Nonsense: "If the MMR was effective only unvaccinated people would get measles."

Jonathan Benson is spreading misinformation on Natural News.

Regarding the latest measles outbreak he writes:

If the vaccine for measles -- in the U.S., this vaccine is the combination measles, mumps and rubella (MMR) injection -- really did work as claimed, then all the measles cases identified at Disneyland would have been in unvaccinated people.

If Jonathan had looked at what the CDC claims about the MMR in the pink book, he would know that the MMR vaccine efficacy isn't 100% (as Jonathan suggests) but around 95% for one shot and 99% for two doses.

Is such a high efficacy reflected in the current outbreak? Let's take a look at the numbers...

Out of the cases where the vaccination status was known, 28 people were unvaccinated.

About 90% of Americans have had two doses of the MMR, for every unvaccinated person in the USA there are about 9 vaccinated people in the USA. Therefore if measles affected unvaccinated and vaccinated people equally we would expect there to be 9 times more cases in vaccinated people than unvaccinated people. This would be about 252 cases in vaccinated people in the current outbreak.

There were 6 cases of measles in vaccinated people.

Six cases of measles in vaccinated people is 246 (or 97.6%) fewer cases than what we'd expect if measles affected vaccinated people no differently to unvaccinated people.

If somebody wants to claim that the MMR isn't effective they need to be able to explain why unvaccinated people are disproportionally represented in measles outbreaks.

United States Measles Case Fatality Rate

Key Points:

• Case Fatality Rate for Measles in the USA is 1-3 deaths per 1,000 cases
• This rate is based on USA measles figures, not global figures

There's an article on VaxTruth, 'Measles at Disneyland!' about the measles cases traced back to Disneyland the 2012 Indiana outbreak. It's a behemoth post so I can completely understand the author not wanting to "reinvent the wheel" by writing something new for the Disneyland cases. Personally I'm not a fan of such massive articles, preferring smaller more specific posts instead as I think they tend to be a bit more constructive. So that's exactly what I'm going to do, I'm going to look into the alleged problems with the case fatality rate (CFR) provided by the CDC.

From the VaxTruth article:

The statement that 1 out of 1,000 “children” who get measles will die from it is misleading. That’s because those numbers are based on the global measles problem; not measles in the United States.

When I wrote the article on the Indiana “outbreak” in 2012, there was a CDC MMWR publication I used and linked to, to show how inflated the 1/1000 number was. That publication has either been moved or taken down. I will try to find it and include it here, but for now I have to leave this information without the citation (due to limited time). In the CDC’s MMWR report on measles, it stated there are approximately 20 Million cases of measles each year worldwide and of those cases, there are approximately 197,000 deaths. This appears to be where they are getting their figure of 1 or 2 deaths per 1,000 cases.  The MMWR report also stated that about 1/2 of the deaths from measles occur in India.  So if half of the roughly 200,000 deaths from measles occurs in India, then the rest of the world splits the remaining 100,000 deaths per year. That still sounds like a lot. And SOME of them were children – not all. So the 1 in 1,000 deaths among children statement just doesn’t make sense, unless you are talking about children in third-world countries.

Before I get into the case fatality rate I'll just clear up the "missing MMWR report". Looking at the original article from 2012, the figures don't come from an MMWR but from the CDC's old overview page for measles. I'm not sure why there's any confusion about it considering she still has the link in the original article.

There's a couple of changes from the 2012 version to the present form of the article. Most noticeable of all, the author is now more definite about where the figures comes from: "...those numbers are based on the global measles problem...".

There doesn't appear to be any reason for such confidence.

The author didn't seem to have bothered trying to find the source of the case fatality rate provided by the CDC, instead they made an assumption based on a mathematical error.

(197,000 deaths ÷ 20,000,000 cases) × 1,000 = 9.85 deaths per 1,000 cases

Unless a person thinks that 200,000 divided by 20 million is 1/1,000 there is no reason to think the case fatality rate used by the CDC is based on the global figures listed in the overview.

