Efficacy of 2012/2013 Flu Vaccine

[prosciencemum]

Seems like the media in the US is going crazy over the flu....!

Anyway in the midst of it I one thing caught my eye - a discussion of the efficacy of this season's flu vaccine (which as we all know varies annually). 

http://edition.cnn.com/2013/01/10/health/flu-vaccine-effectiveness/index.html

Quote:

it's about 62% effective, said the director of the Centers for Disease Control and Prevention, Dr. Thomas Frieden

and 

Quote:

this year's North American vaccine matches well with the most predominant type of flu spreading in the United States, but is less well matched to the No. 2 type of virus.

Does anyone know how this compares with the general efficacy over recent years? 

[Rrrrrachel]

There was an interesting piece on the Diane rehm show (NPR) the other day. This years flu vaccine is about a 90% match for the a strain and about 60% effective. It's not nearly as good of a match for the b strain, but it's much more effective against the b strain!

Speaking from memory it sounded like this years match was good and the effectiveness is about average

http://thedianerehmshow.org/shows/2013-01-10/battle-against-flu/transcript

[t2009]

Amidst all this information I am super confused as to whether it's a good idea to vax at this point. We have gotten the vax in prior years & DS, DH & I have all tolerated it well. Last fall, when we would have done it without batting an eye, we were all under the weather so we waited. But then we forgot. Now I'm not sure it's even worth it.

I'm not worried we'd have any bad reactions, but I worry about the tax on our immune systems as we battle whatever we're exposed to on a daily basis at school, work, on the bus, etc. is that an irrational worry? Is it worth getting vax'd at this point? I'm so confused given all the hype.

[Rrrrrachel]

It is still worth getting the vaccine. There is still lots of flu season left.

[philomom]

We never get flu vaccines. We stay pretty healthy at our house and wash our hands a lot when coming and going. I don't see the need.

[bankamundi]

I wouldn't do a flu shot.  I don't give them to my children, either.  Even if it's 60% effective (and I've read other places it's more like 50%, at least, the one of the two that actually is a close enough match) it's not effective enough for me to feel safe using it.  This does seem to be a hyper-alarmist flu year.  We had a flu related child death in Maine this year and she was not vaccinated. The newspapers are having a field day with it.  Too bad the newspapers don't get as excited over children being damaged by the vaccines. If these shots became more effective, I'd consider using them.

[emmy526]

http://www.thelibertybeacon.com/2013/01/21/flu-epidemic-strikes-millions-of-americans-already-vaccinated-against-the-flu/

http://www.naturalnews.com/038648_flu_pandemic_vaccines_shots.html#ixzz2IfQXHK7P

[prosciencemum]

Originally Posted by emmy526 

http://www.thelibertybeacon.com/2013/01/21/flu-epidemic-strikes-millions-of-americans-already-vaccinated-against-the-flu/

Most people who get flu have been vaccinated against flu, because most people have been vaccinated against flu. It's not related to the efficacy - which is the comparison of the fraction vaccinated people who get the flu, with the fraction of unvaccinated who get the flu. 

(I admit it's confusing but this is different from the fraction of people who get the flu who are vaccinated - see?).

 This isn't a thread to debate if flu vaccine is a good idea (Mindful Vaccination board remember) but was meant to be a discussion of the efficacy of this year's vaccine.... 

Edited by prosciencemum - 1/22/13 at 5:49am

[prosciencemum]

Originally Posted by emmy526 

http://www.thelibertybeacon.com/2013/01/21/flu-epidemic-strikes-millions-of-americans-already-vaccinated-against-the-flu/

http://www.naturalnews.com/038648_flu_pandemic_vaccines_shots.html#ixzz2IfQXHK7P

Both of those link to the exact same article replicated in two locations. They also contain lots of misinformation and half truths.

I don't see how this was a useful contribution to this thread. 

[kathymuggle]

Originally Posted by prosciencemum 

Most people who get flu have been vaccinated against flu, because most people have been vaccinated against flu. It's not related to the efficacy - which is the comparison of the fraction vaccinated people who get the flu, with the fraction of unvaccinated who get the flu. 

