flu vaccine / statistics / herd immunity

[iangoeswest]

I apologize in advance if this has been covered elsewhere on the forum, my search did not reveal discussion on these particular questions.

I post this here not because of any general vaccine skepticism but in hopes of picking the brains of some more medically-informed members. I feel compelled to offer the caveat at the outset that I received all childhood vaccinations, have had all three of my school-age children vaccinated at the recommended schedules, and have what I feel to be a decent woo-filter in place as regards claims around the benefits and detriments of vaccines writ large.

THAT BEING SAID, we are in the midst of flu season here in the U.S., and there is considerable news-chatter (bordering on alarmist) about the flu and the importance of being vaccinated. I have never gotten a flu vaccine, nor have any of my children. None of us have ever gotten influenza, and relative to the anecdotal information available to me it seems my family gets sick somewhat less frequently than is common. My feeling about the flu vaccine has been “if it ain’t broke, don’t fix it,” resolving that I would revisit my declining this vaccine if and when anyone in my family ever got the flu. Still, with the considerable chatter around us, my wife and I have decided to revisit this issue now.

Notwithstanding my caveats I reveal an obvious dis-inclination to get the vaccine for reasons I am only now exploring; they seem to revolve around concerns that I might somehow be interfering with my body’s ably-functioning immunology by vaccinating. So, here are the questions:

1) Does the immunological response stimulated by the flu vaccine tax my body’s natural ability to fight off invaders? With three kids in school (and a wife who works in several schools) I assume that I’m exposed to all manner of microscopic nasties, and that my body is doing its job in developing antibodies as they invade. I’m uptight about altering this balance, but don’t know if anything supports this uptightness beyond my own experience (which for a long time was all anyone had to go on! But you know, internet.)

2) It is said that the vaccine is 60% effective. Does this mean that, of a randomized sample of people, some of whom haven’t gotten the vaccine and some of whom have, that for every 100 people in the former group who get the flu there are only 40 people in the latter group who get it? Or does it mean something else? From where are these (widely-circulated) data drawn?

3) If I am correct that, by dint of fortune or happenstance, I am one of those sorts of people who rarely gets the flu because I am successfully fighting off the flu, am I nonetheless detracting from our collective “herd” immunity by failing to get the flu shot, or does the notion of herd immunity depend on the assumption that everyone is equally likely to get a given illness?

I think I’ll start there. Again, I’m not looking to stir a fruitless debate about vaccines writ large, nor necessarily a discussion (although I welcome any productive discussion!) about the wisdom of pre-emptive flu vaccination as a policy matter; rather, I’m trying to find answers to some particular questions bearing on my own decisions, answers that my semi-diligent googling hasn’t otherwise been able to reveal.

Thanks, all, in advance.

 

[quarky]

I admire the intelligence of your query.

That's all I've got, for now.

 

[Capsid]

In response to 1) I need to know why you think that the flu vaccine would upset the balance, then I can answer more specifically.

In response to 2), your interpretation is correct but I'm not sure where you get your 60% figure from. It's not as simple as that since it depends who gets the vaccine; elderly people respond less well and also it's possible to be vaccinated but still get flu since you may be infected by a virus strain that is not the same as that in the vaccine.

In response to 3), the more people that get vaccinated then the less likely that the virus can spread through a population and thereby reduce mortality in those that don't respond to the vaccine or can't be vaccinated because they have a medial condition which precludes them from getting the shot. So it's about protecting the population not just the individual.

 

[jdc324]

In response to 1) I need to know why you think that the flu vaccine would upset the balance, then I can answer more specifically.

In response to 2), your interpretation is correct but I'm not sure where you get your 60% figure from. It's not as simple as that since it depends who gets the vaccine; elderly people respond less well and also it's possible to be vaccinated but still get flu since you may be infected by a virus strain that is not the same as that in the vaccine.

In response to 3), the more people that get vaccinated then the less likely that the virus can spread through a population and thereby reduce mortality in those that don't respond to the vaccine or can't be vaccinated because they have a medial condition which precludes them from getting the shot. So it's about protecting the population not just the individual.

