How many Aussies had a short term reaction to their first two COVID-19 vaccines?

ACTIVE surveillance by AusVaxSafety has confirmed the short-term safety of the COVID-19 vaccines Cominarty (Pfizer-BioNTech BNT162b2) and Vaxzevria (AstraZeneca ChAdOx1) in the Australian context.

In the largest published post-marketing analysis of the safety of Comirnaty and Vaxzevria to date, data was analysed from 3 035 983 people who received COVID-19 vaccines at participating sentinel sites between 22 February ‒ 30 August 2021.

Led by AusVaxSafety, the Australian active vaccine safety surveillance system led by the National Centre for Immunisation Research and Surveillance (NCIRS), researchers found that adverse events were more frequently reported by people with underlying medical conditions, including a history of anaphylaxis. Adverse event frequency was similar for Indigenous people and other Australians.


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“[We found that] 35.9% of respondents reported one or more adverse events following immunization (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,” Deng and colleagues reported.

“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, for people with a history of anaphylaxis, and for people reporting certain underlying conditions, including obesity, immunodeficiency, or chronic inflammatory disease.

“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%).”

The surveillance program included frontline workers from February 2021, older adults, people with underlying medical conditions, and Indigenous Australians from March 2021, and the general population from July 2021.

“The frequency rates of adverse events in our study were higher than for other vaccines used in Australia, perhaps because mRNA and viral vector vaccines more often elicit transient mild to moderate side effects than other vaccine types,” Deng and colleagues wrote.

“Most reported AEFIs were short-lived, and a lower proportion of respondents reported AEFIs in the day 8 surveys than in the day 3 surveys. An impact of symptoms on daily activities was most frequently reported after the second Comirnaty dose and the first Vaxzevria dose.

“AusVaxSafety continues to monitor COVID-19 vaccine safety in Australia, including that of booster and future doses as our vaccination program evolves,” the authors concluded.

IMAGE CREDIT: Annie Spratt on Unsplash

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