Reactogenicity to ChAdOx1 nCoV-19 vaccine in health care workers: A multicenter observational study in Sri Lanka.

Introduction: 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. There is paucity of data on the systemic and local reactions experienced by COVD-19 vaccine recipients in South Asia.

Objectives: To identify the early local and systemic reactogenicity of ChAdOx1 nCoV-19 vaccine.

Method: A multicenter observational study was performed to identify the reactogenicity to ChAdOx1 nCoV-19 vaccine in healthcare workers following the first dose.

Results: 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 reactogenicity was reported by 4151 (92.7%). Local reactions were reported by 2612 (58.3%). 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. There was no association between reactogenicity and comorbidities. There were 342 (7.6%) reports of palpitations and one case of ventricular bigeminy. There was one report of anaphylaxis and hospital admissions were reported by 24 (0.5%). One vaccine recipient was managed for possible aseptic meningitis.

Conclusion: This study demonstrates that early systemic and local reactions are common. Systemic reactions were more frequent in females and in the younger population. Most symptoms were self- limiting and did not require medical attention or hospital admission. ChAdOx1 nCoV-19 vaccine appears safe in the studied population.