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Experts Watch H1N1 Changes In NZ

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Fuseworks Media
Fuseworks Media
Experts Watch H1N1 Changes In NZ

Wellington, Oct 22 NZPA - Overseas medical researchers watching mutations in the H1N1 2009 swine flu virus in New Zealand say that so far minor genetic changes in the 2009 flu virus don't seem to make existing vaccines less effective, but the altered strains bear watching.

"At this stage, these signature changes in the ... proteins have not resulted in significant antigenic changes which might make the current vaccine less effective," Australian and Singaporean researchers said today in Eurosurveillance, an epidemiology magazine.

But they said the "adaptive mutations" should be carefully monitored as the northern hemisphere enters its winter flu season.

In New Zealand, the head of the World Health Organisation's national influenza centre at state science company Environmental Science and Research, Dr Sue Huang, told NZPA that the genetic changes were happening all the time as part of the normal evolution of the virus.

But whether the virus was "fit" for survival was only one part of the issue.

More important was a process known as "antigenic drift" -- changes in the way the virus interacted with the immune systems of humans, Dr Huang said.

The virus variations had not been found in any New Zealand cases where patients had died, or in cases where H1N1 had broken though the protection given by a vaccination.

Since January, 1810 cases of pandemic (H1N1) 09 virus have been recorded in New Zealand, including 1759 confirmed, 24 probable, and 27 still under investigation.

The original H1N1 swine flu virus has appeared relatively stable, but all such viruses are constantly evolving genetically.

Two such genetic changes in the virus were first identified in Singapore during April, and by the middle of the year that genetic type of the virus had become dominant there. It was found in New Zealand in July and August.

Viruses with both the main variations have not yet been reported in any northern hemisphere countries.

The researchers speculated that in Australia and Singapore, the variants may have been associated with several cases where infections occurred in spite of vaccination, as well as in a number of fatal cases, but said this could not be proved.

"It remains to be seen whether this variant will continue to predominate for the rest of the influenza season in Oceania and in other parts of the southern hemisphere and then spread to the northern hemisphere or merely die out," the researchers wrote.

The variations might be an early signal of the start of a genetic "drift" to create a new human influenza virus that may require a vaccine update sooner than expected.

Dr Huang said the data used in the study was considered when WHO experts made their recommendations for the vaccine strains to be used for the Southern Hemisphere's 2011 flu season.

Next year's New Zealand seasonal flu vaccine will have the same strains as this year: A/California/7/2009 (H1N1)-like virus; A/Perth/16/2009 (H3N2)-like virus; B/Brisbane/60/2008-like virus.

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