For 2) I saw a reference earlier (elsewhere) to a new study on the 2012-13 vaccine and the figure being bandied around was 60% - the CDC has this on "early estimates": http://www.cdc.gov/MMWr/preview/mmwrhtml/mm62e0111a1.htm?s_cid=mm62e0111a1_w (caveats re it being interim data, final estimates being likely to differ etc...)

This season, early data from 1,155 children and adults with ARI enrolled during December 3, 2012–January 2, 2013 were used to estimate the overall effectiveness of seasonal influenza vaccine for preventing laboratory-confirmed influenza virus infection associated with medically attended ARI. After adjustment for study site, but not for other factors, the estimated vaccine effectiveness (VE) was 62% (95% confidence intervals [CIs] = 51%–71%). This interim estimate indicates moderate effectiveness, and is similar to a summary VE estimate from a meta-analysis of randomized controlled clinical trial data (2); final estimates likely will differ slightly.

So it looks like provisional estimates based on children & adults.

 

[iangoeswest]

@quarky - I'll take it!

@Capsid - While appreciating that the flu vaccine - containing as it does dead or weakened viruses - cannot itself give me the flu, I am wondering about its effect on what I'd call (not necessarily accurately, and I invite correction) the "viral load" - the day-to-day exposure that my body is already processing in the background. In re-reading my post I see that I used the word "balance," which was imprecise on my part; I was not meaning to imply Qi or those sorts of conceptions of bodily balance, rather, the "balance" is that I get regularly exposed to pathogens and my body regularly repels them.

People who are already sick (in any sort of way) are discouraged from getting the flu shot, which suggests to me that its effect on my immune system is more complex than is answered by the observation that it contains no viable virus. Does a flu shot make me more succeptible to other illness? How MUCH more so? A trivial amount? A non-trivial amount? Is this known?

That last question is the most relevant one to me; I'm not JAQ-ing off here, just looking to confirm my own opinions; I'm trying to figure out what is known and what is not known, by people who actually understand such matters.

As to #2, I was most concerned to know that I was interpreting the statistic correctly rather than to confirm the veracity of the statistic itself; that stat is ubiquitously reported, but I have no way of knowing that everyone isn't parroting the same source; such statistics are necessarily of limited value, becuase of course the truth is that the vaccine is 100% effective in some portion of the population, less effective in others, and not at all effective for those people exposed to strains not vaccinated against (or exposed pre-vaccination). In truth, such numbers don't address the better of my curiosity about the cost/benefit of the vaccine; I more wanted to scratch the itch to understand that I was looking at the stat the right way.

As to #3, I appreciate your responding but this seems more just a restatement of the theory of herd immunity itself (I apologize if the foregoing sounds at all snotty and implore that, in person, I would speak more deftly). I recognize this truth; indeed, as I sit here now about the ONLY argument in favor of my taking the flu vaccine is a sense of social responsibility. OTOH, I wonder that I'm not overdoing it, inasmuch as I have not gotten influenza in my adult life despite what seems like considerable probable exposure.

I welcome your continued thoughts, and appreciate your expertise.

 

[Capsid]

For 2) I saw a reference earlier (elsewhere) to a new study on the 2012-13 vaccine and the figure being bandied around was 60% - the CDC has this on "early estimates": http://www.cdc.gov/MMWr/preview/mmwrhtml/mm62e0111a1.htm?s_cid=mm62e0111a1_w (caveats re it being interim data, final estimates being likely to differ etc...)



So it looks like provisional estimates based on children & adults.

So that was for this season's vaccine. The effectiveness will vary from year to year based on how well they matched the vaccine strain to the circulating flu strain(s).

 

[BowlOfRed]

People who are already sick (in any sort of way) are discouraged from getting the flu shot, which suggests to me that its effect on my immune system is more complex than is answered by the observation that it contains no viable virus. Does a flu shot make me more succeptible to other illness? How MUCH more so? A trivial amount? A non-trivial amount? Is this known?

I have zero information, but I'd always assumed it was folks trying to limit the people that get sick (anyway) after a shot and blame the vaccine. Not that there was a physical reason for it.

I'd love to see that information as well.

