Closer adult child–parent relations the stronger the vaccine hesitancy: A cross-sectional study of adult Children’s attitudes toward pneumococcal vaccination of elderly parents and its determinants in Guangzhou, China

ABSTRACT

Pneumococcal disease (PD) has a serious effect on older people aged 60 years and above. However, pneumococcal vaccination rates for older people in China remain low. This study aimed to explore adult children’s perspectives on the vaccination of their parents and to examine the determinants of vaccine hesitancy. In October 2022, a cross-sectional survey was conducted in Guangzhou, China. The questionnaire assesses data on the sociodemographic characteristics of adult children and their parents, health beliefs about vaccination, and variables measuring adult child–parent relationships. Adult child–parent relationships types were identified by Latent Class Analysis (LCA). Binary logistic regression was employed to examine the factors associated with vaccine hesitancy. A total of 1,597 respondents were enrolled in the study, and 59.8% of the adult children expressed hesitancy about vaccinating their elderly parents. The LCA model identified three distinct types of adult child–parent relations: detached, intimate but distant, and tight-knit. Binary logistic regression analyses revealed that respondents with intimate but distant (OR = 3.04) and tight-knit (OR = 3.01) adult child – parent relationships, high literacy (OR = 2.63), and high perceived barriers of vaccine (OR = 1.18) were more likely to be hesitant. Conversely, those with high income (OR = 0.35) and parents with difficulties in activities of daily living (OR = 0.44) were less likely to exhibit vaccine hesitancy. Close adult child–parent relations were positively associated with vaccine hesitancy. Health education related to the vaccination of older persons should be extended to adult children.

Introduction

Pneumococcal disease (PD), including noninvasive disease, is a common infectious disease in older adults. Older adults are vulnerable to severe consequences due to a decline in immune system function and the high prevalence of chronic illnesses, resulting in a high risk of severe complications and mortality,¹ thereby imposing a considerable public health burden.^2–4

Pneumococcal vaccination not only reduces PD in older adults but also reduces the incidence of complications and the risk of hospitalization and mortality.^5,6 Chinese health authorities encourage pneumococcal vaccination for people aged 60 years and older, but the vaccination rate remains low, at 3.2% for people aged 60 years and older who were vaccinated in inland China in 2022. Pneumococcal vaccines are not included in China’s national immunization program, and vaccination requires individuals to pay out-of-pocket, which may partially account for the low vaccination rates. However, several economically developed regions, such as Shanghai, Beijing, and Shenzhen, have implemented free pneumococcal vaccination for the elderly through local government funding.^7,8 Despite the provision of free vaccinations, the vaccination rate in 2022 remains approximately 30.0% in Shanghai and 11.5% in Beijing.⁹ In comparison, the rates of older adults in the United States and the United Kingdom are 69.0% and 70.5%, respectively, showing a significant disparity.^10,11 To increase vaccination among older adults, studies have shown that the knowledge, beliefs and attitudes of elderly people toward pneumonia and vaccination, socioeconomic status, education level, vaccine cost, availability of health education, history of pneumonia, and physician recommendations are factors associated with pneumococcal vaccination,^12,13 but researchers have emphasized the role of healthcare professionals in vaccination uptake. However, a study conducted in Hong Kong found that 53.4% of healthcare workers actively recommend pneumococcal immunization for patients 65 years and older, and that 18.8% advocate pneumococcal immunization for individuals aged 50–64 years.¹⁴ In inland China, 46.8% of healthcare workers would suggest vaccinations to this target population.¹⁵ Therefore, new strategies may be needed to address the issue of low vaccination rates among the elderly in China.

Previous studies have identified associations between kinship and the health outcomes of older adults.^16,17 Recent research has provided new insights into the vaccination of older adults. Wang et al. reported that family members’ recommendations were positively associated with higher vaccination rates among older adults,¹⁸ and Liu et al. found that family members’ persuasion, rather than physician advice, positively influenced the willingness of urban older adults to receive pneumococcal vaccination.¹⁹ Traditional Chinese family structures and ethics have fostered intergenerational proximity,²⁰ with older adults and their children maintaining strong physical and emotional ties, suggesting that children serve as reliable caregivers. Family members and friends are preferred sources of public health information for the elderly.²¹ All this research shows that kinship has a potentially positive role in promoting vaccination and the adoption of health behaviors among older adults.

