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Why vaccines *won’t* overwhelm your immune system

A very quick post today, but a topical one given the situation in Wales (and the UK in general) with regards to measles.  The latest press release from the Welsh NHS has said that there are now 765 known cases, and that over 70 of these people have been hospitalised.  That’s one in ten of the people affected who have ended up in hospital.

There has been (entirely reasonable) supposition in the press that the people affected are largely children who were not vaccinated with the MMR due to the completely false suggestion that the vaccine may cause autism or bowel disorders.  It is felt in some circles that the vaccine may somehow overwhelm a child’s immune system, and lead to illness.

Numerous studies have disproven ths link, and the original paper that suggested it has been withdrawn by the publisher.  The paper itself has been called not only wrong, but downright fraudulent.  Sadly this hasn’t been enough to undo the damage done by the original paper, and by the subsequent media storm that erupted around it.  Measles is not a trivial infection, and as the Welsh NHS press release rightly says, “it is just a matter of time before a child is left with serious and permanent complications such as eye disorders, deafness or brain damage, or dies.”

So in light of all that, I stumbled across this quote this morning in an article published at Medscape.  It’s a rather eloquent way of highlighting the scale of immune assault that we all face every single day, and how unlikely it is that any vaccine could pose a risk on these grounds:

In general, however, if you take a step back and look at this question, the notion that the number of immunologic components in vaccines could in some way weaken, overwhelm, or perturb the immune system is fanciful. When we are in the womb, we are in a sterile environment. When we leave the womb and enter the birth canal and the world very quickly, we are colonized with trillions of bacteria, to which we make an immune response. The total number of immunologic components in today’s vaccines is approximately 165. When you think about the number of antigens that you encounter (remembering that a single bacterium has 2000-6000 immunologic components) and that you are making grams of immunoglobulin every day, that the dust you inhale isn’t sterile, and the food and water that you eat and drink aren’t sterile…The notion that vaccines would somehow weaken or overwhelm the immune system is certainly not supported by what we know about immunology and microbiology.

To put it another way, one single bacterium has 12-36 times as many immunologic components as the average vaccine.  The average person has trillions of bacteria on and in their bodies (in fact in terms of cell numbers we’re more bacteria than we are human), so the addition of a few extra antigens in a vaccine is really a vanishingly tiny drop in a huge ocean.

While I’m not trying suggest that vaccines are risk-free (because that can’t be said of any medicine), the risk of being vaccinated is certainly much lower than the risk of complications from catching something like measles.

Postscript: Medscape have a second article about a recent study that found no link between childhood vaccination and autism; it’s worth a look if you have a login.

EDIT: thanks to Nico in the comments for pointing out a factual error.  I originally asserted that by weight a human being is more bacteria than human.  That is of course wrong (we’re 1-3% bacteria by weight).  We do however contain 10 times as many bacterial cells as our own cells.  Which is either quite wonderful or rather creepy, depending on how you look at it.


Homeopathic Harms vol 5: interactions

I might be a little quiet for the next wee while due to some unforeseen circumstances,  but to tide you over here’s the next installment in the Homeopathic Harms series by @SparkleWildfire – interactions.

In the next installment of our series on the harms of homeopathy, I want to talk about interactions. I’ve covered this a bit in the past, but let’s have a look at this area in a bit more detail.

We all hopefully know by now that homeopathic medicines pretty much have no trace of active ingredient in them by now. Do we need to worry about drug interactions with homeopathic remedies?

Can homeopathic medicines interact with conventional medicines?
The obvious answer is no. Magic Sugar Water Pills are highly unlikely to affect any conventional medicines. There’s a lack of actual evidence to prove this, but I think it’s pretty safe to rely on a theoretical basis here. So that’s great, right, blog post over and see you later. If only it were that simple.

Read the rest over at A Healthy Dose of Skepticism.

Plain language summary: calcium supplements and heart attacks

The research:

Calcium supplements with or without vitamin D and risk of cardiovascular events: reanalysis of the Women’s Health Initiative limited access dataset and meta-analysis

The summary:

This trial took information from 36,282 women who had been through the menopause, and looked at them to see whether taking calcium supplements made them more likely to have a heart attack.  Half of the women were given calcium and vitamin D supplements, while half were given a placebo (sugar-pill).  The trial found that taking calcium and vitamin D increased the risk of heart problems slightly, including heart attacks.  Some women took their own personal calcium supplements as well as those provided by the study, and these women had no increased risk of heart attack.

Re-analysis of some older trials found that calcium and vitamin D increased the risk of heart attacks and strokes.  The way that calcium supplements are used should be examined, to see if change is needed.

The caveats:

This paper appears to find that women who take the highest amount of calcium (their own tablets plus the ones provided by the study) have no increase in risk compared to women who don’t take any calcium at all.  If this was a true effect, we would expect women who take the most calcium to have the highest risk. Other authors have published papers that find no evidence of risk with calium and vitamin D supplements.

This paper is discussed in more detail in this blog post.

Plain language summary: Trastuzumab emtansine for breast cancer

The research:

Trastuzumab Emtansine for HER2-Positive Advanced Breast Cancer.

The summary:

This trial looked at a drug called T-DM1, which is designed to treat a type of breast cancer called HER-2 positive breast cancer. T-DM1 was compared to a combination of two drugs that are already available.  It found that cancer progression was delayed by about three months in women who received T-DM1, from 6.5 months to 9.5 months.  These women also lived roughly six months longer than the other group. Serious side effects were common in both groups, however they were less common in women receiving T-DM1.

The caveats:

The women recruited for this trial were reasonably healthy when they started.  Women were only allowed to enrol if:

  • they had breast cancer that had failed to respond to treatment with trastuzumab (which is one of the components of T-DM1) plus another drug
  • their breast cancer had spread (either locally or more widely).
  • they were still able to perform light work, such as housework or an office job.

In real-world conditions, women who receive treatment with T-DM1 might not be this fit, so might not get the same benefits as the women in the trial.