ABSTRACT
Background: The intention of Chinese people older than age 5 to accept the pertussis vaccination is unknown, which is important for the future design of an effective pertussis vaccination program in China.
Method: We conducted a cross-sectional survey among people older than age 5 in China. A 24-item questionnaire was used to explore the determinants of intention to accept a pertussis vaccination, and for children and adolescents (≦15 years old), their guardian was required to help answer the questionnaire on their behalf. Univariate and multivariate logistic regression was used to analyze the influencing factors of intention.
Results: A total of 3,041 individuals participated in our survey and 3025 completed the questionnaire, among which 1938 (64.07%) reported a positive intention to be vaccinated. A multiple logistic regression analysis revealed that the main positive factors for the intention to accept pertussis vaccination were younger age (Odd ratio [OR] 0.838, P < .001), higher educational attainment (OR 1.171, P = .002), no hospitalization because of the most recent cough (OR 2.468, P < .001), awareness about pertussis (OR 1.958, P < .001), and consideration of pertussis vaccination to be safe (OR 1.450, P = .026).
Conclusion: There is a relatively high level of intention to receive the pertussis vaccine among people older than age 5 in China. Future pertussis vaccination strategies geared at them should consider focusing on middle-aged and older individuals and those with a low education as well as strengthen the promotion of disease characteristics, vaccine effectiveness, and safety.
Introduction
Pertussis is one of the most common respiratory infectious diseases that seriously affects the health of children around the world. As a result of the successful implementation of an immunization program, transmission of pertussis used to be effectively controlled.Citation1 In fact, the incidence of pertussis reached its lowest level in the 1980s, but this soon changed and many researchers began to report a rise in the incidence of pertussis, aptly named the “re-emergence of pertussis”.Citation2 In China, after the implementation of planned immunization in 1978, the incidence of pertussis dropped from 100 per 100,000–200 per 100,000 to less than 1 per 100,000 in 1990s.Citation3 However, the incidence of pertussis has been rising in the recent years, despite the high coverage range of pertussis containing vaccine for several decades. In 2019, more than 30,000 cases (2.15 cases per 100,000 residents) were reported in China, a 1,800% increase compared with 2009.Citation4,Citation5
Meanwhile, the reemergence of pertussis had also created a new challenge, as the age distribution of pertussis cases significantly changed.Citation6 In the past, pertussis was generally considered to be a disease most commonly found in infants and young children.Citation7 However, in recent years, there has been a sharp increase in the number of adolescent and adult pertussis cases, representing an important factor in the global reemergence of pertussis.Citation8Similar to some Western countries, pertussis infections are considerably common in adolescents and adults in China by serological studies,Citation9which brings greater challenges to the current prevention and control efforts.Citation10
It became clear that vaccination focused on young children would not be enough to control the epidemic situation, given the incidence of pertussis among adolescents and adults; this strategy would not block the spread of pertussis.Citation11 Furthermore, the protection provided by the diphtheria, tetanus, pertussis vaccine (DTaP) decreases over time, as children grow up. This suggests that the immunization strategy for teenagers may need to be adjusted in order to reduce the infection and transmission of pertussis.Citation12 In addition to vaccinating infants and young children with DTaP, a booster dose for adolescents with the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine has been recommended by the Advisory Committee on Immunization Practice (ACIP) since 2005.Citation13 The World Health Organization position paper also recommends booster doses against pertussis for adolescents and/or adults based on the local epidemiology and the epidemiological situation in China fits with the WHO recommendation well.Citation6
DTaP was now administered in the third, fourth, and fifth months of infancy, and a booster dose was given between 18 and 24 months in China.Citation14 It is under consideration that the booster pertussis vaccination for people older than 6 years in China.Citation15 In order to better implement this strategy, we need to fully understand the operability and feasibility. However, the intention of people than 5 years to receive the vaccine against pertussis is unknown. This information may help with the future design of an effective vaccination program for people than 5 years in China. Therefore, the purpose of this study was to address their intention to accept pertussis vaccination and the corresponding determinants based on a community population survey.