Many studies have investigated parents’ attitudes toward childhood vaccinations,^22,23 but fewer studies have reported adult children’s attitudes toward pneumococcal vaccination for their elderly parents. Our study hypothesizes that adult children may influence older adults’ vaccination decisions and that educating them could improve their attitudes and behavior toward vaccination. This study investigated adult children’s willingness to vaccinate their elderly parents with the pneumococcal vaccine and its determinants in Guangzhou, China, exploring potential countermeasures to improve pneumococcal vaccination behavior among elderly individuals in China from the perspective of family members.

Methods

Sampling methods and study population

This cross-sectional survey involved 1,597 residents from six districts in Guangzhou and assessed their willingness to vaccinate their elderly parents with pneumococcal vaccines between October 2022 and June 2023. The sample was initially calculated using the following formula:

$$\mathrm{n}={\left(\frac{Z_{\frac{\alpha }{2}}}{\mathit{\delta }}\right)}^2\times \mathit{p}\left(1-\mathit{p}\right),\mathit{\alpha }=\mathit{\hspace{0.17em}}0.05,\mathit{\delta }=\mathit{\hspace{0.17em}}0.02$$

Beijing and Guangzhou are both first-tier cities with comparable levels of economic development and similar demographics, Using Beijing’s vaccination rate of 11.53% to estimate the sample size, we estimated that at least 980 people would be needed. We developed online questionnaires, which were distributed offline to respondents by surveyors. The participants completed the questionnaire by scanning the provided QR code. Additionally, the surveyor was responsible for explaining the purpose and content of the questionnaire to the respondents to ensure that each participant could clearly understand and accurately complete the questionnaire. Guangzhou’s 11 districts were categorized into three major districts on the basis of their gross domestic product (GDP): high GDP (Huangpu, Yuexiu, and Tianhe), medium GDP (Panyu, Haizhu, Baiyun, Nansha, and Huadu), and low GDP (Zengcheng, Liwan, and Conghua). Two districts of each type were selected. The final survey sites were the Yuexiu, Tianhe, Panyu, Baiyun, Liwan, and Conghua districts. Quota sampling was used to assign each district the required sample size, which was distributed and collected offline. The inclusion criteria were as follows: (1) were residents of Guangzhou, (2) were aged ≥18 years, (3) had a living father or mother aged ≥60 years, and (4) voluntarily participated in this survey. A total of 1597 participants were included in the analysis.

Measure

This study defines vaccine hesitancy on the basis of the six stages of the vaccination-related decision-making process proposed by Zheng et al.²⁴ The participants were asked, ‘What is your willingness to vaccinate your elderly parents against pneumococcal disease? (Never heard of it/known but never considered/considered but not yet decided/willing but not vaccinated/willing and vaccinated/refused).’ Based on participants’ responses, ‘never heard of it,’ ‘knew of it but never considered,’ ‘considered but not yet decided,’ and ‘refused’ were considered ‘hesitant,’ while ‘willing but not yet decided’ and ‘willing and vaccinated’ were considered ‘non-hesitant.’

Five indicators were used to analyze adult child–parent relationships between adult children and their elderly parents. Participants were asked a series of questions about the nature of their relationship with their living parent. Closeness measured by ‘Are you close to your parent? (1 = close, 0 = distant),’ and similarity of opinion measured by the question: ‘Do you agree with your parents most of the time? (1= agree, 0 = disagree),’ proximity by ‘Do you live with your parents? (1 = live together, 0 = do not live together),’ frequency of contact by ‘How often do you contact your parents (1 = 1–2 times per month or more, 0 = less than 1–2 times per month),’ and care provided by: ‘Do you provide your parents with living assistance and care? (1 = yes, 0 = no).’

Consistent with previous studies,^25,26 demographic characteristics of adult children, health beliefs about vaccination, and basic information about elderly parents were collected. The demographic variables included age (18–35 years, > 35 years), sex (male, female), education level (high school or below, bachelor’s degree or above), residence (urban, rural), and annual per capita household income (<100,000 CNY, > 100,000 CNY). The basic information of the elderly parents included age (60–69 years, ≥ 70 years), history of pneumonia (yes, no), presence of chronic diseases (yes, no), and difficulties in activities of daily living (ADL, yes, no).

