ABSTRACT
OBJECTIVE: To assess the short term safety of the COVID-19 vaccines Comirnaty (Pfizer-BioNTech BNT162b2) and Vaxzevria (AstraZeneca ChAdOx1) in Australia. DESIGN: Prospective observational cohort study; online surveys by AusVaxSafety, a national active vaccine safety surveillance system, three and eight days after vaccination. SETTING, PARTICIPANTS: People aged 16 years or more who received COVID-19 vaccines at sentinel vaccination hubs, general practices, or Aboriginal Community Controlled Health Organisation clinics, 22 February - 30 August 2021. MAIN OUTCOME MEASURES: Primary outcome: proportion of respondents who reported any adverse event following immunisation (AEFI) 0-3 days after vaccination. SECONDARY OUTCOMES: proportions of respondents who reported specific adverse events or medical review for AEFI within seven days of vaccination; impact on usual daily activities; recovery. RESULTS: 4 851 480 people received COVID-19 vaccines at participating sentinel sites during the study period (25% of all COVID-19 vaccine doses administered in Australia to 30 August 2021). 3 035 983 people responded to both surveys (response rate, 62.6%); 35.9% of respondents reported one or more AEFI 0-3 days after Comirnaty dose 1, 54.7% after Comirnaty dose 2, 52.8% after Vaxzevria dose 1, and 22.0% after Vaxzevria dose 2. Local pain, fatigue, headache, and myalgia were the most frequently reported symptoms. After adjusting for demographic characteristics, vaccination site type, jurisdiction, and self-reported medical conditions, the odds of reporting any AEFI were higher for women than men (range of adjusted odd ratios [aORs], by vaccine and dose, 1.53-1.84), for people with a history of anaphylaxis (aOR range, 1.28-1.45), and for people reporting certain underlying conditions, including obesity (aOR range, 1.15-1.75), immunodeficiency (aOR range, 1.04-2.24), or chronic inflammatory disease (aOR range, 1.05-1.75). 0.9% of respondents sought medical advice in the three days following vaccination, most frequently after Comirnaty dose 2 (1.4%) and Vaxzevria dose 1 (1.2%). CONCLUSION: AusVaxSafety active surveillance affirms the short term safety profile of Comirnaty and Vaxzevria vaccines in a large population sample during the first six months of the Australian COVID-19 vaccination program.