Mumps outbreak in Washingon--are anti-vaccers to blame?

While browsing news this week I came across a story of a mumps outbreak in Washington and Arkansas (Scutti, 2017).  I couldn’t help but think about the “anti-vaccine” movement that seems to pop up in the news every few months.  To the best of my knowledge, this movement stems from a 1998 paper by a British gastroenterologist claiming that the MMR (measles, mumps, and rubella) vaccine was linked to autism (PublicHealth).  His paper has since been retracted by the publisher, but the myth that vaccines may cause autism, or otherwise be harmful, still persists. (PublicHealth debunks this myth along with several other vaccine myths here)

A 2013 study shows that an outbreak of pertussis in California was clustered in geographic areas with high rates of non-medical exemptions for vaccines.  These exemptions are granted for religious or philosophical reasons to parents who wish to leave their children unvaccinated (Atwell et al, 2013).  One thing I’ve learned about in my pre-med classes is the idea of herd immunity.  The basic concept is that if most the individuals in a population are vaccinated against a disease, those that haven’t been immunized will still be protected.  It is important that vaccination rates don’t drop low enough that leaves vulnerable populations at risk.  These populations might include infants too young to be vaccinated and individuals that got the vaccination but did not acquire immunity. 

According to scientists, the MMR vaccine is 88% effective after two doses.  In some states, that vaccination rate is as low as 87.1% for children entering kindergarten (Scutti, 2017).  By doing some simple calculations, it is evident that the true immunity rate may only be about 77%, leaving about one-quarter of the population vulnerable.  Despite the risks that under-vaccination may present, the outbreak in Arkansas is more likely due to crowding and poverty, says state epidemiologist Dirk Haselow (Scutti, 2017). 

Whatever the cause of these outbreaks is, one thing is certain: getting vaccinated can only help to stop them.

Sources:

Atwell, JE, Van Otterloo, J, Zipprich, J, Winter, K, Hariiman, K, Salmon, D,…, Omer, SB. Nonmedical (October, 2013) Vaccine Exemptions and Pertussis in California, 2010.  Pediatrics, 132(4). Retrieved from: http://pediatrics.aappublications.org/content/pediatrics/early/2013/09/24/peds.2013-0878.full.pdf

PublicHealth.  Understanding Vaccines.  Retrieved from: http://www.publichealth.org/public-awareness/understanding-vaccines/vaccine-myths-debunked/

Scutti, S. (9 February 2017). With 404 cases, Washington mumps outbreak continues to grow. Retrieved from: http://www.cnn.com/2017/02/08/health/mumps-washington-outbreak/index.html