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Introduction: With China's accelerating urbanization, migrant workers comprise up to 40% of the urban population of China's largest cities. More mobile than non-migrant urban dwellers, migrants are more likely to contract and spread hepatitis B (HB) than non-migrants. Due to the mandatory system of household registration (hukou), migrants are less likely to be covered by national HB immunization programs and also to have more limited access to public health services where they work than non-migrants. Migrants form a significant sub-group in all Chinese cities posing unique public policy vaccination challenges. Objective: Using protection motivation theory (PMT), we developed and measured HB cognitive variables and analyze the factors affecting HB vaccination behavior and willingness to vaccinate by migrant workers. We propose public policy interventions to increase HB vaccination rates of migrant workers. Methods: We developed a questionnaire to collect information on the HB vaccination characteristics of 1684 respondents from 6 provinces and Beijing. Exploratory factor analysis was used to create PMT variables and a binary logistic regression model was used to analyze the factors affecting migrant workers' HB vaccination behavior and willingness to vaccinate. Results: Vulnerability and response-efficacy were significant PMT cognition factors determining HB vaccination behavior. The HB vaccination rate for migrants decreased with increasing age and was smaller for the primary education than the high education group. The vaccination rate of the medical insurance group was significantly greater than the non-insured group, and the vaccination probability was significantly higher for the self-rated good health compared to the self-rated poor health group. Geographical birth location mattered: the vaccination rate for Beijing city and Ningxia province migrants were higher than for Hebei province and the vaccination rate was lower for migrants born far from health facilities compared to those located middle-near distances from health facilities. We also studied vaccination willingness for the unvaccinated group. For this group, vulnerability and self-efficacy cognition factors were significant factors determining HB vaccination willingness. The probability of willingness to vaccinate for the 46+ age group was significantly smaller than the 16–25 age group and the willingness to vaccinate was lower in Jiangsu and Hainan province than in Hebei province. Conclusion: Increased knowledge of HB cognition is an effective way for improving HB vaccination behavior and HB vaccination willingness of migrant workers. We also found that health intervention policies should focus on older migrants (age 46+), without medical insurance, with poorer self-reported health status and poor health services accessibility.
Introduction
Hepatitis B (HB) is the most serious and common type of viral hepatitis in China and a major worldwide public health problem. About 3 billion people, mainly in East Asia and sub-Saharan Africa, have been exposed to HB,Citation1 with more than 780,000 deaths every year due to HB complications, including cirrhosis and liver cancer.Citation2 Ranked top of the national infectious class A and B diseases in China, HB infects nearly 1 million people each year.Citation3 In China, it is estimated that there are 90 million chronic HB patientsCitation4 with estimated direct medical cost of RMB 900 billion each year.
At present, the most efficient and economical way to prevent and control HB is through HB vaccination.Citation5,6 While HB immunization of babies in the first 24 h after birth is 95% effective against HB, HB vaccination of adults still reduces HB by around 75%, with significant economic and social benefits.Citation7,8 Since 2002, the Chinese government began to provide free HB vaccine for neonates and from 2009–2011 the government has provided free HB vaccine for children aged 8–15.Citation9 While there is a major program to HB inoculate all new-born babies and children in China, given China's finite health resources, it is not feasible to provide free inoculations for adults. However, there are compelling public health reasons for targeting sub-sets of the adult population, such as migrant workers, through public health campaigns to educate the population about HB and to encourage them to inoculate.
With China's accelerating urbanization, the number of migration workers is increasing, with an estimated 274 million migration workers in China in 2014.Citation10 Over the past 15 y, an estimated 300 million rural workers have migrated to China's cities, with migrants accounting for 50% of Guangzhou's, 40.3% of Shanghai's and 38% of Beijing's population. Rural HB inoculation rates are lower than urban inoculation rates. Traveling frequently between China's largest cities and their home townships, migrant workers have a higher likelihood of spreading HB than non-migrant workers.Citation11 Migrant workers increase HB exposure within the Chinese population and make HB control more difficult.Citation12
Previous research has suggested that cognition limitations about HB and the HB vaccine constrain vaccination rates.Citation13,14 Currently, researchers have applied one or several related questions to measure HB vaccination cognition. For example, Tan used a single route of transmission, having dinner with HB patients or carriers, as an independent variable to analyze HB vaccination behaviorCitation15 and Zhu employed knowledge scores about HB symptoms to analyze HB vaccinations.Citation16 These approaches are partial measures of the HB cognition level. We systematically measure an individual's HB cognition level and evaluate its effect on both their HB vaccination rates and their HB vaccination willingness.
