Immunization Coverage and Adverse Events Following Vaccination: A Retrospective Cohorts Study
Keywords:
Immunization coverage, Adverse events following immunization, Vaccine safety, Retrospective cohort study, Public health.Abstract
Immunization is a global health goal that has greatly minimized the burden of infectious diseases. But vaccine uptake is driven by public opinion about vaccine safety and AEFI reports. The aim of this study is to assess the association between reported AEFIs and immunization coverage in a large retrospective cohort. This is a retrospective cohort study using health care data from one million individuals between 2010 and 2022. Immunization registers were reviewed to determine rates of vaccination coverage for recommended vaccines. AEFI reports were gathered from health databases, and they were organized based on the severity (mild, moderate, severe) and type (local, systemic or allergic). Statistical analyses were carried out to establish a relationship between vaccination coverage and incidence of AEFIs after adjusting for confounders such as age, sex and the underlying health conditions. The immunization coverage ranged at 85%. AEFI reporting rates were 0.3 per 1,000 doses with mild events amounting to 90% of reports. There were no significant time trends in reporting of severe AEFI. The incidence of AEFI was not related to vaccines with greater coverage rates. Using regression analysis showed that higher levels of education and living in urban areas were associated with increased vaccine uptake, as well as mild AEFIs but not for moderate or severe ones. The results indicated no relationship between high immunization coverage and occurrence of adverse events which supports the safety profile of vaccines. Also, the trend of AEFIs is constant and there is no marked increase in severe reactions observed over a twelve-year period. The relationship between socio-demographic factors and immunization coverage as well as AEFI reporting, reveals that there is a need for strategic communication interventions to maintain vaccine confidence. This study confirms the need to follow AEFI in order to strengthen public health initiatives and improve immunization coverage.
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