Methods
Study design and population
We performed a cross-sectional survey in Yiwu – a county-level city of about 2,000,000 people – situated in the central Zhejiang Province of China. The survey was targeted toward participants over the age of 5 during the months of October to December 2019.
Probability proportionate to size sampling (PPS) was used to adopt 50 investigation points with at least 58 people at each point. The investigators went to the survey points, using the quota sampling method based on age and sex to select a fixed number of people from each survey point for the questionnaire survey.
The survey was conducted by face-to-face interviews. Well-trained centers for disease control and prevention (CDC) staff collected data into the panel computer after obtaining written informed consent from each respondent under household and interception survey. In China, it is usually parents/carers of children and adolescents (≦15 years old) to decide whether to receive a pertussis vaccine. So for these children, an agent (their guardian) was required to help answer the questionnaire on their behalf.
Any impermanent residents who lived in Yiwu for less than 6 months were excluded. If there were two or more eligible people from one family, only one was randomly selected to participate in the survey.
Study questionnaire
We used a 24-item questionnaire to explore the determinants of intention to accept pertussis vaccination of the participants. The questionnaire was further revised after discussion and revision by the project team experts and on-site pre-investigation before it was officially used to achieve our expected purpose. In the design, logical verification was carried out to avoid wrong filling and missing filling. The questionnaire consists of four parts. The first part included the basic information of participants, including age, gender, ethnic group, occupation, educational attainment, family size, and annual family income. The second part included the participants’ smoking and chronic disease history as well as if they had experienced a prolonged cough within the last month, whether they went to a doctor because of the most recent cough, and whether they had been hospitalized because of it, the participants’ immunization record. The third part consisted of the main body of the questionnaire, including knowledge of pertussis and DTaP, intention to receive the DTaP vaccine, and the factors that may influence their intention.
Data collection
We used a panel computer for our data collection in the field survey. No items were missing in the completed electronic questionnaires since this was required for completion. Incomplete paper questionnaires were excluded from the analysis.
Data analysis
Statistical software was used to clean up the data and eliminate unqualified questionnaires, so as to ensure the authenticity and objectivity of the survey data. After checking the data, IBM SPSS 20.0 software was used for statistical analysis, and the test level was α = 0.05. Comparison of counting data between groups was conducted using a chi-square test. Univariate and multivariate logistic regressions were used to analyze the influencing factors of intention.
Ethical review
The design and procedure of this study were approved by the ethics committee of Zhejiang provincial center for disease control and prevention. Written informed consent was obtained from the legal guardians of the children or from the participant before enrollment.
Results
Population
A total of 3,041 respondents participated in the interviews. A total of 16 respondents were excluded from the analysis as they did not complete the survey.
Of 3,025 respondents, 49.26% were male and 50.74% were female. The average age of the respondents was 38.2 years with the youngest being 5 years old and the eldest being 90 years old. presents the socio-demographic characteristics of the participants. The majority (96.89%) were of the Han ethnic group. In occupation, business and service constituted the majority (28.46%). By education status, the majority (37.19%) were middle school. The average family size was four members per family. More than half of the families (55.70%) had no children under the age of five while 43.74% of the families had one or two children under the age of five. The majority (31.34%) of families had annual family income between 100,000 and 190,000 RMB.
Table 1. Descriptive characteristics of respondents by intention to accept pertussis vaccine in Yiwu
Intention
Among the 3,025 effective respondents, a total of 1,938 persons (64.07%) were willing to be vaccinated with the pertussis vaccine, 739 (24.43%) respondents were unsure about accepting a pertussis vaccine, and 348 (11.50%) would not accept pertussis vaccine. Considering the uncertainty of the willingness of the 739 respondents, only the respondents who were clearly willing (1,938) and unwilling (348) are analyzed in the analysis of the influencing factors on the willingness to be vaccinated. Therefore, the overall impact factor analysis included 2,286 persons.
