Role of Information Sources in Vaccination Uptake: Insights From a Cross-Sectional Household Survey in Sierra Leone, 2019

"Understanding the association between the exposure to varied sources of information and vaccine confidence and uptake may inform the tailoring of effective immunization communication strategies."

The Government of Sierra Leone has a strong emphasis on community engagement for immunisation services. In this context, caregivers receive vaccination messages through various sources, such as community health workers (CHWs) and faith leaders. Contextual factors, such as local beliefs and religious issues, health service delivery system issues, and infrastructure, can affect availability and exposure to different sources of immunisation information. A priority for the Sierra Leone Ministry of Health and Sanitation for this assessment was to understand the differential impact of vaccination information sources to prioritise future investments and strategies.

A cross-sectional household survey was conducted in February 2019 among 621 caregivers of children aged 12-23 months in 4 mostly rural districts in Sierra Leone (Kambia, Kono, Moyamba, and Western Area Rural). These districts were selected because they had the lowest coverage of the third dose of pentavalent vaccine-containing diphtheria-pertussis-tetanus-hepatitis B-Haemophilus influenzae type-b-vaccine (penta-3) in their respective geographic regions. The researchers measured exposure to various sources of immunisation information and 2 outcomes: (i) vaccination confidence using an aggregate score (from 12 Likert items) that was dichotomised into a binary variable; and (ii) uptake of penta-3 based on card record or through caregiver recall when card was unavailable. Associations between information sources and the outcomes were examined using modified Poisson regression with robust variance estimator.

Weighted estimates indicated 78% of caregivers expressed high vaccination confidence, and 81% of the children had received the penta-3 vaccine.

On average, caregivers were exposed to 4 different immunisation information sources. There was greater exposure through health facilities compared to community engagement events, which points to the dominant role of health workers as the primary health communicators. More than half of all caregivers were exposed to information from CHWs and faith leaders. Radio and print materials were also common channels of receiving information. Exposure to a greater number of information sources was associated with high penta-3 uptake (adjusted prevalence ratio [aPR]=1.05, 95% confidence interval [CI]=1.02, 1.1). (However, some high-exposure sources, such as radio and printed materials, were not at all associated with increased vaccination confidence or vaccine uptake.) The researchers reflect: "Multiple information sources may create positive reinforcement of health messages and help generate social norms that could support child immunization..."

Based on adjusted estimates, caregivers who were exposed to information from health facilities were 26% more likely to have their child vaccinated with the penta-3 vaccine. Similarly, there was a significant positive relationship between vaccine uptake and exposure to information from faith leaders (16%) and CHW and television (13% each).

A key implication of the study is that social and behaviour change communication (SBCC) interventions may optimise the promotion of immunisation services through multiple information sources such as health facilities and community-based assets, including:

• Lay CHWs - for instance, the findings point to the important role of interpersonal communication between health workers and caregivers, as well as health worker attitudes and knowledge about vaccination as influencers of vaccination uptake; and
• Faith leaders - Messages from religious leaders tend to be respected and followed and have been found to resonate with caregivers' values and beliefs while conveying the importance of vaccines from their specific sociocultural perspective. In the 1980s in Sierra Leone, religious leaders led a social mobilisation strategy that delivered messages drawn from religious scriptures to highlight the importance of vaccines, consequently improving child vaccination coverage. During the Ebola outbreak in Sierra Leone, the role of faith leaders in public health was strongly highlighted once again when they promoted protective behaviors for safe burials.

Based on this analysis, the researchers suggest: "Faith leaders and other important community leaders should be actively engaged not only in the delivery of messages but also in the development of messages that align and resonate with the community's beliefs and values in promoting immunization services to safeguard resilient demand and uptake of life-saving vaccines."

Looking ahead, the researchers suggest that this assessment could inform future longitudinal studies to evaluate the causal effect of information exposure on immunisation outcomes in other low-resource settings. For example, studies could consider experimental designs to assess the differences in effectiveness across information sources based on their settings, channels, and messengers, including content of the messaging, consistency in messaging, and/or any dose-response relationship between number of times a message is received. Furthermore, qualitative approaches can provide a richer understanding of how people receive, engage with, and act upon the vaccine-related information within local settings.

In conclusion: "This study in Sierra Leone has implications for measuring and addressing vaccination behaviors in similar LMIC settings....[H]igh level of exposure to immunization information from radio programming and printed materials alone may not sufficiently translate into improving vaccination confidence and uptake. Efforts to optimize vaccination outcomes may benefit from strengthening interpersonal communication during health facility visits and maximizing...community engagement through use of trusted messengers."