Protection motivation theory (PMT) has been used to measure cognition of other vaccines, such as the AIDS vaccine,Citation17 malaria vaccineCitation18 and typhoid vaccine.Citation19 But previous research on HB vaccination has not investigated the full range of protection motivation factors. For example, Bodenheimer's study of hospital workers only verified vulnerability as the key factor determining one's acceptance of the HB vaccineCitation20 and Rosenthal et al. found expectancy of their children being exposed to HB risk effected parents' acceptance of HB vaccinations.Citation21 Studies employing PMT and combining vaccination behavior and willingness are rare. In a study of Chinese farmers, Liu found that vulnerability and self-efficacy were important factors determining HB vaccination willingness and behavior.Citation22 There has been no equivalent research focusing both on HB vaccination willingness and behavior of migrant workers. To better understand HB vaccination rates in China, further studies of sub-sections of the Chinese population, such as migrant workers that make up such a significant section of the population, are required. Understanding individual's HB cognition levels and evaluating how HB cognition affects both HB vaccination willingness and HB behavior is a prerequisite to understanding HB vaccination rates.
Using protection motivation theory, this study conducts both a theoretical and empirical study of the HB cognition factors. Specifically, we focus on HB cognition factors determining vaccination willingness and vaccination behavior of migration workers, with the added aim of providing policy recommendations for HB vaccine immunization regimes in China. Our research: (1) identifies the appropriate method to measure migrant workers' HB cognition levels and HB vaccination behavior to generate PMT factors; (2) analyzes the influencing factors on migrant workers' HB vaccination willingness and behavior; and (3) undertakes stratified research of the total migrant sample to identify differential policy responses to sub-groups of migrant workers.
Results
Characteristics of respondents
The sample groups are shown in . In our sample of 1684 migrants, 467 had received the HB vaccine (391 had received all doses, while 76 had received some but not all recommended doses) and 1217 were unvaccinated (852) or uncertain (365). In the latter groups, 402 answered they would be willing to take the vaccine, while 815 were either not willing (417) or unsure (398).
Figure 1. Sample groups.
displays the characteristics of the 1684 survey respondents. Of all respondents, 29.98% were female, 85.1% were aged 16–45, and average age 32.6 y (Hebei 33.6 y, Shandong 32.4 y, Heilongjiang 30 y, Jiangsu 43 y, Hainan 28.6 y, Ningxia 28.7 y and Beijing 34.5 y); 23.99% had an education level above primary and 76.01% primary education only. Most respondents had medical insurance (91.69%) and self-reported good health (81.53%). For the unvaccinated respondents, 27.36% were female, 80.53% aged 16–45, 20.95% with an education above primary and 70.05% with a primary education only. For those not vaccinated, 90.88% had health insurance and 79.21% had self-reported good health.
Table 1. Characteristics of respondents.
As shown in , the home provinces of migrants differed in terms of income and health service provision, measured by health care spending and health care workers per capita. As expected, rural areas had lower income and poorer health service provision than urban areas. Beijing had the highest per capita income, health spending and health workers. Heilongjiang had the lowest per capita income. But, the health spending and health workers per capita were generally comparable across provinces, except for Beijing.
Table 2. Characters of income and health resources in 2010.
