| BackgroundHepatitis B (HB) is the severest one in all types of viral hepatitis, being top10on the list of global cause of death. Approximately1million people die from chronic HB disease, including liver cirrhosis and cancer, which is8times higher than AIDS infected patients. China, with, is currently the only country with high prevalence of HB in Asia with a total number of130million HB infected patients. The prevalence of HB in rural China is significantly higher than urban residents, and in the perspective of nationwide HB vaccination strategy, the vaccination rate has reached a relatively-high level in urban area while it is still a weak link to the rural area. Meanwhile, different from morbidity and age distribution in foreign countries, vertical transmission is dominant in our country (60%-80%), with most cases during prenatal period. Positive HBsAg rate under3years old reaches12.5%, taking a mainly responsibility for chronic infection in the population. It has been proved that timely first dose is the key factor to cut off maternal-neonatal transmission. Currently, although newborn HB vaccination has been integrated into Expanded Program on Immunization (EPI), the timely first dose cannot be guaranteed due to the limitation of guardian's cognition. As proved by the program collaborated by our country and Global Alliance for Vaccines and Immunization (GAVI), HB vaccination coverage rate for the newborn in the majority of provinces reached above95%, while timely first dose rate is about70%and there is large variation among provinces. At the same time, the prevalence of adults'HB tends to recur recently, and the morbidity and mortality of viral hepatitis in our country have been increasing, while the HBsAg positive rate and HB prevalence have not dropped significantly. In2009, the prevalence of virus hepatitis remained the top among class A and B of infectious diseases and with average life expectancy increasing, the HBsAg positive rate of adults would not decrease significantly.HB vaccination is the most effective way to prevent and control transmission of HB virus. Owing to the lack of resources, immunization for the whole population is not feasible in current China. The literature has showed that knowledge limitation on HB and HB vaccine will hinder the vaccination. Moreover, controlling the vaccination policy and individual's cognition level may play the key role in the vaccination. However, rural residents'cognition level is relatively low and no specific conception and systematic analysis about this factor was found in previous studies. Some studies applied one or several related questions as variables or transform knowledge score to the analyzing variables, but these methods cannot measure the cognition level and its effect. Meanwhile, studies on HB vaccination willingness are relatively rare, especially the ones combining vaccination willingness and behavior. Therefore, it is so difficult to locate the effect of cognition level in each behavioral phase that targeted intervention measures for population's cognition level cannot be proposed. Therefore, systematically to measure individual's cognition level and then to evaluate its effect on HB vaccination willingness and behavior is requisite. Based on this, the targeted suggestions aiming to improve the population's cognition level can be proposed.The application of Protection Motivation Theory (PMT) in this study focused on the individuals'cognition level. The PMT assumed that individual protection motivation is a linear function of4individual cognition factors:perceived severity of threat, individual susceptibility of threat, effectiveness of protection behavior against threat and the capacity of conducting protection behavior. Among them, factors including severity and susceptibility of threat can reduce adverse behavior reaction, while effectiveness of reaction and individual capacity enhance individual health behaviors effectively. A mass of researches have already demonstrated that PMT is of great importance to explain individual health-related willingness and behaviors. Quantitative studies on applying PMT to HB vaccination have not been found. Based on PMT, this study is trying to establish a systematic measurement tool for individuals' cognition level, to generate PMT factors, which make a theoretic evidence and quantitative structure expression for individuals'cognition level. At the same time, HB vaccination willingness and behavior is a continuous process, and they are combined to be analyzed in this study to evaluate the effect of PMT factors in these two behavior phases. So, on the one hand, to specify the logic relationship between individuals'level, vaccination willingness and behavior will be of great value in theory; on the other hand, based on attaining the respective significant cognition variables in each behavior phase to improve targeted population's cognition level, and then let them overcome other obstacles and realize their HB vaccination and their offspring's timely first dose vaccination aiming at decreasing the horizontal and vertical transmission