How is the seasonal flu vaccine is chosen?

[gfunkusarelius]

A lot of people at work have been getting the flu and my wife was concerned, but I said I am careful and that I was vaccinated, so we should be okay. This prompted her to say her doctor (a chiropractor) told her she shouldn't get vaccinated because it "is useless." She proceeded to drag out the argument that the flu virus changes every ear and that "they" just guess, the implication (if not outright claim) being that they are almost always wrong.

I have to bite my tongue with my wife since she loves her chiropractor and acupuncture, so I just said she didn't understand the process and would get her the info. My wife has a degree in biology, and she is rational in most all aspects of life, so I think a good, concise and informative article could help her "remember" some of the biology she learned.

I did some searches and didn't come up with anything specifically about how they determine the flu strand to prepare for and roughly how effective it is- I know it isn't anywhere near 100% effective, but I want her to see how far it is from "useless." I know I have heard summaries on podcasts like SGU and QuackCast, but there's no way my wife would sit thru that, so I thought I would see if anyone had good links.

Thanks!

 

[CynicalSkeptic]

In a way she's right, but I heard a story on NPR that this year the "guess" was very good, so it's expected to be a very effective vaccine this year.

 

[Tiktaalik]

When I got a flu vaccine earlier this year the tech told me it contained vaccines for H1N1 plus two other strains which seemed to be the most widespread this year. So that is three flu viruses I will not get even if I do get one other.

Unfortunately I had an allergic reaction to it, but that is beside the point.

 

[Emet]

Selecting the Viruses in the Seasonal Influenza (Flu) Vaccine

http://www.cdc.gov/flu/professionals/vaccination/virusqa.htm

 

[Emet]

Questions & Answers
Seasonal Flu Shot

How effective is the flu shot?
In studies of the seasonal flu shot, when the "match" between vaccine viruses and circulating viruses is close, the vaccine has been shown to prevent influenza in about 70%-90% of healthy persons younger than age 65 years. Among elderly persons living outside chronic-care facilities (such as nursing homes) and those persons with long-term (chronic) medical conditions (such as asthma, diabetes, or heart disease), the flu shot has been shown to be between 30% and 70% effective in preventing hospitalization for pneumonia and influenza. Among elderly nursing home residents, the flu shot has been shown to be most effective in preventing severe illness, secondary complications, and deaths related to the flu. In this population, the shot has been shown to be between 50% and 60% effective in preventing hospitalization or pneumonia and 80% effective in preventing death from the flu.

http://www.cdc.gov/flu/about/qa/flushot.htm

 

[gfunkusarelius]

thanks, that CDC link is great, tho I suppose they are probably just part of a vast conspiracy, lol.

 

[George 152]

Examination of a cows entrails while still in the cow

 

[Skeptic Ginger]

In a way she's right, but I heard a story on NPR that this year the "guess" was very good, so it's expected to be a very effective vaccine this year.

What garbage. Whomever said the strains included in seasonal vaccine were a 'guess' doesn't have a clue about the actual process. See Emet's links.

Influenza genetic drift is one of the most closely followed events in microbiological evolution. Every time the HPAI H5N1 (bird flu) shows up in a new location, the virus, if a specimen can be recovered, is genetically analyzed by leading influenza scientists. Reports go out assessing where the virus moved to the new location from and how is the virus drifting genetically. Much of the time movement of domestic poultry is involved in the new outbreak, and some of the time, migration of wild birds are involved. We detect this genetically as well as watching for any hint the virus is becoming more adapted to humans.

The novel H1N1 strain which emerged recently was detected in the US specifically because a sample made its way into the sentinel monitoring system. It demonstrated the problem that the world wide influenza genetic drift monitoring system has big holes in countries which don't have the public health outbreak monitoring systems in place. But the nature of influenza is, it doesn't take long for a new strain (reassortment) to show up in a location where monitoring is more thorough.

And new strains which are the result of genetic drift take on average about 18 months to change enough to evade a previously infected person's immune system. In other words, it takes about 18 months on average before there is a strain circulating which the previously infected people will generally be at risk of re-infection.

Most years the seasonal vaccine is closely matched. Once in a great while the drift of the virus will be mis-timed so that it changes after the vaccine is in production. Even in those years the vaccine strains usually are close enough to provide partial immunity and people might still be infected but they'll have a milder case.

When genetic shift occurs, and if the strain is particularly pathogenic, we rely on the world wide monitoring systems in place to detect it early enough to produce a vaccine and get it distributed. Considering what was involved we did a pretty good job with the novel H1N1.


And as a side note, 3 strains are used in seasonal vaccine because of the law of diminishing returns. If one added more strains to the vaccine, you begin to cover fewer and fewer cases of additional circulating strains.


There is no guess work here. The seasonal vaccine recommendation is updated every 6 months, once for each hemisphere's flu season, based on sound science.

Believing the vaccine is some thrown together gamble is but one more piece of evidence for a population which has little clue how dangerous influenza has the potential to be. If public health spent a bit more time educating the public that the medical world takes this pathogen so seriously that it has an extensive monitoring system world wide, maybe that would impress on some people influenza is not 'just a cold'.

 

[Skeptic Ginger]

When I got a flu vaccine earlier this year the tech told me it contained vaccines for H1N1 plus two other strains which seemed to be the most widespread this year. So that is three flu viruses I will not get even if I do get one other.

Unfortunately I had an allergic reaction to it, but that is beside the point.

If you had a true allergy, it most likely was to the preservative. Get thimerosal free vaccine next time. The allergy to thimerosal is rare, but it does occur.