Door-to-door vaccination in a fragile urban setting: results from descriptive observational study in Bangui, Central African Republic

¹Link Campus University, Rome, Italy, ²Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy, ³Community of Sant'Egidio, DREAM Program, Bangui, Central African Republic, ⁴Community of Sant´Egidio, DREAM Program, Rome, Italy, ⁵LUMSA University, Rome, Italy

^&Corresponding author
Fausto Ciccacci, Department of Biomedicine and Prevention, University of Rome Tor Vergata, Rome, Italy

Introduction    

Vaccination remains one of the most powerful and cost-effective public health interventions for reducing childhood morbidity and mortality, particularly in low- and middle-income countries (LMICs). According to the World Health Organization (WHO), immunization prevents over 3 million deaths annually and contributes significantly to controlling communicable diseases and strengthening health system resilience [1]. Since the establishment of the Expanded Programme on Immunization (EPI) in 1974, global efforts have focused on achieving equitable access to life-saving vaccines [2].

Despite international support, sub-Saharan African countries often fall short of these targets [3,4]. Socioeconomic inequities, prolonged political instability, underfunded health sectors, and insufficient healthcare workforce continue to obstruct progress [5,6]. The Central African Republic (CAR) is emblematic of these challenges. Decades of conflict and insecurity have severely compromised the country's health system, limiting access to essential services, including routine immunization [7]. Although CAR's immunization schedule aligns with WHO and UNICEF recommendations covering BCG, DTP, Polio, Hepatitis B, Hib, PCV13, Measles, and Yellow Fever coverage remains alarmingly low, with wide disparities across regions and socio-economic groups.

Barriers to vaccination in CAR are multifaceted. Structural weaknesses, including underfunded systems, weak civil registration, and shortages of trained personnel, are compounded by insecurity that hampers service delivery and data collection, particularly in regions controlled by armed groups [8]. Geographic inaccessibility, lack of transportation, and low community awareness further undermine vaccination uptake. Social and economic inequities exacerbate these barriers, particularly among rural and impoverished populations. Despite Gavi's financial support exceeding USD 160 million between 2021-2026—including over USD 6.8 million for cold chain optimization coverage goals remain unmet [9].

In this context, innovative and context-specific models are urgently needed. The DREAM program (Diseases Relief through Excellent and Advanced Means), launched by the Community of Sant'Egidio, has operated in CAR since 2018, in partnership with national ministries. Originally focused on HIV/AIDS, DREAM has expanded to provide integrated services including chronic disease management and maternal-child health at its main center in Bangui [10]. DREAM program has developed adaptive and context-sensitive strategies to address the immunization gap in Bangui, CAR. Through the use of mobile health teams, DREAM has aimed to bring vaccination services directly to communities that are traditionally underserved or completely disconnected from the formal health system [11-13]. This paper presents an analysis of DREAM's immunization initiative in Bangui, examining its strategies, operational model, and early outcomes, while highlighting its potential as a scalable approach in fragile settings.

Methods     

Study design and setting: this is a descriptive observational study of a door-to-door immunization initiative implemented in Bangui, Central African Republic, to address low routine vaccination coverage among children under two years of age. The Ministry of Health identified specific neighborhoods with historically low vaccination rates, and two door-to-door vaccination campaigns were subsequently organized in those areas. The first campaign ran from November 2023 to September 2024 and covered the neighborhoods of Bafio, Dédengué I, Dédengué II, Dédengué III, Kaimba, Ouham I, Ouham Pendé, Votongbo I, and Votongbo II. The second campaign was carried out between October 2024 and May 2025 in the neighborhoods of Bacongo, Batambo, Bruxelles, Sapéké II, Yapelé I, Yapelé II, Yapelé III, and Yapelé IV (Figure 1). Neighborhoods highlighted in light purple were covered during Campaign 1 (November 2023-September 2024), while those in dark purple were targeted in Campaign 2 (October 2024-May 2025). The map illustrates the spatial extent and non-overlapping implementation zones of the two interventions. Both campaigns were implemented by the Community of Sant'Egidio with support from the Italian Agency for Development Cooperation (AICS). The main objective was to increase the uptake of routine childhood vaccinations through a proactive outreach strategy.

