# 6104
The detection of a new swine H3N2v virus among a handful of people across five states in recent months has sparked concerns that a new influenza virus might be trying to establish a foothold in the human population.
Since the infections reported in the 2nd half of 2011 were predominantly among young children, there has been some speculation that those over the age of 20 might have some limited immunity to this strain.
The CDC, in their January 6th MMWR Update: Influenza A (H3N2)v Transmission and Guidelines — Five States, 2011, writes:
Limited serologic studies conducted to date indicate that young children have little preexisting immunity to influenza A (H3N2)v viruses. Because the hemagglutinin genes of these viruses are related to human influenza A (H3N2) viruses that circulated in the 1990s, older children and adults might have limited immunity against these viruses
Yesterday the Journal Eurosurveillance printed an article called:
by DM Skowronski, G De Serres, NZ Janjua, JL Gardy, V Gilca, M Dionne, ME Hamelin, C Rhéaume, G Boivin
As the title might suggest, this isn’t exactly `light’ reading.
Luckily we’ve the talented Helen Branswell to lead us through this medical morass, in her report for the Canadian Press. As with any Branswell article, you would be well served to follow the link and read the whole thing.
Older adults may also be vulnerable to new swine influenza virus, study suggests
By: Helen Branswell, The Canadian Press
Briefly, the Eurosurveillance study finds indications that acquired immunity carried by adults from exposure to similar viruses that were circulating prior to 1990 may wear off as adults age.
Since years when the H3N2 seasonal flu dominates often result in a more severe flu season, any decline in immunity among the elderly elicits concern.
Right now, the H3N2v virus hasn’t shown the ability to spread efficiently in the human population, although some human-to-human transmission has occurred.
But over time, it may acquire that ability.
Which is why the CDC is working on a vaccine (see H3N2v Vaccine Trials) for this new strain should the need arise.
Meanwhile, with the exception of reports out of Mexico where they are seeing a large number of H1N1 cases, influenza reports in North America and Europe remain well below average for this time of year.
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