 

[Capsid]

People who are already sick (in any sort of way) are discouraged from getting the flu shot, which suggests to me that its effect on my immune system is more complex than is answered by the observation that it contains no viable virus. Does a flu shot make me more succeptible to other illness? How MUCH more so? A trivial amount? A non-trivial amount? Is this known?

I'm not entirely convinced that there is good evidence that the flu shot is contra-indicated if you are already sick. I had the flu shot this year whilst I had a cold. I suppose that there is concern that there may not be an optimal response to the vaccine but that doesn't make sense to me as the immune system is already working optimally to fight off another illness, this includes cytokine production which stimulates the immune system. I couldn't find a scientific study that properly addressed this.

 

[Dymanic]

I suppose that there is concern that there may not be an optimal response to the vaccine but that doesn't make sense to me as the immune system is already working optimally to fight off another illness, this includes cytokine production which stimulates the immune system.

Doesn't make sense to me either. The goal of immunization is to elicit a humoral response, and diverse B-cell lineages can evolve simultaneously and independently of one another, or we'd see it in the data on simultaneous administration of multiple vaccines. It's not like they're competing for finite resources. Whatever is going on as far as a cell-mediated response to some other pathogen, I don't see how it's going to affect those processes. That's not to say it can't; but if there's anyone who fully understands the relationship between cell-mediated and humoral immunity, it isn't me; therefore, for the sake of simplicity, I prefer to treat them as if they are completely separate whether they really are or not. Admittedly a bit of a Homer Simpson approach, but it's a time saver.



On the Herd Immunity question, I think the answer is that nobody really knows for sure. Osterholm and his crew have this (among other things) to say about it:

Herd immunity is a well-defined concept in public health that occurs when most of a population is immune to an infectious agent (either through previous infection or through vaccination). This widespread immunity prevents circulation of the agent within the entire population, thereby protecting the small number of nonimmune persons in the population. This is a key component of immunization strategies for diseases of childhood, where vaccine coverage rates typically exceed 85% and individual vaccines have efficacies of over 90%. Public health officials have assumed that herd immunity plays a role in population protection following widespread influenza vaccination; however, given the varied coverage rates following vaccination campaigns and the wide ranges of efficacy and effectiveness of influenza vaccines in any given season, it remains unclear whether or not herd immunity play a significant role in influenza prevention and control.

http://www.cidrap.umn.edu/cidrap/files/80/ccivi report.pdf


Here's my back-of-the-envelope take on it:

Since vaccination rates in the U.S. typically run in like the 30 to 40 percentiles, and efficacy/effectiveness is only in the 60 percentiles, even if you add, say, another 15% who obtain immunity through infection, then whatever the herd immunity threshold for influenza is (and it's probably 75% at the very least), we're going to be way short of it whether YOU get vaccinated or not. In a similar sense, you're not going to single-handedly end global warming by riding your bike to work instead of driving. Doesn't mean it's a bad idea, tho.

Personally, I always appreciate it when friends and family members get vaccinated partly so as to protect me (knowing that I am at very high risk). For me, the trick to making herd immunity work is to keep the size of the herd down to a bare minimum.

 

[Skeptic Ginger]

I'm not entirely convinced that there is good evidence that the flu shot is contra-indicated if you are already sick. I had the flu shot this year whilst I had a cold. I suppose that there is concern that there may not be an optimal response to the vaccine but that doesn't make sense to me as the immune system is already working optimally to fight off another illness, this includes cytokine production which stimulates the immune system. I couldn't find a scientific study that properly addressed this.

If one has a fever or is more than mildly ill we defer the vaccine because the vaccine antigen does compete with the antigens already being responded to in your system. But it is a relative contraindication, meaning the effect is minimal and you only defer the vaccine if you are sure you can give the vaccine safely later. So, for example, if you don't think the parents are going to consistently bring the kid back when he/she is well, you give the vaccine even when the child is ill.

 

[Estellea]

If one has a fever or is more than mildly ill we defer the vaccine because the vaccine antigen does compete with the antigens already being responded to in your system. But it is a relative contraindication, meaning the effect is minimal and you only defer the vaccine if you are sure you can give the vaccine safely later. So, for example, if you don't think the parents are going to consistently bring the kid back when he/she is well, you give the vaccine even when the child is ill.

