I’ve been paying attention to the antivaccine movement a long time. Indeed, it’s been just under a decade since I made what was my first big splash in the blogosphere, namely my particularly “Insolent” takedown of Robert F. Kennedy, Jr.’s conspiracy-laden, pseudoscience-spewing super-concentrated antivaccine nonsense known as Deadly Immunity. So here it is, almost ten years later, and RFK, Jr. is still around, spewing the same nonsense that he did ten years ago, except that this time he’s using Holocaust analogies to describe the vaccination program. Unfortunately, some things never seem to change.
Ever since I’ve taken a special interest in the antivaccination movement, periodically the issue comes up of just who makes up the antivaccine movement. The stereotype is that it’s a bunch of liberal, hippy-dippy lovers of “natural” living, but that’s not quite it. As I’ve pointed out more times than I can remember, antivaccine pseudoscience is the pseudoscience that crosses political boundaries, and there are quite a few conservatives with antivaccine beliefs, and antivaccinationism fits in very nicely with libertarianism, including Rand Paul. But this is not about the politics of antivaccine beliefs; rather it’s about another stereotype about antivaccinationists. However, a recent study hot off the presses in Pediatrics actually seems to confirm this particular stereotype, mainly that those who claim nonmedical exemptions from vaccine mandates tend to be white, affluent suburbanites. This study comes out of the Departments of Geographical and Sustainability Sciences and Epidemiology at the University of Iowa and is entitled Personal Belief Exemptions to Vaccination in California: A Spatial Analysis. I’m a little surprised, given the subject matter and its relevance in the wake of recent measles outbreaks, especially the one that occurred at Disneyland over the holidays, that there hasn’t been much in the way of stories about the study, although this one from CBS News gives you a flavor:
Parents who cite “personal beliefs” to get their children exempted from routine vaccinations are typically white and well-to-do — at least in California, a new study finds.
The results, published June 1 in Pediatrics, confirm what other studies have suggested: Anti-vaccine sentiment in the United States appears strongest among wealthier white families.
My first reaction upon reading this is that it’s about as close to what I call a “Well, duh!” study that there is. Just look at the most prominent voices in the antivaccine movement. They’re almost all white and, if not affluent, at least solidly upper middle class. J. B. Handley, for example, is very well off and makes his money off investments. Pediatricians like “Dr. Bob” Sears and “Dr. Jay” Gordon cater mainly to well-off white people. On the other hand, that concept could be a stereotype too for all we know, hence the study.
So how did the investigators (Margaret Carrel and Patrick Bitterman) do their analysis and what did they find? First, they started with school level data for personal belief exemption and personal medical exemption rates in 5,147 kindergarten in California schools. Basically, they looked at two years, the 2001/2002 and the 2013/2014 school years.
In 2003, May and Silverman16 warned against the rise in families claiming personal belief or other nonmedical exemptions to public school requirements for vaccination and their tendency to cluster geographically. Data have indicated that clusters of high exemption rates are spatially congruent with outbreak clusters of pertussis and measles. Within California, there is high heterogeneity in the rates of personal belief exemptions (PBEs), with northern and southern coastal regions exhibiting higher PBE proportions. This spatial heterogeneity exists at higher geographic scales as well, with high variation in exemption rates among US states. High exemption rates have been correlated with schools that have higher numbers of white students and greater wealth, and with charter and private schools.
The current study examines PBE data from California between the 2001/2002 and 2014/2015 school years to determine spatial patterns of PBEs in kindergartners as well as the type of school populations associated with higher rates of PBEs. We explore the spatial overlap between schools with high PBE rates and high rates of personal medical exemptions (PMEs) for students who are unable to receive childhood immunizations. This analysis identifies locations of children who are unprotected from VPDs not by choice and are surrounded by other students who remain unprotected because of parental choice.
As you will see, one of the disturbing findings is just how high the rate of overlap is between areas with high levels of PBEs and PMEs. But first, let’s look a bit more at the methods used. The data were obtained from the California Department of Public Health, which records the number of PBEs and PMEs for individual schools, although it suppresses data from schools with fewer than ten kindergartners for privacy reasons. The proportion of kindergartners in each school who received a PBE and PME were calculated, and then, using school codes, the investigators matched sociodemographic characteristics from California Department of Education Data. School locations were geocoded using geoprocessing services provided by Texas A&M and Google Earth. Pieces of information available and studied included:
- Race and ethnicity
- Proportion of students receiving free lunch or reduced price lunch (FRL)
- Charter school status
- Private school versus public school
- Urban versus suburban versus rural
The first thing that stands out is just how much variability there is in PBE rates among schools, which during the 2013/2014 school year ranged from 0% to 79%, while PMEs ranged from 0% to 17%, up from the 2001/2002 school year, where they were 0% to 63.2% and 0% to 19.23% for PBEs and PMEs, respectively. The authors divided up the PBE rates into three “clusters” because it was the best fit for the data:
- Cluster 1: Schools with low average PBE proportions across all years of study
- Cluster 2: These schools have higher PBE rates than cluster 1 and had an increase beginning in the 2008/2009 school year.
