Safety and Reactogenicity of the ChAdOx1 (AZD1222) COVID-19 Vaccine in Saudi Arabia

Introduction: The Kingdom of Saudi Arabia was one of the first countries to implement a COVID-19 vaccination program. This study estimated the safety and reactogenicity of the ChAdOx1-S vaccine after the first dose administered to adults. Methods: This cross-sectional study included 1592 randomly selected vaccinees from April to May 2021. A questionnaire was delivered to the vaccinees via phone calls 7 and 21 days after the first vaccine dose. Results: Of the 1592 vaccinees who had the first dose, the mean age was 37.4 (± 9.6) years and 81% were males. Of all the vaccinees, 553 (34.7%) reported an adverse reaction on the first telephone call. The most common symptoms were: pain at the site of injection (485, 30.5%), musculoskeletal symptoms (438, 27.5%), skin rash (307, 19.2%), gastrointestinal symptoms (379, 23.8%) and fever (498, 31.3%). Men were more likely to report fever (76.9% vs. 23.1%; P = 0.005), skin rash (81.1% vs. 18.9%, P = 0.005) and pain at the injection site (77.3% vs. 22.7%, P < 0.0001). Post-vaccine COVID-19 infection was 0.5% and there were no hospitalizations. Conclusion: This study observed no major side effects of the ChAdOx1-S vaccine and no reported breakthrough infection during the observation period.