Door-to-door campaign implementation: the campaign employed a structured, phased door-to-door strategy to ensure the identification and immunization of all eligible children. The process was organized into two main phases each week. During the first phase, conducted over three days, trained mobilizers visited every household in the designated area. They interviewed caregivers of children aged 0 to 2 years and reviewed any available vaccination cards. In cases where the child's vaccination card was not available, mobilizers and vaccinators relied on caregiver recall to reconstruct the immunization history using a structured set of questions regarding the number and timing of previous doses, in accordance with national EPI guidance. The mobilizers recorded missing doses for each child and informed the families of upcoming vaccination visits. The second phase took place on the following two days, during which trained vaccinators returned to the households to administer the identified missing vaccines. Vaccinations were recorded both on the child's health card and in a standardized campaign register. When necessary, follow-up visits were scheduled to complete the immunization schedule. Each field team included five mobilizers, two vaccinators, and one data officer. Prior to deployment, all team members received a three-day training session that covered community engagement, vaccination protocols, safe administration practices, and data collection procedures. Mapping tools were used to segment each neighborhood and guide daily coverage, while vaccine stocks were managed in coordination with the Expanded Program on Immunization (EPI) office of Health District 3, Bangui. Despite this coordination, occasional vaccine stockouts (particularly of yellow fever and meningitis A vaccines) were encountered.

Results     

During the two vaccination campaigns conducted by the DREAM program in Bangui, a total of 10,551 children under five years of age were reached and assessed across 17 neighborhoods: 6,263 in the 4th arrondissement (Campaign 1, November 2023 to September 2024) and 4,288 in the 2nd arrondissement (Campaign 2, October 2024 to May 2025). Immunization status was verified according to the child's age and the national immunization schedule. Overall, 64.2% (6,779 children) were found to be fully immunized, while 3,772 (35.8%) were identified as not fully vaccinated for their age. During the campaign 1 a slightly higher coverage (65.3%) compared to Campaign 2 (62.7%) was recorded.

Notably, no zero-dose children were encountered during the campaign; all partially vaccinated children had received at least one dose before the intervention. Of the 3,772, a total of 3,556 (94.3%) received at least one additional vaccine dose during the campaign, indicating a high responsiveness to the door-to-door mobilization strategy and effective catch-up capacity. Although direct linkage between each screening and subsequent vaccination was not systematically tracked at the individual level, this estimate indicates the campaign's operational success. As shown in Figure 2, coverage rates varied markedly between neighborhoods, ranging from 46.9% in Kaimba to 75.8% in Dedengue 2. Such heterogeneity reflects underlying socio-economic and geographic inequities within the city.

Table 1 summarizes the number of children reached and doses administered for each vaccine during the two campaigns. In total, 3,556 children received at least one vaccine dose through the campaign activities: 1,979 during the first campaign and 1,577 in the second. Vaccination was balanced between sexes, with 1,807 boys and 1,745 girls immunized. A cumulative total of 14,942 doses were administered, with the highest numbers recorded for measles (2,540 doses), meningitis A (2,371 doses), and yellow fever (2,343 doses). For the three-dose series vaccines such as Pentavalent, PCV13, and Oral Polio Vaccine (OPV), a notable number of children received second or third doses, indicating that the campaign effectively served both as an entry point for zero-dose children and a catch-up mechanism for those who had missed one or more scheduled doses.

Discussion     

The community-based vaccination initiative implemented by the DREAM program in Bangui demonstrated the feasibility and effectiveness of a door-to-door strategy in a fragile urban context. Among more than 10,000 children assessed across 17 neighborhoods, 64.2% were found to be fully immunized according to age. Notably, no zero-dose children were identified, and over 94% of those partially immunized received at least one additional vaccine dose during the campaign. These findings indicate a high responsiveness to targeted outreach efforts and suggest that barriers to full immunization in this setting are more likely related to access than to vaccine hesitancy or refusal.

The absence of zero-dose children is particularly significant in the context of the Central African Republic, where national coverage for the first dose of the measles-containing vaccine was estimated at only 41% in 2023 (Gavi, 2024; ICASEES, 2021). This result may reflect incremental improvements in the EPI's outreach in Bangui, but could also be influenced by the specific characteristics of the neighborhoods selected for the intervention. Moreover, as the campaign was conducted in the capital city, where health services and infrastructure are relatively more accessible than in rural or conflict-affected areas, the findings may not be generalizable to the national level. The wide range in coverage observed across neighborhoods, from 46.9% to 75.8% suggests that local socioeconomic and geographic factors continue to influence vaccine uptake, even within the same urban area. The DREAM strategy combined community mobilization, home-based vaccination, and follow-up mechanisms. These elements enabled the program to reach children who had been previously missed, deliver a substantial number of second and third doses, and contribute to continuity in routine immunization. The approach is consistent with existing literature highlighting the importance of localized and context-sensitive strategies in fragile settings [11-13]. The use of trained mobilizers, structured mapping, and standardized data collection methods appears to have facilitated efficient delivery and operational accountability.

