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With millions of flu vaccines administered every year, monitoring their safety is crucial.
As misinformation about the safety of vaccines continues to spread online, many people may be unaware that Australia has a robust process of vaccine pharmacovigilance, which monitors vaccine safety to detect any adverse events following immunisation (AEFI).
In a perspective published in the Medical Journal of Australia, researchers from the Therapeutic Goods Administration (TGA), the National Centre for Immunisation Research and Surveillance, and the Telethon Kids Institute, have outlined the processes used to monitor seasonal influenza vaccines for safety.
“This article aims to support the seasonal influenza vaccine program by providing confidence in the robust national pharmacovigilance processes for seasonal influenza vaccines in Australia,” the authors wrote.
Annual influenza vaccination is recommended for all people aged six months and over, and is available free for many people.
Approximately 9 million influenza vaccines were administered in Australia in 2023 — a significant drop from the 11 million vaccines administered in 2022.
Due to the widespread distribution of flu vaccines, it is imperative that pharmacovigilance systems are quick to respond to any AEFI.
“The purpose of these pharmacovigilance systems is to monitor for unexpected types and rates of AEFI, including rare and population-specific events,” the authors wrote.
“The identification and investigation of potential safety concerns is a key function of these systems, with the TGA also focused on ensuring that vaccines registered for use in Australia maintain a favourable benefit–risk profile.”
Multiple methods of surveillance
Vaccine pharmacovigilance is a collaborative process between the TGA, the nationally funded surveillance initiative AusVaxSafety, and state and territory health departments.
The TGA receives reports of any AEFI submitted by health care professionals, pharmaceutical companies, state and territory health departments, and the public, and these reports are entered into a national database.
Vaccines are also monitored through other national and international data, data mining algorithms, and, in the case of seasonal influenza vaccines, monthly safety surveillance reports throughout the influenza season.
Serious adverse events that would warrant further investigation include any events that cause fatal or life-threatening conditions, new or prolonged hospitalisation, persistent or significant disability, birth defects, or any medical event that requires intervention to prevent serious adverse events.
“The TGA identifies and reviews cases of regulatory significance, including serious AEFI reports of concern, and may consider convening the Vaccine Safety Investigation Group when an AEFI of concern is identified that has the potential to change the favourable benefit–risk balance of a vaccine, or affect public confidence in vaccine safety,” the authors wrote.
“The outcomes from the Vaccine Safety Investigation Group are publicly available and serve to inform regulatory action and the vaccine program.”
AusVaxSafety has also actively monitored influenza vaccine safety since 2014 using surveys, which are sent to vaccine recipients via SMS or email three days after vaccination.
The survey results are reported to the TGA, the Department of Health and Aged Care, and state and territory jurisdictions.
The challenges of monitoring flu vaccine safety
Despite comprehensive surveillance programs, the authors note there are ongoing challenges when it comes to monitoring adverse effects from influenza vaccines.
Under-reporting and incomplete reports can undermine data in the system, especially in the case of patient self-reporting.
“The quality of information provided in these self-reports and the presence of missing data may have an impact on safety signal detection and investigation,” the authors wrote.
“Reporters are encouraged to provide as much information as possible either at the time of reporting an adverse event, or when further information is sought.”
Long term and late onset reactions to vaccines are also difficult to capture in surveillance surveys, and clinicians are encouraged to be aware of late-onset conditions and report any such incidents to the TGA.
To maintain ongoing improvements in pharmacovigilance systems, the TGA is currently working on improvements to AEFI data quality, as well as functionality of the database system itself.
They are also developing educational models to support health practitioners in engaging with adverse event reporting.
“The TGA and AusVaxSafety recognise the importance of providing timely and transparent information on seasonal influenza vaccine safety to the Australian public,” the authors wrote.
“Close collaboration between national pharmacovigilance systems continues to support the health and safety of Australians through close monitoring of seasonal influenza vaccines and rapid communication of any emerging safety signals.”
Read the perspective in the Medical Journal of Australia.
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