will make great contributions to the prevention and control on HB in China.ObjectivesThe overall objective of this study is to conduct both theoretical and empirical study to establish PMT factors on HB and HB vaccine for China rural residents, to explore the effect and roles of these factors played in HB vaccination willingness and behavior of rural residents, and then to provide policy recommendations for HB vaccine immunization in China. Specifically, our research objectives include:(1) Based on PMT, to explore the appropriate measurement method for cognitive level of rural residents awareness of HB and HB vaccine, which aimed to generate PMT factors;(2) To analyze the influencing factors of HB vaccination willingness and behavior focusing on the effect and its extend of PMT factors;(3) Combining Trans-theoretical model and HB vaccine immunization strategy, to do stratified research of the total sample and compare the differentiated impact which PMT variables takes to HB vaccine willingness and behavior, and then to provide specific recommendations to targeted people who are under different policy background and behavioral phases. MethodsA cross-sectional study design is applied and the data derives from the project "Does User fee affect the Hepatitis B Vaccination Coverage in China?" In the empirical study, we selected39villages in6provinces according to economic developmental level and geographic location. Preliminary data processing leaves21538individuals from6071households due to lost to follow-up and not willing to answer, etc. Because PMT, willingness and behavior research target at individual level, to increase the samples'representativeness, the research adopted a combination of PPS and cluster sampling based on the relationship of sample size and the actual number of households. Considering cost and dialects, our interviewers mainly come from local medical colleges. Using Data Easy, we input data twice double-blindly to guarantee accuracy. After data cleaning, we conduct statistical description and analysis by SPSS16.0and STATA10.0.As the HB willingness and behavior is a continuous process by the trans-theoretical model, we first set general population for vaccination behavior analysis and unvaccinated population for willingness analysis. Then took changes in our HB vaccination policy and the implementation of Supplementary Immunization Activities (SIAs) under the15years old, we subdivided general population sample and our target populations as following:(1) Behavior group under15year old for timely first dose of HB vaccination research, because the population enjoys full coverage and vaccination rate is relatively-high, while for newborn, timely first dose plays a more important part in cutting off maternal-neonatal transmission, which is the key point of our immunization policy;(2) Behavior group above15year old:whether they got vaccinated or not;(3) Vaccination willingness group above15years old:Whether they have plans for HB vaccination, because there is no preferential policy for the15years old due to limited resource. On the basis of control variables, the study explored how the knowledge of HB and vaccine affect individual vaccination willingness and behavior and work out more targeted interventions to make resident realize importance of HB and HB vaccination, overcome difficulties to get vaccinated, so as to improve adult's HB vaccination rate in China and reduce horizontal transmission.Based on PMT, PMT factors (perceived-severity factor, perceived-vulnerability factor, response-efficacy factor and self-efficacy factor) were produced by decomposing PMT variables into individuals'cognition on HB and HB vaccine, which developed the measurement tool for individuals'cognition; meanwhile, with the application of TTM theory, HB vaccination willingness and behavior were considered as an integrated and continuous process, on which based the quantitative effect of PMT factors on HB vaccination willingness and behavior were evaluated.In empirical study, based on PMT, the study applied Likert Scale and social evaluation method to measure all the variables related to HB and HB vaccine. The key variables, PMT factors were produced by Exploratory Factor Analysis, Reliability Analysis and Validity Analysis. Indicators about HB vaccination willingness and behavior were conducted as dependent variables. Controlled variables suitable for each stratified sample were generated by reviewing the previous studies. According to the dependent variables, the study used Unconditional Binary Logistic Regression to analysis the effect and its value of PMT factors.Main ResultsIn our research of HB vaccination willingness and vaccination behavior, the introduction of PMT factors can improve the goodness of fit of logistic regression model, and the PMT factors were statistically significant. Therefore, these factors have influences on HB vaccination willingness and behavior of each stratified target people.