The overview page is intended as a bit of light reading so it doesn't delve into its sources. For a more complete look at vaccine-preventable diseases on the CDC site, a good place to start is the pink book. Looking at the complications section in the measles chapter, the case fatality rate is given as approximately 2 deaths per 1,000 cases and this is based on "the cases in the United States from 1985 through 1992."

Alternatively, by searching pubmed for the measles case fatality rate in the USA, one of the earliest results found is this paper which gives a case fatality rate of 3 deaths per 1,000 cases based on measles cases in the USA from 1987 to 2000.

It didn't require much effort to confirm that the case fatality rate provided by the CDC was indeed based on measles in the USA and not on global information. It's unfortunate that the author at VaxTruth didn't appear to put in any effort to confirm it herself.

UPDATE: Added key points to the top of the post. (Mar 5th, 2015)

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Want to help eradicate measles? Donate to the Measles & Rubella Initiative (non-US) and fight measles instead of a brick wall.

updates to the 'autism and vaccines' infographic

Every so often this infographic makes the rounds. Overall it's a good infographic (definitely better than anything I could come up with) but there's several parts that really irked me. So without any authorization or demand for it whatsoever I decided to make an updated version of it.

(image opens in a new window)

The following changes were made:

1. Removed text: "the science facts about"

I won't go into it here but I try to avoid using 'science' except in certain circumstances.

2. Added text: "updated Dec 24th, 2014"

Makes it clear it's not the original and adds a date to give people a point of reference.

3. Changed the portrait of Andrew Wakefield

As much as I like the original infographic I really didn't like most of the images and this one I could do something about.

4. Added text: "a study of 12 children"

Helps to put the later numbers in context.

5. Changed the image of the study

Initially changed to make room for the additional text but also changed it so it's clear the the "link" was dubious.

6. Changed text from "Lancet published a paper by Dr. Andrew Wakefield, a dramatic study that found a connection between autism and vaccines" to "Lancet published a paper by Dr. Andrew Wakefield, a study which made dramatic claims of a connection between autism and vaccines."

Being cautious about the way the information is portrayed to ensure it doesn't accidentally leave people with the idea that there was a link.

7. Changed text from "2005 A review of 31 studies covering more than 10,000,000 children also found no connection" to "2005 A review of 6 studies covering more than 1,100,000 children also found no connection"

This refers to the 2005 Cochrane review 'Vaccines for measles, mumps and rubella in children', numbers were corrected to reflect the part of the review concerned with autism.

Honestly I still think it's a bit dodgy including it at all instead of just the updated version but then it messes up the layout a bit too much: http://i.imgur.com/uCsXHqB.png

8. Changed text from "2012 A review of 27 cohort studies, 17 case control studies, 6 self-controlled case series studies, 5 time series trials, 2 ecological studies, 1 case cross-over trial covering over 14,700,000 children" to "2012 A review of 3 cohort studies, 3 case control studies, 1 self-controlled case series studies, 2 time series trials and 1 case-only study covering over 1,150,000 children"

Refers to the 2012 Cochrane review 'Vaccines for measles, mumps and rubella in children' which is an update to the 2005 review. Numbers were corrected to reflect the part of the review concerned with autism.

9. Changed text from "Recently an anti-vaccine..." to "In 2013 an anti-vaccine..."

Adding a specific year will help the infographic age better.

10. Changed text from "Although declared eradicated in 2000..." to "Although eliminated in the USA in 2000..."

This was downright misleading, especially in the context of the cases in the UK & France.

Eradicated means the disease has been wiped out whereas eliminated from a region means that the disease is no longer endemic to that region (i.e. it needs to be imported).

In 2000, measles was declared eliminated in the USA.

11. Changed text from "Before widespread vaccinations of babies" to "Before worldwide vaccinations of babies"

Just wanted to clarify that the figures are global.

