Adverse Events Following COVID-19 Vaccination in Rivers State, Nigeria: A Cross-Sectional Study

Context: Coronavirus disease (COVID-19) has led to over 2,589,638 deaths globally as of March 2021 and speedy discovery of vaccines. Nigeria started the phase one COVID-19 vaccination in March 2021 using the Oxford AstraZeneca vaccine. Reports of severe adverse events with the Oxford AstraZeneca vaccine resulted in its suspension in some countries necessitating the need to determine its safety. Aims: To assess the prevalence, types and severity of the adverse events following COVID-19 vaccination in Rivers State, Nigeria. Settings and Design: A cross-sectional study design was adopted. Subjects and Methods: Simple random sampling method was used to select a total of 428 adults from recipients of the first dose of COVID-19 vaccine within 28 days of vaccination. A questionnaire adapted from World Health Organisation was interviewer-administered through phone calls; responses were recorded on Kobo Toolbox. Statistical Analysis Used: Descriptive analysis of variables was done and the association between adverse events and age, allergy and medical history were determined. The level of statistical significance was predetermined at a P < 0.05. Results: In this study, 50.5% of respondents reported post-vaccination adverse events out of which 10 (4.6%) were severe (30% of the severe cases were life-threatening, 60% were hospitalised and 10% were placed on bed rest). The most common side effects were fever (73.0%), pain at the injection site (41.2%), fatigue (33.3%), body ache (17.5%) and headache (13.8%). No significant association was observed between the incidence of severe adverse events and participants with allergies or medical history. Conclusions: The adverse events associated with the COVID-19 vaccine were largely mild and resolved within a few days. Further research is required to classify adverse events into categories.