Adverse events of Oxford/AstraZeneca's COVID-19 vaccine among health care workers of Ayder Comprehensive Specialized Hospital, Tigray, Ethiopia.

Background: : The safety of COVID vaccines should be continuously followed. This study reports adverse events of the Oxford/AstraZeneca COVID-19 vaccine.

Methods: : A prospective single-cohort study design was conducted to assess adverse events following immunization and associated factors of the first dose of Oxford/AstraZeneca's COVID-19 vaccine in Ayder Comprehensive specialized hospital. A structured questionnaire was administered consecutively to 423 participants. Follow-up data were collected 72 hours after vaccination via phone. Bivariate and multivariate logistic regression models were used to find associations between adverse events and independent variables. Statistical significance was declared at P <0.05.

Results: : Out of 423 health care workers approached, 395 responded. At least one adverse event (95% CI: 63.58, 72.77) was reported by 270 participants. Local and systemic symptoms occurred in 46.8% (95% CI: 41.94, 51.79) and 58.48% (95% CI: 53.53, 63.26)], respectively. Muscle ache, fatigue, headache and fever were the most common local symptoms. No reports of hospitalization, disability or death. Age (adjusted odds ratio [AOR]=0.97, P =0.048), female sex (AOR=1.84, P =0.028), and comorbidity (AOR=2.28, P =0.040) were independent predictors of adverse events.

Conclusion and recommendation: : Adverse events following immunization are commonly reported after the first dose of the Oxford/AstraZeneca COVID-19 vaccine; age, female sex and comorbidity are independent predictors.