Why Are NZ Children Dying Of Influenza B?

Thursday, 30 June 2005, 4:13 pm
Opinion: Scoop Reader Opinion

Why are New Zealand children dying of influenza B?

I asked this question to Dr Sue Huang, virologist at the Institute of Environmental Science and Research (ESR), last week.

Dr Huang admitted that she ‘was puzzled’, and that the ESR had been unable to ascertain why influenza B was affecting children and young people so seriously. She told me that tests done on the Hong Kong B virus in Melbourne had shown that it had not mutated to a more virulent strain.

Dr Huang is on the vaccine committee which decides the vaccine composition for each year’s flu vaccine. The vaccine is the same for NZ, Australia and South Africa.

The reason I asked this question to Dr Huang is because influenza B has always been considered less serious than influenza A. The ESR’s website states that ‘the frequency of serious influenza B infection requiring hospitalisation is about 4-fold less than that of influenza A virus.’

Dr Pat Tuohy, at the Ministry of Health, is now saying that the “impact of influenza B on children and adolescents can be much more severe than has been previously recognised.” This information has apparently come from the Centre for Disease Control (CDC) in the United States, which as yet I have been unable to view.

However, I wonder why Australia’s children are not experiencing similar complications from influenza B, since they are currently exposed to the same B strains, namely Hong Kong and Shanghai.

Dr Pat Tuohy also states that ‘In New Zealand we have not seen large numbers of people infected with this type of influenza (Hong Kong B) since 1987, although a few people had it in 2002. What that means is that most people born since 1987 will not have natural immunity, so are more likely to be susceptible.’

In fact, the original ‘Hong Kong B’ strain observed in NZ in 1987 was called B/Victoria/2/87. This strain then remained geographically restricted to Asia until 2001, i.e. it was not seen in NZ for 14 years, and underwent independent evolution as an antigenically distinct lineage. It was then called B/Hong Kong/330/2001.

Dr Huang explained that people exposed to the original virus in 1987 may have some limited immunity to the more recent virus, but that it is a different lineage to the original strain.

To say that ‘only a few people had it in 2002’ is rather an understatement. Hong Kong B was the dominant influenza B strain in NZ that year, and predominated for much of the latter part of the season.

A significant proportion of New Zealanders would have been exposed to the Hong Kong B virus in 2002, given that there was a total of 34,730 cases, both influenza A and B.

In fact, 2002 was considered such a significant year for Hong Kong B that it was included in the flu vaccine for 2003 and 2004.

ESR’s website makes no mention of 2002 as a significant year for hospitalisation of influenza cases. In contrast, 2003 recorded the highest hospital admissions for influenza in 14 years. In 2003, influenza A accounted for 99.7% of isolates, and Hong Kong B accounted for 0.01% of isolates.

So I ask the question again, ‘Why are New Zealand children dying from influenza B?’

It appears that 2 of the children who died of influenza B recently were healthy young people, an 11 year old Masterton boy and a Hamilton teenager. I have been informed that the third child had ongoing health complications.

The Ministry of Health reported last week that a further 3 children had died of acute bacterial infections. So far, there is no evidence that influenza B is implicated in the deaths of 2 children, and results are still pending regarding the third child. I still find this very concerning.

However, a further 11 children have become seriously ill, and 7 of these children had influenza B. There is no mention of the geography of these cases, but the initial 3 children who died of influenza B were all from the North Island.

I couldn’t help wondering why the South Island has remained relatively unscathed by the influenza B ‘epidemic’ affecting the North Island. ESR statistics for weekly consultation rates for influenza show disproportionately high numbers for North Island health districts.

I decided to look at the Ministry of Health’s website re: rollout dates for the meningococcal B vaccine around the country.

Time and time again, I saw dates for the administration of meningococcal B vaccine precede an ‘epidemic’ of illness in the region concerned. This has been the case for numerous regions – Manukau, Auckland, Waikato, Wellington, Northland, and Palmerston North, to name a few.

The South Island meningococcal B vaccinations began earlier this month, and I now hear that Southland has been hit by influenza. Is the South Island going to experience the same plummeting school rolls, and the cancelling of elective surgery in small town hospitals as staff take leave to care for sick children (as happened in Palmerston North). Are South Island parents going to experience the devastation of losing healthy children to a viral or bacterial infection?

I sincerely hope not, but the signs are already not good.

Out of the considerable research I’ve carried out on meningococcal B vaccines used in Chile, Cuba, Brazil, and Norway, there are two points of particular concern.

1. The polysaccharide capsule of the group B meningococcus is poorly immunogenic and due to antigenic similarities with human tissue glycoproteins, concerns have been raised regarding possible auto-immune reactions following immunisation.

2. In general, the efficacy in population-based studies of these group B OMV vaccines in children, has paralleled immunogenicity, and has been found to be highest in older children, and where studied, poor or absent in the youngest age groups. The efficacy of OMV vaccines in the youngest and most at risk age group is, as yet, unproven.

It seems we have an Australian heading the Independent Safety Monitoring Board, Professor Terry Nolan, head of population health at Melbourne University. I have not come across any reports from the ISMB.

It is interesting to note that Australia’s vaccination program against meningococcal disease is completely different to New Zealand’s. Australia began vaccinating children over the age of 12 months against meningococcal C on 1st January 2003.

Because meningococcal C conjugate vaccines are considered to provide more predictable and long-lasting immunity than polysaccharide vaccines, Australia chose to administer 1 dose of vaccine for children aged 1-19 years.

Children in Australia are not dying from influenza B.

Lastly, the whole time frame for the meningococcal vaccine has been considered justified because of the public health risk. This is despite the fact that cases for the disease have continued to drop significantly since 2001.

Although the World health Organisation approached vaccine manufacturers in 1998 to produce a Men B vaccine for NZ, it was not until 2002 that Chiron Vaccines (Italy) and the National Institute of Public health (Norway) signed an agreement with NZ MOH.

The Lancet reported this in April 2002 and noted that the vaccine was expected to be produced in 3-4 years.

The Lancet also reported that once the vaccine was produced it typically takes a minimum of 2-4 years to complete the necessary clinical trials, serological assays, data analyses, report writing and regulatory review to obtain a licence.

The vaccine was produced and administered in just over 2 years.

Sally Beale is a mother of two children, aged 21 months and seven years old. She is a trained Naturopath, but certainly not against allopathic medicine. “I believe in truly informed choice regarding all medical decisions,” she says.

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