Background: Two probability surveys, conducted in the same districts of Bihar, India (Aurangabad and Gopalganj) at approximately the same time in 2016 using identical questionnaires and similar survey methods, produced significantly different responses for 37.2% (58/156) of the indicator comparisons. Interviewers for one survey were men while for the other they were women. Respondents were mothers of children aged 0–59 months living in a traditional rural setting. We examined the influence of interviewer gender on mothers’ survey responses and their implications for interpreting survey results. Methods: We used qualitative methods including 10 focus group discussions (FGDs) and 33 in-depth interviews (IDIs) in the same locations as the 2016 surveys. FGD participants were purposefully selected mothers with children 0–59 months, husbands and other in-law family members. IDIs were carried out with frontline health-workers, enumerators and supervisors from the two previous household surveys. Results: Findings revealed a preference for female interviewers for household surveys in study districts as they facilitated access to mothers and reduced their discomfort as survey participants. However, this gender preference was related to the survey question. Regardless of age, caste and educational level, most mothers were not permitted to communicate with men (aside from husbands) about female-specific health topics, including birth preparedness, delivery, menstrual cycles, contraception, breastfeeding, sexual behaviour, sexually transmitted disease, and domestic violence. Mothers in higher castes perceived these social restrictions more acutely than mothers in lower castes. There was no systematic direction of the resulting error. Mothers were willing to discuss child health issues with interviewers of either gender. Conclusions: Interviewer gender is an important consideration when designing survey protocols for maternal and reproductive health studies and when selecting and training enumerators. Female interviewers are optimal for traditional settings in Bihar as they are more likely to obtain accurate data on sensitive topics and reduce the potential for non-sampling error due to their reduced social distance with maternal respondents.

Zero-dose (ZD) children is a critical objective in global health, and it is at the heart of the Immunization Agenda 2030 (IA2030) strategy. Coverage for the first dose of diphtheria–tetanus–pertussis (DTP1)-containing vaccine is the global operational indicator used to estimate ZD children. When surveys are used, DTP1 coverage estimates usually rely on information reported from caregivers of children aged 12–23 months. It is important to have a global definition of ZD children, but learning and operational needs at a country level may require different ZD measurement approaches. This article summarizes a recent workshop discussion on ZD measurement for targeted surveys at local levels related to flexibilities in age cohorts of inclusion from the ZD learning Hub (ZDLH) initiative—a learning initiative involving 5 consortia of 14 different organizations across 4 countries—Bangladesh, Mali, Nigeria, and Uganda—and a global learning partner. Those considerations may include the need to generate insights on immunization timeliness and on catch-up activities, made particularly relevant in the post-pandemic context; the need to compare results across different age cohort years to better identify systematically missed communities and validate programmatic priorities, and also generate insights on changes under dynamic contexts such as the introduction of a new ZD intervention or for recovering from the impact of health system shocks. Some practical considerations such as the potential need for a larger sample size when including comparisons across multiple cohort years but a potential reduction in the need for household visits to find eligible children, an increase in recall bias when older age groups are included and a reduction in recall bias for the first year of life, and a potential reduction in sample size needs and time needed to detect impact when the first year of life is included. Finally, the inclusion of the first year of life cohort in the survey may be particularly relevant and improve the utility of evidence for decision-making and enable its use in rapid learning cycles, as insights will be generated for the population being currently targeted by the program. For some of those reasons, the ZDLH initiative decided to align on a recommendation to include the age cohort from 18 weeks to 23 months, with enough power to enable disaggregation of key results across the two different cohort years. We argue that flexibilities with the age cohort for inclusion in targeted surveys at the local level may be an important principle to be considered. More research is needed to better understand in which contexts improvements in timeliness of DTP1 in the first year of life will translate to improvements in ZD results in the age cohort of 12–23 months as defined by the global DTP1 indicator.

