Pandemic (H1N1) influenza vaccine: Suspected adverse reactions to Panvax reported to the TGA

30 September 2009 to 17 September 2010

6 October 2010

The national immunisation program with Panvax® began on 30 September 2009. The TGA has been closely monitoring any side effects from the use of the vaccine.

As at 17 September 2010 a total of 1960 suspected side effects had been reported to the TGA following vaccination with Panvax® in Australia. The great majority of reported side effects have been mild and common problems such as headache, gastrointestinal upset, and soreness, swelling, or redness at the injection site. Most of the side effects that have been reported are well recognised and listed in the Panvax® Product Information. Of the suspected side effects reported, only 190 related to Panvax Junior®, and the majority of these reports were of fever (151) and/or vomiting (98).

The TGA's assessment remains that Panvax® is a safe, effective vaccine for prevention of the H1N1 influenza.

Further information about the vaccine may be found at Health Emergency.

Common side effects reported to date

Common side-effects reported following Panvax® administration are shown in the table.

Suspected adverse reaction Number of reports for PANVAX®*
Nausea, vomiting or diarrhoea 697
Headache 343
Fatigue, lethargy, general weakness 300
Fever 491
Cough, runny nose or sore throat; flu-like symptoms 414
Injection site reaction 277
Pain (including muscle or joint pain; excluding injection site pain) 505

*The sum of the common side effects exceeds the total number of reports because each report can contain more than 1 reaction, for example, an injection site reaction and flu-like symptoms.

Febrile convulsions are regarded as a rare complication of influenza vaccination with the expected occurrence rate in the published product information described as between 1 in 1,000 and 1 in 10,000 people vaccinated. As at 17 September 2010 the TGA had received 48 reports of febrile convulsions in children following Panvax/Panvax Jr administration. However, of the 48 reports, 6 were considered not to be febrile convulsions on detailed clinical review; and a further 5 occurred in children with a concurrent illness that could have given rise to a fever or febrile convulsion. In addition, 9 children received one or more other vaccines at the same time as the Panvax, and a further 6 reports were of febrile convulsions occurring more than 24 hours post-vaccination. Cases occurring more than 24 hours post-vaccination are considered unlikely to be the result of a reaction to the influenza vaccine. Nine of these had occurred in children who had also been given other vaccines at the same time as they received Panvax. Febrile convulsions are regarded as a rare complication of influenza vaccination with the expected occurrence rate in the published product information described as between 1 in 1,000 and 1 in 10,000 people vaccinated. A joint TGA and Australian Technical Advisory Group on Immunisation (ATAGI) working group has undertaken a detailed analysis of the rate of febrile convulsions associated with Panvax vaccine based on analysis of available state and national data. The working group estimates that the rate of febrile convulsions with Panvax lies between 0.08/1000 and 0.18/1000, which equates approximately to a rate of between 1 in 5000 and 1 in 12,000 doses administered. This estimate is within the predicted rate for influenza vaccines as highlighted in the Product Information for prescribers and vaccine providers, and is less than the 7.0/1000 estimated rate of febrile convulsions reported in associated with Fluvax. See the Analysis of Febrile Convulsions Following Immunisation in Children Following Monovalent Pandemic H1N1 Vaccine (Panvax®/Panvax Junior®, CSL) report.

As a result of concerns regarding a possible association between influenza vaccines and the development of a rare condition known as Guillain-Barré syndrome (GBS), the TGA is continuing to closely monitor the rate of GBS in the Australian community during the Panvax® immunisation program. However, based on all evidence available, and following advice from its independent expert advisory committees, the TGA has concluded that there is no evidence of an increased rate of GBS in people receiving Panvax® compared with that normally seen in the community. In Australia there are approximately 100 new cases of GBS every three months. Viral and bacterial infections, especially food poisoning and acute respiratory tract infections are the commonest precursors to GBS. The TGA has received 10 reports of GBS in people who had received the vaccine and there have been no new reports in the last 3 months. Similar analyses of data relating to GBS by overseas medicines regulators including in the US, Canada and Europe have concluded that there is no evidence of an increased rate of GBS in people receiving the H1N1 influenza vaccine. The World Health Organization has also confirmed that although some cases of GBS have been reported after receipt of pandemic (H1N1) 2009 vaccines, the evidence to date is reassuring, with no increase in reporting rates above what is expected based on background rates1.

An important category of possible reactions to any vaccine is allergy. Severe allergic reactions, such as anaphylaxis, may require adrenaline injections or other treatment, which is the reason why all persons providing vaccines must have the necessary drugs and equipment available. The occurrence of anaphylaxis and allergic reactions is not predictable and can occur in anyone regardless of whether they have a previous history of allergy or not. Anaphylaxis is a rare event but healthcare professionals and patients should be aware of its possible occurrence. As at 17 September 2010, the TGA had received 11 reports of possible anaphylaxis following vaccination with Panvax®. The TGA, together with its expert advisory committees, has thoroughly investigated the details of these suspected cases of anaphylaxis. Using the Brighton Collaboration case definition for anaphylaxis2, the TGA, following advice from its expert advisory committees, has concluded that, based on distribution figures for Panvax®, the current observed rate of anaphylaxis is within the range expected for post-immunisation. All cases reported to the TGA to date have either been treated appropriately or have resolved without treatment.

The TGA continues to work closely with its international regulatory partners and the World Health Organization to detect and respond to any safety signals that may emerge as the H1N1 influenza vaccine is used around the world.

Reference

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  1. WHO Weekly epidemiological record, No. 5, 2010, 85, 29-36 (pdf,749kb)*
  2. Rüggeberg JU, Gold MS, Bayas J-M, Blum MD et al. Anaphylaxis: Case definition and guidelines for data collection, analysis, and presentation of immunization safety data. Vaccine 2007; 25: 5675-5684.

How to report a suspected side effect to Panvax®

Healthcare practitioners and consumers are encouraged to report any suspected adverse events following immunisation with Panvax® by using the online reporting form available from the TGA website.