Challenges in regulating influenza vaccines for children

Lessons need to be drawn from the assessment and licensing of influenza vaccines in previous years

In April 2010, Australia suspended paediatric influenza vaccinations as a result of febrile convulsions associated with seasonal trivalent influenza vaccine (TIV). Epidemiological investigations have established that the increase in febrile reactions was limited to one of three brands of TIV used in Australia that year — CSL Biotherapies Fluvax or Fluvax Junior (CSL TIV), registered as Afluria in the United States and Enzira in the United Kingdom.1-3 Health authorities in Australia estimated that the risk of febrile convulsions in children aged 6 months to 4 years after vaccination with CSL 2010 TIV ranged from 3–10 per 1000 vaccinated.1,3 This figure is remarkable because TIV has an excellent safety record in children and before 2010 was only rarely associated with febrile convulsions. The largest published population-based study found only one febrile convulsion after TIV vaccination of 45 356 children aged 6–23 months,4 giving a risk estimate of 2.2 convulsions per 100 000. Nonetheless, age-related differences in the reactogenicity of influenza vaccines and the potential for influenza vaccines to cause febrile reactions in children had been recognised for decades.5 Reviewing the regulatory history of the CSL influenza vaccine for children (Box) suggests there may be opportunities for improving the licensure of paediatric influenza vaccines.