Six questions were used to assess health beliefs about vaccination across four dimensions: (1) Perceived susceptibility: older adults are at risk of developing pneumonia if they are not vaccinated; (2) Perceived severity: pneumonia poses a serious health threat to older adults; (3) Perceived barriers: vaccination could cause adverse reactions; (4) Perceived benefits: a) vaccination is necessary for protecting health; b) vaccines prevent disease; and c) vaccines are safe. A Likert scale ranging from 1 to 5 was used, with 1 indicating ‘strongly disagree’ and 5 indicating ‘strongly agree.’ Finally, multiple-choice questions were employed to gather participants’ concerns regarding vaccination.

Statistical analysis

Latent class analysis (LCA) was used to identify the types of intergenerational relationships between adult children and elderly parents. Models were constructed with one to five classes, and the ‘best’ model was selected based on the Akaike information criterion (AIC) and the Bayesian information criterion (BIC), which minimize both the AIC and the BIC while providing the best model fit. The best model was chosen based on statistical indicators, category practicality, and interpretability. Participants were categorized into ‘hesitant’ and ‘non-hesitant’ groups based on their willingness to vaccinate their elderly parents. Descriptive statistics were conducted on the participants’ characteristics, with categorical variables expressed as frequencies and percentages and continuous variables expressed as the means with standard deviations. ANOVA and chi-square tests were applied to compare the groups. The determinants of vaccine hesitancy were examined using a binary logistic regression model, with ‘non-hesitant’ as the reference. The outcomes are displayed as odds ratios (ORs) with 95% confidence intervals (95% CIs). We also explored the associations between types of adult child–parent relationships and vaccine hesitancy, stratified by sex, education, income, and residence. All analyses were performed using R Foundation and Statistical Computing version 4.3.1. A two-sided p < .05 was considered statistically significant.

Results

Prevalence of vaccine hesitancy

A total of 59.8% of the adult children expressed hesitation to vaccinate their elderly parents with the pneumococcal vaccine. Among the participants, 30 (1.9%) had never heard of it, 101 (6.3%) knew of it but had never considered it, 751 (47.0%) had considered but not yet decided, and 73 (4.6%) had refused vaccination. (Figure 1).

Figure 1.

Stages of distribution of pneumococcal vaccination willingness.

Types of adult child–parent relations

To determine the types of adult child – parent relationships, LCA was employed to develop models with one to five classes latent classes. The three-class model demonstrated the best goodness-of-fit indicators (Table S1) and the most plausible results regarding interpretability. A total of 1,597 participants were classified into one of the three categories (Figure 2 and Table S2). The three categories identified in Silverstein et al.‘s study were as follows²⁷: intimate but distant, tight-knit, and detached. The ‘intimate but distant’ type was characterized by closeness, frequent contact, similarity of opinion, distance, and absence of caregiving; the ‘tight-knit’ type was characterized by closeness, frequent contact, similarity of opinion, living near, and caregiving; and the ‘detached’ type was characterized by low levels of all five indicators. As shown in Figure 1, 209 (13.1%) of the respondents were the ‘intimate but distant,’ 942 (59.0%) were ‘tight-knit,’ and 446 (27.9%) were ‘detached.’

Figure 2.

Three-class model of adult child–parent relations.

Characteristics of the participants

Of the 1,597 participants, 814 (51.0%) were males and 783 (49.0%) were females. The majority of participants (70.7%) were aged between 18 and 35 years. Regarding the information provided by participants about their elderly parents, 1,283 (80.3%) were aged 60–69 years, 71 (4.5%) had pneumonia, 391 (24.5%) had chronic conditions, and 702 (44.0%) had ADL impairment. Additional characteristics are provided in Table 1.

Table 1.

Participant characteristics of the overall sample by hesitancy status toward vaccination.

