Measles Marches to the Tune of the Vaccine-Hesitant

How misplaced skepticism about biomedical science endangers public health.

Posted May 06, 2019

wikicommons
Source: wikicommons

Resurgent Measles

The USA has already seen more cases of measles in the first four months of 2019 than in any year this century.  By the end of April, more than seven hundred cases had been reported across twenty-two states.  This is remarkable, given that since 2000 the disease had been regarded as eliminated in the USA, i.e., it no longer circulated in the American population.

In his landmark work, Guns, Germs, and Steel, Jared Diamond characterizes measles as one of the highly contagious “crowd diseases.”  Crowd diseases depend upon large, sedentary populations of susceptible individuals to persist.  They are comparatively new diseases in the history of our species, arising since the invention of agriculture over the last ten thousand years.  Because measles is so easily transmitted and spreads so fast, even without vaccination local populations of less than a half million people are unlikely to sustain it for the long term.  Measles will spread rapidly in smaller isolated populations until virtually everyone gets the disease.  People either die or recover, and the recovered subsequently possess a natural immunity.  Then measles disappears until a large enough cohort of vulnerable people has been born to sustain a new epidemic all over again.  These days victims usually recover, but somewhere between one-tenth of a percent and ten percent die, depending upon the quality of the available medical care and nutrition.  In 2017 approximately 110,000 people died worldwide from measles or its complications.  (Measles in pregnant women also endangers successful childbirth.)

The Vaccine-Hesitant   The medical world employs the euphemism “vaccine-hesitant” to describe parents who resist having their children vaccinated against measles and other diseases.  The World Health Organization (WHO) includes vaccine-hesitancy among its list of ten major threats to global health.  That is, in part, because vaccination against measles protects not only the vaccinated; it also protects people such as infants too young for the vaccine and people who for various medical reasons, such as suppressed immune systems, cannot receive it.  The safety of these vulnerable individuals relies on the herd immunity of the community, which in modern cities requires immunity in well above ninety percent of the population.  These vulnerable people do not get and spread measles, because the vaccinated community around them does not get and spread measles.

Why are some people vaccine-hesitant?  WHO notes that “complacency, inconvenience in accessing vaccines, and lack of confidence are key reasons underlying hesitancy.”  A few comments on the first and third of these considerations follow.

Complacency, Ignorance, and Misplaced Skepticism

Complacency arises, first, (ironically) from the effectiveness of public health measures like programs of mandatory or widespread vaccination and, second, from ignorance of the long, grim history of crowd disease epidemics.  For example, in 1875 a Fijian chief carried measles back to Fiji after a visit to Australia.  Approximately twenty-five percent of Fijians died as a result.  In his gripping book, Pox, Michael Willrich documents a long-standing wariness about vaccination among the less educated in America.  People opposed to vaccinations have forgotten or have never known about the devastating effects of crowd diseases on unprotected individuals and human populations. 

It is the third consideration that WHO notes, viz., “lack of confidence,” however, that is the most worrisome.  This is of a piece with a growing skepticism about science in contemporary culture, abetted by, among other things, the strikingly counter-intuitive character of most scientific ideas, inadequate science education, rampant anti-intellectualism fueled by some religious and political groups, and, concerning vaccination, in particular, recent Russian disinformation campaigns on social media. 

Philosophers of science repeatedly concede the limitations and the failures of the sciences but affirm, nonetheless, science’s unsurpassed status as a means for gaining penetrating explanations, correct predictions, and unprecedented control of the natural world.  For the last four hundred years that has been consistently true over the long term and most of the time even over the short term.  To be sure, scientists both change their minds and make mistakes of all sorts, but no collective human enterprise is more rigorous, vigilant, or effective than modern science in its self-scrutiny and internal correction.  Certainly, over the long haul, modern biomedical science’s history of the vaccination of populations to protect them from insidious crowd diseases, including measles, has been a parade case of scientific success.  Anyone who ignores this history and downplays this accomplishment does so at our peril. 

References

Diamond, Jared. (1998).   Guns, Germs, and Steel:  The Fates of Human Societies.  New York:  Norton.

Willrich, Michael.  (2011).  Pox:  An American History.  New York:  Penguin.