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Current H3N2 Vaccine Efficacy in Australia 10%!

Printed From: Avian Flu Talk
Category: General Discussion
Forum Name: Latest News
Forum Description: (Latest Breaking News)
Printed Date: October 21 2018 at 12:47am

Topic: Current H3N2 Vaccine Efficacy in Australia 10%!
Posted By: John L.
Subject: Current H3N2 Vaccine Efficacy in Australia 10%!
Date Posted: October 26 2017 at 3:33pm

Bad news for us in the Northern Hemisphere facing the Aussie flu with this vaccine.  From CIDRAP

Interim results from Australia put flu vaccine effectiveness at 33%

An interim estimate of seasonal flu vaccine effectiveness from Australia found moderate protection against 2009 H1N1 and influenza B, but very low protection against the H3N2 strain. Researchers, basing their findings on two outpatient clinic surveillance networks and information through much of September, reported their findings today in Eurosurveillance.

Australia's flu season, still under way, has been marked by a record number of lab-confirmed flu cases and high numbers of clinic visits, severe illnesses, institutional outbreaks, and deaths, with New South Wales state especially hard hit, the team wrote. H3N2 has been the dominant strain.

Overall vaccine effectiveness (VE) was low at 33% (95% confidence interval [CI], 17% to 46%). Against 2009 H1N1, VE was 50% (95% CI, 8% to 74%), but for H3N2 it was a statistically insignificant 10% (95% CI, -16 to 31%). The level for influenza B was 57% (95% CI, 41% to 69%).

For H3N2, VE was lowest in older people and those vaccinated in the current and prior seasons, a pattern the authors didn't see for influenza B, for which vaccine virus composition was also the same as the previous season.

The researchers said their findings point to ongoing problems with H3N2 candidate vaccine viruses grown in eggs, which acquire adaptive changes during the process that alter antigenicity. Cell-based vaccines, not as affected by the changes, were not available in Australia this year. They also said that significant genetic diversity in circulating viruses makes it hard to select candidate vaccine viruses with high coverage.

They warned that if H3N2 viruses dominate the Northern Hemisphere's flu season, the seasonal flu vaccine may not provide much protection.

John L.

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