https://orcid.org/0000-0002-4045-1709
ABSTRACT
The rise in pertussis incidence among infants in Guizhou, China underscores the need for maternal acellular pertussis vaccine (aP) immunization, a key strategy in protecting infants from severe health consequences. However, the willingness of pregnant women in Guizhou to receive this vaccine is not well-understood. This study aimed to explore pregnant women’s intentions toward maternal pertussis vaccination in Guizhou and identify the associated factors. A questionnaire based on the health belief model, was administered in an exploratory cross-sectional study from January to February 2022. Data from 564 participants were collected and analyzed. The chi-square test, Mann-Whitney U test, and Poisson regression were used to identify potential factors associated with vaccination intentions. Participants’ median age was 27 y (interquartile range (IQR): 24–31), and the median number of children per participant was one. The study found that only 36.0% of the participants intended to receive the aP vaccine while 64.0% were uncertain or negative in this regard. Significant factors associated with intentions to vaccinate included perceived barriers and cues for action and perceived benefits. The major barriers for low vaccination intentions were safety concerns for both the fetus and the mother, and family members’ negative attitudes. Free vaccines, perceiving preventive benefits, observing other pregnant women getting vaccinated, and healthcare provider recommendations may facilitate vaccination intentions. Multiple immune strategies should be developed or optimized to cope with the resurgence of pertussis.
Introduction
Pertussis, also known as whooping cough, remains a significant cause of morbidity and mortality among infants worldwide. Despite being preventable with vaccination, pertussis continues to pose a public health challenge.Citation1 Children in mainland China are provided with diphtheria-tetanus-acellular pertussis (DTaP) vaccines as part of the nation’s publicly funded National Immunization Program. The vaccinations are administered according to the recommended schedule at 3, 4, 5, and 18 months of ages.Citation2 In recent years, the incidence of national pertussis has surged rapidly despite high DTaP vaccine coverage rates.Citation3–5 The number of reported cases in mainland China reached over 30,000 in 2019, paralleling levels last observed in the late 1980s.Citation6 These cases are predominantly observed in infants and young children.Citation2
In Guizhou Province, China, the epidemiological profile of pertussis mirrors the national trend.Citation7 Despite local DTaP vaccination coverage rates exceeding 95%, the province has witnessed an alarming increase in the incidence of pertussis since 2014, with the rate among infants soaring to 91.20 per 100,000 in 2017–2019.Citation8 A notable proportion of these infants required hospitalization due to complications, and over 70% were younger than six months.Citation7,Citation9
To protect infants who are too young to be vaccinated, immunizing pregnant women against pertussis has been shown to be a safe and effective strategy.Citation10–12 Maternal vaccination with acellular pertussis-containing vaccines (aP) has been adopted in numerous countries for several years.Citation12–16 It is recommended that aP be administered during each pregnancy, as it has been found to prevent more cases of infant pertussis as well as related hospitalizations and deaths than either postpartum vaccination or cocooning strategies.Citation17,Citation18 However, the aP coverage rates among pregnant women vary across countries, cultures, ethnic groups, educational levels, and contexts.Citation14,Citation19–22 Additionally, disseminating appropriate data for vaccine recommendations, ensuring stakeholder endorsement, achieving in-country distribution and administration, adequate vaccine supply, a well-organized healthcare system, and ideally offering immunization free of charge influence vaccination coverage.Citation23
In mainland China, experience with maternal vaccination is limited, with only few reports concerning the willingness and attitude of pregnant women toward influenza A vaccination during the 2009–2010 H1N1 influenza pandemic.Citation24,Citation25 To date, maternal vaccination with influenza vaccines, aP, or other vaccines has not been integrated into healthcare practices in mainland China. Furthermore, aP vaccines are currently unavailable in the markets of mainland China.Citation26 Data on the willingness of pregnant women in mainland China to receive maternal aP vaccination and factors influencing their decision-making are scarce. Given the necessity of preventing pertussis, particularly in infants, it is imperative to adopt of a strategy for maternal vaccination against pertussis. As the intentions of pregnant women regarding maternal pertussis vaccination are not well understood, it is essential to assess the feasibility and acceptability of antenatal pertussis vaccination prior to the potential implementation of a national program.
The health belief model (HBM) is often utilized to elucidate a variety of health behaviors, and has demonstrated efficacy in explaining and predicting the intention to accept or the actual uptake of pertussis vaccination during pregnancy.Citation27–29 The HBM encompasses several dimensions: perceived susceptibility, perceived severity, perceived benefits, perceived barriers, and cues for action. The application of the HBM constructs varies across vaccines, programs, population groups, and subgroups.