Introduction: A limited number of studies focus on estimating the costs of interventions to increase childhood immunization coverage in low- and middle-income countries (LMICs). Existing reviews often compare estimated costs but lack information on the methods used. The objective of this review is to summarize the methods used in costing studies that assessed interventions to reach zero-dose (ZD) children. Methods: We conducted a review of existing studies that estimate the costs of increasing childhood vaccination and reducing prevalence of ZD children in LMICs. We conducted searches of PubMed using terms including “immunization”, “cost”, “coverage increase”, “zero-dose”, and “LMIC”, and further extended our search to bibliographies and gray literature from organizations working to reach ZD children. We only included articles that estimated the cost of interventions to increase childhood vaccination and/or reach ZD children and not articles about introducing new vaccines or other age groups. We categorized each article according to their costing methods, cost components, types of costs calculated, and presence of uncertainty analysis. Results: Eleven articles met our inclusion criteria. Interventions costs varied from USD 0.08 per additional dose for SMS reminders in Kenya to USD 67 per dose for cash transfers in Nicaragua. Most of the studies were from South Asia: India (4), Pakistan (2), and Bangladesh (1). The rest were from Africa (3) and Latin America (1). Most articles did not include a description of their costing methods. Only three described their methods in detail. Conclusions: Few studies have estimated the costs of increasing childhood vaccination coverage and reducing the number of ZD children in LMICs. The wide variation in intervention costs underscores the need for standardized costing methodologies to enhance comparability across studies. Only three studies detailed their costing methods, making comparisons challenging. Establishing research principles for costing ZD interventions could strengthen future evidence for policymaking.

Background: Immunization coverage in Nigeria is low, with many children missing out on important lifesaving vaccines. To enable a better understanding of contextual factors towards increasing uptake, we piloted a Decentralized Immunization Monitoring (DIM) approach in the Kumbotso local government area (LGA) of Kano state, Nigeria, to identify wards with low vaccination rates and understand why this is happening. The findings were used to improve routine immunization (RI) programs and reduce the number of unvaccinated children and children yet to receive their first dose of diphtheria–pertussis–tetanus (DPT) vaccine, referred to as Zero-Dose children (ZD). Methods: This study adopted a cross-sectional design approach using the Behavioural and Social Drivers of Vaccination (BeSD) framework and the Lot Quality Assurance Sampling (LQAS). The study population comprised caregivers of children aged 0–11 months and 12–23 months across the 11 wards in Kumbotso District, Kano State, Nigeria, using a segmentation sampling approach. The study covered 209 settlements selected using probability proportionate to size (PPS) sampling from the wards. Univariate and bivariate analyses were performed to show patterns and relations across variables. Results: Out of 418 caregivers surveyed, 98.1% were female. Delayed vaccination was experienced by 21.9% of children aged 4.5–11 months, while the prevalence of ZD was estimated at 26.8% amongst the older cohort (12–23 months). A total of 71.4% of the delayed group and 89.1% of the ZD group remained unvaccinated. Caregiver education, rural residence, and home births correlated with delayed/ZD status (p < 0.05). Logistic regression associated higher caregiver education with reduced delayed vaccination odds (OR:0.34, p < 0.001) and urban residence with lower ZD odds (OR:1.89, p = 0.036). The antigen coverages of BCG (81.5%), DPT3 (63.6%), and measles 1 (59.7%) all surpassed the national dropout thresholds. Kumbotso, Unguwar Rimi, and Kureken Sani wards were all identified as underperforming and therefore targeted for intervention. Negative vaccine perceptions (50% delayed, 53.6% ZD) and distrust in health workers (46.4% delayed, 48.2% ZD) were significant barriers, though the caregiver intent to vaccinate was protective (OR: 0.27, p < 0.001). The cost of accessing immunization services appeared to have a minor effect on coverage, as the majority of caregivers of delayed and ZD children reported spending less than 200 Naira (equivalent to USD 0.15) on transport. Conclusions: This pilot study highlighted the utility of LQAS and BeSD in identifying low-performing wards, barriers, and routine immunization gaps. Barriers included low caregiver education, rural residence, and negative vaccine perceptions/safety. Caregiver education and urban residence were protective factors against delayed and ZD vaccination, suggesting social and systemic barriers, particularly in rural and less educated populations. Antigen-specific coverage showed disparities, with dropouts for multi-dose vaccines exceeding the national thresholds of 10%. Targeted measures addressing education, trust, and systemic issues are needed. Findings emphasize decentralized monitoring, community engagement, and context-specific strategies to reduce ZD children and ensure equitable vaccination in Nigeria.

