What is Vaccine Safety Surveillance?
In simple terms, vaccine safety surveillance is the ongoing process of checking that vaccines remain safe.
How Does the Australian Vaccine Safety Surveillance System Work?
In general, the safety information available for vaccines and drugs is largely based on the data obtained from large clinical trials. However, even in clinical trial some adverse reactions to vaccines may be missed, particularly if these are rare, delayed, occur in populations with risk factors or result from vaccine combinations not evaluated in trials. For certain vaccines such as the seasonal influenza vaccine, extensive trials are not feasible due to the limited time between strain identification and the requirement for vaccination prior to the onset of winter.
What Is an Adverse Event Following Immunisation?
An adverse event following immunisation (AEFI) is any untoward medical occurrence which follows immunisation and which does not necessarily have a causal relationship with the usage of the vaccine.
The adverse event may be any unfavorable or unintended sign, abnormal laboratory finding, symptom or disease.
For more information on AEFI and their clinical management, please visit Immunise Australia.
How Is an AEFI Reported?
The safety assessment of vaccines prior to (and following) their public release is conducted by Australia’s medicines regulatory agency, the Therapeutic Goods Administration (TGA).
In Australia, the current way of reporting AEFI is voluntary and is called "passive" reporting. Adverse events can be reported by consumers or their doctor, nurse or by a hospital. Each adverse event is investigated independently by each State Health authority. If the case requires further investigation, the TGA will assess the case and take appropriate action.
Adverse events can be either reported to the TGA or the State Health Departments. For more information on how to report in each Australian state, please refer to the section "How to report an adverse event" in the Immunise Australia website.
Is There a Difference Between an Adverse Event and an Adverse Reaction?
The TGA maintains a searchable database of adverse events notifications; DAEN. However, it is essential to distinguish between an adverse event and an adverse reaction. An adverse event report does not mean that the vaccine is the cause of the adverse event. Adverse event and adverse reaction are fundamentally different.
To establish if the vaccine caused the adverse event, it is necessary to conduct an assessment – only if the causality link has been confirmed the adverse event can be called an adverse reaction.
This monitoring process is therefore important in making a decision about the safety of a vaccine, and can lead to issuing a safety alert, changing the product labelling, adding warnings, or even de-registering the vaccine.
Post-marketing surveillance of all vaccines therefore remains critical for identifying any further adverse vaccine reactions and completing a detailed safety evaluation.