Comparison of vaccination rate by age
Since the age distribution can affect the vaccination rate across different regions, we standardize the age of each province on the standard of whole sample age composition, using the formula:(1)
(1)
Where Ni is the number of each age group of standard group population, and N is the total number of standard group population, and pi is the rate of each age group that needs to be standardized.
provides the age-adjusted vaccination rate and the standardized vaccination rates by age group, for the independent variables. shows that vaccination rates were sensitive to age, with lower age groups having higher vaccination rates than older age groups for all independent variables. For the total vaccination rate, vaccinations were greater for the high education group (36.88%) than those with a primary education (24.84%); for females (31.76%) than males (26.09%); and for the medical insurance group (28.37%) than those having no medical insurance (20.71%). For self-rated health, those self-rated good (29.79%) had higher vaccination rates than the poor health group (18.65%). For accessibility of health services, the middle (27.27%) and near (29.10%) distant from health facilities groups had a higher vaccination rate than the far distance (11.96%) group. There was significant variation in vaccination rates by province, ranging from 37.05% for Beijing, 32.81% for Ningxia, 30.52% for Shandong, 23.58% for Hebei, 21.75% for Jiangsu, 21.05% for Heilongjiang and 17.09% for Hainan.
Table 3. HB vaccination rate.
Table 4. Factor analysis results of HB vaccination behavior's PMT factors.
Results of PMT factor analysis
Using factor analysis, those factors (“The probability infected by HBV in 3 y” and “The probability your son or daughter will be infected by HBV in 3 y”) whose contribution rate was less than 0.3, were screened out of both the vaccination behavior and the vaccination willingness samples. Next, the PMT factors of vaccination behavior sample and vaccination willingness sample were generated. As we can see from for vaccination behavior, Sev1-5 explained Severity; Res 1–3 loaded onto Response-efficacy; Vul1-3 explained Vulnerability and Sel1-3 explained Self-efficacy. From for vaccination willingness, Sev1-5 loaded on to Severity; Res1-3 explained Response-efficacy; Sel1-3 loaded onto Self-efficacy; and Vul1-3 explained Vulnerability.
Table 5. Factor analysis results of HB vaccination willingness' PMT factors.
The regression results of HB vaccination behavior
We set vaccinated or not as the dependent variable to build 2 binary logistic regression models (using formula (3)) for 1684 migrant workers. Model 2 comprised only control variables, while Model 1 included both control variables and PMT variables. Based on the log likelihood value, Model 1 (−816.41) out-performed Model 2 (−825.99) in . Therefore, we used Model 1 to explain HB vaccination behavior.
Table 6. Regression result of HB vaccination behavior.
As shown in Model 1, vulnerability and response-efficacy were all significant factors determining HB vaccination behavior. The HB vaccination rate decreased with increasing age, and the vaccination probability was significantly greater for the high education group, the medical insurance group and the self-rated good health group. Finally there were significant differences in vaccination rates across provinces: the vaccination rates of Beijing city and Ningxia province were greater than for Hebei province. Second, the vaccination rate of the near-middle distance from a health service group was higher than the far distance from a health facility group.
The regression results of HB vaccination willingness
We also tested the willingness to vaccinate in the future or not as the dependent variable to build 2 binary logistic regression models for 1217 unvaccinated respondents. Based on the log likelihood value, Model 4 (−738.90), with only control variables, was out-performed by Model 3 (−744.56) in , therefore, we used Model 3 to explain HB vaccination willingness.
Table 7. Regression result of HB vaccination willingness.
As shown in Model 3, vulnerability and self-efficacy were significant cognition factors determining HB vaccination willingness. Also, the probability of willingness to vaccinate was significantly smaller for the 46+ age group and respondents from Jiangsu and Hainan province, and the probability of vaccination willingness was significantly higher for those from Hebei province.
Discussion
The PMT factors determining HB vaccination behavior and willingness
Validating our PMT approach, Model 1 shows that vulnerability, self-efficacy and response-efficacy were the key cognition factors determining HB vaccination behavior. The odds-ratio (OR) value of vulnerability was 1.395, which indicates that the HB vaccination rate increased 1.395 units as the vulnerability factor increased one unit. This means that when respondents believed the probability of HB exposure was high, there was a higher probability of them having received the HB vaccine. Also, when respondents believed that the HB vaccine was more efficient (response-efficacy OR = 1.211), the probability of having receiving the HB vaccine was higher. For those not vaccinated, we investigated vaccination willingness. Model 3 shows that vulnerability and self-efficacy were key factors determining HB vaccination willingness. When respondents believed that the probability of exposure to HB was high (vulnerability OR = 1.249), their willingness to receive the HB vaccine was greater. For self-efficacy (OR = 1.253), when respondents identified a likelihood of HB infection in the future, their willingness to receive the HB vaccine was stronger. Therefore, knowledge about HB vulnerability and response-efficacy were significant factors explaining HB vaccination behavior, while vulnerability and self-efficacy were determining factors of HB vaccination willingness.
