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Home » Anti-vaccine statistics – back to simple math again

Anti-vaccine statistics – back to simple math again

One of the age-old tropes of the anti-vaccine statistics world is that kids who have been vaccinated against the measles are more likely to get measles than those who are not vaccinated. I squashed this myth several times; unfortunately, those are old articles with broken links and such.

Now, the anti-vaccine statistics monsters persevere with their alternative facts. So, once more unto the breach, dear friends, once more. We will take down this trope.

Anti-vaccine statistics – getting it all wrong

We will start right at the top. The vaccine deniers claim vaccinated kids are more at risk of measles than unvaccinated kids. They use amateurish statistics to make these assertions.

Occasionally, measles outbreaks do show higher measles numbers in vaccinated children. However, this data rarely shows a higher rate. Those bolded words are completely different, in case you are keeping score.

The anti-vaccine crowd uses the raw number to compare vaccinated and unvaccinated populations. However, that is not the appropriate way to examine this.

Let’s use an imaginary school in an imaginary state in the middle of an imaginary country. The Skeptical Raptor High School includes a total of 2,000 students, just to make the math quick and simple

According to the CDC, 91.9% of these students received the MMR vaccine (against measles, mumps and rubella) .

Based on that average, 1838 students received the measles vaccine, and 162 did not. A measles outbreak hits SRHS a few months ago, subsequently, 40 vaccinated students catch the measles. On the other hand, only 10 unvaccinated students catch the measles.


Examining anti-vaccine statistics more closely

If you just use the raw numbers, you would conclude that 80% of measles cases were in vaccinated students. But the appropriate method to examine these numbers is to look at incidence or rate.

The incidence for measles in unvaccinated children would be 10 out of 162, or 61.7 measles cases for every 1000 unvaccinated kids. Alternatively, the measles incidence for vaccinated children calculates to 40 out of 1838, or 21.8 cases for every 1000 vaccinated ones.

In other words, the rate, or risk, of measles is about 3 times higher in unvaccinated kids. In fact, real world outbreaks show much higher rates of measles in unvaccinated children, although the raw numbers are generally very close.

There is an argument that the incidence for vaccinated children should not be that high. That is a valid point, but the MMR vaccine is not 100% effective against the measles. In fact, the CDC reports the measles vaccine effectiveness is approximately 97%.

Thus, in our imaginary pool of 1838 vaccinated kids, 55 kids are susceptible to the measles virus, based on vaccine effectiveness only. Moreover, there are lapsed immunity cases in an immunized population, where immunity against measles is lost. This issue increases the risk of measles in vaccinated kids.

Vaccines are not 100% effective. No one ever claims that any medical procedure is 100% effective. But if you look at the rate of measles instead of the raw numbers, the only reasonable conclusion is the vaccinated population is more protected.

Remember this about measles

Many people think measles is a minor disease. This belief results from a lack of personal history with the disease. It has been over 30 years since major measles epidemics swept through children.

The CDC estimates approximately 3 out of 10 adults or children who get measles will develop one or more complications including pneumonia, ear infections, or diarrhea. The myth that measles is “nothing” is simply a myth.

Measles is a serious and dangerous disease. Just examine the real measles statistics.

  • About 1 out of 20 children with measles contracts pneumonia. This is the most common cause of death from measles in young children. Pneumonia often requires hospitalization, sometimes in a pediatric intensive care unit.
  • About 1 out of 1000 children with measles develop encephalitis, a swelling of the brain that can lead to convulsions and neurodevelopmental disorders.
  • About 1-2 out of 1000 children with measles die.


Considering the danger of measles, we need accurate statistics about measles and the measles vaccine. There are no cases of large measles outbreaks where the incidence or rate of measles infection was higher in vaccinated than unvaccinated kids.

But the anti-vaccine statistics pushers want us to believe that measles is a disease of immunized children. They are wrong.

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Michael Simpson

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