12. Changed the pertussis cases image

The graph was bizarre to say the least with numbers given for only the 1960s, 1970s, 1980s, 2004 & 2012 which made it seem cherry picked.

The numbers also didn't seem to match up with the CDC figures (I think 1959 may have been added to the 1960s).

13. Changed text from "a new study concluded that vaccine refusals were largely to blame for a 2010 outbreak of whooping cough in California" to "A 2013 study conclude that vaccine refusals contributed to the 2010 outbreak of whooping cough in California."

Changing 'new' to '2013' helps the infographic age better.

The study states, "Our data suggest clustering of NMEs may have been 1 of several factors in the 2010 California pertussis resurgence." which is very different from saying non-medical exemptions are "largely to blame".

Nonsense: "Estimates suggest that 30% to 45% of all prescription drugs are nothing more than placebos."

According to Payam Saljoughian & Manouchehr Saljoughian, "Many believe that some of the most widely used drugs in modern medicine are completely inert, and estimates suggest that 30% to 45% of all prescription drugs are nothing more than placebos." Which is quite astounding and also quite baseless. For a start it doesn't even match up with their source:

Some estimates suggest that placebos comprise of 30-45 per cent of all prescriptions.

Prescription drugs vary in how often they're used so the percent of prescriptions is not the same as the percent of prescription drugs. Further it's possible to use an effective medication as a placebo (e.g. antibiotics for a viral infection).

Following the chain back further, it turns out that the lower-end of the figure comes from 1952 and the higher end of the estimate comes from 1906:

Dunlap, Henderson, and Inch (1952) analyzed over 17,000 prescriptions of physicians from representative areas in Great Britain for a one month period. Approximately one third were considered to be in the placebo category. The British Medical Journal (1952) editorialized that, "...a bottle of medicine is given as a placebo in about 40 per cent" of the patients seen in the general practice, a figure that is close to Cabot's (1906) estimate of 44 per cent of the prescriptions filled by Boston Bac Bay drug stores.

Sometimes following the source of the information really feels like witnessing a game of broken telephone.

a few thoughts on the anti-vaccine body count

The anti-vaccine body count is a website that keeps a tally of all of the vaccine preventable deaths that have occurred in the USA since mid-2007. I really appreciate the effort that's been put in setting up the site and maintaining it (it's done by a single person) but there are a few things I think I would do differently.

I'll just quickly note at this point I've written this post with only the body count in mind and I'm not sure how much applies to the cases.

Starting with something minor I think I'd probably call it the 'unvaccinated body count' rather than the 'anti-vaccine body count'. Anti-vaccine is a fairly nebulous term (e.g. should it apply to people not getting a flu shot?) and isn't something people self-identify as. By keeping to the broader 'unvaccinated' phrasing it avoids potential arguments as to what is and isn't an anti-vaxxer (e.g. should the influenza associated deaths be included in an "anti-vaccine" body count).

Secondly, an unnecessarily large number of sources are used for the tallies (which also creates a few minor inaccuracies as the figures used are preliminary). Take 2014 for example, on the anti-vaccine body count there are 31 reports listed to get the figures. It looks impressive. It's also completely unnecessary as you can get the cumulative total for the year from the final report (and for the five previous years as well). By listing only the necessary reports it would make the numbers easier to verify and thus make them stronger.

Thirdly, there's no real breakdown on the cause of death and for most of the reports listed on the source page it doesn't mention the cause (generally influenza-associated infant mortality). I think it'd be nice to have that information readily available (in a chart or a table).

Figure 1: The cause of deaths in the anti-vaccine body count

Finally, as a number of the deaths would still have occurred in the absence of unvaccinated people I think it's unfortunate that all vaccine preventable deaths were given and no attempt was made to refine the number. While I think it would be extremely difficult to do accurately I think the following formula could be used to work out the lower limit of the body count:

body count = VE×( (1-VC) / (1-VC)+VC×VE )

Where VE is 'vaccine effectiveness' and VC is 'vaccination coverage'. The formula doesn't take into account different mortality with the disease in vaccinated and unvaccinated people and it doesn't take into account the fact that a lot of vaccinated people who were exposed wouldn't have been had there been no unvaccinated population. I'm unsure if there's a way these things factors could be incorporated but until then the formula should provide a lower limit to the body count.