To improve cognition of HB vulnerability, any public health education campaign should focus on knowledge of the route of transmission, epidemic situations and trends in HB. For self-efficacy, previous research has identified the lack of information about vaccination places and vaccination times as important causes of low HB vaccination rates.Citation23 While free HBV vaccines have been available in China since 2002, public health information and training of health workers are crucial factors in the vaccine being provided. With lower per capita spending on health and lower per capita health workers (see ), rural and remote health centers were likely to have provided poorer information to parents than better funded urban health centers. Public health interventions should include enhanced knowledge of injection sites, injection times and injection patterns. Knowledge about the HB vaccine, especially its effectiveness, should be improved.
The control factors influencing HB vaccination behavior and willingness
The vaccination rate decreased with increasing age, and increased with education, medical insurance and self-rated good health. This suggests that HB policy prevention and control should focus on older and primary educated groups, without medical insurance and self-rated poor health status. As a shortcut, government might provide preferential policies of HB vaccination for low-income migrant families. Given the significant differences in vaccinations rates across provinces, the government should investigate differences in health services in Beijing city and Ningxia province compared with Hebei province. Distance from health services was a significant factor in vaccination rates. The cost of vaccination increased with the distance from health services due to costs of travel time, especially for more rural-remote participants. Also, the quality of health services varied geographically, with rural and remote services more poorly funded and likely providing poorer information on HBV vaccinations.
The willingness to receive the HB vaccine was significantly smaller for the aged 46+ group and respondents from Jiangsu and Hainan province. Clearly, for migrant workers who did not have a willingness to vaccinate, there is an urgent need to improve their HB vaccination willingness. Improving cognition of vulnerability and self-efficacy, especially for those migrant workers aged over 45 y and from Jiangsu and Hainan province, would provide enhanced public health outcomes.
Limitations
For migrant workers it is generally difficult to obtain a well-defined population from which to draw a random sample. This is in particular the case for floating migrants, because they move frequently between dormitories owned by their employers. We did not record the destination of outbound migrant and we expect that some had settled at one workplace while others were “floating” between workplaces. For non-participants we have no information except that most of them had moved with their families to other regions. Thus, it is likely that floating migrants are under-represented in our sample. Combined with the relatively small sample size, our results should be regarded as exploratory and not necessarily representative for the entire Chinese population of migrant workers.
Conclusion and policy implications
For migrant workers, our PMT models were confirmed. For vaccination behavior, knowledge of vulnerability, self-efficacy and response-efficacy were important determinants of the HB vaccination rate. Age, education level, income level, medical insurance, self-rated health status, accessibility of health services and provinces were significant control variables. Determination of HB vaccination willingness included 2 cognition factors, vulnerability and self-efficacy, plus age and geographical location. Based on these results, there is an urgent need to improve the HB vaccination rate of unvaccinated migrant workers by improving their HB knowledge, especially vulnerability, self-efficacy and response-efficacy. For migrant workers, education campaigns should focus on the older aged (over 45 y) group, and those with only a primary education, in the lowest income strata, without medical insurance, with bad self-rated health status and living far from health services institutions. Certain provinces, such as Beijing and Ningxia province, had high vaccination rates, and reasons for these high rates might inform vaccination practices in low HB vaccination provinces. Second, unvaccinated migrant workers, who do not have a vaccination willingness, form an HB vaccination target group. The key factors in a campaign for the unwilling to vaccinate cohort is to increase HB cognition related to vulnerability and self-efficacy, especially migrant workers aged over 45 y from Jiangsu and Hainan province.
