Bad news for us in the Northern Hemisphere facing the Aussie flu with this vaccine. From CIDRAP http://www.cidrap.umn.edu/news-perspective/2017/10/news-scan-oct-26-2017Interim 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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