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Childhood mortality and vaccines

Posted Oct 02 2011 4:03am

One of the ideas that gets presented as fact all too often on the internet is “the United States is the most vaccinated country in the world and has one of the worst childhood mortality rates”. There are variations of this, of course. Unfortunately, this notion gets put forth by autism-parents and even autism-parent organizations.

This sticks in my mind since a rather blatant attempt at misinformation from Generation Rescue in the form of a pseudo-paper “special report”: . I wrote about the many failings of that document at the time.

One major failing in the childhood mortality comparisons is that the U.S. measures infant mortality (which is a big piece of under 5 mortality) differently than other countries. As Bernadine Healy (a source highly respected by groups such as Generation Rescue) wrote:

While the United States reports every case of infant mortality, it has been suggested that some other developed countries do not. A 2006 article in U.S. News & World Report claims that “First, it’s shaky ground to compare U.S. infant mortality with reports from other countries. The United States counts all births as live if they show any sign of life, regardless of prematurity or size. This includes what many other countries report as stillbirths. In Austria and Germany, fetal weight must be at least 500 grams (1 pound) to count as a live birth; in other parts of Europe, such as Switzerland, the fetus must be at least 30 centimeters (12 inches) long. In Belgium and France, births at less than 26 weeks of pregnancy are registered as lifeless.

But why bring this up again? The reason is simple: I found a very interesting source of data and in reviewing it, I found information on vaccines and on childhood mortality: the Google Public Data Explorer . The Wold Bank dataset includes childhood and infant mortality figures.

What does the childhood mortality rate look like as a function of time for the United States? Not surprising (to most) it has been dropping over the past 30 years. In fact, from 1989 to 2009 the rate dropped from 12.1 per 1,000 to 7.8 per 1,000. ( click to enlarge ):

Why pick 1989 onward? This is the period when the vaccine schedule in the U.S. increased dramatically. If the idea that vaccines are somehow linked to worse childhood mortality we would expect this trend to be increasing, not decreasing.

Here is a good example of why we can’t say that correlation means causation. Consider childhood mortality for a country. Consider CO2 emissions for a country. Guess what, there is a big trend towards lower childhood mortality with higher CO2 emissions. ( click to enlarge )

The “effect” (quotes mean it isn’t real) is huge. Note that the graph is a log-log plot. Countries with high CO2 emissions have 20 times, or more, lower childhood mortality. If we were in the “correlation equals causation” camp, we would decide that CO2 prevents childhood mortality. We could take this another step into the ridiculous and say, “Since CO2 emissions will coincide with higher atmospheric mercury due to coal burning and other sources, mercury must prevent childhood deaths”.

So keep that lesson in humility in mind as we play armchair epidemiologist and look further into the World Bank data. What is correlated with childhood mortality that might make sense? Being from a country in sub-Saharan Africa is correlated with high infant mortality rate. Low income countries have high infant mortality rates. Having a skilled person to attend the birth is correlated with low infant mortality rates.

Vaccines? What about them? They only have data for measles vaccine uptake. Again, not surprisingly, childhood mortality is lower for countries with higher measles vaccine uptake ( click to enlarge )

I chose 2003 for the year for this comparison. That year has data as well for the fraction of births attended by skilled health staff. The datapoints are color coded with this to show that this is a big correlate. The more births have a skilled health worker in attendance, the more kids live. Could be a proxy for some hidden variable, but it makes some level of sense that having a health worker would reduce infant mortality. It also makes sense that countries with access to healthcare in general would have lower infant mortality.

But, that brings us back to the measles vaccine and infant/childhood mortality. Does the vaccine reduce infant mortality? Certainly in countries where measles is endemic. But measles vaccination isn’t the reason why childhood mortality figures are higher in, say, Chad than in the United States. And that’s why researchers try to control for other factors, like wealth and access to health care, when trying to correlate factors and diseases.

Otherwise, you end up with “mercury causes autism”. Or, using the World Bank data, “Cell phones cause low fertility rates”. Or other strange ideas .

