Swine flu vaccine  Fever

Opinion: Unnecessary injection of risk: vaccination


May1, 2010

VACCINATION is one of the most important public health measures in history, but there have been problems with this year's seasonal plus swine flu vaccine. It has been withdrawn for young children because of adverse side effects experienced by numbers of children across various states, involving different batches of vaccine.

Health departments still recommend the stand-alone swine flu vaccine Panvax Junior for youngsters, even though Panvax was associated with fever in more than 30 per cent of children under three in the only published study on its use, funded by pharmaceutical manufacturer CSL and reported last year in The Journal of the American Medical Association.

Although media reports so far suggest the seasonal flu vaccine causes worse side effects in young children, Panvax also has caused side effects such as fever in children of all ages.

That's why I don't think it's a good idea to give Panvax to children until we have further data, based on a study of a large group of children, which shows no significant increased rates of fever and other side effects associated with its use.

Fever was a common reaction in all children receiving the swine flu vaccine and, not surprisingly, febrile convulsions were also likely to occur more frequently in vaccinated children, with large numbers being taken to doctors or hospitals with high fever.

Reports suggest that of the 20,000 to 30,000 children vaccinated in Western Australia, 250 had adverse reactions and 55 had febrile convulsions. This means that about one child in every 500 vaccinated had a febrile convulsion, a very high rate.

Internationally, there's relatively little data on the effects of vaccinating young children against influenza. Some pharmaceutical companies have even withheld data they possess from clinical studies.

The recent CSL study in which 370 Australian children received the H1N1 vaccine has greatly increased the available data.

This data shows that a large percentage of children had fever following vaccination. It also shows a dose response effect -- the larger the vaccine dose, the greater the side effects -- and an age relationship: the younger the child, the more side effects they experienced. Children under three developed more than twice the rate of fever after vaccination compared with older children.

Overall, 25 per cent of children receiving the 15 microgram vaccine dose developed a fever and 41 per cent of those who received the 30mcg dose got a fever.

This was the data used by Australia's regulatory body, the Therapeutic Goods Administration, to approve this vaccine for use in children.

Breaking that down further, the percentages of children under three who developed a fever after vaccination were very high: 35.4 per cent of those given a 15mcg dose and 62 per cent of those given the larger dose.

In many cases, the fever was high. Response was classified as a moderate or severe systemic reaction -- more than over 38.5C -- in 14.6 per cent and 30.4 per cent of those receiving the low and high doses respectively.

Why did such a high percentage of children develop fevers after the swine flu vaccine?

I think it is likely that many were already immune. So when when they were again exposed to swine flu components, this time in the vaccine, they mounted a brisk immune response that included fever.

That's possible, as it is estimated that half of all Australian children were infected with swine flu last winter.

The CSL study was conducted in October, when Australia was already well past the July peak of swine flu. Although children known to have previously been infected with swine flu were excluded from the study, many may have had asymptomatic or mild swine flu infections.

It would be possible to test this idea by re-examining the data in the CSL study to see if there's any relationship between pre-existing antibodies at any level and subsequent reactions.

If this isn't the explanation, we need to quickly pursue and investigate other explanations since we need to know why we've seen such high rates of febrile reactions.

A large number of children across Australia have been taken to hospitals with fevers or febrile seizures after receiving vaccines designed to protect them against swine and seasonal flu.

We know from the CSL study that if we inject children with swine flu vaccines, a high percentage of them are likely to develop fevers of more than 38.5C. We also know that those who get a fever are at risk of developing potentially dangerous febrile convulsions. Given these findings, I again argue that -- until further studies show that fever is infrequent in children after receiving influenza vaccines -- we should only vaccinate children with serious risk factors such as underlying heart, lung or neurological diseases.

Last winter, the likelihood that a child without risk factors would die from swine flu was less than one in a million. When such a high proportion of children develop moderate to severe febrile reactions to the influenza vaccine, it's likely that we'll cause more harm than good by vaccinating the entire population.

I remain surprised that a vaccine that produces fever in such a high proportion of children, especially those under three, was allowed to be used in Australia without explicit warnings to parents and without any formal, prospective, post-marketing surveillance to look at this issue in large numbers of children.

Peter Collignon, a professor at the Australian National University, is an infectious diseases physician and clinical microbiologist.