-related information from health professionals to increase vaccination awareness,³¹ and to be able to apply the Ottawa Charter guidelines⁵⁶ by focusing on promoting confidence. For example, at the government level, policies and healthcare systems should be developed to enhance trust in the efficacy and safety of vaccines, thereby boosting confidence in vaccination. Moreover, in terms of collective responsibility, community empowerment initiatives should be implemented to foster a sense of ownership and community protection. The community can create a feeling of ownership and community protection⁵⁷ to reduce rejection rates of pneumococcal vaccination, particularly among the elderly population.

Limitations

This study has some limitations. First, the target population mainly included individuals eligible for treatment under civil servant insurance, which aligns with the characteristics of patients at our setting. As a result, the diversity of patient characteristics is less than in other population groups. Second, all participants were elderly individuals with morbidities, as per the inclusion criteria, and there were no elderly participants without morbidities, as they are also advised to get vaccinated against pneumococcal infection. Including elderly individuals without morbidities in future studies could provide more useful information for promoting and preventing the condition. Finally, this study had a small sample size. Future research should include a larger sample and a more diverse population to provide more precise effect estimates.

Conclusion

This research study among the elderly group resulted in the finding that the 5C factors in terms of increased confidence and a greater sense of collective responsibility were associated with less vaccine refusal. This insight can be used as a guideline and policies can be formulated which are aimed at reducing pneumococcal vaccine refusal in the elderly by enhancing communication about the benefits, efficacy, and risks of vaccines.

Footnotes

Acknowledgements

We are deeply grateful to the patients who participated and the staff of the office in the outpatient clinic of the Department of Family Medicine, Chiang Mai University.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was supported by Faculty of Medicine, Chiang Mai University, grant number 027/2567 and was partially supported by Chiang Mai University.

Ethical Approval and Consent to Participate

This study has been approved by the medical council of the faculty of Medicine Chiangmai University. Study code: FAM-2556-0164, Research ID: 0164. All the participants gave their consents and signed their signature before the data collection process. The collected data does not include personal identity information.

ORCID iDs

Nida Buawangpong

Thanachat Yotruangsri

Wichuda Jiraporncharoen

Kanokporn Pinyopornpanish

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Vaccine Hesitancy Affecting Pneumococcal Vaccine Refusal in Older Adults with Morbidities