Rogue H3N2 seasonal flu strain a mismatch to vaccine?

[Shiloh]

Source: http://www.vancouversun.com/health/E...605/story.html

Early flu outbreaks hit seniors’ care homes
By Erin Ellis, Vancouver Sun October 31, 2014


Seven outbreaks of influenza in Metro Vancouver long-term care homes mark an unusually early start to the flu season, a spokesman for the BC Centre for Disease Control said Friday.

“That’s not a good sign,” said Dr. Danuta Skowronski.

Its weekly update on communicable illnesses noted “low-level” influenza is above historical averages for the third week in a row. Most flu cases have been in people over 65 and the predominant type of virus is A H3N2 which is also the strain found in outbreaks reported in Alberta, Ontario and Quebec...

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The flu vaccine now available throughout B.C. contains a type of H3N2 virus, but is not an exact match to the strain currently affecting patients. It has mutated since the World Health Organization identified it earlier this year for inclusion in North American vaccine programs, she explained.

[sharon sanders]

Rogue H3N2 seasonal flu strain a mismatch to vaccine?

hat tip Vibrant62


Vaccine no match for rogue flu strain
DEIDRE MUSSEN
10/23/14

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But about 8 per cent of cases have involved a new strain that had changed quite a lot, National Influenza Centre director Sue Huang said yesterday, and there had been a reported surge in immunised people catching flu.

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The problem was caused by a different strain of the H3N2 influenza A virus surfacing unexpectedly this year, she said.

The flu vaccine had three components - two influenza A strains and one B strain - which were selected each year to match the strains predicted to strike the following winter.

However, the H3N2 flu virus, an A/Texas/50/2012 strain, had drifted quite a lot by the time it arrived in New Zealand, she said.

That meant those who contracted it had little or no immunity to it.

http://www.stuff.co.nz/national/health/10650629/Vaccine-no-match-for-rogue-flu-strain?

[sharon sanders]

Re: Rogue H3N2 seasonal flu strain a mismatch to vaccine?

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Antigenic Characterization:
CDC has antigenically characterized 10 influenza A (H3N2) viruses collected by U.S. laboratories since October 1, 2014 by hemagglutination inhibition (HI).

Influenza A (H3N2) [10]:

Seven (70%) of the 10 influenza A (H3N2) viruses tested have been characterized as A/Texas/50/2012-like, the influenza A (H3N2) component of the 2014-2015 Northern Hemisphere influenza vaccine.


Three (30%) viruses showed reduced titers with antiserum raised against A/Texas/50/2012 but were antigenically similar to A/Switzerland/9715293/2013, the H3N2 virus selected for the 2015 Southern Hemisphere influenza vaccine.

A/Switzerland/9715293/2013 is related to, but antigenically and genetically distinguishable from the A/Texas/50/2012 vaccine virus. A/Switzerland-like H3N2 viruses were first detected in the United States in small numbers in March of 2014 and began to circulate in greater numbers over the spring and summer.
CDC previously reported that 49% of H3N2 viruses collected worldwide from May 18-September 20, 2014 were antigenically similar to A/Texas/50/2012 ("Update: Influenza Activity ? United States and Worldwide, May 18-September 20, 2013" in the MMWR) and 42% of H3N2 viruses collected in the United States during that time were antigenically similar to A/Texas/50/2012 (FluView Week 40). CDC conducts antigenic characterization of influenza viruses year-round to compare how similar currently circulating influenza viruses are to those included in the influenza vaccine, and to monitor for changes in circulating influenza viruses.

http://www.cdc.gov/flu/weekly/

[AlaskaDenise]

Re: Rogue H3N2 seasonal flu strain a mismatch to vaccine?

A discussion of the H3N2 exact changes is on page 5 here:

http://www.ecdc.europa.eu/en/publica...-july-2014.pdf

.....Antisera raised against cell-propagated reference viruses A/Stockholm/6/2014 and A/Norway/466/2014 recognised the majority of viruses from each genetic grouping at titres within twofold of the titres of the antisera with their homologous viruses.

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Looking at the sequences on GenBank, the newest H3N2 that is different from the vaccine, appears to match sequnces from Helsenki.

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