Does Seasonal Influenza Vaccination Increase the Risk of H1N1?

Mike Adams thinks it does.  In fact, he’s sure of it.  And boy, is he excited.  Check out his recent column, and compare that with what the actual study says.  First, Adams, with Seasonal flu vaccines increase risk of pandemic H1N1 flu, stunned scientists discover:

The CDC and health authorities were pushing a double-barreled vaccine strategy that demanded people get both a seasonal flu shot as well as an H1N1 pandemic flu shot. Those who questioned the sensibility of vaccines for fighting the flu were attacked as "baby killers" for not kow-towing to the vaccine mythology that drives Big Pharma's profits to record profits nearly every flu season.

[…]

Care to guess what the study found? In short, it found that people who received the seasonal flu vaccine shot in 2008 were up to 274% more likely to be infected by H1N1 swine flu than those who skipped the season flu shots.

[Bold in original.]

Note that the CDC recommended getting both the seasonal and H1N1 vaccines.  Also note that 274% figure that Adams quotes.

What did this study do, and what does it say?  The study is titled Does Seasonal Influenza Vaccination Increase the Risk of Illness with the 2009 A/H1N1 Pandemic Virus?  First, you’ll note it starts “Does..” and ends with a question mark.  Compare that with Adams’s “…vaccines increase risk…” and no question about it.  Adams seems to be a lot more sure than the people who published the actual study.  What did they do in this study?  Well, they took patients who presented with influenza-like illness at  a network of Canadian doctors, and tested them for H1N1 and seasonal influenza.  They also determined if the patients had been vaccinated against the seasonal flu.  They used this information to compare vaccination status among influenza-positive (both seasonal and H1N1) patients with influenza-negative controls.  What did they find?

… receipt of [the seasonal flu vaccine] in the previous season (autumn 2008) appeared to increase the risk of pH1N1 illness by 1.03- to 2.74-fold, even after adjustment for comorbidities, age, and geography [4]. The investigators were prudent and conducted multiple sensitivity analyses to attempt to explain their perplexing findings. Importantly, [the seasonal flu vaccine] remained protective against seasonal influenza viruses circulating in April through May 2009, with an effectiveness estimated at 56% (41%–67%)  [My bold.]

Note, they reported that the increased risk was 1.03 to 2.74 fold. Now, I suppose Adams is technically correct in saying the increased risk was “up to 274%” as high, since the phrase “up to” includes the figure zero.  Technically correct, but intellectually dishonest.  (I guess "more than 1.03 times the risk" wouldn't have sounded so scary.)  Also, note that the seasonal vaccine was 56% effective against the seasonal flu – a tidbit that Adams somehow managed to overlook.  More importantly, note that the study did not show the merits of getting both a seasonal flu shot as well as an H1N1 pandemic flu shot (compared with no vaccine at all) as Adams himself admits was the CDC’s recommendation.  (Presumably they didn’t do this because the H1N1 vaccine wasn’t widely available at the time.)

Still, this did seem (as far as I can tell) to be a decent study, and its results certainly warrant further investigation into this phenomenon.  Does this study prove that the seasonal flu vaccine increases the risk of getting H1N1, as Adams thinks?  Well, not really.  From the report, again:

Given the uncertainty associated with observational studies, we believe it would be premature to conclude that TIV increased the risk of 2009 pandemic illness, especially in light of six other contemporaneous observational studies in civilian populations that have produced highly conflicting results (see Table 1 for details on study design, population sampled, and results) [10]–[15]. We note the large spread of vaccine effectiveness estimates in those studies; indeed, four of the studies set in the US and Australia did not show any association [12]–[15], whereas two Mexican studies suggested a protective effect of 35%–73% [10],[11]. The most recent Canadian study in this issue of PLoS Medicine [4] is clearly at odds with these results, with an estimated average negative effectiveness of −68% based on their Sentinel system. Only one study, set in the US military population, potentially corroborated the findings of the Canadian study [16].

[My bold.]

So there are numerous other studies, many of which show no difference, and two that actually show the seasonal vaccine reduces the risk of getting H1N1. Nothing wrong with that – real world studies are not always as clear cut as we would like, which is why science requires replication, especially where the results are hard to explain or surprising, based on current knowledge.  Strange that Adams didn’t notice that bit, though.  Well, it did come nearer the end of the paper - perhaps Adams got so excited by the first part that he didn’t finish reading.

To summarize Adam’s technique, he:

1. Cherry picks a study that has results he likes, and ignores at least six other studies (that were even reported in the actual paper he cited) that report different results
2. Exaggerates the risk - “1.03 to to 2.74” increased risk becomes “up to 274%”
3. Ignores the fact that the seasonal vaccine is 56% effective against seasonal flu anyway
4. Ignores the fact that the CDC recommendation is to get both the seasonal and the H1N1 vaccine – something that was not covered by this study.  (And presumably the H1N1 will be included in next season’s seasonal fu vaccine.)
5. Jumps from all of this to state that therefore “vaccines are a medical scam, folks! A Big Pharma hoax,” and that the real solution to protect you against the flu is vitamin D.  Seriously.

