As the northern hemisphere braces itself for the flu season, and for the first time the US recommends flu vaccination for everyone over 6 months of age, Australia has confirmed that its main seasonal flu vaccine, Fluvax, caused convulsions in 99 children, all of whom recovered. Fluvax is made by the Australian firm CSL.
Epidemiologists insist that the benefits of flu vaccines outweigh the risks, however, and are calling for better surveillance to pick up occasional problems faster.
Last March, Australia started vaccinating ahead of the southern hemisphere’s flu season. All the drug firms’ vaccines contained three killed strains of flu, one of which was last year’s pandemic strain, which persists as the dominant seasonal virus in Australia, North America and elsewhere.
In early April, reports came in of children with fever and convulsions following vaccination. On 22 April Australia suspended flu vaccination for children under 5. In late July, vaccination resumed with other makers’ vaccines, but not CSL‘s Fluvax.
Fevers and convulsions
Last week the Australian Department of Health and Ageing reported that flu vaccination was “causally related” to fever and convulsions in 99 Australian children this year. Of those, 74 had no other possible cause, and Fluvax had been given to all 66 of those where the vaccine’s name was known, CSL says it is trying to identify the problem.
Fever is an occasional side effect in children given flu vaccines, and about 1.4 per 10,000 people vaccinated have seizures. High fever can cause seizures in 2 to 4 per cent of otherwise normal children 3 years and under, though no one is sure why. Fluvax caused seizures 50 times as often as would be expected with a vaccine.
In an analysis published in the journal Eurosurveillance, Heath Kelly, head of epidemiology at the state infectious diseases laboratory in Melbourne, calculates that Fluvax might have been worse than flu, causing two or three cases of convulsions for every case of flu it prevented that would have required a hospital stay during the pandemic.
But David Isaacs, professor of paediatric infectious diseases at the University of Sydney says the comparison is unfair. Children usually recover completely from fever-related seizures, though there can be brain damage in rare cases. By contrast, 1 per cent of children admitted to hospital with pandemic flu in Australia died.
Fluvax may well have prevented additional cases of convulsions caused by flu itself. In the biggest study so far of the neurological effects of the 2009 pandemic, Joshua Bonkowsky of the University of Utah reported last week that swine flu caused as many cases of neurological complications in five months as ordinary flu had in the previous four years. The most common were seizures. Moreover, the complications were more severe and lasting than ordinary flu. “Given how bad some of the complications from the H1N1 influenza were, we are really encouraging people to get vaccinated,” he says.
Kelly is also adamant about the need for vaccination. “The issue is not influenza vaccines in general, but one manufacturer’s vaccine in one year,” he says. “Such problems must be acknowledged rapidly on the rare occasions when they occur.”
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