This study aimed to investigate pregnant women’s intentions toward maternal pertussis vaccination, and examine the factors associated with aP intentions based on the HBM framework. We intend to provide a foundation for policymaking aimed at preventing pertussis in infants and to identify strategies to enhance future vaccination coverage. Our hypothesis posited that the factors associated with willingness to obtain maternal pertussis vaccination could be attributed to the dimensions of the HBM framework.
Materials and methods
Study design and participants
To examine the factors associated with maternal vaccination intentions against pertussis among pregnant women, a cross-sectional survey was conducted from January 20 to February 9, 2022, in Guizhou Province, China. This survey was integrated with a study assessing the knowledge and willingness to vaccinate.Citation30 From a list of 484 registered facilities including general hospitals, maternal and child healthcare hospitals, and hospitals practicing traditional Chinese medicine, 15 hospitals were randomly selected for participation. Among them, 11 provided obstetrics and antenatal examination services. Geographically, these 11 hospitals were situated across nine counties in Guizhou province-five were state-owned while six were private. At the medical institution level, one was a tertiary institution, five were secondary hospitals, and the remaining five were primary hospitals or below.
The study population comprised pregnant women attending gynecology and obstetrics clinics at the selected hospitals, who were surveyed after obtaining their informed consent. Additionally, the questionnaire was distributed through the hospitals’ digital contact groups for pregnant women. The inclusion criteria were currently pregnant, first-time participation in the study, and provision of informed consent. Records containing blatant errors in information were excluded from the analysis.Citation30
Ethical approval
This study adhered to the principles of the Declaration of Helsinki and was approved by the Ethics Committee of the Guizhou Provincial Center for Disease Control and Prevention (IRB No. S2020–06; approval granted on October 25, 2021). Informed consent was obtained from all the participants.
Study tools
The study questionnaire (Supplementary File 1) was developed based on the HBM framework and refined following a pilot survey. The items addressing pregnant women’s maternal aP vaccination intentions offered three response options: Disagree, Unsure, and Agree. To create a simple and suitable scale, item choices were determined through an exploratory factor analysis (EFA). Principal component analysis followed by rotation varimax was employed to retain the factors and maximize their interpretation of included factors. The eigenvalue (>1), scree plot, and interpretability determined the number of retained factors, which resulted in a three-dimensional 12-item scale.
The questionnaire included the following aspects: participants’ willingness to receive maternal vaccines and constructs based on the HBM framework encompassing three dimensions: perceived susceptibility and severity (four items), perceived barriers (three items), and cues for action and perceived benefits (five items). A 5-point Likert scale was employed for item responses, with options ranging from “Strongly Disagree” (one point) to “Strongly Agree” (five points). All responses, including those related to perceived barriers, were phrased positively to reflect more supportive attitudes toward receiving the maternal aP vaccine. Finally, the questionnaire collected demographic and health-related information about the participants such as birth date, gestational age, number of children apart from the present pregnancy, educational level, occupation, city/county of residence, type of household registration, ethnicity, preexisting and pregnancy-induced illnesses, and monthly per capita household income.
Data analysis
We conducted an EFA of the questionnaire items based on the HBM framework, and validity and reliability assessments using SPSS software. Each individual’s response to each HBM item was scored on a 5-point Likert scale (1–5 scores). The sum of items’ scores generated the scores for each dimension. Categorical and ordinal variables were presented as numbers (%), whereas quantitative variables were summarized using the mean (SD) or median (IQR). To investigate the potential factors associated with maternal vaccination against pertussis, a chi-square test was used to examine the relationship between vaccination intentions and sociodemographic characteristics. The Mann-Whitney U test was used to compare the distribution of individual items and dimensions across groups with different vaccination intentions. The mean and variance of vaccination intention (Disagree/Unsure = 0; Agree = 1) were calculated. We chose the Poisson regression rather than the negative binomial regression in the multivariate analysis for variances lower than the mean. A Vuong test with zero-inflated Poisson regression was also used. The results of the Vuong test indicate that the zero-inflation Poisson regression is not superior to the standard Poisson regression. Hence, standard Poisson (log-link) regression with robust variance and incidence rate ratios was applied to examine the associated factors in the multivariable analysis. Variables with a P-value <.1 in univariate analyses were included in a multivariable Poisson regression model to calculate the prevalence ratio (PR). Four models were developed: Model 1 comprised three dimensions of perceived susceptibility and severity, perceived barriers, and cues for action and perceived benefits; Model 2 was additionally adjusted for age and educational level; Model 3 continued to add adjustments for occupation, monthly per capita household income, registered residence, and type of residence; and Model 4 was additionally adjusted for preexisting disease. A sensitivity analysis was conducted among participants working in medical and non-medical institutions. Data were analyzed using the SPSS software (version 22.0; IBM Corp., Armonk, NY, USA) and STATA version 12.0 software (StataCorp LLC, TX, USA). Statistical significance was defined as a two-tailed P-value <.05.