I can see intraantigenic competition but not inter antigenic competition. I have always seen the recommendation that moderate illness is not a contraindication to vaccination but that "severe" i.e. febrile illness while not physiologically a contraindication is still listed as a contraindication for the simple reason of being unable to determine a vaccine reaction in the event of one.

Este

 

[Skeptic Ginger]

@Capsid - While appreciating that the flu vaccine - containing as it does dead or weakened viruses - cannot itself give me the flu, I am wondering about its effect on what I'd call (not necessarily accurately, and I invite correction) the "viral load" - the day-to-day exposure that my body is already processing in the background.

Your body isn't processing a 'viral load' daily unless you have a chronic infection. I think what you mean to say is processing foreign antigens (all sorts of foreign proteins your body encounters). Most people's immune systems are well equipped to handle the trillions of trillions of trillions of antigens they are exposed to every year.

In re-reading my post I see that I used the word "balance," which was imprecise on my part; I was not meaning to imply Qi or those sorts of conceptions of bodily balance, rather, the "balance" is that I get regularly exposed to pathogens and my body regularly repels them.

People who are already sick (in any sort of way) are discouraged from getting the flu shot, which suggests to me that its effect on my immune system is more complex than is answered by the observation that it contains no viable virus. Does a flu shot make me more succeptible to other illness? How MUCH more so? A trivial amount? A non-trivial amount? Is this known?

Your immune system is very complex and attacks foreign invaders on a number of different levels.

Vaccines give you very specific tools so to speak to deal with very specific invaders. Vaccines do not tax your immune system's capacity. When you are acutely ill in a very small number of cases the vaccine won't have an ideal response. But that because the body is responding to a pathogen (a full on attack). Vaccines don't do the same things a pathogen does in a full on attack.

...just looking to confirm my own opinions;

You should look to confirm or refute your existing opinions depending on what you learn.

As to #2, [2) It is said that the vaccine is 60% effective. Does this mean that, of a randomized sample of people, some of whom haven’t gotten the vaccine and some of whom have, that for every 100 people in the former group who get the flu there are only 40 people in the latter group who get it? Or does it mean something else? From where are these (widely-circulated) data drawn?] I was most concerned to know that I was interpreting the statistic correctly rather than to confirm the veracity of the statistic itself; that stat is ubiquitously reported, but I have no way of knowing that everyone isn't parroting the same source; such statistics are necessarily of limited value, becuase of course the truth is that the vaccine is 100% effective in some portion of the population, less effective in others, and not at all effective for those people exposed to strains not vaccinated against (or exposed pre-vaccination). In truth, such numbers don't address the better of my curiosity about the cost/benefit of the vaccine; I more wanted to scratch the itch to understand that I was looking at the stat the right way.

The hi-lighted part is more accurate. Add to that, influenza vaccine effectiveness varies from year to year with some years being very effective and other years less so. Most years the vaccine closely matches most circulating strains. A lot of the vaccine failures are in the elderly and just last year a high dose vaccine was introduced to see if that improved vaccine outcomes.

Bottom line, for a healthy person under age 65, the vaccine effectiveness is much higher than the average in most studies.

As to #3, I appreciate your responding but this seems more just a restatement of the theory of herd immunity itself (I apologize if the foregoing sounds at all snotty and implore that, in person, I would speak more deftly). I recognize this truth; indeed, as I sit here now about the ONLY argument in favor of my taking the flu vaccine is a sense of social responsibility. OTOH, I wonder that I'm not overdoing it, inasmuch as I have not gotten influenza in my adult life despite what seems like considerable probable exposure....

This is not true. There are many reasons to get a flu vaccination from preventing severe illness, hospitalization, time loss from work or school to preventing some deaths even in otherwise healthy people.

Studies show in some years 30-40% of influenza deaths occur in people with no identified risk factors. That means otherwise healthy people between the ages of 5 and 65 die from flu. Granted the total numbers are low, 100 give or take. But flu severity is unpredictable until the outbreaks are in full swing.