Methods
Data source and variables collected
Our cross-sectional survey data were collected as part of a project on how user fees affected HB vaccination coverage rates in China.Citation24 A questionnaire-based household survey collected information including HB awareness, HB immunization status, and detailed household characteristics. The survey was conducted in 42 villages from 6 provinces (Hebei, Shandong, Heilongjiang, Jiangsu, Hainan and Ningxia) and Beijing city. In larger villages, we selected households randomly by using household size to create weighted sampling (probability proportionate to size), while all households in small villages were surveyed. In total 7948 households and 22618 individuals participated. The overall nonparticipation rate was about 18% and the main reason for non-participation was that all household members had moved to industrialized regions.Citation24 All statistical analyses were performed using STATA version 12.0.
Definition of migrant workers
In accordance with official definitions,Citation25 we defined migrant workers as individuals who had left their home county for work for one month or more. In this setting, home county means the address in the mandatory system of household registration (hukou). The resulting sample consisted of 1684 respondents aged 15 y or older.
Protection Motivation Theory (PMT)
In 1975, Rogers developed protection motivation theory (PMT).Citation26,27 PMT argues that the protection motivation decision is made after people utilize information to assess a threat and the ability to deal with that threat. Two appraisal processes, threat appraisal and coping appraisal, are utilized before people take action. Threat appraisal relies on the individual's cognition of the threat, including the severity of threat and the expectancy of being exposed to the threat, or one's vulnerability, which causes fear arousal. Severity refers to the possible damage to the individual's interests caused by hazards, and vulnerability refers to individual's perception of how serious the hazards or the possibility of developing the disease.Citation27 The coping appraisal process evaluates an individual's ability to cope with and avert the threatened danger, including self-efficacy and response-efficacy.Citation28 Self-efficacy expectancy is the belief that one is, or is not, capable of performing a behaviorCitation29 and response-efficacy refers to one's cognition about whether such actions work or not. displays the PMT model.
Figure 2. Protection Motivation Theory.
Using the PMT model, we focused on the individual's cognition level. PMT assumes that individual protection motivation is a linear function of 4 individual cognition factors: perceived severity of the threat, the individual's susceptibility to the threat, effectiveness of protection behavior against threat and the capacity of conducting protection behavior.Citation26 It is assumed that severity and susceptibility of the threat reduce adverse behavior reactions, while the effectiveness of the reaction and individual capacity enhance individual health behaviors.Citation28
Using Exploratory Factor Analysis method to build PMT factors
In the questionnaire, we designed relevant questions for each PMT factor, with appropriately assigned values. We used exploratory factor analysis to make sure that each question explained the relevant PMT factor fully, deleting the questions that explained relevant PMT factor weakly or in the opposite direction. displays the questions, codes for each question and the assigned scores.
Table 8. Questions of PMT factors and assignment for answers.
Dependent variables: vaccination status and vaccination willingness
HB vaccination status was mainly measured by self-reports because few adults had vaccination cards Citation[5,24]. We defined 2 dependent variables: First, HB vaccination behavior was defined by separating the migrants into one group who had received full or partial vaccination (Y = 1), and one group who had received no vaccination or was uncertain of vaccination status (Y = 0). Second, for the latter group only, HB vaccination willingness was defined by separating those who answered they would receive vaccination (Y = 1) from those who would not receive vaccination or were uncertain (Y = 0).
Control variables
According to previous research and our questionnaire, we selected gender, age, education level, average income level, medical insurance, self-rated health status, provinces and accessibility of health services as control variables.
Regression model building
The dependent variables are binary variables, so we use binary logistic regression to analyze the relationship between the dependent variable and explanatory variables. In this model, the dependent variable vaccinated or future vaccination (Y) is assigned a value 0 or 1. The probability of vaccinated or future vaccination is(2)
(2) where X is a vector of independent variables including a constant term, and B represents the coefficients to be estimated.
Usually, (2) is written as a logit or the log odds ratio(3)
(3)
Individual coefficients in B reflects the degree of influence an independent variable have on the dependent variable.
