Adverse events associated with AstraZeneca COVID-19 vaccine among adults in Greater Kampala, Uganda: a cross-sectional study

Abstract Background: Tracking adverse events helps to assess vaccine safety. Uganda rolled out the AstraZeneca vaccination in March 2021 primarily targeting teachers, health workers, security personnel, and older persons. However, information about adverse events following the nationwide rollout of the AstraZeneca vaccination in Uganda is limited. We, therefore, assessed the prevalence and factors associated with adverse events following AstraZeneca vaccination among adults in the Greater Kampala region in Uganda. Methods: We used routinely collected data about AstraZeneca vaccination to identify persons who received ≥1 dose of the vaccine. Data were collected between March 10 and April 30, 2021, through telephone interviews with a random sample of vaccinated individuals. We defined adverse events as any untoward medical occurrence after vaccination and serious adverse events as any event leading to hospitalization, persistent disability ˃28 days, death, or congenital anomaly. We summarized data descriptively, performed bivariate analysis, and determined the factors independently associated with adverse events using multivariable logistic regression, expressed as adjusted odds ratio (AOR) and 95% confidence interval (CI). Results: We studied 374 participants aged 20-85 years and found 235 (62.8%) had received only the first dose of the Astra-Zeneca vaccine while 139 (37.2%) received two doses of the vaccine. The prevalence of adverse events was 76.5% and the common adverse events included injection site redness, pain, itching, and headache but no serious adverse event was reported. Participants aged 20–29 years (AOR 4.58; 95% CI: 1.92–10.95), 30-39 years (AOR 3.69; 95% CI: 1.81–7.51) and 40-49 years (AOR 2.78; 95% CI 1.26–4.90) were more likely to develop adverse events compared to those aged ≥50 years. Conclusion: Adverse events are prevalent among persons vaccinated with the Astra-Zeneca vaccine, largely among those below 50 years old. However, serious adverse events are rare. Persons <50 years old should be targeted for surveillance of adverse events and receive appropriate health education and counseling.