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

OBJECTIVE

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.

DESIGN

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.

PARTICIPANTS AND

SETTING

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.

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

RESULTS

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.

CONCLUSIONS

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.