Flu Vaccine Not As Effective As We Thought: Ring The Alarm?

Science is a funny thing. Just when you think you have it all figured out, something comes along that challenges the status quo, and we scientists end up going back to the drawing board. It happened to Einstein, believe it or not. When Edwin Hubble came along with observations that stated that the universe was expanding, Einstein didn’t quite want to believe it. When those observations were shown to be true, Einstein didn’t hold fast to his own views. He analyzed the evidence and judged it for what it was. Then he changed his mind.

Likewise, when we are talking about vaccines with an anti-vax person — and most discussions are not really about “talking” — the accusation comes up that we, the people who support and encourage the use of vaccines to prevent some horrible epidemics, somehow belong to a “cult” or a “religion” that worships vaccines. Nothing could be further from the truth. What we do is take in the evidence that has shown that vaccines — the licensed ones — are safe and effective against some nasty diseases. We weigh that evidence against what we know, and then we render judgment on that evidence.

Once in a while, like it happened with Einstein, something will come along to change our view about vaccines, or a vaccine, and we do change our view. Again, we weigh the evidence. (Can you see a recurring theme here?)

The National Association of County and City Health Officials (NACCHO) did an extensive study of the influenza vaccine in the United States. Guess what? It’s not as good as we thought it was.

Let that sink in for a minute or two.

Did you catch your breath? Well, you shouldn’t be out of breath to begin with because this is not earth-shattering news. It’s not to us epidemiologists, anyway. We’ve been noticing that, despite some pretty good vaccine coverages in different populations, we were still seeing some gnarly flu outbreaks each year. We were lacking the evidence on why this was occurring, but now we have it.

Here is the full report.

The long and short of it is that the flu vaccine is not as effective as public relations campaigns will have you believe. Were they lying? No. They were making those statements based on sub-par scientific evidence. (That’s why we weigh evidence before we render judgment, though it doesn’t always happen that way.) Also, the Advisory Committee on Immunization Practices (ACIP) has been making some of the flu vaccine recommendations based on expert opinion and not hard data. So the NACCHO report suggests that better vaccines be developed, that current vaccine recommendations be based on hard data, and that we don’t stop vaccinating in light of this evidence.

Why not? Because the flu vaccine is still the best thing we have against a disease that kills thousands of Americans each year and millions worldwide. So, while we work on the next best thing — and we must — we must also continue to use what we have.

It’s kind of hard to think about this from a scientific point of view, so it will not surprise me at all if the anti-vax crowd twists and bends what is in the report to fit their views. I’ll bet you $5 that they will.

Nevertheless, this report tells us that there are dedicated public health officials looking at these things and not being afraid to criticize them. If Edwin had been afraid to tell Albert that his general theory of relativity was a bit off, our GPS systems would be off. (They really would.) So, while the anti-vax crowd will raise this report as a failure of vaccine policy in this country, I raise it here as a success.

Now that we know what is going on with the flu vaccine, we can make a better, more efficacious one. And that is not a bad thing at all.

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Let’s play with numbers, and your head, just a little bit

From this site:

“New research brought to us by The Lancet shows some startling news regarding the true effectiveness of the flu vaccination. The study involved a control group of 13,095 adults who were not vaccinated. The group were watched to see if they caught the influenza virus, but 97 percent of them did not. Only 2.7 percent, or 357 people, of the non-vaccinated group ended up catching the virus. Another group of adults whom were vaccinated with a trivalent inactivated influenza vaccine ended up with 1.2 percent of them not catching the flu. The difference between the two outcomes is 1.5 people out of 100 which shows that the flu vaccine only prevents the flu in 1.5 out of every 100 adults injected with the flu vaccine.”
 
Emphasis so totally not mine.

But the person then explains their own misunderstanding:

“While the media runs around “spreading the rumor” that flu shots are 60 percent effective, one would assume that 60 out of 100 people receive the flu based on those claims. The problem with this claim is that it’s wrong. Anyone who takes a crash course in college statistics knows how to skew data. Methods for exaggerating data range from manipulating the graph to using complex statistical algorithms to eventually reach the desired conclusion. In this case, the 60 percent effectiveness claim births from an ongoing equation which transforms the numbers properly. First, 2.73% is taken for the people who got the flu in the control group. That number is then divided into 1.18% which stands for the percentage of people who got the flu in the treatment group. The answer comes out  to be 0.43. You are now able to say that 0.43 is 43% of 2.73 (control group people who got the flu) and make the claim 57% are protected by the flu vaccine.”

Well, yes, that’s how it works. This is what we epidemiologists call a “case-control” study, and it is very robust in terms of determining whether or not things happen by chance. In short, that reduction in influenza was not by chance, and it was significant, and it was by more than a half. But let me explain it differently.

The problem with looking at things in terms of percentages is that you lose sight of the magnitude of what you are looking at. If I tell you that 1% of the population of the United States has an ailment, you might think that’s not worth it to try and find a cure or prevention for it. But that 1% translates into roughly 3 million people. That’s a large city!

In the study cited by this particular anti-vaxer, you had a reduction in cases from 2.73% to 1.18%. Using our example of the US population, this would translate into helping 4.65 million people avoid the flu. In this person’s mind, going from 8.19 million to 4.65 million is meaningless. This person seems to be playing mind games to try and convince you that this is not a significant finding. It is, very much. It just seems small because, again, you’re looking at percentages.

So don’t just look at the percentages. Look a the whole picture. Even a reduction in disease burden of 1% or 2% is huge when it comes to saving lives and maintaining productivity.