Adams will quote a scientific study if it supports his point of view (even if it doesn’t, really), but then he rails against the rest of science that doesn’t.  That’s what makes him a crank.  The truth is, this is an interesting but inconclusive study that should probably be investigated further.  Possibly there is some reason that the seasonal vaccine could make people more susceptible to the H1N1 virus.  If so, real scientists would like to find out what it is - although it is almost certainly not that the flu vaccine "weakens the immune system" as Adams claims, but some other reason.  More likely (given the numerous confounding studies), there is no real effect here.  Either way, it will be real scientists doing real science, not cranks like Mike Adams, who will come up with the actual answer.  And you are almost certainly going to be better off getting both seasonal and H1N1 vaccines, than getting neither.

Update

Effect Measure has a good post on this subject this morning, Did getting vaccinated for seasonal flu up the risk of pandemic flu infection?  They conclude, like me, maybe, but you’re still better off getting the flu vaccine especially as H1N1 will be a component of the next seasonal vaccine strain.

Comments

[Bing]

Good call. I was going to write that one up, but there is something about Adams' M.O. that makes me vomit blood.

[Ryan W.]

Thanks for the takedown Skep. I'm sure someone will forward me this guy's article as "proof" vaccines are eeevilll

I will promptly direct them here.

[yakaru]

Good work again on this clown, Skeptico.

[Theo]

56% effective huh....well, I guess the sun even shines on a dog's arse once a day too. Seeing how the flu shot has been a complete failure the last few years, I would say I'm unimpressed.

I will take my 100% effective approach of not getting the flu shot and not getting the flu.

BTW, do you think the increase in getting the H1N1 has anything to do with the seasonal flu shot HAVING H1N1 in it? At least that is what it says on the insert...

[Yojimbo]

"I will take my 100% effective approach of not getting the flu shot and not getting the flu."

Ah yes indeed - the old "Rely on Dumb Luck" ploy. Great track record, that one. It ranks right up there with "Don't wear seat belts and don't have an accident".

[TechSkeptic]

do you think the increase in getting the H1N1 has anything to do with the seasonal flu shot HAVING H1N1 in it? At least that is what it says on the insert..

oh really now, and perhaps you can link to an actual picture of that insert from a 2009 era flu vax?

H1N1 ANTIGENs, not the virus, is going to appear in the 2010 seasonal flu vaccine because its still around as a common strain.

get your facts straight before you start babbling around like that. The number of dumb things you compressed into one post is astounding.

[Lonnie]

Great write up, this is essential a "classic" case here. Picking out one part of one study and running with it to make a blanket statement, conveniently in line with your particular ideology.

Skepticism is hard work at times (Often tedious and arduous work... Not fun), a glancing read through of the study may have yeilded ANYONE with a similar conclusion as Adams... But when you look at the whole picture (Other studies on the same issue and factors associated with the study) it becomes much more involved.

[_Arthur]

Yes, the good Dr. Cannell of the Vitamin D Pushers Association became convinced that Vitamin D prevents the flu when, after giving vitamin D to all the patients of his ward, NOT A ONE CAUGHT THE FLU, that season. So, he gave up criminal psychiatry, and become a respected pill pusher, that's as good as it gets for scientific proof.

Oh, and if you do get the flu despite the megadoses of vitamin D Dr. Cannell recommends, (50,000 UI ?), just take 2 pills (100,000 UI) and it will go away.

[Nico]

Arthur, if you wish to prove Vitamin D works, cite a study, not random claims by your woo woo doctors.

Besides Dr. Canell did not use a control group with placebos, and did not use another group with standard medicine.

[_Arthur]

Nico: duh !

[Ryan W.]

Arthur:

Are you trying to be funny? Irony can be tough to pick up on the Nternets, especially when it's done poorly.

[_Arthur]

I was kinda trolling, maybe I'm out of practice.

[Ryan W.]

I get it. The usual suspects here are typically on their toes though. So you may want to go full-on believer or use a little more sarcasm.

Have fun trolling.

[Nico]

Arthur, you were being sarcastic? sorry, my apologies

[Chris]

I see getting my sarcasometer calibrated last week paid off. I did recognize the sarcasm!

;-)

[Lady Lizard]

Hey, hold the phone - "I took my 100% effective approach of getting both shots and not getting the flu."

Would theo care to do the analysis of our two data points?

[Yojimbo]

No need - Theo's report is obviously rigorous data, while yours is merely anecdote and can be safely dismissed.

[Orange Lantern]

Wait, I got both flu shots and did not get the flu! Add that to Lady Lizards and you get:

Anecdote + anecdote = data!

Win!

[Ryan]

Lantern:

That is the woo-woo definition of science:

I can make up whatever I like the sound of and if other people agree with me, I'm right.

[Nico]

Great points from Theo and L.Lizard, a sample of two totally unverifiable anecdotes is irrefutable evidence.

[Joseph]

1.03 is barely significant. It could be a chance finding. If it's a real effect, I wonder why it might happen that way.

However, it should be noted that countries in the Northern Hemisphere had a mild H1N1 season, and I think that's simply because people got vaccinated, the vaccine worked, and there's probably some herd immunity at play.

I say that because if you look at trends.google.com results for, say, the word "cough" narrowed for Australia vs. the US, the search patterns are very different. (Australia had its season mid year, before the vaccine, obviously.) There were early indications that the season could be a bad one for the US, but then it went away, right at the time the vaccine was introduced.