(1) The influencing factors of HB vaccination willingness and effect of PMT factorsThere are some controlled variables and PMT factors significantly influencing the HB vaccination willingness in adults aged15and above. Among the controlled variables: age, marital status, place of birth, level of education, occupation, income level, convenience of the health service and region were the determinate factors; among the PMT factors, perceived-vulnerability factor had statistical significance. When other variables are controlled, with a one unit increase of perceived-vulnerability factor, people aged15and above were1.149times more likely to take the HB vaccine than those who would not. The stronger self-feel of suffering HB, the higher probability to take HB vaccine in the future.(2) The influencing factors of HB vaccination behavior and effect of PMT factorsThere were some controlled variables and PMT factors significantly influencing timely immunization of the first dose in target people below15. Among controlled variables:age, place of birth, whether parents engaged in medical industry, income level and region are the significant factors; among PMT factors, perceived-severity factor and perceived-vulnerability factor were statistically significant. When other variables remain constant, one unit increase in perceived-severity and perceived--vulnerability factor would raise the probability of timely taking the first dose of HB vaccine among people below15by0.127and0.145times respectively. That is to say, the guardians'cognition level on the probability and severity of children below15suffering the HB was a positive factor to timely immunization of the first dose.There are also some controlled variables and PMT factors significantly influencing HB vaccine behavior in targeted people aged15and above. Among the controlled variables:age, marital status, level of education, occupation, going out status, income level, convenience of the health service and region were the significant factors; among PMT factors, perceived-vulnerability factor and self-efficacy factor were statistically significant. When other variables remain constant, one unit increase in perceived-vulnerability factor leaded to1.506times more likely to take the HB vaccine among people aged15and above is which means the stronger feeling of risk of hepatitis, the higher probability to take HB vaccine in the future. Besides, when other variables remained constant, people aged15and above were1.247times more likely to take the HB vaccine with self-efficacy factors increasing by one unit. The stronger feeling of suffering the HB and confidence to complete the injection, the higher probability to take HB vaccine in the future.Conclusions and policy implicationsThere are different factors affecting injection behavior and willingness of HB vaccination, and PMT factors had affections both on the HB vaccination willingness and behavior. Therefore, the cognition of all population groups about HB and HB vaccination should be enhanced specifically for:(1) To the target people aged15and above who haven't taken HB vaccine before and will not take it in the future, the key to taking HB vaccine is the improvement of the knowledge about the vulnerability of HB, such as the route of transmission, epidemic situation and trends of HB;(2) In order to enhance the behavior of timely immunization of the first dose in targeting people below15, the first strategy is to improve the cognition of their guardian about the vulnerability of HB, and make them know the role of timely immunization of the first dose in cutting off HB virus transmission and reducing population susceptibility; Secondly, the cognition of their guardian about the knowledge of HB and HB vaccination should be improved, especially the serious consequences of infants who were infected with the HB virus.(3) In order to improve the vaccination rates of HB vaccine in targeting people15and above, the key point should be placed on the enhance of the knowledge of injection sites, injection time and injection pattern while improve the cognition about the vulnerability of HB, providing enough messages, conveniences of injection sites and injection time to the targeting people for the injection. Meanwhile, make good use of preferential policies of the New Rural Cooperative Medical System to people who take HB vaccine, and make them know the injection of HB vaccine is no longer a costly, time consuming, labor-intensive issue.The following policy suggestions were proposed:(1) Spread the knowledge on transmission routes, trends and development of HB through education, and expand on the information dissemination of effects on HB vaccine, injection sites, injection time and injection pattern, contents should be suitable to groups of people targeted on the basis of PMT, the form should be diversified;(2) The injection sites, time and pattern should be set conveniently and reasonably;(3) Focus on priority and vulnerable groups, increase government funding, integrate injection strategy into the insurance scheme, such as new rural cooperative medical care system and so on, to attract the population who are15and above to take HB vaccination initiatively.
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