Evidence from other contexts supports the effectiveness of outreach-based immunization models. In Migori County, Kenya, a door-to-door campaign integrated with facility-based services increased coverage rates for several vaccines, with BCG rising from 74% to 90%, Penta3 from 92% to 112%, and MR1 from 82% to 112% [14]. Similarly, in Sierra Leone, the implementation of last-mile mobile vaccination delivery, combined with community engagement and logistical support, was associated with an 8% weekly increase in COVID-19 vaccine uptake in remote and conflict-affected areas [15]. In Somalia, an integrated campaign combining COVID-19 and routine pediatric immunization raised vaccine coverage from 5.5% to 42.1% over one year and reached more than 84,000 children previously classified as zero-dose [16]. These improvements were attributed to the door-to-door modality, the integration of services, and the use of digital tools. In northwest Syria, despite challenges related to prolonged conflict, vaccination efforts were successful when supported by local governance mechanisms and inclusive outreach strategies [17]. In Mozambique, a preventive oral cholera vaccination campaign implemented in dense urban areas through house-to-house visits achieved 69.5% coverage for at least one dose [18]. In Kalemie, Democratic Republic of Congo, a targeted cholera vaccination effort reached 67% two-dose coverage using a door-to-door approach [19]. In Malawi, a canine rabies vaccination campaign achieved over 70% coverage through a combination of fixed-point and door-to-door strategies in both rural and urban areas [20]. In the post-conflict context of the Central African Republic, a multi-antigen campaign reached more than 85% coverage for several first doses [21].

This study presents some limitations. In many cases, baseline immunization status was reconstructed based on caregiver recall due to the limited availability of vaccination cards, which may have introduced misclassification. Although aggregate data on vaccine doses administered were recorded, individual-level linkage between the screening data and subsequent vaccination was not systematically tracked. As a result, while it is clear that the administered doses were delivered through the campaign, it is not possible to confirm whether each child identified as partially vaccinated received all the required doses to become fully immunized. The focus on urban areas in Bangui also limits generalizability to rural or highly insecure regions, where logistical and social challenges may be more pronounced. Additionally, the evaluation did not include a longer-term follow-up to assess sustained adherence to the immunization schedule or potential changes in health-seeking behavior over time.

Nonetheless, the findings suggest that door-to-door vaccination strategies, when combined with local mapping, trained personnel, and community engagement, can offer an effective response to persistent immunization gaps in fragile urban settings. Future applications of this model should include digital tracking systems, broader geographic implementation, and assessment of cost-effectiveness. Expanding such interventions to rural districts, strengthening civil registration and vaccine documentation, and fostering collaboration with local health authorities may further enhance their sustainability and impact. Long-term success will also depend on continued investment, policy support, and community ownership to ensure equitable immunization services in the CAR and similar contexts.

Conclusion     

This study provides evidence that a structured door-to-door vaccination strategy can substantially improve immunization uptake in fragile urban contexts. The approach's feasibility, adaptability, and strong community engagement highlight its potential for replication in other underserved urban settings. Scaling up such targeted outreach, coupled with sustained policy support and integration into national immunization programs, could play a critical role in reducing intra-urban disparities and advancing progress toward universal vaccine coverage in the Central African Republic and comparable contexts.

Competing interests     

The auhors declare no competing interests.

Authors' contributions     

Annamaria Doro Altan contributed to the conceptualization of the study, led the drafting and critical revision of the manuscript. Emanuela Ruggieri and Gianluca Salonia contributed to data analysis and manuscript editing. Yvon Sadrack Bessarin and Noel Ningalao coordinated field implementation in Bangui and contributed to data collection. Marina Ciardo and Gabriella Bortolot supported field supervision and community mobilization activities, and contributed to the development of the study protocol and provided technical input on immunization strategies. Boris Tchenebou supported local coordination, logistics, communication with health authorities, and local health system engagement. Stefano Orlando and Paola Scarcella provided methodological input, supported analysis, and contributed to manuscript revision. Fausto Ciccacci supervised the overall study design, contributed to data interpretation, and provided substantial input to the final version of the manuscript.

Table and figures     

Table 1: number of children vaccinated and doses administered for each antigen during the two DREAM vaccination campaigns in Bangui

Figure 1: geographic distribution of the two door-to-door vaccination campaigns conducted in Bangui, Central African Republic. Neighborhoods highlighted in light purple were covered during Campaign 1 (November 2023-September 2024), while those in dark purple were targeted in Campaign 2 (October 2024-May 2025). The map illustrates the spatial extent and non-overlapping implementation zones of the two interventions

Figure 2: immunization coverage by neighborhood. The figure illustrates the percentage of children fully immunized according to age in each surveyed area, highlighting variability in vaccination uptake

References