After writing this post I might set up a page on this blog for the 'unvaccinated body count' to be a compliment tally that can be used alongside the 'anti-vaccine body count'.

UPDATE: Put together some rough figures and made the unvaccinated body count.

Vaccine Effectiveness

Vaccine Effectiveness is the approximate measure of the percentage of cases that a vaccine prevents in an outbreak. It is calculated using the following formula:

VE = (ARU - ARV)/ARU [x100%]

Where VE is the vaccine effectiveness, ARU is the attack rate in the unvaccinated and ARV is the attack rate in the vaccinated. The attack rate is the proportion of the given population (unvaccinated or vaccinated) that are infected with the disease.

Figure 1: ARU 0.3, ARV 0.06

In Figure 1 it's easy to visualize how the formula works. The shaded area is the unvaccinated attack rate applied to the vaccinated population. The people within the shaded area would have been infected had there been no vaccinations. All of the healthy people in the grey area represents an infection that the vaccine prevented, this can be calculated using (ARU - ARV). Then to get the proportion of cases prevented as a proportion of the cases that would have occurred the full formula is used: (ARU - ARV)/ARU.

In the above example the ARU is 0.3 (3 out of 10) and the ARV is 0.06 (6 out of 100) so the proportion of cases prevented (ARU - ARV) is 0.3 - 0.06 = 0.24 which means the vaccine effectiveness is 0.24/0.3 = 0.8 or 80% (the vaccine prevented 24 out of 30 cases that would have occurred in an unvaccinated population).

Another thing to notice is that even with an effective vaccine, when there is a high vaccination rate it is expected that there will be more cases in the vaccinated population than the unvaccinated population. Only if the ARV was equal to the ARU would the vaccine be ineffective.

Herd Immunity Threshold

When reading an article about vaccines and vaccine preventable diseases it's not uncommon for there to be a statement in the article along the lines of, "With 90% of full immunisation needed for herd immunity..." or, "When the number of people vaccinated drops below 95%, a community loses herd immunity to highly contagious germs like pertussis..." What are these numbers and how are they determined?

The numbers are referring to the 'herd immunity threshold' which is the approximate proportion of the population that's needed to be immunised so that the infectious disease will die out  in that population and it is worked out with the following formula:

threshold = 1 - 1/R₀

The key to understanding this formula is the 'basic reproduction number' (R₀). The basic reproduction number is the average number of additional people that will be infected for each case in a population with no immunity.

Figure 1: A disease with an R₀ of 4

If a disease has a reproduction number greater than 1 then the disease will increase in numbers in the population whereas if the reproduction number is less than 1 then eventually the disease will die out in the population. To create a population in which a disease cannot persist then it is necessary to reduce the reproduction number to less than 1 (or thereabouts).

Figure 2: A disease with an effective reproductive number reduced to 1

So out of all the number of additional people that would be infected from a case (R₀), all of them except one needs to be immunised (R₀-1), or as a proportion this can be written as:

(R₀-1)/R₀

Which can be arranged to arrive at the herd immunity threshold formula:

=> R₀/R₀ - 1/R₀

=> 1 - 1/R₀

The final figure given is an approximate figure and doesn't take into account things like vaccine effectiveness or other public health efforts used to combat infectious diseases. Finally, herd immunity is not all or nothing and even if the vaccination rates aren't as high as the herd immunity threshold it's still possible for unvaccinated people to benefit from the cocooning effect of herd immunity. If you vaccinate you're not only protecting yourself, you're also helping to protect those who can't (or won't) be vaccinated.