Reaching and fully immunizing zero-dose (ZD) children and missed communities is at the core of the Gavi, The Vaccine Alliance 5.0/5.1 and Immunization Agenda 2030 strategies. This is critical to ensure equitable immunization coverage and access to other primary health care services and to prevent outbreaks. The diversity of settings where these children live and the complexity of vaccination barriers require a complementary set of activities embedded in national systems. Learning approaches are needed to use evidence to improve equity and reach. Gavi has helped fill this gap with the Zero-Dose Learning Hub (ZDLH) initiative, which is composed of consortia partners in four countries—Mali, Nigeria, Uganda, and Bangladesh—and a global-level consortium. This paper describes the ZDLH design, theory of change, methods, and measures of success. Then, future papers will present ZDLH results, successes and challenges, and recommendations. The ZDLH initiative is prospective and runs through 2025. It features primary evidence generation through rapid assessments, improved monitoring, implementation research in targeted subnational areas where ZD children are located, and country-specific learning agendas and knowledge translation activities to facilitate evidence use. The global-level consortium offers technical assistance to country learning hubs and facilitates synthesis, dissemination, and improves evidence use across low- and middle-income countries. A common measurement, evaluation, and learning plan documents whether evidence is generated and used and how the overall model works to inform future adaptation. Target audiences for evidence are the Gavi Board; Gavi strategy, programme, and country teams; countries’ ministry of health and immunization programmes at national and subnational level; and other donors and implementing partners working to improve immunization equity. The ZDLH initiative is a coherent approach to evidence generation and learning, and the implementation experience informs how to better design and support learning systems embedded within National Health Systems.

The world's refugee populations primarily reside in low- and middle-income countries, where they face protracted displacement and limited financial and human capital. Social capital is among the few assets they can leverage for resilience. Despite its importance, few studies have examined how social capital influences the uptake of healthcare services during protracted displacement. This study examines the associations of refugee with access to maternal, newborn and child health (MNCH) services in northern Uganda's long-term settlements. We conducted cross-sectional probability household surveys across four refugee settlements with independent samples of caregivers of children 0-5, 12-23, and 0-59 months (n = 570). Caregivers' demographic characteristics and responses to 57 items from the Shortened Adapted Social Capital Assessment Tool were analyzed as independent variables. Dependent variables were MNCH service coverage and young child feeding practices. Factor analysis revealed three distinct social capital dimensions: Social Support (Ω = 0.73), Social Action (Ω = 0.72), and Community Cohesion (Ω = 0.48 indicating lower reliability). In adjusted multiple regression analyses, Social Support was positively associated with minimum dietary diversity (aOR = 1.35, 95 %CI = 1.04-1.74). Social Action was positively associated with antenatal care during the first trimester (aOR = 3.93, 95 %CI = 1.47-10.50), Tetanus Toxoid vaccination during pregnancy (aOR = 4.00, 95 %CI = 1.33-12.04) and postnatal care (aOR = 2.48, 95 %CI = 1.02-6.05). Community Cohesion showed positive associations with early initiation of breastfeeding (aOR = 3.47, 95 %CI = 1.00-12.06) and Vitamin A supplementation (aOR = 3.51, 95 %CI = 1.15-10.68). These findings suggest that social capital is linked to the uptake of essential MNCH services, with distinct dimensions showing positive associations with key health behaviors. Understanding these dynamics is important for designing effective, community-based health interventions in refugee settings.