And the vaccine is very safe contrary to what a lot of people believe.

There are many citations in this thread you might find useful. You can skip a lot of the arguing with a certain person in the thread and just look at the posts with citations in them.

 

[quarky]

Sure, vaccines sound good...but what if an evil government decides to put mind control substances in them...and we become zombies?

Didn't think of that, I guess.

 

[Skeptic Ginger]

I'm going to post this AMA handout in both threads: Influenza: More serious than you may think - U.S. influenza Disease Burden and Prevention profile

It sums things up quite well.

 

[iangoeswest]

@Dymanic - Thank you for the citation, I'm going to give it some sustained attention; I'm no slave to data in and of itself, but this is just the sort of starting point I was looking for; again, thank you. As for

> you're not going to single-handedly end global warming by riding your bike to work instead of driving. Doesn't mean it's a bad idea, tho.

Of course! The Onion had a good one on this vis-a-vis plastic bottles, and in fact I'm not generally that responsible a global citizen. I do, however, have an elderly grandmother in a "home" as we call them here - one which my children and I visit on a near-weekly basis - and if there is measurable upside to our being vaccinated (again, none of us has ever contracted influenza), I want to know; it's not about single-handed change, but the (first) world is built on decisions, and I want to make mine in an informed fashion; such is my luxury.

@Skeptic Ginger -

> You should look to confirm or refute your existing opinions depending on what you learn.

Darn tootin! Good catch, thank you. I like to think that this is what I "meant" to say, and you - and these boards - will deservedly judge me on that point. Anyway, sometimes a cigar is just a cigar, and yes, I appreciate the correction; I thought that was what I was saying (I was, apparently, wrong. Go figure!)

> There are many citations in (a thread)

Oy vey iz mir! That is, whew! There's a lot there, and I haven't been able to digest even a small piece of it, as the signal / noise ratio is less than optimal. I appreciate the cite, and will dig in.

The AMA handout, however, does little to inform my particulars; it is relevant generally, and specifically for those who feel that the flu is no big deal; I recognize its signficance as a disease, but return to the fact that I and my family have never been afflicted. Given THAT fact, I'm just not sure how to proceed, but I don't think my uncertainty flows from a failure to appreciate the significance of influenza generally (feel free to correct me if I just seem too glib here; a second read of the handout seems to suggest vaccination as maybe a general strategy towards eliminating influenza writ large; am I reading it right?). Again, I dutifully vaccinated my kids against all recommended illnesses of childhood; the flu just seems sui generis, a thing unto itself worthy of its own consideration. I do appreciate the citations and will give the other thread my attention as I can bear it, for my guilty pleasure at watching the train wreck of weak minds get pwned has waned in proportion to my appreciation of thoughtful people's input.

That is to say, thanks for the cites, I'm gonna read 'em all and make more informed decisions on those bases. Keep 'em comin'.

- Ian

 

[Capsid]

I can see intraantigenic competition but not inter antigenic competition. I have always seen the recommendation that moderate illness is not a contraindication to vaccination but that "severe" i.e. febrile illness while not physiologically a contraindication is still listed as a contraindication for the simple reason of being unable to determine a vaccine reaction in the event of one.

Este

+1

 

[Skeptic Ginger]

I can see intraantigenic competition but not inter antigenic competition. I have always seen the recommendation that moderate illness is not a contraindication to vaccination but that "severe" i.e. febrile illness while not physiologically a contraindication is still listed as a contraindication for the simple reason of being unable to determine a vaccine reaction in the event of one.

Este

"Unable to determine" is a pretty weak argument with perhaps the exception of pertussis vaccine or DPTs because febrile seizure is one reason to defer further vaccinations with the pertussis component of the vaccine.

We already know it is safe and effective to vaccinate people with mild illnesses. I said as much. And obviously you get a good response to combined vaccinations. So a mild illness would not interfere with the antigenic response of a vaccine (live nasal spray vaccine isn't given when nasal congestion is present). Vaccine fever on top of acute infection fever is a consideration, but not typically with preexisting low grade fever.