Not true.  Less than 1/2 of Americans traditionally get a flu shot :

"WASHINGTON, Jan. 15, 2013 /PRNewswire-USNewswire/ --  A new review of flu vaccination trends and policies issued by the Trust for America's Health (TFAH) found fewer than half of Americans ages 6 months and older were vaccinated against the flu in the last two flu season (2010-11 and 2011-12
PR Newswire (http://s.tt/1ytE7)"

Just a reminder for any newbies on how vaccine efficacy is counted, from wikipedia:

"Vaccine efficacy is defined as the reduction in the incidence of a disease among people who have received a vaccine compared to the incidence in unvaccinated people…...The basic formula^[1][2] is written as:

VE = (ARU - ARV)/ARU (x 100)

where

VE = vaccine efficacy;

ARU = attack rate in the unvaccinated population

and

ARV = attack rate in the vaccinated population."

 

 

So, using stats from this article  http://www.nelsonstar.com/opinion/letters/133914023.html   (which used stats from The Lancet)…..a meta analysis showed about 2.73 percent of non-vaccinated people come down with the flu in any given year.  1.18 percent of vaccinated  individuals  come down with the flu.   

 

=aru-arv/aru x 100

= 2.73-1.18 /  2.73 (x 100)

=56.7 % efficacy.

 

Personally, I find discussing efficacy without discussing prevalence of very little use.  

 

 

[prosciencemum]

Kathymuggle - good point. Flu vaccine uptake is lower than for most vaccines.

Thanks for the details on efficacy.

Sure prevalence of flu is low, but half of a low number is still half the risk

And a reminder again of which board we're on here.

[prosciencemum]

Back to the original topic, this did get me wondering about possible bias in efficacy measurements with the flu vaccine. I maybe wrong, but I think higher risk groups are more likely to get the vaccine (e.g the elderly living in care homes). Does this bias the efficacy low because these groups are both more likely to be vaccinated and have a higher prevalence of flu, and if not, how is it accounted for I wonder.....

[kathymuggle]

Originally Posted by prosciencemum 

Kathymuggle - good point. Flu vaccine uptake is lower than for most vaccines.

Thanks for the details on efficacy.

Sure prevalence of flu is low, but half of a low number is still half the risk

And a reminder again of which board we're on here.

I was not lost. 

I figure as long as I play by the guidelines, it is all good. 

Back to your regularly scheduled programming.....

[t2009]

Sorry - didn't mean to start a debate on the wrong board with my question! But the conversation has been super useful. And thanks, Kathymuggle for the tutorial on how efficacy is calculated!

[Cynthia Mosher]

While some members are posting from a position of selectively vaccinating I do need to remind others of our posting guidelines:

Quote:

Mindful Vaccination -  This is a support-only forum for those who are vaccinating selectively, on a delayed schedule or fully vaccinating on schedule. Members who aren't vaccinating should not post here to debate or argue accuracy or opinion of things posted. 

[TCMoulton]

Originally Posted by Cynthia Mosher 

While some members are posting from a position of selectively vaccinating I do need to remind others of our posting guidelines:

Shouldn't they be asked to edit as mindful vaxers are on the I'm not vaxing board? If the post doesn't follow the forum guidelines it should be edited as appropriate.

[Cynthia Mosher]

TCMoulton, your flagging of a discussion is sufficient. We'll handle things as we see appropriate and necessary. 

[Cynthia Mosher]

I think a clarification is in order. All posting to this forum must adhere to the guidelines of the forum, which are:

Quote:

Mindful Vaccination -  This is a support-only forum for those who are vaccinating selectively, on a delayed schedule or fully vaccinating on schedule. Members who aren't vaccinating should not post here to debate or argue accuracy or opinion of things posted. 

Members who are vaccinating should not post here to debate or argue accuracy or opinion of things posted. If you are not vaccinating and coming here to post an argument against something you are not following the guidelines and will be removed from the discussion.