Results
A total of 762 questionnaire responses were collected, but 198 were discarded for various reasons such as not providing informed consent (134), failure to meet the inclusion criteria of current pregnancy (14), and logically inconsistent responses (50: 26 for incorrect response to screening questions, 11 for conflicting responses on multiple-choice questions, and 13 for entering inappropriate birthdates). Consequently, the analysis included 564 eligible questionnaires.Citation29 Among this pool, 203 (36.0%, 95% CI: 32.09–39.89) pregnant women expressed positive intentions toward receiving the maternal aP vaccine, while 361 (64.0%, 95% CI: 60.10–67.91) disagreed or were unsure about the vaccination.
Exploratory factor analysis (EFA) of the questionnaire items based on the HBM framework
A 12-item scale was deemed adequate because of its alignment with the model’s constructs. The Kaiser-Meyer-Olkin (KMO) value was 0.851, and Bartlett’s test of sphericity was significant (chi-square value = 4960.297, p < .001), indicating that the constructs were valid and suitable for principal component analysis. The overall internal consistency, as measured by the Cronbach’s alpha coefficient, was high (0.906). The distribution of the eigenvalues of the scale is depicted in a scree plot. Three factors had eigenvalues above one and were named Factor 1 (cues for action and perceived benefits, eigenvalue = 5.918), Factor 2 (perceived barriers, eigenvalue = 1.700), and Factor 3 (perceived susceptibility and severity, eigenvalue = 1.414). These three factors accounted for 75.3% of the accumulated variance. The scree plot and the results of the factor analysis are provided in Supplementary File 2.
Sociodemographic characteristics of respondents
The median age of the participants was 27 y (IQR 24–31), and the median number of children per participant was one (IQR 0–1), excluding the current pregnancy. The distribution of educational attainment was as follows: middle school or below (205 participants, 36.3%), high school/technical school (205 participants, 36.3%), and a bachelor’s degree or higher (154 participants, 27.3%). Residential types were categorized as cities (251 participants, 44.5%), towns (136 participants, 24.1%), and villages (177 participants, 31.4%). Most participants, 471 (83.5%), were employed in non-medical institutions, while 93 (16.5%) worked in medical institutions. Preexisting medical conditions were reported by 36 participants (6.4%), and 57 participants (10.1%) were diagnosed with pregnancy-induced illnesses. The average gestational age of the pregnant women at the time of the survey was 29 weeks (IQR 18–36). None of the respondents had received maternal vaccines during the course of their current pregnancy.
Univariate analysis between vaccination intentions and sociodemographic characteristics
Among sociodemographic characteristics, the variables with P-value <.05 included the pregnant women’s age, educational level, occupation, type of residence, registered residence, and monthly per capita household income. Participants over 30 y of age had significantly higher intention to receive maternal aP vaccines than their younger counterparts (χ2 = 6.130, p = .047); those with bachelor’s degree and above had significantly higher intention to receive maternal aP vaccines compared to those with lower educational levels (χ2 = 10.796, p = .005); those working in medical institutions showed higher intention for maternal aP vaccines than those working in non-medical institutions (50.5% vs. 33.1%, χ2 = 10.226, p = .001); and those residing in cities showed higher intentions for aP vaccinations than those living in towns and villages (χ2 = 7.834, p = .020). Moreover, participants with urban registered residence had a higher intention to vaccinate compared to those with agriculture registered residence (45.6% vs 32.2%, χ2 = 8.995, p = .003). Finally, participants with monthly per capita household income of 714 USD and above had higher aP vaccination intention compared to lower income groups (χ2 = 6.512, p = .039) ().
Table 1. Sociodemographic characteristics and maternal aP vaccination willingness among pregnant women in Guizhou Province, 2022.
Comparison of HBM items’ scores
In the cohort of pregnant women, 10 out of 12 HBM elements exhibited significantly lower response scores among those expressing “No” or “Unsure” intentions toward accepting maternal aP vaccines compared to those with “Yes” intentions (items 1 through 8, and 11: p < .001; item 9 and 10: p > .05; item 12: p = .001) ().
Table 2. Comparison of HBM items’ scores in maternal aP vaccination intentions among pregnant women, Guizhou Province, 2022.