Descriptive characteristics and intention
A univariate analysis showed that occupation, age, education, total persons in household, number of children under the age of 5, and annual family income showed a significant association with respondents’ intention to accept the vaccine. On the other hand, the gender and ethnic group had no significant relationship with the respondents’ intention ().
Health status, immunization history, and intention
A univariate analysis revealed that chronic disease, going to a doctor because of the most recent cough, hospitalization because of the most recent cough, and immunization history were significantly associated with intention to accept the vaccine. Whereas, smoking history, hypertension medication, cough history within one month, and how many weeks the cough lasted had no significant relationship with respondents intention to accept the vaccine ().
Table 2. Health status of respondents by intention to accept pertussis vaccine
Knowledge about pertussis and intention
The univariate analysis showed that respondents who reported that they know of pertussis, think pertussis can lead to hospitalization, pertussis may cause death, heard of pertussis vaccine, and consider the adult pertussis vaccine safe had a significantly higher intention to accept the vaccine. There was no significant relationship between respondents with a pertussis vaccine history who think they may suffer pertussis again and their intention to accept the vaccine ().
Table 3. Pertussis knowledge of respondents by intention to accept pertussis vaccine
Determinants of intention
The multiple logistic regression analysis showed that the main positive factors for the intention to accept pertussis vaccination were younger age (OR = 0.838, 95 CI%: 0.796–0.883), higher educational attainment (OR = 1.171, 95 CI%: 1.060–1.294), no hospitalization because of the most recent cough (OR = 2.468, 95 CI%: 1.875–3.249), heard of pertussis (OR = 1.958, 95 CI%: 1.468–2.611), consider pertussis vaccine safe (OR = 1.450, 95 CI%: 1.046–2.009; ). Hospitalization because of the most recent cough (OR = 1.504, 95 CI%: 0.593–3.820), consider pertussis vaccine unsafe (OR = 0.670, 95 CI%: 0.440–1.022) or not sure about the safety of vaccine (OR = 1.022, 95 CI%: 0.223–4.679) showed no significant relationship with vaccine acceptance.
Table 4. Factors in relation to pertussis vaccine acceptance
Discussion
The intention to vaccinate against pertussis is related to future formulation and implementation of an effective booster vaccination program for people older than age 5 in China.Citation16 To the best of our knowledge, this is the first survey about people’s intention to accept a pertussis vaccination in China. A total of 3,025 respondents over than the age of 5 from October to December, 2019, were included. Our study was conducted using a high-quality face to face survey with a questionnaire validity rate of 99.47%. Furthermore, we used community population-based PPS sampling, which is very representative of the population.
Our survey indicated that the intention rate for pertussis vaccination among people older than age 5 in Yiwu was 64.07% (1938/3025). This finding is in agreement with a study by Sushena et al.Citation17 who found a 63% rate of intention for pertussis vaccination among women attending antenatal care.Citation17 In previous studies in China, adults’ intention to accept Hepatitis E vaccine was 54.93%Citation18 and medical staffs’ intention to accept vaccine was 63.67%.Citation19 Therefore, the willingness rate we surveyed is relatively high. However, the intention rate we observed is lower than that in a study conducted among Dutch parents (78%)Citation20 and a study conducted among medical students in Germany and Hungary (86.2% & 69.8%).Citation21 Because these countries had already implemented pertussis vaccination for adolescents and adults for many years,Citation22 the recognition rate or willingness to receive the vaccine is relatively high. Further, these studies were aimed at special groups such as parents, pregnant women or medical staff, while our research is aimed at the community population. Combined, this may explain the difference in willingness rate between studies. In particular, according to the WHO guidance for the development of evidence-based vaccination-related recommendations, social values and preferences, and acceptability are important factors that should take into consideration when making recommendations.Citation23 In our study, our findings about values and preferences of the target population could be used to inform program materials for people than 5 years and to develop communication strategies for future programs in China.Citation24