- Cluster 3: These schools had high PBE rates in the 2001/2002 school year and their PBE rates increased over time.
This resulted in maps like this:
The authors observed:
Although cluster assignments were derived without consideration of spatial relationships, these types of schools exhibit interesting and significantly nonrandom patterns. The Central Valley of California, a primarily agricultural region with small and medium-size cities, is dominated by schools in the low and medium PBE clusters (Fig 3). High PBE cluster schools appear across much of northern California and in the suburban or peripheral areas of large urban areas. The Los Angeles area exhibits a distinctive spatial pattern of cluster assignments, with hotspots of low PBE schools centrally located, ringed by transitional hotspots and high PBE hotspots located along the coast to the north and south (Fig 4). This could indicate that (1) belief exemptions are diffusing from suburban/peripheral areas of cities inward toward the urban core, or (2) that those with specific vaccine beliefs have left the core and moved to the periphery.
I’d bet that both are probably going on, although determining the relative contribution of each will be difficult.
More importantly, though, high PBE rates were positively correlated with the percentage of white students, with charter status, and private schools. In contrast, public schools with high percentages receiving subsidized lunches have higher than expected membership in the low PBE cluster and lower than expected membership in the medium and high PBE clusters, while schools with low FRL percentages have high medium and high PBE cluster membership. Overall, the authors found that low PBE schools were likely to be public, noncharter, and nonsuburban, with lower percentages of white students and higher percentages of students receiving subsidized lunches. In contrast, high PBE schools tend to be charter or private nonreligious schools in suburban areas with high percentages of white students and low percentages of students receiving subsidized lunch. Among private schools, religious schools were associated with decreased PBE rates, which makes sense to me intuitively, at least for Catholic schools (with which I have some experience, having attended them 8 out of my 12 years of education as a child). The Catholic Church, for instance, supports vaccination and promotes it as a good. True, there are outliers, such as the Kenyan Catholic Bishops who have been spreading antivaccine misinformation that tetanus vaccines are actually designed as contraceptives to keep their women from having children, but, by and large, in the US the Catholic Church is solidly pro-vaccine, as are the other large, mainstream religions here.
Finally, perhaps the most depressing finding is an unexpected one, specifically that there is a disturbing amount of overlap between PMEs and PBEs. This is particularly worrisome because it implies that it is in the areas where vaccine uptake is below the level necessary to maintain herd immunity where there are more children with PMEs. Obviously, these children received PMEs for a reason, either due to allergies or problems with their immune system due to cancer or other illness. The authors didn’t know why there was this spatial overlap between areas with high PBEs and high PMEs. Neither did Paul Offit, who is quotes saying as much about the study, although he speculated that part of the reason might be because parents at the schools with high PBEs are more likely to get a doctor to give their child a medical exemption, legitimate or not. Certainly there is no shortage of doctors like Dr. Jay and Dr. Bob who would be willing to do just that based on concerns that are—shall we say?—not particularly well-grounded in science.
Be that as it may, the authors did note:
The potential for spatial overlap between schools with high PBE rates and high PMEs is particularly concerning, especially where rates of exemptions exceed 5% to 10% and threaten the protective effects of measles herd immunity. There are more than 800 schools in the 2014/2015 school year that exceeded this threshold of exemptions, primarily because of PBEs. These schools are located principally in the areas surrounding Los Angeles, San Francisco, and Sacramento (Fig 5). Statistical analysis indicates that significant hotspots of PBEs in 2014/2015 also overlap with areas of elevated PMEs (Fig 6). When outbreaks of measles or pertussis do occur, these are places where students with PMEs may be at greatest risk.
So it turns out that, in California (and probably in most developed countries with a white majority), it is affluent white people living in suburban areas who are the primary drivers of declining vaccination rates, because they appear to be the ones who claim the most nonmedical exemptions. It is true that this is only in California, but it wouldn’t surprise me if this pattern holds true elsewhere. In particular, it will be interesting to see if these results hold true, minus the racial preponderance, in other developed countries, as I rather suspect it is socioeconomic status more than race that is associated with antivaccine beliefs like this. In any case, based on these data, it’s hard not to speculate how privileged, entitled people tend to cluster together in mutually reinforcing echo chambers where antivaccine views not only are unchallenged but become the norm. Unfortunately, their choices have a negative impact not only on their own children, but on the children they come in contact with and their entire community.