The Socioecological Model as a Framework for Exploring Factors Influencing Childhood Immunization Uptake in Lagos State, Nigeria

"...results can inform the design of culturally appropriate and effective interventions to address Nigeria's suboptimal immunization coverage."

Multiple studies have examined individual-level factors contributing to Nigeria's suboptimal childhood immunisation uptake. The findings have shaped interventions aim to overcome specific supply- and demand-side barriers related to affordability, accessibility, availability, awareness, and knowledge of immunisation services. However, the socioecological model (SEM) demonstrates that individual behaviour is shaped by factors at multiple levels. In that vein, this study used the SEM as a conceptual and organising framework to explore factors influencing childhood immunisation in Nigeria from various stakeholders' perspectives, with the premise that investigating socioecological influences on childhood immunisation practices "from lived perspectives is critical to the development of comprehensive and effective interventions."

The researchers conducted ten focus group sessions with 44 mothers/caregivers and 24 community leaders and nine semi-structured interviews with 19 routine immunisation focal persons in Lagos state primary healthcare facilities. Participants hailed from all the 20 local government areas (LGAs) in Lagos state. All caregivers and nurses were female; 10 of the 24 community leaders were male, and 14 were female. Study participants discussed factors at each level of the SEM that influence childhood immunisation uptake, including:

• Intrapersonal-level factors included those that are intrinsic, such as knowledge, and extrinsic, referring to factors such as caregivers' time constraints. Participants reported caregivers' accurate and adequate knowledge of immunisation services as being a positive influence on immunisation uptake. Essential elements of knowledge included understanding vaccine benefits, being aware of the immunisation schedule, and potential adverse events following immunisation (AEFIs). A related but separate theme was caregivers' negative beliefs and misperceptions of immunisation. Caregivers' welfare and love of children was another individual-level factor that participants described as being important to consider for its role in immunisation.
• Interpersonal-level factors included those relating to the caregivers' relationships and social networks, such as family, friends, and neighbours. Some caregivers discussed how other mothers within their networks had educated them about immunisation and encouraged them to immunise their child/ren. They also highlighted the roles that husbands, mothers, and mothers-in-law played in their decision-making about childhood immunisation.
• Institutional factors included geographical and financial access to health facilities, health facility attributes, staff coverage, and healthcare worker attributes. Some discussed the importance of having healthcare workers who could educate them about the importance of immunisations as a positive contributor to improving immunisation acceptance.
• Community factors included influences of informal networks such as community leaders and the availability of community resources. Participants described the positive value of house-to-house immunisation campaigns conducted by trained volunteers, such as National Immunization Plus Days (NIPDs), during which supplemental oral polio vaccine (OPV) is distributed to children less than five years of age. Furthermore, participants described the importance of leveraging community resources such as community leaders, including traditional and religious leaders, and those in formal community leadership positions, such as members of the Ward Development Committee, to encourage caregivers' immunisation uptake.
• Policy-level factors included free immunisation services and provision of child immunisation cards.

As reviewed in the discussion section, the findings corroborate other studies - for example, those that have reported that people who believe that individuals within their social network want their children to be vaccinated are more likely to accept vaccines. The present study also reinforces existing evidence that as acceptance of vaccination within a community increases, making it a social norm, vaccine uptake by people within that community will also increase.

Thus, this study found that factors at all SEM levels affect childhood immunisation uptake and decision-making. Several of the factors are intertwined and could be used in tandem. For example, organisational efforts in which health workers provided immunisation health talks to caregivers as early as during antenatal care, coupled with community efforts in which local leaders create awareness about the relevance of immunisation, could together influence mothers' knowledge of immunisation benefits and assist with debunking misperceptions.

In conclusion, the researchers encourage immunisation stakeholders, including government officials and partner agencies, to design interventions that simultaneously target multiple SEM levels to foster positive immunisation decision-making and increase childhood immunisation uptake.