There is a fair amount of data verifying the efficacy of vaccinating an ill child which presumably can be applied to conclusions about adults as well. But there is not the same amount of data verifying the efficacy of vaccinating a person with a severe illness or high fever. And it isn't the most practical kind of research to undertake. Nor is it often one would need to vaccinate a severely acutely ill person or someone with a high fever.

But we do have evidence from studying combined live vaccines that inter-antigenic competition can occur on some level in some cases.

Mutual interference on the immune response to yellow fever vaccine and a combined vaccine against measles, mumps and rubella.

Without studies of seroconversion rates in people vaccinated during severe illness, it makes no sense to give vaccines to them.


**BTW, thanks to both of you for keeping me on my toes.

 

[Skeptic Ginger]

....
The AMA handout, however, does little to inform my particulars; it is relevant generally, and specifically for those who feel that the flu is no big deal; I recognize its signficance as a disease, but return to the fact that I and my family have never been afflicted. Given THAT fact, I'm just not sure how to proceed, but I don't think my uncertainty flows from a failure to appreciate the significance of influenza generally (feel free to correct me if I just seem too glib here; a second read of the handout seems to suggest vaccination as maybe a general strategy towards eliminating influenza writ large; am I reading it right?). Again, I dutifully vaccinated my kids against all recommended illnesses of childhood; the flu just seems sui generis, a thing unto itself worthy of its own consideration.

Ask yourself a couple questions:

Why do you believe you and your family have never been afflicted?

Why do you not accept the recommendation to vaccinate your kids against flu while accepting other recommendations?

It seems to me you are filtering those answers differently than you would for other vaccine choices.

You recognize your kids have presumably never had tetanus, yet you recognize they are still susceptible. Why is that?

You accept the expertise of the official vaccine recommendations, except for flu vaccine. Why is that?


(The following applies to some people, not all people.) People's beliefs about flu are distorted for a number of reasons. People don't recognize influenza as a single entity. They tend to confuse it with 'stomach flu' (not the same thing at all) and every other upper respiratory infection out there.

There are a couple of upper respiratory viruses that are more severe or potentially more severe than the rest. Like the SARS virus, how many people recognize corona viruses that are one cause of the common cold are only a little genetically drifted apart from SARS?

I digress. The bottom line, think of flu like you think of measles. It's a bad disease. Not everyone who gets it gets severe illness but anyone who gets it could. The fact you haven't gotten it yet doesn't mean this won't be the year you do.

The other misconception people have is that the vaccine causes illness and carries significant risk. It doesn't and it doesn't.

The CDC doesn't make vaccine recommendations lightly.

 

[iangoeswest]

Skeptic Ginger - Fair questions. I'll ask 'em here, for better pick-apart pleasure:

> Why do you believe you and your family have never been afflicted?

I suppose if I examine it closely, I labor under the belief that I have a strong immune system (and good hygene / handwashing habits) and have passed that along to my children. Is this the sort of belief susceptible to proof / debunking? Some people have weakened immune systems; do others have strengthened ones? None of this explains why my wife hasn't gotten the flu, of course, but she generally gets sick more often than any of the other four of us. I also live in Northern California, which at least this year has seen less flu. I have never examined this belief closely (and don't know how I would, beyond the observation that we seem to get sick less than our respective peers).

> Why do you not accept the recommendation to vaccinate your kids against flu while accepting other recommendations?

Inarticulate distrust, obviously, not of tainting nor government conspiracy, but of the fear that I'll break something not broken; no more or less than I originally suggested. Perhaps mere ignorance.

> You recognize your kids have presumably never had tetanus, yet you recognize they are still susceptible. Why is that?

Huh. I hadn't thought of it quite like that. Tetanus may not be a great example (don't we get that from stepping on rusty nails?) but I take your point. So, following that to its logical conclusion, I apparently believe me and my children to be less susceptible to influenza (than who? just, "the average?").

I have never had the chicken pox, but shortly after the birth of my first child dutifully presented myself for vaccination, understanding it to be a particularly nasty disease of adulthood. My doctor - following a protocol either of his or my health provider's devise - first tested me for the antibody. Turns out I'd (apparently) been exposed and had apparently developed the necessary antibodies. I haven't thought of that story in some time, but I suppose it informs my (somewhat unexamined) belief around such things.