In the multivariate analysis results, we found that younger and higher educational attainment residents had a stronger willingness to receive the pertussis vaccine. Importantly, some young respondents are still at the stage of vaccination, and therefore have the opportunity to receive vaccination recommendations from doctors to improve their vaccine acceptance.Citation25 Whereas the higher education population has a high level of knowledge, and it is easy for them to acquire vaccine-related knowledge from internet, and understand relevant knowledge about vaccines against diseases which improves their vaccine acceptance.Citation26,Citation27 In addition, our survey demonstrated that those who had no hospitalization because of the most recent cough preferred to receive the pertussis vaccine. This suggests that these individuals attach great importance to their own health, and seek medical help in time when they are sick as to not allow the disease to develop to a very serious degree, thus they have a positive attitude toward the pertussis vaccination to keep themselves healthy.Citation28 Those who had heard of pertussis were more likely to accept the pertussis vaccine, which is in agreement with a study by Siddiqui et al. (2017) study.Citation29 This is likely because they understand the dangers of this disease such as that it can negatively influence work and life, cause hospitalization, or even death. Further, if they consider the pertussis vaccine safe, this changes their attitude toward the vaccine, increases their confidence in the effectiveness of the vaccine, and promotes the increase of vaccination will.Citation30,Citation31
To improve vaccination intention, knowledge related to pertussis, prevention and vaccine safety should be emphasized, establishing a media environment for the dissemination of vaccine information. It is also necessary to popularize the knowledge of preventing pertussis through various ways, provide information about the symptoms of this disease as well as how vaccines can help prevent this serious disease for people of all ages. Additionally, it will be important to promote the willingness of people older than age 5 to reduce the risk of pertussis infection.
Our research study is not without limitations. First, some respondents were too young to express their own willingness, so we had to ask their parents or grandparents to help them complete the survey, which may have impacted the results. Second, our survey was conducted in Yiwu, which boasts a developed, self-employed, and private economy with a level of economic development that is different from that of other remote regions. Therefore, our results must be interpreted with caution. Third, several significant bivariate associations between the factors and intention lost their significance when other factors were taken into account, these factors may have collinearity with some of the other factors, or possibly influence intention independently, future studies are needed in order to confirm our findings. In addition, no respondents’ refusal was captured during the conduct of the survey, that may lead to a higher response rate than other survey. Only the respondents who were clearly willing and unwilling are analyzed in the analysis of the influencing factors on the willingness to be vaccinated. We had performed a univariate analysis of the respondents who were unsure about accepting a pertussis vaccine, and the results for main research factors obtained are similar to the results in our paper.
Conclusion
The intention to receive the pertussis vaccination among people older than age 5 in Yiwu is positive. Young age, high education, cough history, understanding whooping cough disease, and thinking that the pertussis vaccine is safe are contributing factors to the intention to obtain vaccination. In the formulation and implementation of a vaccine strategy, we should consider focusing on those with a low-education, and middle-aged and older people as well as strengthen the promotion of disease characteristics, vaccine effectiveness and safety.
Abbreviations
| OR | = | odds ratio |
| CI | = | confidence interval; |
| DTaP | = | diphtheria, tetanus, pertussis vaccine |
| Tdap | = | tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis |
| PPS | = | Probability proportionate to size sampling |
| CDC | = | Center of Disease Control and Prevention |
| ACIP | = | Advisory Committee on Immunization Practices |
Disclosure of potential conflicts of interest
No potential conflicts of interest were disclosed.
Supplemental Material
Download Zip (36.8 KB)Acknowledgments
We thank all investigators in the field for their super work. We sincerely thank Dr. Jianxin Yu (Chinese Center for Disease Control and Prevention) for his critical review and help to design this study.
Supplementary material
Supplemental data for this article can be accessed on the publisher’s website.
Additional information
Funding
References
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