Short-Term Safety and Adverse Event Risk Profiles for SARS-CoV-2 Booster Vaccine Doses in Australian Adults: A Survey...

This study quantifies the short-term risk profiles of seven severe acute respiratory syndrome coronavirus 2 virus (SARS-CoV-2) vaccines-Comirnaty Bivalent BA.1, Comirnaty Bivalent BA.4-5, Comirnaty XBB.1.5, Spikevax Bivalent BA.1, Spikevax Bivalent BA.4-5, Spikevax XBB.1.5 and Nuvaxovid-administered as booster doses in Australia.

This is a survey study using data collected from online surveys sent via AusVaxSafety, the Australian active vaccine safety surveillance system, 3 days post-vaccination, soliciting reports of adverse events following vaccination.

Individuals 18 years and older who received a SARS-CoV-2 vaccine booster at an AusVaxSafety vaccine surveillance site between 1 January 2023 and 31 August 2024.

Bayesian logistic regression was used to estimate risk of reported adverse events, seeking medical advice and impact on daily activities.

Of 197,476 respondents, 59,089 (29.9%) reported at least one adverse event, of which the most commonly reported symptoms were injection site reaction (23.8% [46,988/197,476]) and fatigue (19.4% [38,352/197,476]). Symptom resolution was reported by 69.9% (41,299/59,089) by day 3 and 5.6% (11,006/197,476) reported any time lost from daily activities. The unadjusted proportion of respondents who sought medical advice was higher in those who received Spikevax XBB.1.5 (1.2% [212/17,551]) than the other vaccines (0.5% [379/69,493] to 0.7% [147/20,271]), but the modelled, adjusted mean risk of medical advice was similar (< 2.5%) across subgroups for vaccine brands, co-administered vaccines, medical conditions, age, sex and Indigenous status. The modelled risk of any adverse event at age 40 years ranged from 35.2% (95% credible interval [CrI], 32.2%-38.5%) for men who had received Comirnaty XBB.1.5 to 75.5% (95% CrI, 71.9%-78.8%) for women who had received Spikevax XBB.1.5. At age 80 years, this risk was lowest across all vaccines, ranging from 12.0% (95% CrI, 11.2%-13.0%) for men who had received Comirnaty BA4-5 to 36.7% (95% CrI, 34.6%-38.7%) for women who had received Spikevax XBB.1.5.

The results of this study confirm the short-term safety and low impact on daily living of SARS-CoV-2 booster vaccine administration to Australian adults.