Zero-Dose Childhood Vaccination Status in Rural Democratic Republic of Congo: Quantifying the Relative Impact of Geographic Accessibility and Attitudes toward Vaccination

"In the case of rural areas in DRC, attitudes toward vaccination are much more impactful than geographic accessibility. This evidence suggests that efforts to improve demand and address parental concerns will be a critical component of addressing the large zero-dose problem in DRC."

Approximately 20% of infants in the Democratic Republic of the Congo (DRC) have not started their routine immunisation schedule and thus are considered zero-dose (ZD) children. Prior efforts to understand the drivers of persistently low coverage in DRC identified several system-side challenges, but there is a need to move beyond the sole focus on supply-side drivers to more effectively and sustainably overcome the intersecting barriers to vaccination, including those related to vaccine demand. To that end, this study aims to evaluate the relative influence of both geospatial access to health facilities and caregiver perceptions of vaccines on the vaccination status of children in rural DRC.

Pooled data from two consecutive nationwide immunisation surveys conducted in 2022 and 2023 were used. The study sample included 80,313 12- to 23-month-old children living in rural settings. Geographic accessibility was assessed based on travel time from households to their nearest health facility. Caregiver attitudes to vaccination were assessed using the survey question "How good do you think vaccines are for your child?" The researchers used logistic regression to assess the relationship between geographic accessibility, caregiver attitudes toward vaccination, and their child's vaccination status.

Geographic accessibility to health facilities was high in rural DRC, with 88% of the population living within an hour's walk to a health facility. Children who live further away from health facilities were more likely to be unvaccinated. Among children who live within 5 minutes of a health facility, 21% were ZD, while 26% of those living more than an hour from a facility were ZD.

Caregiver attitudes were strongly correlated with non-vaccination. Of the 9% of caregivers (N = 6,285) who reported that vaccines are "Bad, Very Bad, or Don't Know", 87% of their children were ZD. Only 8.6% of children were ZD among caregivers who rated vaccines as "Very Good" for their child. However, within each level of parental attitude, there still appeared to be some effect of travel time. Across every time point in travel time, having a lower attitude status was the more important factor.

Put another way, responding that vaccines are "Bad, Very Bad, or Don't Know" relative to "Very Good" for children was associated with a many-fold increased odds of a ZD status (odds ratios [ORs] 69.3 [95% confidence interval (CI): 63.4-75.8]) compared to the odds for those living 60 or more minutes from a health facility, relative to less than 5 minutes (1.3 [95%CI: 1.1-1.4]). Similar proportions of the population fell into these two at-risk categories. The researchers did not find evidence of an interaction between caregiver attitude toward vaccination and travel time to care.

Thus, this study found that caregiver attitudes toward childhood vaccination, a proxy for intent to vaccinate, is a many-fold stronger predictor of non-vaccination than geographic accessibility. While geographic access to health facilities is crucial, caregiver demand appears to be a more important driver in improving vaccination rates in rural DRC. This information is critical for making strategic programmatic choices under resource constraints. For example, based on the evidence presented in this paper, an intensive remote rural strategy is likely to reach fewer children than a near-facility demand-generation strategy, such as mobilising the network of community health workers (relais communautaire, or RECOs) for educational campaigns.

This paper may motivate future study in several areas. For example:

• Given the importance of caregiver attitudes toward vaccination, a more thorough investigation of the intent to vaccinate is needed. In addition to caregiver attitudes toward vaccination, components like awareness, knowledge, agency, and community norms interact in complex ways to impact on intent to vaccinate. Implementation of questions based on the World Health Organization (WHO)'s Behavioral and Social Drivers (BeSD) framework in future surveys will be a welcome increase in the availability of such data.
• Further studies should also aim to include a fuller set of determinants across intent to vaccinate, community access, and health facility readiness (e.g., using WHO Service Availability and Readiness Assessment (SARA) immunisation indicators). It might be fruitful to explore the relative prioritisation of child immunization amongst the multiple priorities caregivers have to address, possibly through a structural causal modeling framework.
• Even in terms of access, the present analysis is relatively narrowly focused on geographic access, while access is a wider concept that encompasses the convenience and acceptability of services. As such, barriers, including wait times and caregiver costs (both direct and indirect), are not included here but may contribute significantly to ZD status.

In conclusion: "Findings from this study may provide important insight relevant to improving targeted programming and policies to address barriers to vaccination in DRC and improve more equitable coverage."