Flu vaccines given to children should be more rigorously tested before before being allowed onto the market, researchers say, to prevent a repeat of the 2010 vaccine release, which caused a spate of high fevers and febrile convulsions in young children.
The paper, published in the Medical Journal of Australia, reviews the regulatory history of CSL Fluvax trivalent influenza vaccine (TIV) in Australia and overseas and recommends a tougher licensing system to protect patient safety.
Australian health authorities estimate that the risk of febrile convulsions in young children after vaccination with CSL TIV ranged from three to ten per 1,000 children vaccinated in Australia, before the program was suspended in April 2010.
As a result, CSL TIV is no longer recommended for children less than five years of age in Australia, the United States and the United Kingdom.
The paper reports that in 2002 thiomersal-free CSL TIV was approved for use in Australia in people aged six months and older, even though no controlled clinical studies had been conducted in children.
"Ideally, adequately powered, controlled paediatric studies should be conducted before a vaccine is licensed for children," study authors Health Kelly and Nicholas Kelley say in the paper.
The first and only randomised controlled trial to date commenced in 2005 and was reported on in 2009, seven years after the vaccine was licensed for children in Australia.
The paper re-examined the data from that trial, which involved 298 children, aged less than nine years, who each received two doses of the 2005 formulation of TIV and a "booster" of the 2006 formulation, which had different virus antigens.
"The study results, published in 2009, showed a marked difference between the risk of reported fever, depending on the annual formulation of the CSL TIV administered," the new paper said.
Once a flu vaccine is licensed for use in Australia, the manufacturer is able to alter the formulation of the vaccine each year to protect against new flu strains that may be circulating.
Professor Robert Booy, Professor and Head of Clinical Research, National Centre for Immunisation Research and Surveillance (NCIRS) at University of Sydney said this was an important paper that deserved recognition.
"More research is needed before flu vaccines are introduced," he said.
"At NCIRS we have been conducting a systematic review of all relevant literature, published or not.
"We hope the various pharmaceutical companies will cooperate with us in providing anonymised individual level data."
Professor Booy said he agreed with the authors that thorough post-marketing monitoring for adverse events after all paediatric flu vaccines was essential and proposed an integrated yearly study involving at least 1,000 children per year for the next three years.
Professor Anton Middelberg, Deputy Director of The Australian Institute for Bioengineering and Nanotechnology at the The University of Queensland said the study served as a reminder of the need to strictly control vaccine manufacture processes.
"Vaccine quality, and adverse effects, have on occasion been linked to variations in batch-to-batch manufacture," Professor Middelberg said.
"Subtle changes in process conditions can magnify in a chaotic fashion to compromise product quality, if not fundamentally understood and strictly controlled," he said.
"The problems become more acute when old technology is pushed to operate more quickly than it is designed to do, for example, when we are faced with a pandemic.
"There is a clear need for new, quicker and better-understood vaccine manufacture technology."
More information: www.mja.com.au/journal/2013/198/7/evidence-based-policies-control-influenza