Characteristics	Total (n, %)	Hesitancy status		p value
		Non-hesitant (n, %)	Hesitant (n, %)
Total	1597	642	955
Demographics of subjects
Sex
Male	814 (50.97)	321 (50.00)	493 (51.62)	0.558
Female	783 (49.03)	321 (50.00)	462 (48.38)
Age group(y)
≤ 35	1129 (70.70)	401 (62.46)	728 (76.23)	<0.001
> 35	468 (29.30)	241 (37.54)	227 (23.77)
Residence
Rural	991 (62.05)	314 (48.91)	677 (70.89)	<0.001
Urban	606 (37.95)	328 (51.09)	278 (29.11)
Education level
High school/college or lower	598 (37.45)	370 (57.63)	228 (23.87)	<0.001
Bachelor or above	999 (62.55)	272 (42.37)	727 (76.13)
Annual per capita household income (thousand, CNY)
< 100	605 (37.88)	120 (18.69)	485 (50.79)	<0.001
≥ 100	992 (62.12)	522 (81.31)	470 (49.21)
Characteristics of elderly
Elderly age group(y)
60-69	1283 (80.34)	498 (77.57)	785 (82.20)	0.027
> 70	314 (19.66)	144 (22.43)	170 (17.80)
Had pneumonia experiences
No	1526 (95.55)	617 (96.11)	909 (95.18)	0.451
Yes	71 (4.45)	25 (3.89)	46 (4.82)
Elderly with Chronic illness
No	1206 (75.52)	439 (68.38)	767 (80.31)	<0.001
Yes	391 (24.48)	203 (31.62)	188 (19.69)
ADL (activity in daily life)
No	895 (56.04)	221 (34.42)	674 (70.58)	<0.001
Yes	702 (43.96)	421 (65.58)	281 (29.42)
Health Belief of Vaccination
Perceived benefits	10.66 (2.12)	10.64 (2.41)	10.67 (1.90)	0.749
Perceived susceptibility	3.62 (0.91)	3.50 (0.86)	3.70 (0.93)	<0.001
Perceived severity	3.05 (1.03)	3.25 (0.89)	2.91 (1.09)	<0.001
Perceived barriers	3.50 (0.93)	3.36 (0.82)	3.60 (0.98)	<0.001
Types of Adult Child–Parent Relations
Detached	446 (27.93)	322 (50.16)	124 (12.98)	<0.001
Intimate but distant	209 (13.09)	82 (12.77)	127 (13.30)
Tight-knit	942 (58.99)	238 (37.07)	704 (73.72)

Determinants of pneumococcal vaccine hesitancy

Table 1 displays the univariate associations between vaccine hesitancy and the characteristics of both participants and their elderly parents. Demographic characteristics of the participants, including age, education level, income, and residence, as well as information about older parents, such as age and health status (ADL, presence of chronic diseases), as well as health beliefs about vaccination were significantly associated with vaccine hesitancy (p < .05).

Figure 3 depicts the determinants of vaccine hesitancy, with ‘non-hesitant’ individuals serving as the reference group. Participants with intimate but distant relationships with older parents (OR = 3.04; 95% CI = 2.05–4.52) and those with tight-knit relationships (OR = 3.01; 95% CI = 2.23–4.06) were more likely to be hesitant than those with detached relationships were. Individuals with a bachelor’s degree or above (OR = 2.63; 95% CI = 2.04–3.39), those with higher perceived barriers (OR = 1.18; 95% CI = 1.01–1.38), and those whose parents experienced pneumonia (OR = 1.95; 95% CI = 1.11–3.48) were more likely to be hesitant. Respondents with an annual per capita household income of ≥ 100,000 CNY (OR = 0.35; 95% CI = 0.26–0.46) and parents with difficulty in ADLs (OR = 0.44; 95% CI = 0.34–0.57) were less likely to be hesitant in vaccinating their parents.

Figure 3.

Determinants of vaccine hesitancy (based on logistic regression analysis).

We conducted subgroup analyses to examine the associations between types of adult child – parent relationships and vaccine hesitancy. We found significant heterogeneity in terms of sex and residence. (Table 2)

Table 2.

Subgroup analyses of adult child – parent relations and vaccine hesitancy.

Subgroups	Adult Child–Parent Relations				P for interaction
	Intimate but distant		Tight-knit
	OR (95%CI)	p-value	OR (95%CI)	p-value
All participant	3.04 (2.05,4.52)	<0.001	3.01 (2.23,4.06)	<0.001
Sex					0.055
Male	1.72 (0.92, 3.23)	0.091	2.87 (1.89, 4.34)	<0.001
Female	4.89 (2.85, 8.39)	<0.001	3.20 (2.04, 5.04)	<0.001
Living residence					<0.001
Rural	1.89 (0.95, 3.76)	0.07	3.30 (2.13, 5.12)	<0.001
Urban	2.81 (1.66, 4.78)	<0.001	1.55 (0.97, 2.49)	0.037
Education level					0.266
High school/college or lower	2.46 (1.39, 4.33)	0.001	2.02 (1.26, 3.22)	<0.001
Bachelor or above	4.07 (2.28, 7.24)	<0.001	4.01 (2.65, 6.05)	<0.001
Annual per capita household Income (thousand, CNY)					0.505
<100	6.67 (2.37, 18.75)	<0.001	3.01 (1.54, 5.88)	0.001
≥100	2.68 (1.71, 4.19)	<0.001	3.01 (2.13, 4.26)	<0.001

Note: ‘Detached’ was set as reference.