Ethics
Participants were informed that they could refuse to answer any question. The questionnaire did not ask about infection status, and no biological samples were collected. The project was approved by the Medical Ethics Committee at the Shandong University School of Medicine (Grant No. 201001052).
Disclosure of potential conflicts of interest
No potential conflicts of interest were disclosed.
Authors' contributions
All authors have read and approved the final manuscript.
Acknowledgments
The authors thank the health workers in all the participating provinces for their support and assistance.
Funding
This work was supported by the Norwegian Research Council (Project no. 196400/S50).
References
- Hu M, Chen W. Assessment of total economic burden of chronic hepatitis B (CHB)‐related diseases in Beijing and Guangzhou, China. Value Health 2009; 12: S89-92; PMID:20586991; http://dx.doi.org/10.1111/j.1524-4733.2009.00636.x
- Lozano R, Naghavi M, Foreman K, Lim S, Shibuya K, Aboyans V, Abraham J, Adair T, Aggarwal R, Ahn SY et al. Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 2013; 380: 2095-128; PMID:NOT_FOUND; http://dx.doi.org/10.1016/S0140-6736(12)61728-0
- National Health and Family Planning Committee of the People's Republic of China. Annual national epidemic report of statutory infectious diseases in 2013. [EB/OL](2014.02.13)[2015.03.29]. http://www.nhfpc.gov.cn/jkj/s3578/201402/26700e8a83c04205913a106545069a11.shtml[In Chinese].
- World Health Organization. Guidelines for the prevention, care and treatment of persons with chronic hepatitis b infection. Geneva: WHO; 2015. 134 p.
- Liang X, Bi S, Yang W, Wang L, Cui G, Cui F, Zhang Y, Liu J, Gong X, Chen Y, et al. Epidemiological serosurvey of hepatitis B in China—declining HBV prevalence due to hepatitis B vaccination. Vaccine 2009; 27: 6550-7; PMID:19729084; http://dx.doi.org/10.1016/j.vaccine.2009.08.048
- Centers for Disease Control and Prevention (CDC). Progress in hepatitis B prevention through universal infant vaccination-China, 1997–2006. MMWR Morb Mortal Weekly Rep 2007; 56: 441; PMID:17495790
- Wu GY, Zhao X, Zhao N. Meta-analysis of the Immunization with Hepatitis B Gene Vaccine on Adults and Vaccination Necessity of Adult. Chinese J Health Stat 2005; 22:359-61 [In Chinese].
- McMahon BJ, Parkinson AJ, Helminiak C, Wainwright RB, Bulkow L, Kellerman-Douglas A, Schoenberg S, Ritter D. Response to hepatitis B vaccine of persons positive for antibody to hepatitis B core antigen. Gastroenterology 1992; 103: 590-4; PMID:1386048
- The health ministry of the People's Republic of China. China's hepatitis B prevention and control strategy and work progress. Capital Journal of Public Health 2010; 4:145-7. [In Chinese].
- National bureau of statistics of the People's Republic of China. The national monitoring report of migrant workers in 2014. [EB/OL] (2015.09.29)[2015.02.01]. [In Chinese].
- Zhang Y, Cheng J, Hao Y, Hao Y, Chen W, Ma Z, Liao Y, Zhang R, Zhu Q. Comparisons and analysis of the hepatitis B infection status of transient population and registered residents in Shenzhen City. Chinese J Dis Control Prevent 2012; 16:424-7 [In Chinese].
- Kong H. Survey on status of knowledge and behaviors of priority infectious diseases prevention among floating population in Chaoyang district of Beijing and Datong City. Peking: Chinese CentersforDisease Control and Prevention, 2011 [In Chinese].
- Zhu D, Wangen KR, Wang J, Guo N, Wang ZH. Influencing factors of vaccination of hepatitis B vaccine in rural adults in China. Chin J Public Health 2012; 28:1291-3 [In Chinese].
