Prevalence and Patterns of Adverse Events Following Childhood Immunization and the Responses of Mothers in Ile-Ife, South West Nigeria: A Facility-based Cross-sectional Survey

"Regardless of the actual cause, an AEFI [adverse event following immunisation] may lead to public suspicion about vaccines, resulting in vaccine hesitancy among parents who may refuse further vaccination for their children."

Although childhood immunisation has been proven to be objectively beneficial, occasional adverse events following immunisation (AEFIs) are a source of concern, as they could heighten vaccine hesitancy and potentially lead to a loss of immunisation gains. AEFIs affect vaccination uptake due to parental concerns about the health of children, as it did in the early 21st century in northern Nigeria, when there was widespread parental polio vaccine refusal due to widespread rumours and distrust about the oral polio vaccine. In light of the risk of public suspicion about vaccines, this study aimed to examine the prevalence and pattern of AEFIs and the responses of mothers in Ile-Ife, South West Nigeria.

The descriptive cross-sectional study was conducted among 422 mothers of children aged 0 to 24 months attending any of the 3 leading immunisation clinics in Ile-Ife, Nigeria. The chi-square test was used to test associations, while binary logistic regression was used to determine the predictors of mothers' responses to AEFIs. AEFIs were defined as any untoward medical occurrence that followed immunisation and that did not necessarily have a causal relationship with vaccine use that occurred within 28 days after vaccination. A p-value of <0.05 was considered statistically significant.

About 38% of the children had experienced an AEFI. Most mothers believed that the pentavalent vaccine was the most common cause of AEFIs (67.5%). Fever (88.0%) and pain and swelling (76.0%) were the most common AEFIs. Most mothers (53.7%) treated the child at home using paracetamol, tepid sponging, or other methods. However, in addition to initial treatment at home, it would have been appropriate for the mothers to report the AEFI to a healthcare facility within 24 hours to receive a health worker's assessment and reassurance, which only about a quarter of the mothers in this study did. Reporting at healthcare facilities is important not only to the child but also for the health system to record AEFIs in order to respond appropriately due to vaccine safety concerns and issues with handling and monitoring vaccines.

Younger mothers (odds ratio [OR], 2.43; 95% confidence interval [CI], 1.20-5.01), mothers who delivered their children at a healthcare facility (OR, 3.24; 95% CI, 1.08-9.69), and mothers who were knowledgeable about reporting AEFIs (OR, 2.53; 95% CI, 1.04-7.70) were most likely to respond appropriately to AEFIs. The finding that younger mothers were more likely to report AEFIs than older mothers in this study could be due to the fact that younger mothers may not have had any experience with AEFIs and thus responded to their child's symptoms with more urgency. The fact that mothers who delivered at healthcare facilities were more likely to report AEFIs could be linked to their being previously informed about immunisation by health workers and thus having had the opportunity to be educated before or during the child's first vaccination. Lastly, the finding about AEFI awareness and the appropriateness of mothers' responses may not be surprising, since knowledge improves children's health practices and care-seeking behaviours, as established in previous studies.

In conclusion: "To improve mothers' awareness of AEFIs and strengthen their responses to AEFIs, [the researchers] recommend the implementation of targeted educational programs for mothers about AEFI-related issues."