Vaccine hesitation concerns

Figure 4 depicts the reasons reported by the hesitant for not vaccinating their parents, along with their corresponding response rates. ‘Contraindications’ exhibited the highest response rate of 22.2%. ‘Opinion of the elderly’ ranked second with a response rate of 16.2%, while ‘cost of vaccine’ ranked third, with a response rate of 16.1%.

Figure 4.

Concerns about pneumococcal vaccination.

Note: *Response rate is the percentage of all possible choices for which a particular option is selected.

Discussion

A total of 59.8% of adult children in Guangzhou, China, were hesitant to vaccinate their elderly parents with the pneumococcal vaccine. Although few studies have examined attitudes toward vaccinating older adults from the perspective of adult children, previous research on older adults’ or parents’ willingness to vaccinate their children has indicated similar rates of vaccine hesitancy. A meta-analysis of pneumococcal vaccination intentions in inland China revealed that 48.5% of older adults and 61.4% of parents with children were willing to receive the vaccine.¹² In Hangzhou, China, the willingness rate was only 21.8% among the elderly.¹⁹

In this study, we found that adult child – parent relationships in Guangzhou were categorized into three distinct types: tight-knit, intimate but distant, and detached, which aligns with the findings of previous studies.^28,29 Influenced by traditional Chinese filial piety, nearly 60% of Chinese adult children maintain close relationships with their elderly parents. Due to China’s socioeconomic transformation and increased mobility of young people, some adult children often compensate for the absence of direct care by offering emotional support from afar,³⁰ resulting in intimate but distant relationships, which constitute 13.1% of the population. Fewer than 30% of children are also detached from their parents. With social development and changing attitudes, relationships between adult children and parents are likely to place greater emphasis on emotional exchanges and spiritual support, while maintaining a suitable physical distance to ensure independence. The proportion of intimate but distant relationships is expected to increase in the coming years.^31,32

This study examines whether the type of adult child – parent relations affects adult children’s decision-making about vaccinating their elderly parents. We observed that close relationships positively affect vaccination attitudes. In other words, the closer the relationship is, the more hesitant individuals tend to be in making vaccination decisions. They maintain close relationships with older parents and are concerned about their health; therefore, this is likely due to a ‘concern for the elderly.’ When faced with the trade-off between the benefits and risks of vaccination, there is a tendency to be overly concerned about the potential risks. In addition, the ‘neoliberal logic’ theory, was proposed by Sara. In their study of parental willingness to vaccinate children, implies that parents may view vaccination as a personal choice rather than social responsibility.³³ This theory may similarly explain adult children’s decision-making. Our study revealed that participants placed greater weight on their parents’ opinions. The ambivalence that adult children experience in decision-making, as they may wish to respect their parents’ autonomy while also being concerned about their health, may also explain the close relationships and vaccine hesitancy.

The internet has become the preferred way for individuals aged 18–50 years to seek health information. They are more likely to obtain health-related information through the internet and social media, especially WeChat (a social software similar to Facebook).³⁴ Additionally, owing to the traditional doctor – patient relationship in China, patients prefer to obtain health information from doctors in a ‘paternalistic’ and ‘push’ manner. Older persons share health information more through interpersonal interactions³⁵ and prefer family guidance for internet health information.³⁶ The government may be able to disseminate authoritative advice on vaccination for the elderly to adult children through internet platforms such as WeChat, and encourage them to relay health information to older adults to reduce vaccine hesitancy. At the same time, it may be able to distribute vaccination-related information for older adults to their adult children who come for vaccination through doctors at adult vaccination clinics.

Subgroup analysis showed that this association was stronger among women and rural residents. Women are more concerned with uncertainty, consequences, the environment, and intimacy, and are more influenced by emotions in decision-making.³⁷ They are generally more hesitant than men when making decisions about their parental health, and similar findings have been reported in a study of parental vaccinations for children.³⁸ In addition, lower economic development, poor healthcare services, and limited access to health information in rural areas result in lower health literacy among rural residents,^39,40 making them more likely to be hesitant.