Comparison of HBM dimension scores
At the HBM dimension level, we compared the scores across the three principal component categories. The scores within the three dimensions associated with “No and Unsure” intentions toward maternal pertussis vaccination were significantly lower than those linked to “Yes” intentions ().
Table 3. Comparison of HBM dimension scores for maternal aP vaccination intentions among pregnant women, Guizhou Province, 2022.
Multivariable analysis
In the univariate analyses examining variables with p < .1, such as cues for action and perceived benefits, perceived barriers, perceived susceptibility and severity, age, occupation, educational level, preexisting disease, type of residence, registered residence, and monthly per capita income, we assessed the correlations among these factors. The highest absolute value of the correlation coefficient was 0.547, indicating that the aforementioned variables demonstrated low-to-moderate correlations and did not exhibit multicollinearity.
We developed four models using Poisson regression analysis to identify the factors associated with maternal intentions to receive the aP vaccine. Our results indicated that perceived barriers (PR = 1.08, 95% CI: 1.04–1.12, p < .01) and cues for action and perceived benefits (PR = 1.06, 95% CI: 1.03–1.10, p < .01) were significantly associated with vaccination intentions. In contrast, perceived susceptibility and severity, and sociodemographic factors did not show significant associations ().
Table 4. Poisson regression analysis of associated factors of maternal pertussis vaccination willingness among pregnant women in Guizhou Province, 2022.
Sensitivity analysis revealed that for respondents working in non-medical institutions, perceived barriers (PR = 1.06, 95% CI: 1.03–1.10, p < .01) and cues for action and perceived benefits (PR = 1.06, 95% CI: 1.03–1.10, p < .01) were significantly associated with vaccination intentions. In contrast, for respondents working in medical institutions, only perceived barriers (PR = 1.11, 95% CI: 1.02–1.20, p = .011) showed significant association (Supplementary File 2).
Discussion
The study revealed that the intention to receive maternal vaccination against pertussis among pregnant women is alarmingly low in Guizhou province, at 36%. Employing the HBM framework, we identified factors associated with maternal vaccination willingness against pertussis to include perceived barriers and cues for action and perceived benefits, which appeared to play critical roles in shaping the intentions of pregnant women to receive the pertussis vaccine.
The willingness to receive maternal aP vaccination in Guizhou Province aligns closely with the acceptance rate (36.5%) of tetanus toxoid and reduced-dose diphtheria (TdaP) vaccines among pregnant Italian women during 2021–2022Citation31 and the surveyed TdaP vaccination rate (36%) of pregnant women in Uruguay in 2017.Citation32 However, this was significantly lower than the rates reported in Mexico City in 2012 (57%), and that in Karachi 2013 (83%).Citation33,Citation34 Since the introduction of the aP vaccine recommendations for pregnant women, coverage rates have been reported as suboptimal in many countries, such as the Germany, the United States, and the United Kingdom.Citation35,Citation36 A previous study in Australia reported that pertussis vaccine uptake was independently associated with living areas and migration background.Citation37 However, in our study, sociodemographic characteristics, including geographic location, residence, and registered residence showed no independent associations with aP vaccination willingness. In this study, the medical institution staff showed higher aP vaccination willingness than the non-medical institution staff (50.5% vs. 33.1%); this was much higher than that of a survey in which only 13% of the healthcare workers intended to receive the pertussis vaccine.Citation38
Maternal vaccination is an essential component of strategies aimed at protecting mothers and newborns from potentially severe infections.Citation39 However, there are several challenges and barriers to this. Interventions often address patient-, provider-, and policy-level strategies to increase vaccination during pregnancy.Citation40 In this study, we mainly explored the factors associated with maternal aP vaccination from the patients’ perspectives. Pregnant women identified several barriers to accepting the recommended maternal immunization, most common being vaccine safety perceptions.Citation40 Our study corroborates these findings by identifying perceived barriers as the most influential element related to the willingness of pregnant women in Guizhou to receive the maternal aP vaccine. The primary concerns centered on vaccine safety for their unborn children and themselves, along with the attitudes of their families. Vaccine safety concerns for self as well as the unborn child were pivotal in their decision-making process regarding vaccination. Surprisingly, this was also the most concerning factor even for pregnant women working in medical institutions. Pregnant women are often concerned about unsafe injection of vaccines or foreign substances into their bodies during their pregnancies, and this historical fact is applicable worldwide.Citation21 Therefore, healthcare providers and pregnant women need to be educated regarding vaccine safety to improve maternal vaccination rates.Citation41
Another independent factor associated with the willingness to vaccinate was the presence of cues for action and perceived benefits. Factors such as the provision of a free vaccine, the perceived preventive benefits of vaccines against pertussis, the vaccination behaviors of other pregnant women, and healthcare practitioners’ recommendations were significantly associated with willingness to vaccinate and could potentially serve as facilitators to improve coverage.Citation42,Citation43 Vaccine costs are one of the primary barriers to immunizations.Citation44 The provision of a free vaccine is usually an effective measure to enhance vaccination uptake.Citation45,Citation46 Furthermore, recommendations from healthcare professionals, along with more perceived benefits of pertussis vaccination, could increase willingness for maternal aP vaccination. Healthcare provider’s recommendation was the most frequently reported reason for vaccination among pregnant women.Citation40 In contrast, a lack of immunization advice from healthcare providers and safety concerns were the main barriers to maternal vaccination.Citation42 More studies on vaccination recommendation frames, contents, and methods should be conducted to increase vaccine confidence and achieve expected vaccination rates.Citation47,Citation48 Additionally, people’s trust in medical information from their peers influences their decision to be vaccinated.Citation49 This corresponds with our results, which showed that the vaccination behaviors of other pregnant women were positively associated with aP vaccination intentions.
