Reactogenicity Following the First Dose of ChAdOx1 nCoV-19 Vaccine Against SARS-CoV-2: A Multicenter Observational Study

Abstract

Background: The acceptability of a vaccine is an important factor during mass vaccination programs and this is largely dependent on the symptoms of local and systemic reactogenicity. The objective of this study was to identify the symptoms of reactogenicity within eight days following vaccination with the ChAdOx1 nCoV-19 vaccine. \n \nMethods: A multicenter study was performed to identify the reactogenicity of ChAdOx1 nCoV-19 vaccine in health care workers of five selected hospitals. Healthcare workers who received the vaccine over four days from 29.01.2021 were included. The local and systemic symptoms of reactogenicity occurring within eight days of vaccination were recorded using an electronic or paper-based form. \n \nFindings: There were 4478 participants with a median age of 42 years (IQR 34-51) and 2863 (63·9%) were females. At least one symptom of local or systemic reactogenicity was reported by 4151 (92·7%). Local reactions were reported by 2612 (58·3%) with two receiving antibiotics. Anaphylaxis was noted in one vaccine recipient and 2 (0·04%) reported urticaria. Commonest systemic reactions were bodyache (3244,72·4%), fatigue (2379, 53·1%), headache (2277, 50·8%), fever (2290, 51·1%), feverishness (1912, 42·7%) and chills (2295, 51·3%). Lower age (p<0·0001) and female gender (p 0·002) were associated with a higher frequency of developing systemic reactions in the study group. Hospital admissions were reported by 24 (0·5%) vaccine recipients for severe systemic symptoms. There were 342 (7·6%) reports of palpitations and one hospital admission due to ventricular bigeminy. One healthcare worker was hospitalized for possible aseptic meningitis. \n \nInterpretation: This study demonstrates that early systemic and local reactions are common. Most symptoms were self-limiting and did not require medical attention or hospital admission. Systemic reactions were less frequent in males and reduced with increasing age. ChAdOx1 nCoV-19 vaccine appears safe in the studied population. \n \nFunding Information: This study did not receive any funding. \n \nDeclaration of Interests: All authors do not declare any competing interests. \n \nEthics Approval Statement: Approval was obtained from the Ethics Review Committee of University of Sri Jayewardenepura (number COVID 02/21) for the study and administrative approval was taken from the Ministry of Health of Sri Lanka and administrators of the study centers.