High education levels and high perceived barriers of vaccination are recognized as risk factors for adult children’s hesitancy to vaccinate their elderly parents, whereas high income and ADL impairment are protective factors against vaccine hesitancy. These factors have been significant determinants.^41,42 Notably, participants whose elderly parents had experienced pneumonia exhibited greater hesitancy. Such experiences may have eroded their trust in the healthcare system, thereby intensifying vaccine hesitancy. In the future, public health policies should enhance the dissemination of information on the safety and efficacy of vaccines. Personalized medical services should be provided to help families understand the risks and benefits of vaccination and to address concerns and correct misconceptions.

The present investigation showed that Chinese adult children’s attitudes toward pneumococcal vaccination were positively associated with closer relationships. Adult Chinese children are more hesitant to vaccinate their elderly parents with the pneumococcal vaccine the closer the relationship. To alleviate the vaccination concerns of both adult children and elderly individuals, health education should be taken to promote vaccination guidelines, particularly side effects and contraindications. The current focus of health education strategies for vaccination of older adults may need to be broadened to target adult children (18–50 years old), with a particular focus on female and rural adult children. This approach will not only improve vaccination rates among older adults through family relationships, in the long run, benefit these children when they themselves reach old age, as they will have early access to health education. At the same time, adult children should be encouraged to take an active role in health decision-making for their parents by helping them schedule vaccination appointments, accompanying them to vaccination and offering financial support.

In 2023, during the time of our survey, Guangzhou initiated a policy offering free pneumococcal vaccinations to residents aged 65 and above. Further researches are needed to evaluate the long-term effects of a permanent free policy on vaccination rates in Guangzhou. Interventional studies to assess the role of adult children in the vaccination of older adults are also necessary. This study has several limitations. First, we could not determine causality due to the use of a cross-sectional survey. Second, the survey was largely self-reported by the respondents, which may introduce information bias, particularly regarding parental data. Third, few studies have explored attitudes toward the vaccination of older adults from the perspective of adult children, and there is a lack of standardized instruments for measuring adult child – parent relationships and health beliefs about vaccination. Finally, the sample was limited to the city of Guangzhou, which may limit the representativeness of the study, particularly in economically disadvantaged regions.

Conclusion

Over half of the adult children in Guangzhou, China, are hesitant to vaccinate their elderly parents against pneumococcal disease. The most common types of adult child – parent relations included detached, intimate but distant, and tight-knit relationships. Close relationships, education level, income, perceived barrier of vaccination, history of pneumonia, and ADLs are identified as determinants of vaccine hesitancy. Contraindications and older adults’ opinions were the main reasons for adult children’s hesitation. Disseminating public health messages through close relationships is a promising strategy. Moving forward, vaccine health education and promotion should target young adults, and adult children must be encouraged to actively participate in the vaccine decision-making process for older adults.

CRediT authorship contribution statement

Qiqi Wu: Formal analysis, Methodology, Writing-original draft, Writing-review & editing. Haiyuan Zhu: Methodology, Writing-original draft. Runquan Zhang: Methodology, Writing-original draft. Cuizhi Li: Investigation, Methodology. Qin Xiao: Investigation. Yuqing Jin: Investigation. Xiaofeng Liang: Conceptualization. Xiongfei Chen: Conceptualization. Xiaomei Dong: Conceptualization, Writing-review & editing.

Biographies

Xiongfei Chen is currently appointed at the Department of Primary Public Health, Guangzhou Center for Disease Control and Prevention, Guangdong, China. His principal area of research focuses on the control and prevention of chronic non-communicable diseases.

Xiaomei Dong, ph.D, is a professor at School of Public Health, Jinan University, specializing in Epidemiology and Health Statistics. She has been dedicated to teaching and research in epidemiology. Her primary research interests include injury prevention and control, emergency response to public health incidents, community-based chronic disease prevention, and HIV/AIDS prevention among populations.

Funding Statement

This work was supported by the Jinan University-BioKangtai Vaccine Institute, [Number: KTR001].

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethical statement

Ethical approval for this study was obtained from the Institutional Review Board of Jinan University. (Approval ID: JNUKY-2023–0038).

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website at https://doi.org/10.1080/21645515.2024.2440959.