Friday, April 30, 2010

A shot in the dark


Fears are mounting over flu vaccinations for young children


With the recent reports of young children suffering adverse reactions after receiving the seasonal flu shot, I thought I’d do a bit of research into what’s really going on.
When it appears “vaccinations have gone wrong” it adds fuel to the fire of anti-vaccinators, and puts fear in the hearts of parents.
At the time of writing this column, 251 children in the past month in Western Australia had fevers after getting the seasonal flu vaccine. At least 55 were taken to hospital suffering fits, fevers and vomiting. This week we also learned that a two-year-old girl died in Brisbane the day after she, and her twin sister, had the flu shot in early April. So far this year in Queensland 15 children aged five and under have experienced adverse reactions to the vaccine. And a child in Darwin has been admitted to hospital with fever and convulsions following vaccination. There have been no similar reported cases in other states.
On April 23, a national vaccination ban was enforced for children under five. Health authorities across the country are on alert. Australia’s Chief Medical Officer, Professor Jim Bishop, has ordered a review of hospital records to understand and determine the scope of the problem.
The maker of the vaccine, CSL, has stopped distributing children’s doses, and samples from WA are being tested for abnormalities.
It is too early to know whether the batch was contaminated or a virus was already circulating which, when combined with the vaccination, resulted in convulsions.
So what exactly is in this year’s seasonal flu vaccine?

For the first time in Australia, the flu shot rolled out last month combined two strains of seasonal flu (Influenza A and B) as well as H1N1 (swine flu). The Panvax H1N1 vaccine was tested on 400 children aged between 6 months and 9 years before its release last year, and was shown to be safe. The trial data was evaluated by the Therapeutic Goods Administration (TGA) and reviewed by the Australian Drug Evaluation Committee (ADEC). Both found the vaccine was best administered in two doses not less than 28 days apart.
This junior vaccine does not contain the preservative thiomersal, which is widely assumed by anti-vaccinators to cause developmental or neurological abnormalities, even though this theory has been proven false.
In fact, thiomersal was removed from all vaccines in Australia given to young children to reassure parents. While thiomersal is not in junior vaccines, it is still used in adult doses.
A lot of people are unnerved that clinical tests were not carried out on this year’s seasonal flu vaccine, even though it was a first-time mix with swine flu.
Deputy-director of the World Health Organization’s influenza centre in Melbourne, Ian Barr, told ABC radio: “In Australia we don’t require that the influenza vaccine, the seasonal vaccine, is tested for combinations but they have done that overseas. So they have tested, in fact, giving a full seasonal vaccine with the swine flu, so four vaccines at once, if you like, and there were no untoward effects.”
The influenza vaccines used in most parts of the world are prepared from influenza virus which has been highly purified and then deactivated.
The virus is broken apart chemically to produce split-product vaccines, which are further purified by removing some of the virus components. Because they have been deactivated, the vaccines cannot cause infection or influenza symptoms.
However, when injected, the body’s immune system recognises fragments of virus as foreign and responds by producing antibodies which will prevent or modify an injection with strains similar to those in the vaccine.
Each year, the influenza vaccine is reformulated for a few specific flu strains, but cannot possibly include all the strains in the world.
“The vaccine is essentially the same, but there’s very minor genetic changes in some of the strains, as we keep up with the usual change of the flu,” Professor Bishop said. These changes didn’t necessarily warrant a new round of testing. Seasonal flu vaccines have been used for about 40 years with an “incredibly good safety record”, he said.
Professor Bishop said nothing suggested the swine flu component of the vaccine was the cause of the reactions in children.
In Australia, about 8 million people receive the flu shot each year and from 2004 to 2008, only 655 people reported adverse reactions. The 251 affected children last month in WA were from an estimated 20,000 to 30,000 vaccines.
This is far less than the WHO’s data that shows on average 10 per cent of people vaccinated have an adverse reaction.
Professor in paediatrics at the National Centre for Immunisation Research at the Children’s Hospital at Westmead, Robert Booy, said a small proportion of children will always get a fever after vaccination and a smaller proportion will have convulsions.
He said he did not believe the reactions were a result of the combination of flu strains.
So where to find the vaccination balance? In Australia we know influenza results in an average of 2500 deaths, 18,000 hospitalisations and 300,000 GP visits per year. Many more people are admitted to hospital with diagnoses that have been precipitated by an influenza infection.
Already this year almost 50 cases of swine flu have been confirmed. Last year we had 37,636 cases (7700 of these were children under 10) and 191 deaths from the virus.
Influenza vaccination has been shown to reduce hospitalisation and death, particularly among susceptible groups.
Australian Medical Association president Dr Andrew Pesce said it is a statistical fact that there will be some reactions to the flu vaccine.
“The question is; are they at a level which in general protects the public and can give them the confidence that by far and away the public, including children, are better off vaccinated than not vaccinated? Because the flu itself can kill people,” he said.
“In WA, the roll out of the seasonal flu vaccination for young children was encouraged after a sequence of about four or five young children died of complications of the flu a few years ago.”
Dr Pesce is concerned that the latest developments may lead to a drop in immunisation rates.
The number of Australian parents refusing to vaccinate their children against preventable diseases has more than doubled in the past decade.
Medicare said figures from the Australian Childhood Immunisation Register (ACIR) showed 26,000 or 1.3 per cent of children were registered as conscientious objectors by March 31, 2010. In 2000, this figure was 12,050 children.
However, there is likely to be at least 52,000 unvaccinated children as many parents do not record their intentions with the ACIR.
Health experts maintain that children who are denied immunisation are putting themselves and others at risk.
“If your child isn’t immunised, they remain at risk of diseases that have pretty much gone away for everyone else,” National Centre for Immunisation Research and Surveillance director Professor Peter McIntyre said.
“They’re protected by other people being vaccinated but, if a disease does emerge, they’re the ones who are going to get it.
“There’s the individual risk to the child, but there’s also the risk to other kids, such as those with immune deficiency and other problems.”
Professor McIntyre said unvaccinated children are 15 to 20 times more likely to get Influenza type B meningitis, which can result in brain damage or death.
Vaccination is a contentious issue, with opposing sides armed with plenty of facts and figures. Let’s hope that federal health authorities will soon have clear answers for worried parents.

  •  You can report adverse reactions to vaccinations to the Adverse Medicine Events Line on 1300 134 237 or online at http://www.tga.gov.au/

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