B.C., Canada: Early flu outbreaks hit seniors? care homes - possible H3N2 vaccine mismatch - November 1, 2014

[Shiloh]

Source: http://www.vancouversun.com/health/Early+outbreaks+seniors+care+homes/10342605/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...

 

[AlaskaDenise]

Re: B.C., Canada: Early flu outbreaks hit seniors? care homes

Re: B.C., Canada: Early flu outbreaks hit seniors? care homes

Source: http://www.vancouversun.com/health/Early+outbreaks+seniors+care+homes/10342605/story.html

Early flu outbreaks hit seniors? care homes
..... 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...

?... For the elderly it really can be life-threatening.?

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.

?Even if the protection is not perfect and its never 100-per-cent, quite frankly, still some protection for someone who is at high risk of hospitalization or even death is certainly worthwhile. I emphasize it for people who are at high risk, their caregivers, health care workers.?

I'd love to read details of how it "...is still some protection" so we can see if that statement "is supported by science". Especially since I'm in the over-65 group.

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[AlaskaDenise]

Re: B.C., Canada: Early flu outbreaks hit seniors? care homes

Re: B.C., Canada: Early flu outbreaks hit seniors? care homes

CDC guidance for mismatched flu vaccines:

What if there is a mismatch between circulating viruses and the vaccine viruses?

A ?mismatch? is said to occur when the viruses in the vaccine are significantly different from those circulating in the community. In years when the vaccine strains are not well matched to circulating strains, vaccine effectiveness can be reduced. However, even when the viruses in the vaccine and circulating viruses are not well matched, a vaccine may still offer some protection against circulating viruses.

For example, in a study among persons 50-64 years of age during the 2003-04 influenza season, when the vaccine strains were not optimally matched, inactivated influenza vaccine effectiveness against laboratory-confirmed influenza was 60% among persons without high-risk conditions, and 48% among those with high risk conditions. However, vaccine effectiveness was 90% against laboratory-confirmed influenza hospitalization (Herrera, et al Vaccine 2006). A study in children during the same year found vaccine effectiveness of about 50% against medically diagnosed influenza and pneumonia without laboratory confirmation (Ritzwoller, Pediatrics 2005). Still, in some years when vaccine and circulating strains were not well-matched, no vaccine effectiveness may be able to be demonstrated (Bridges, JAMA 2000). It is not possible in advance of the influenza season to predict how well the vaccine and circulating strains will be matched, and how that may affect vaccine effectiveness. For more information, see Vaccine Effectiveness - How Well Does the Flu Vaccine Work?

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[Emily]

Re: B.C., Canada: Early flu outbreaks hit seniors? care homes - possible H3N2 vaccine mismatch

Re: B.C., Canada: Early flu outbreaks hit seniors? care homes - possible H3N2 vaccine mismatch

http://www.biomedcentral.com/1741-7015/11/153/

Tricco AC, Chit A, Soobiah C, et al. Comparing influenza vaccine efficacy against mismatched and matched strains: a systematic review and meta-analysis. BMC Med. 2013;11:153.
...
We identified three RCTs reporting data among seniors [33,36,51], yet none reported our primary outcome of interest or provided data on mismatched influenza. This finding is consistent with previous influenza reviews, for which few RCTs were identified among this age group [2,5]. Future RCTs are needed in this area to provide patients, healthcare providers, and health policymakers with guidance related to vaccination among seniors during seasons when the vaccine composition does not match circulating strains [5].

Full text at the link.

 

[sharon sanders]

Re: B.C., Canada: Early flu outbreaks hit seniors? care homes - possible H3N2 vaccine mismatch

Re: B.C., Canada: Early flu outbreaks hit seniors? care homes - possible H3N2 vaccine mismatch

Please see the CDC health advisory issued last night about this issue:


CDC Health Advisory Regarding the Potential for Circulation of Drifted Influenza A H3N2 Viruses