In light of these factors associated with aP vaccination willingness, we recommend that aP vaccines should be provided free of charge to pregnant women to achieve higher coverage, and the safety and effectiveness of maternal vaccination needs to be communicated effectively and understood by healthcare practitioners, pregnant women, and their families.Citation50–52 To date, few studies have explored maternal aP vaccination intentions in Mainland China. This study offers valuable data for mainland China to inform pertussis prevention policies and suggests that methodologies that could enhance maternal vaccination coverage rates should be implemented in the future. Furthermore, this study demonstrates that a research tool based on the HBM framework can effectively identify barriers to and facilitators of maternal aP vaccination willingness; future research tools for assessing maternal vaccination willingness should incorporate multiple theories and considerations to create a more comprehensive approach.Citation53–56
Vaccine hesitancy is a multifactorial issue. In our research, the associated factors based on the HBM framework of aP vaccination willingness among pregnant women were significant, but with a small effect. A meta-analysis showed that interventions for pertussis vaccination among pregnant women were ineffective.Citation46 This finding differs from the findings of our study. These differences may be attributed to diversity in countries, cultures, populations, scientific beliefs, and contexts. Moreover, the consistency and gap between the willingness to vaccinate and actual vaccination should be considered.Citation49 To tackle pertussis emergencies in infants, multiple immune strategies should be developed and optimized, including maternal aP vaccination, shifting the initial aP vaccination age from three months to six weeks, and expanding aP vaccination coverage.Citation1,Citation16
Limitations
This study has some limitations that must be considered. First, the questionnaire was self-developed and not based on a validated scale. Second, the study assumed that the aP vaccine was available to pregnant women and that actual availability may influence respondents’ choices in practice. Third, the small sample size may have led to a selection bias. Fourth, because the questionnaire was self-administered, reporting bias must also be considered. In future, studies should use larger sample sizes from diverse background and cultures to further corroborate our findings and present comparative analyses.
Conclusion
Our study findings revealed that in Guizhou Province, China, the percentage of pregnant women who indicated an intention to receive the maternal aP vaccine was rather low at 36%. The perceived barriers and cues for action and perceived benefits were found to be the most significantly correlated dimensions as per the health belief model. The foremost barrier identified was concerns regarding the vaccine’s safety for both the fetuses and the mothers-to-be, compounded by the attitudes of family members. Offering the vaccination free of charge, perceiving vaccine’s preventive benefits against pertussis, observing the vaccination behavior of other pregnant women, and recommendations from healthcare practitioners could potentially enhance their intentions to vaccinate. Multiple immune strategies should be developed or optimized to cope with the resurgence of pertussis. Further research is required to verify, augment, supplement, and refine these findings concerning maternal aP vaccination intentions.
Authors contributions
F.J., Y.W., and J.F. conceived and designed the survey; F.J., N.T., and Y.G. conducted the survey; F.J. analyzed the data and drafted the manuscript; F.J. and M.B. revised the manuscript; F.J. and X.Y. approved the final version of the manuscript. All authors agree to be accountable for all aspects of this study.
Acknowledgments
We extend our gratitude to all participants and medical professionals who contributed to this study by participating in the survey. We also thank our family members and colleagues for their unwavering support throughout this study.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Supplementary material
Supplemental data for this article can be accessed on the publisher’s website at https://doi.org/10.1080/21645515.2024.2331870.
Additional information
Funding
References
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