Background: Adverse events following immunization (AEFI) refers to any unfavourable event that occurs following vaccination related to the vaccine administration and or its handling An AEFI can lead to death or a life-threatening condition requiring hospitalization with or without permanent sequel. Surveillance for adverse events following immunization is an important component of any national immunization program because it is critical to assessing the safety of vaccines and to detecting potentially rare and severe adverse events and responding in a timely manner.
Objectives: This study aimed to identify adverse events following COVID-19 vaccination in two tertiary health facilities in Lagos State.
Methods: A retrospective active surveillance method was used at evaluating the incidence of adverse events following immunization (AEFI) with COVID-19 vaccine (AstraZeneca} as well as its safety. All the 2,082 first dose COVISHIELD vaccine recipients in the health facilities used in the study were approached through phone calls to collect data on AEFI. The frequency, duration, severity, and outcome of the adverse reactions were recorded. Incidence of AEFIs in different age groups and gender were analysed. Presence of any Adverse Events of Special Interest (AESI) were also evaluated. Data were analyzed using SPSS version 20.0. Any p-value < 0.05 was considered to be statistically significant
Results: Out of the 2,082 vaccine recipients, 888 (43%) did not experience any adverse effects while 1,194 (57%) vaccine recipients experienced adverse effects. A total of 83 adverse effects were reported and the most frequently reported adverse reactions were headache (30.6%), fever (28.8%) and pain at the injection site (24.3%). Others included nausea , general body pains, dizziness, drowsiness, myalgia, joint pains, fatigue, heavy arm, increased appetite and pain in the arm. The adverse reactions reported by the participants were mild to moderate in severity and resolved within a few days. There was no report of hospitalization, anaphylaxis or death.
Conclusions: The AEFIs of the vaccine were mild to moderate in severity and short in duration. The findings of this study will help to address vaccine hesitancy caused by worries about severe adverse effects associated with the COVID-19 vaccine. Since the COVID-19 vaccine is a new vaccine, further studies need to be carried out to observe the long-term effects of the vaccine.
