This study analysed the determinants of full vaccination among children in Nepal using the most recent NDHS 2022. The odds of Nepalese children being fully vaccinated concerning their geographical, sociodemographic, maternal, and child health service use, accessibility, and HMG characteristics were measured. Further, wealth-related inequality in fully vaccinated children was computed, and a decomposition analysis was performed to determine the key determinants that explain the inequality [41]. The study found that after adjusting for other variables, mothers’ ANC visits, awareness of HMG meetings in the ward, and household size were significant determinants for full vaccination among children.
The proportion of fully vaccinated children was disproportionately higher among the children belonging to wealthy households. The concentration index decomposition showed that wealth-related inequality in childhood full vaccination was primarily explained by place of delivery, maternal education, money needed to each health facility, and ANC ≥4 visits.
Our study reported the socioeconomic inequality in childhood vaccine uptake from the poorest households. This finding was consistent with previously published studies from Nepal [11, 21]. As observed in earlier analysis conducted using four rounds of the NDHS (Year 2001, 2006, 2011, 2016), the socio-economic inequality concerning full vaccination coverage between the socio-economic groups measured by relative CIX has, on average, narrowed over this period [21]. The relative CIX obtained from these four rounds of NDHS were 0.21, 0.20, 0.08, and 0.054, respectively [21]. The analysis presented in this paper using the data from NDHS 2022 has shown that the relative CIX for full vaccination has slightly increased to 0.090.
Nevertheless, the global burden of diseases caused by vaccine-preventable pathogens has declined following the introduction of basic antigens in immunization programs, leading to healthier lives for millions of children over the last two and half decades [55]. More importantly, vaccines have a pronounced impact on reducing health inequities among impoverished people, who are at greater risk of infection. A study done among 16,000 children during the phased introduction of the measles vaccine in Bangladesh in 1982 demonstrated improved health equity, as evidenced by the reduction in under-five mortality rates [56]. Hence, identifying the factors driving the inequalities is a preliminary step in designing effective policy measures to reduce observed socioeconomic inequality.
The decomposition analysis revealed that maternal health service utilization inequalities, including antenatal care and institutional delivery, largely explain inequalities in the uptake of full vaccinations. Both factors accounted for about 29% of the total inequality in full vaccination uptake. Provided that immunization services are furnished at the same health facility where maternal health care is provided, the utilization of maternal health care can serve as a proxy indicator for accessibility of health facilities offering immunization services. Hence, observed inequality could be associated with disparity in access to immunization services. On the other hand, though maternal health care services are supposed to be provided free at public health facilities in Nepal, women with low socioeconomic status experience a financial burden for maternity care, as they have to pay not only for transportation, accommodation, and food but also loss earning due to absenteeism from work [57, 58]. This could impede the use of services among socioeconomically disadvantaged populations, especially those who rely predominantly on public health facilities for their health care requirement. Our findings also align with other studies, which found antenatal check-ups a significant factor contributing to the inequality in childhood full vaccination [17, 49, 59].
From a policy perspective, targeted efforts are necessary to enhance maternal health service utilization among the socioeconomically disadvantaged individuals in Nepal. This targeted approach is crucial for mitigating the inequality in vaccination uptake. Earlier studies, including this study, also reported a positive association of antenatal visits with childhood full vaccination in Nepal [11, 27, 60] including other countries such as Bangladesh [61], Indonesia [20], and Nigeria [62].
Likewise, acute poverty reflected through the inability of the families to visit the health facility was a significant contributor (14.25%) to inequality in childhood full vaccination in this study. This finding corroborates a previous study that analysed inequalities in complete childhood immunization in Nepal based on NDHS 2016 [60]. This is likely because the government in Nepal has been offering free vaccines since the initiation of the Expanded Programme on Immunisation in 1979 [8]. Though vaccines are accessible through immunization clinics throughout Nepal, acute poverty restricts some women's ability to reach them. Mothers facing financial challenges were less likely to vaccinate their children fully. We suggest expanding the demand-side financing program for poor households to reward mothers vaccinating their children, alleviating financial obstacles to vaccination.
The maternal educational level accounted for a relatively substantial portion of the inequality in childhood full vaccination (16.79%), consistent with earlier studies [16] [49]. In addition to improving health literacy, better education for mothers can transform women into financially independent, increase self-confidence, and ultimately empower them to address their and their children’s health needs [63]. Almost one-third (33.67%) of the poorest women had no education, relative to one among eighty women(1.22%) in the richest household [28]. That’s why, besides improving women’s education equitably, the NIP can leverage and ensure the involvement of Female Community Health Volunteers (FCHVs) and other community health workers in communicating with problematic households at the community level in collaboration with local government. Previous studies in Nepal also identified maternal education as a potential determinant of full vaccination [19, 26].
It was also observed that caste/ethnicity accounts for some of the socioeconomic inequalities in the uptake of the full vaccines (3.03%). The study found that a significant portion of this contribution mainly stemmed from the Dalit caste (21.28%), as these children were disproportionately concentrated among mothers from less wealthy households [28]. Meanwhile, the relatively lower literacy rate and sociocultural practice prevalence among the Dalit could be the reason behind the lower rate of full vaccination among the children in that group, as reported in previous studies [11, 33, 60, 64]. In this regard, community engagement can also be ensured through dialogue meetings by mobilizing and influencing persons among targeted groups at the local level to address misconceptions and concerns about vaccinations.
Our decomposition analysis also identified the HMG meeting as an important contributor to the reduction in socioeconomic inequality of full vaccine (-12.95%). The likelihood of full vaccination among children was greater among the children whose mothers were aware of the HMG meeting in their respective wards. This emphasizes the importance of the HMG, community groups led by FCHVs that bring together women of reproductive age (15-49 years) monthly to discuss and promote several areas of health, particularly related to maternal, newborn, and child health [65].
This study also reported that approximately 60% of the socioeconomic inequality (excluding the wealth quintile) remained unexplained. This was inevitable as we did not consider supply-side factors, which have been explained as potential predictors in other studies for vaccination coverage, such as cold chain maintenance, availability of vaccines, and adequacy of staff in the facility [13, 14]. Furthermore, other demand-side factors might explain the socioeconomic inequality for childhood vaccination uptake that need to be assessed in future studies.
Strengths and Limitations
Apart from assessing socioeconomic inequality, this study also helped understand the underlying factors, providing policymakers with crucial information for developing strategies to address the existing inequality in routine childhood immunization programs. Rigorous statistical techniques were applied to determine the odds of full vaccination among children while controlling for potential geographic and socio-demographic factors. Moreover, this study adds to the body of literature in Nepal by introducing a composite measure of inequality using established methodologies. We also performed a decomposition analysis to identify critical determinants of wealth-related inequality in the country's childhood full vaccination uptake.
However, our study has also some limitations. First, including the vaccination status of the children from verbal reports of the mothers might have introduced differential misclassification into this study due to the potential under-reporting of children who were not fully vaccinated. This is because mothers can provide false reports about the immunization status of their children in the absence of health cards to appear socially acceptable. Secondly, vaccine stockouts, poor cold chain systems, and the non-readiness of health service providers to administer the vaccines during mothers’ use of maternal health services are some of the health system barriers to the child being fully vaccinated that were not captured in the data used for this study, which could have led to an underestimation of the impact of maternal health service use (ANC and place of delivery) on routine vaccine coverage found in this study. Thirdly, the full vaccination status of children was analysed in this study based on only eight basic antigens. However, the national immunization program currently offers 13 vaccines to children free of cost.