While I think these data show pretty clearly that childhood mortality is not likely increased by vaccines, they also show the pitfalls of being an armchair epidemiologist. With the internet, data abound. One can find many correlations. Some are just random. Some are due to some unseen variable. Some are an indication of actual causation.

Do I believe that there is a reason why childhood mortality is lower in wealthy countries? Yes. Do I believe that there is a reason why childhood mortality is lower in countries with high CO2 emissions? No*. Both show correlations. What about the idea that measured autism rates went up as the exposure to thimerosal increased? Sure, there’s a correlation, just like with CO2 and childhood mortality. And, just like with childhood mortality and CO2, there are other factors at play.

*note—CO2 emissions are linked to countries with greater wealth. In that respect, yes there is a reason for the correlation. But there is no direct correlation of CO2 and childhood mortality.

  1. Autism Blog – Childhood mortality and vaccines « Left Brain/Right … | My Autism Site | All About Autism:
    [...] See more here: Autism Blog – Childhood mortality and vaccines « Left Brain/Right … [...]
  2. David N. Brown:
    A bit of nitpicking: I don't think phrasings like " 20 times lower" are valid. At least, it's far more clear and accurate mathematically and gramatically to say eg. "one-twentieth". As far as this issue, any suggestion that the US is behind most of the world in infant mortality SHOULD be a sick joke. I cannot comprehend how anyone could believe it, unless they knew nothing about conditions in the developing world, or for that matter our own country up to the early to mid-20th century. What makes this all the more bizare is that there are absolutely horrific reports of problems associated with vaccination in the developing world, up to and including HIV infections resulting from incompetent procedures. But the anti-vaxxers are evidently too self-centered to pay attention to what goes on outside the US and (maybe!) western Europe, even for what suits their own agenda. David N. Brown Mesa Arizona
  3. Prometheus:
    Sullivan, Your truncation of the US under-five mortality figures at 1989 is a shameless distortion of the data! When I went to the same source, I found that in 1960 - prior to the introduction of the measles vaccine in 1963 - the under-five mortality rate in the US was 30 per 1,000 - five years after the measles vaccine was introduced (1968), the under-five mortality was 25.3 per 1,000 and by ten years after the measles vaccine was introduced (1973), the under-five mortality was all the way to 20.4 per 1,000. That's over a 30% decrease in just ten years! By 1989 - where your graph begins - the under-five mortality had dropped almost 60%! Your graph cuts off most of the improvement in under-five mortality seen in the period 1960 - 1990, a period of explosive development in childhood vaccines. If we look at the time just before the so-called "autism epidemic" (which, we are assured, was caused by vaccines), we see that in 1985, the under-five mortality was 12.8 per 1,000. After the introduction of literally dozens of vaccinations (as opposed to vaccines), that figure was a shocking 7.8 per 1,000 (in 2009, the last year in the database). That means in the 24 years of the "autism epidemic", while the number of vaccinations given to children went "through the roof", under-five mortality dropped almost 40%! You'll pardon me if I find that a little bit astonishing, not to mention shocking. Of course, what astonishes and shocks me is that any sentient being on the planet bought into GR's anonymous "study" purporting to link vaccinations with under-five mortality. Of course, I'm sure the anti-vaccinationistas will insist that back to the idyllic days before vaccinations (i.e. the early 18th Century), child mortality was even lower than it is today, since they ignore any data contrary to their own fantasies. Prometheus
  4. Sullivan:
    In my defense-- the discussion truncates at 1989. The graph does go back to 1960. http://leftbrainrightbrain.co.uk/wp-content/uploads/2011/09/US_child_mortality.png No matter what era one focuses upon, the idea that vaccines are somehow linked to poor childhood mortality rates is bogus. I prefer your presentation to my own dry account, though.
  5. stanley seigler:
    [Prometheus say]...(i.e. the early 18th Century), child mortality was even lower than it is today... lets return to "those thrilling days of yesteryear"...there was no autism...ergo no need for cause/cure discussions... stanley seigler

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