> You accept the expertise of the official vaccine recommendations, except for flu vaccine. Why is that?

This I'm not sure about and will have to think on. But think on it I will.

Your "digressions" would seem to cut in favor of the other direction (i.e., I thought I had the "flu" but I really didn't), and I've been banging the "it's not the stomach flu, it's food poisoning" drum whenever it comes up. At any rate, I take your larger point vis a vis the risk, and wouldn't be here considering these issues in this forum if all I wanted was navel gazing or confirmation bias.

My concerns are NOT that the vaccine will give me the flu, nor that it carries the sorts of risks that the anti-vaxxer crowd brings up. I am apparently concerned that regular vaccination of this type might compromise my body's ability to fight off similar pathogens for LACK of the vaccine on a particular year, and it was to this point that my (rambling, ill-focused) queries have been driven; it's data I'm after, and I acknowledge (and have from the jump) that I'm obviously laboring under some sort of poorly-examined bias.

I've been given more to read than I've had a chance to, but your having taken the time to ask questions it seemed impolite not to address them a bit (I recognize the questions were for ME, not for your insatiable curiosity about all things iangoeswest, but answering them publicly invites proper criticism, or at least the possibility of someone seeing a blind spot I might myself miss. Bias, after all, deceives the holder.) Thanks, Ian

 

[Dymanic]

I suppose if I examine it closely, I labor under the belief that I have a strong immune system (and good hygene / handwashing habits) and have passed that along to my children. Is this the sort of belief susceptible to proof / debunking? Some people have weakened immune systems; do others have strengthened ones?

It's important to define "immune system" a little more crisply in order to consider these questions. Immunity may be considered as having two distinct aspects which operate independently of one another (they don't, actually; not entirely, but as I noted above, it's just simpler to consider them independently). One thing to consider is that in severe cases of influenza (in particular), it is the body's own immune response which produces the unpleasant symptoms, and is most often the proximate cause of death in fatal cases (the viral infection itself being the ultimate cause).

The cell-mediated response has the advantage of being fast, the downside being that it is rather heavy-handed. It relies on methods like inflammation and destruction of infected cells. There's a lot of collateral damage. Fluid and detritus from the killed cells ends up in the lungs, which makes it hard to breathe. Eventually, it becomes impossible to breathe, and if the illness has not resolved by then, you're done. So having a "strengthened immune system" isn't necessarily all that, if what we mean by that is cell-mediated immunity.

What you're looking for from vaccination is antibody immunity (traditionally referred to as "humoral immunity"). We all begin life with naive immune systems. Like hygene habits, this type of immunity cannot be inherited, but is aquired through a form of training (one of the first things naive B-cells have to "learn" is to respond only to foreign antigens). We (normally) develop antibodies in response to exposure to foreign antigens, and afterward we retain immunological memory specific to each antigen, enabling us to respond much more quickly to a subsequent encounter with the same pathogen.

Flu has evolved the ability to outflank our immune memory by making changes to the sites where the antibodies bind. Our immune systems respond by "evolving" B-cells that can produce antibodies that will bind to the altered structures. It's a much more elegant solution, but it takes longer to develop (though once a well-matched antibody is aquired, the B-cells start replicating exponentially within a very short time). The rare person who truly has never been exposed to any influenza antigen -- either through infection or vaccination -- would surely be more susceptible to influenza infection than a person with an extensive library of flu antibodies, imperfectly matched to the new strain though they may be at the outset. With that in mind:

I am apparently concerned that regular vaccination of this type might compromise my body's ability to fight off similar pathogens for LACK of the vaccine on a particular year...

It's like hoping to become a better fighter by avoiding getting into fights. Antibodies which are an imperfect match may still reduce the severity and duration of illness, and B-cells don't know or care whether the antigens they're responding to came from vaccination or infection.

There is this thing called "original antigenic sin", but... maybe we're not ready to get into that. (I know I'm not. Hi Kelly).