Authorities are no closer to determining what caused hundreds of adverse reactions in the under 5s receiving the 2010 trivalent influenza vaccine.

But investigations are being hampered somewhat, due to a software glitch which has prevented optimum recording of doses on the Australian Childhood Immunisation Register (ACIR).

A spokesperson for Medicare Australia, which administers ACIR, said they were aware that software had affected the transmission of data from some practices, and were advising all providers to review products.

The Western Australian Department of Health issued a letter to providers on May 6th;

“One of the major deficiencies in interpreting the data is the lack of reliable information on numbers of children vaccinated, including the brand and batch of vaccine used. This has arisen because of problems with the transfer of influenza vaccination data from practice software systems to the ACIR.”
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“Better data on total numbers of children vaccinated and the brands/batches used will allow calculation of rates of adverse events, and a clearer determination as to whether the risk is truly elevated compared to expectation (e.g. relative to the 2008 and 2009 WA programs and international experience), and whether any increase is specific to a particular vaccine brand or batch used.”

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They are also asking for providers to supply them with the numbers of children having received the vaccine manually.

“Because uncertainty remains as to how effective the ACIR upload approach may be, WA DoH would be very grateful if you could also complete the attached form, indicating numbers of children vaccinated with a trivalent influenza vaccine between the dates of 8 March and 23 April 2010, by age group, vaccine brand and batch. This information will also help to clarify how well influenza vaccination data entered in practice software systems is being transferred to ACIR.”

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The latest figures indicate 400 cases of fever and 77 convulsions in five states. Those reports led the Chief Medical Officer to suspend flu vaccination in all children younger than five years.

Associate Professor Richmond, a consultant at Princess Margaret hospital, (where most of the cases have appeared), and head of the WA influenza vaccine trial, said the adverse events this year appeared excessive compared to last year when 60,000 children – around half of the eligible cohort – received free influenza vaccine funded by the West Australian Government.

“The original whole flu virus seemed to be associated with more fevers, but now the virus gets split. So that will be something people will be looking at – is there more or less flu virus in this year’s vaccine which could be causing problems.”

However, some children who presented at hospital with high fever had gone on to have a second dose of vaccine without incident, he said.

In Australia the flu season is rapidly approaching, resulting in a rush on the vaccine for those still eligible and a subsequent exhaustion of supplies.

Those most vulnerable to such flu complications are adults over 65, especially those in nursing homes and kids under 2. Kids under 5 have been at higher risk of swine flu complications.

In Australia in 2009 there 47, 736 cases of laboratory confirmed influenza and so far in 2010 there have been 488.

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