Drivers of Routine and Outbreak Vaccination Uptake in the Western Democratic Republic of Congo: An Exploratory Study in Ten Health Zones

"Implementation of targeted interventions can positively influence vaccination uptake."

Understanding the determinants of insufficient vaccine uptake, both on the demand side (e.g., knowledge, perception, vaccine acceptance, socioeconomic factors) and on the supply side (e.g., resources, cold chain) is crucial to enable optimal vaccination impact. This study aimed to identify determinants of routine and outbreak vaccination that could either promote or hamper uptake among different stakeholders in ten health zones in four western provinces of the Democratic Republic of Congo (DRC): Kinshasa, Kongo Central, Kwango, and Kwilu. The DRC is an epidemic-prone country with limited resources but with considerable experience in outbreak control.

The researchers conducted a cross-sectional study to collect data on demographics, and on six knowledge, attitudes, and practices (KAP) concepts (belief, knowledge, attitude, risk perception of side effects, feeling informed about vaccination, and risk perception of vaccine-preventable diseases, or VPDs). An additional KAP concept of trust (combining trust towards vaccination, vaccination programmes, and providers) was investigated only among the parents of children under age five. Vaccine acceptance was assessed for specific routine (Bacillus Calmette-Guérin (BCG), measles, and poliomyelitis) and outbreak (cholera, Ebola, COVID-19) vaccines. Among the healthcare worker (HCW) population, the researchers also collected data on the supply chain of vaccines. In total, 2,751 participants were included: 1,165 parents, 1,040 eldery people, and 546 HCWs.

In general, KAPs expressed were supportive of vaccination uptake, although concerns regarding side effects and feelings of being insufficiently informed were more prevalent among parents and the elderly. Vaccine acceptance was lower for outbreak vaccinations (57%) than for routine vaccinations (90%), especially if there was no direct experience with the outbreak. Vaccine acceptance for outbreak vaccination was lower among people with incorrect knowledge (p-value < 0.001) or people feeling insufficiently informed on vaccination (p-value = 0.002 compared to people with neutral feelings, and p-value < 0.001 compared to people feeling sufficiently informed). Parents living in rural areas reported a higher level of trust than parents living in urban areas. Communication and educational campaigns could be deployed to help shift the attitude of distrust among those in urban areas, where rumours can circulate more rapidly and reach a higher number of people than in other settings.

HCWs expressed the highest vaccine acceptance. High vaccine acceptance in this population provides a key opportunity to involve them early and comprehensively in future campaigns. For many people, the first line healthcare provider is the person they most trust to provide them with relevant and sufficient information. At the same time, for HCWs to fulfill this role effectively and credibly, it is key that the supply chain is functioning well; problems of that nature were reported by 20% of respondents.

Despite a high level of positive KAPs towards vaccination, parents and the elderly expressed a need to be better informed and had concerns regarding vaccine side effects. As fear of side effects fuels vaccine hesitancy, communication initiatives should be geared specifically toward these populations. This is also important, since elderly populations could play an even bigger role than HCWs in influencing the decisions of younger family and communities.

The researchers stress that attitudes, beliefs, risk perceptions, feeling of being sufficiently informed toward vaccination, and vaccine acceptance are not static. They can differ between populations and places, and they change over time. Gathering data as in the present study is key to enable agile, targeted interventions by public authorities to optimise the uptake of vaccinations when aiming to prevent and control outbreaks.

In conclusion, although the researchers did not directly assess the willingness of HCWs to act as promotors of uptake, "it is likely that, provided that supply constraints can be addressed, HCWs can be major agents of change to increase the uptake of live-saving vaccines."