- Scognamiglio P, Girardi E, Fusco M, Piselli P, Spena SR, Maione C, Pisanti FA, Serraino D; Collaborating Study Group. Lack of implementation of Hepatitis B Virus (HBV) vaccination policy in household contacts of HBV carriers in Italy. BMC Infect Dis 2009; 9: 86; PMID:19500412; http://dx.doi.org/10.1186/1471-2334-9-86
- Tan Y, Shen H, Zhao L, Chen J, Zhang L, Wu Y, Ni ZH. Influencing factors of active vaccination of hepatitis B vaccine in adults. Chinese J Public Health 2012; 26:1291-3 [In Chinese].
- Zhu D, Guo N, Wang J. Analysis of the Behavior and Willingness Vaccine among Adults in Rural China. Chinese J Health Stat 2013; 30:203-5 [In Chinese].
- Zimet G D, Blythe MJ, Fortenberry JD. Vaccine characteristics and acceptability of HIV immunization among adolescents[J]. Int J STD AIDS 2000; 11: 143-9; PMID:10726935; http://dx.doi.org/10.1258/0956462001915570
- Xu J. Study on rural residents' acceptability of dysentery vaccine in Zhengding County, Hebei Province [dissertation]. [Shanghai]: Fudan University; 2005. 155p. [In Chinese].
- Wu XH. Study on willingness to pay for typhoid VI vaccine in Lingchuan County, Guangxi [master's thesis]. [Nanning]: Guangxi Medical University; 2007. 123p. [In Chinese].
- Bodenheimer Jr HC, Fulton JP, Kramer PD. Acceptance of hepatitis B vaccine among hospital workers. Am J Public Health 1986; 76: 252-5; PMID:3946712; http://dx.doi.org/10.2105/AJPH.76.3.252
- Rosenthal S L, Kottenhahn R K, Biro F M, Succop PA. Hepatitis B vaccine acceptance among adolescents and their parents. J Adolesc Health 1995; 17: 248-54; PMID:8580126; http://dx.doi.org/10.1016/1054-139X(95)00164-N
- Liu C. An application of protection motivation theory to hepatitis b vaccination willingness and behavior in rural China [dissertation]. [Jinan]: Shandong University; 2012. 177p. [In Chinese]. http://xueshu.baidu.com/s?wd=paperuri%3A%28be42c5a9357d344dbcea5df0a3b0fabf%29&filter=sc_long_sign&tn=SE_xueshusource_2kduw22v&sc_vurl=http%3A%2F%2Fdoi.med.wanfangdata.com.cn%2Fqk%2Fzgjhmy200004001&ie=utf-8
- Zu X, Zhang XL, Wang LX. National EPI vaccination and hepatitis B vaccine coverage rate and the related factors: from the 1999 nationwide survey. Chinese Journal of Vaccines and immunization 2000; 6: 193-7 [In Chinese].
- Zhu DW, Wang J, Wangen KR. Hepatitis B vaccination coverage rates among adults in rural China: Are economic barriers relevant? Vaccine 2013; 32: 6705-10; PMID:23845801; http://dx.doi.org/10.1016/j.vaccine.2013.06.095
- “The regulations on family planning among the floating population” promulgated by the State Council of China & “Method for application for temporary residence permits” promulgated by the China Ministry of Public Security.
- Rogers RW. A protection motivation theory of fear appeals and attitude change1. J psychol 1975; 91: 93-114; http://dx.doi.org/10.1080/00223980.1975.9915803
- Rogers RW, Cacioppo JT, Petty R. Cognitive and physiological processes in fear appeals and attitude change: A revised theory of protection motivation. In book: J T Cacioppo, R Petty, Editors. Social Psychophysiology: A Sourcebook, Publisher: Guilford; 1983. p. 153-177.
- Floyd DL, Prentice-Dunn S, Rogers RW. A meta-analysis of research on protection motivation theory. J Appl Soc Psychol 2000; 30: 407-429; http://dx.doi.org/10.1111/j.1559-1816.2000.tb02323.x
- Bandura A. Self-efficacy: toward a unifying theory of behavioral change. Psychol Rev 1977; 84: 191; PMID:847061; http://dx.doi.org/10.1037/0033-295X.84.2.191