Volume 195 - Issue 1
Ensuring safety of the 2011 trivalent influenza vaccine in young children
Authors: Christopher C Blyth, Tracy Y Markus, Paul V Effler and Peter C Richmond
Med J Aust 2011; 195 (1): 52. || doi: 10.5694/j.1326-5377.2011.tb03194.x
Published online: 4 July 2011
Published online: 4 July 2011
To the Editor: Young children are at increased risk of severe influenza compared with the general population. Routine vaccination of children using trivalent influenza vaccine (TIV) is recommended in the United States and Canada. The Western Australian government, with support from vaccine manufacturers, has been providing TIV free of charge to all children aged 6–59 months since 2008.1
In 2010, high fevers and an increased incidence of convulsions were observed in children aged < 5 years after administration of TIV. Most reports of adverse events were from WA, owing to higher uptake of vaccination associated with the free vaccination program. The national influenza vaccination program for children aged < 5 years was subsequently suspended,2 and high rates of fever and convulsions were confirmed.2,3 The majority of adverse events occurred after administration of Fluvax or Fluvax Junior (CSL Biotherapies). More than 50% of parents of children who were administered Fluvax or Fluvax Junior reported high fever after vaccination. The incidence of febrile convulsions after vaccination with Fluvax and Fluvax Junior was 4.4 per 1000 doses, significantly higher than expected.3,4 Fluvax and Fluvax Junior are not recommended for children aged < 5 years in the Australian 2011 influenza vaccination program.5
In response to these events, WA Health established an online registry for vaccine-associated adverse events — the Western Australian Vaccine Safety Surveillance (WAVSS). Health professionals are required and members of the public encouraged to report adverse events. In addition, a prospective safety study of the 2011 TIV in children aged < 5 years has commenced at Princess Margaret Hospital for Children and the WA Central Immunisation Clinic.
From 15 March to 29 April 2011, 2227 doses of TIV were administered to children aged < 5 years in WA (2130 doses of Vaxigrip [Sanofi Pasteur]; 97 doses of Influvac [Solvay]). Adverse events in four children aged < 5 years have been reported via WAVSS: two with elevated temperature (≥38°C yet < 39.5°C) within 24 hours of vaccination, one with vomiting and diarrhoea after vaccination, and one with fever (not specified) and convulsions 4 days after vaccination (this child had a respiratory tract infection at the time of vaccination). All four children were administered other vaccines with TIV.
In the safety study, 144 children were enrolled between 15 March and 29 April 2011. Adverse events after vaccination were reported in 10 children (7%), two of whom received other vaccines in addition to TIV. All 10 children had fever reported, and one child had a temperature > 39.5°C. Two children developed vomiting. No convulsions were reported and none of the children who had adverse events required assistance from a health care professional.
These data demonstrate that the significant adverse events that occurred after administration of TIV in 2010 have not been observed in WA during early 2011. Ongoing surveillance is underway and will continue. Poor uptake of influenza vaccination in Australian children is likely to result in increased influenza-related hospitalisation, morbidity and mortality. Data such as those reported here are required to reassure the community of the safety of this vaccination program before the expected start of the 2011 influenza season.
Competing interests
Christopher Blyth, Tracy Markus and Peter Richmond are members of the Vaccine Trials Group. The Vaccine Trials Group has received funding for research from vaccine providers including CSL Biotherapies, Sanofi Pasteur and GlaxoSmithKline. Peter Richmond has also previously been a member of a CSL Limited vaccine advisory board.
Acknowledgements
We thank Christine Baker, Dale Carcione, Christine Robins, Caroline Wharton, Filomena Mascaro and Nicky Conway for assisting with collation of data.
References
- Dixon GA, Moore HC, Kelly H, et al. Lessons from the first year of the WAIVE study investigating the protective effect of influenza vaccine against laboratory-confirmed influenza in hospitalised children aged 6–59 months. Influenza Other Respi Viruses 2010; 4: 231-234. 0_BABEJAJH
- Department of Health and Ageing, Therapeutic Goods Administration. Investigation into febrile reactions in young children following 2010 seasonal trivalent influenza vaccination: status report as at 2 July 2010 (updated 24 September 2010). Canberra: TGA, 2010. http://www.tga.gov.au/safety/alerts-medicine-seasonal-flu-100702.htm#fullreport (accessed May 2011).
- Armstrong PK, Dowse GK, Effler PV, et al. Epidemiological study of severe febrile reactions in young children in Western Australia caused by a 2010 trivalent inactivated influenza vaccine. BMJ Open 2011. In press. 0_BABBCCEE
- Blyth CC, Currie AJ, Wiertsema SP, et al. Trivalent influenza vaccine and febrile adverse events in Australia, 2010: clinical features and potential mechanisms. Vaccine 2011. In press. doi: 10.1016/j.vaccine.2011.05.054. 0_pgfId-2353145
- CSL Biotherapies. Fluvax. Product information, October 2010. http://secure.healthlinks.net.au/content/csl/pi.cfm?product=cspfluva11010 (accessed Apr 2011).