Adverse Events Following Immunisation (AEFIs)

Adverse events following immunisation (AEFIs) can understandably cause concern for patients and providers alike. However, it's important to understand what they are—and what they are not. As defined in The Australian Immunisation Handbook, an AEFI is any untoward medical occurrence that follows immunisation, regardless of whether the vaccine caused it.

While most post-vaccine reactions are mild and expected—like a low-grade fever or tenderness at the injection site—more serious reactions are rare. Still, it’s vital for immunisation providers to know how to identify, manage, and report these events appropriately.

This page outlines what qualifies as an AEFI, what to expect after immunisation, when and how to report, and where to find resources to support patients and clinical decision-making.