In comparative effectiveness research, comparison groups should reflect...meaningful choices in real world practice. Comparator Selection – Developing a Protocol for Observational Comparative Effectiveness Research: A User’s Guide
Making a decision often involves making a judgment between A compared to B. In making such decisions we often rig our decision by building our biases into the alternatives we select. We make A appealing while presenting its critical comparator B as nasty or generally unappealing, creating an extremely powerful method of persuasion and has been used to great effect by the anti-vaccine groups.
In 1998 a fraudulent claim was made by Andrew Wakefield, a British gastroenterologist, that measles vaccine caused autism. Despite its having been thoroughly debunked by a large body of research, the claim is used by anti-vaccination advocates as a critical comparator in the argument: when compared with measles which may actually be beneficial, the measles vaccine is extremely dangerous.
This rigged comparison while unsupported by any evidence creates a simple story designed to be compelling to, for example, young parents who are going to take their six month old to the pediatrician for the first round of the MMP vaccine: don't worry about measles, worry about the vaccine.
The anti-vaccine argument has convinced enough parents in some communities to be "vaccine hesitant" with the net effect of a reduction in the vaccination rate to cause a loss of herd immunity in some American communities making them vulnerable to measles outbreaks. When a measles-infected individual comes in contact with unvaccinated community members, an outbreak becomes likely as in the California Disneyland outbreak in 2015 (connected to a Philippine measles outbreak) and the current Williamsburg neighborhood of Brooklyn (connected to a measles outbreak in Israel) this year.
But there is a major flaw in anti-vaccine's simple and compelling story; the real nature of the villain, and the villain itself remains hidden.
The real critical comparator that should be used to judge vaccination is the actual measles virus. Fortunately for the anti-vaccination advocates and unfortunately for the rest of us, measles and its character has been obscured because of the effectiveness of the measles vaccine. Most Americans, including many physicians and health-care workers, have never actually witnessed a case of measles.
The rarity of the infection makes it easy to make claims about the measles and the vaccine in the absence of the example of what an actual child goes through during a case of the measles. Before the measles vaccine appeared in 1964, a measles infection was a common ordeal for nearly all American children--an ordeal that included cough, runny rose, fever, and red watery eyes and which, most, but not all children successfully endured. During each of those pre-vaccine years, measles caused about 48,000 hospitalizations, along with about 450 deaths and including children who suffered deafness or cognitive impairment as a result of the infection.
Despite efforts of anti-vaccine activists when the measles vaccine appeared in 1964, the measles vaccine program was rapidly embraced, in fact, so rapidly that the rate of infection fell steeply so that by 2000 the Centers of Disease Control claimed that measles had been eliminated from the U. S.
We now present the real villain of the story--the measles virus.
Measles is caused by a virus, which is a single strand of RNA wrapped in an envelope and which needs a living cell in order to reproduce itself. Once it succeeds in penetrating a living cell, it takes over the cell’s reproductive machinery and uses it to make copies of itself, eventually so many copies that the cell bursts spewing virus particles into the blood stream. As cells are destroyed key bodily functions, such as its immune response, are crippled.
A new measles infection is caused by a current infection. The characteristic measles’ hacking cough propels aerosolized droplets into the air, each droplet carrying millions of copies of the virus where they linger on air currents or settle on surfaces. The measles virus can live for up to two hours, potentially infecting anyone vulnerable who enters the room during that period. A child’s cough during the third period can not only infect its third period classmates but also children in the fourth and (even possibly those in the fifth period).
In an immunized individual inhaled particles reach the lungs and are engulfed by protective macrophages and dendritic cells and are carried to lymph nodes where the T and B immune cells will destroy them. In a vulnerable individual the virus is able to enter the T and B cells and capture the cells’ reproductive machinery. Now instead of producing more T and B cells, the now-in-charge virus begins to churn out millions of copies of itself. The defending army has been transformed into the invading army, one that is able to suppress the individual’s immune system leaving the body vulnerable to additional infections such as pneumonia.
As these infected T and B cells travel through the blood stream they leave behind them increasing numbers of virus particles that can invade organs throughout the body: the spleen, lymph nodes, liver, thymus, skin and lungs. In one in 1,000 cases, the virus is able to invade the brain, causing dangerous swelling that may cause neurological damage that may last into later life.
For the first four days of the invasion, the infected individual feels terrible will not suspect that the cause of him discomfort is measles but will none-the-less be sharing his infection with every vulnerable contact. The tell-tale measles rash won’t appears about the fourth day as the measles virus appears in the skin capillaries and are detected by immune cells that kill the virus particles using harsh skin-irritating chemicals.
The invasion of the lungs brings on the hacking cough that spews more virus particles into the air where it can be inhaled beginning the disease cycle once more.
Picking a phony critical comparator may be an excellent way to win an argument; it is terrible practice.
Olive, Jacqueline K., Peter J. Hotez, Ashish Damania, Melissa S. Nolan (2018). The state of the antivaccine movement: A focused examination of nonmedical exemptions in states and counties. PLOS https://doi.org/10.1371/journal.pmed.1002578
Shultz, David (2015). What does measles actually do? Science, 1/30/2015. Retrieved from https://www.sciencemag.org/news/2015/01/what-does-measles-actually-do
Setoguichi, Soko and Tobia Gerhard (2013). Chapter 5 Comparator Selection from Developing a Protocol for Observational Comparative Effectiveness Research
Images: Electron microscope image of measles virus from https://www.sciencemag.org/news/2015/01/what-does-measles-actually-do
Dr. John HOlton
Dr. John Holton joined the S²TEM Centers SC in July of 2013, as a research associate with an emphasis on the STEM literature including state and local STEM plans from around the nation.