CAM and low flu vaccine uptake: Fitting together hand in glove

There’s a class of studies that I sometimes refer to as “Well, duh!” studies because their conclusions are so mind-numbingly obvious that one wonders why anyone did the study in the first place. Sometimes that name is meant sarcastically, as in, “Why did these investigators waste the time, effort, and resources to do this study? No, really, why?” Sometimes, though, “Well, duh!” studies are useful and justified because they confirm a conclusion that everyone strongly suspected but for which there wasn’t direct evidence. So it was with a “Well, duh!” study that was published in the October issue of Pediatrics that made the news yesterday in stories with titles like Alternative medicine may be linked to lower vaccination rates and Study: Alternative medicine used to skip flu shots. Those of you who have been reading this blog for any decent length of time probably suspected that this was true, if not outright knew without science that it was.

Now there’s another bit of science to show that it is, in the form of a study that looked at the use of “complementary and alternative medicine” (CAM) among children and correlated it to flu vaccine uptake. The authors note right in the introduction:

Complementary and alternative medicine (CAM), approaches to health that are not considered part of conventional medicine (eg, homeopathy, chiropractic manipulation, chelation therapy),8 have also recently risen in popularity as a form of health care. Estimates from the previous decade (pooled data from 2002, 2007, and 2012) show that one-third of the US population had used at least 1 type of CAM in the previous 12 months.9 The prevalence of CAM is highest among middle-aged, non-Hispanic white women of high socioeconomic status, as well as those with multiple health conditions and who frequently visit medical facilities.8,9 CAM is mostly used in conjunction with conventional medicine10 for prevention of diseases and to improve health and well-being11 and thus should not, in theory, interfere with vaccination uptake. However, CAM has been implicated as lending support to antivaccine/vaccine-hesitant viewpoints via criticism of vaccination, public health, and conventional medicine from adults using CAM,12–14 as well as from CAM practitioners and practitioners-in-training.12,15,16 Even among CAM practitioners who generally support the concept of vaccination, a majority report they recommend a vaccine schedule different from the standard schedule put forth by the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices.17

And it’s true. It’s been studied. Many CAM practitioners, such as chiropractors and naturopaths, tend to be very hostile to vaccines, and the references cited in the passage above definitely show this. None of this is surprising. Some of the most common quackery and tropes adopted by CAM involve antivaccine beliefs or beliefs that feed into antivaccine beliefs, such as the idea that “natural” immunity is better than vaccine-induced immunity, that “detoxification” can treat conditions often blamed on vaccines by antivaccinationists, such as autism. Heck, homeopaths think that their “nosodes” can work as well as vaccines, and, let’s not forget, you can’t have naturopathy without homeopathy because homeopathy is part and parcel of naturopathic education and even a required component of the NPLEX, the naturopathic licensing examination.

So, on to the study.

This study used data from 2012 National Health Interview Survey (NHIS), the most recent NHIS to include the Child Complementary and Alternative Medicine File (CAL). The NHIS annually collects information on the health of the US noninstitutionalized civilian population through household interviews of household adults. The investigators used grouped 37 CAM therapies across 4 domains developed by the National Center for Complementary and Alternative Medicine in 201242–45: (1) alternative medical systems (AMS; eg, acupuncture); (2) biologically based therapies (BBTs; eg, herbal supplements); (3) manipulative and body-based therapies (MBBT; eg, chiropractic manipulation); and (4) mind–body therapies (MBT; eg, yoga). As an aside, I hate the way CAMsters lump yoga into “mind-body” therapies. It’s a form of exercise, people! Nothing more! Calling it a “mind-body” therapy does nothing more than make it seem mystical and magical. End of digression. The authors also separated the use of multivitamins from BBTs because it was by far the largest class. In their analysis, they analyzed the results form 9,000 children and took into account 13 covariates:

Using this model, 13 covariates were selected. At the child level, these covariates were: sex (female/male); age (years); race/ethnicity (non-Hispanic white; non-Hispanic black or African American; non-Hispanic Asian; non-Hispanic other or multiple race; and Hispanic); usual source of care they go to when the child is sick or the parent needs advice about the child’s health (yes/no); well-child checkup in the previous 12 months (yes/no); number of physician visits in the previous 12 months; US-born status (yes/no); presence of at least 1 serious chronic condition or limitation (yes/no [defined as having 1 of the following: Down syndrome, cerebral palsy, muscular dystrophy, cystic fibrosis, sickle cell anemia, autism or autism spectrum disorder, type 1 diabetes mellitus, arthritis, congenital heart disease, or other heart condition]); asthma status (yes/no); and insurance type (private, public, or no coverage). At the family level, these covariates were: highest family education (less than high school, completed high school or the General Educational Development test, associate’s degree or some college [no degree], or bachelor’s degree or higher); family income as a percentage of the federal poverty level (<100%, 100%–199%, or ≥200%); and language of interview (English only or other). These variables come from the NHIS Sample Child, Family, and Person files.

The results were:

Influenza vaccination uptake was lower among children ever (versus never) using AMS (33% vs 43%; P = .008) or MBBT (35% vs 43%; P = .002) but higher by using multivitamins/multiminerals (45% vs 39%; P < .001). In multivariate analyses, multivitamin/multimineral use lost significance, but children ever (versus never) using any AMS or MBBT had lower uptake (respective odds ratios: 0.61 [95% confidence interval: 0.44–0.85]; and 0.74 [0.58–0.94]).

One thing that depressed me about the results of this study is just how low flu vaccine uptake is even among children who have never used CAM. 43%? That’s pathetic. We really need to do better. Seriously. How can anyone think that a flu vaccine uptake among children of a mere 43% is anything less than an utter failure? Be that as it may, CAM use is associated with even poorer flu vaccine uptake. Specifically, any children with a history of using anything from an alternative medical system (AMS) or manipulative and body-based therapies (MBBT) Remember, MBBT includes chiropractic. In contrast, mind–body therapies (MBTs) and biologically-based therapies (BBTs) are not associated with decrease flu vaccine uptake, at least not in this study. This makes sense, because taking multivitamins or supplements doesn’t necessarily track with antivaccinationism, given how common the use of such supplements is. Ditto mind–body therapies (MBTs), which under the National Center for Complementary and Integrative Health (NCCIH) classification, include a lot of interventions that are nothing more than various forms of exercise.

It’s not just CAM, though:

Several covariates were also significantly associated with influenza vaccination uptake and warrant further investigation in a future, longitudinal study as potential mediators and/or moderators of influenza vaccine disparities in children. Consistent with other studies, we found higher uptake among the following groups of children: those with a higher number of recent provider visits49–53 (which is conceptually related to having a well-child visit and a usual source of care, all of which are important given that physician recommendation of the vaccine is one of most commonly cited correlates of higher influenza vaccine uptake51,54–65); those without health insurance66; those with asthma or parental worry about asthma51,67; and those of a younger age.50–52,58,68–70 Although we found no disparities between black and white children, we did observe higher uptake in Asian, Hispanic, and other/multiracial children. There were no significant racial/ethnic disparities nationally among children in most recent influenza seasons,69 although higher uptake among Asian children has been observed.70 Generally, higher parental education is associated with higher influenza vaccine uptake in children.56,68,70 However, this scenario is not always the case, and in this study we found the inverse association. Studies (not including influenza vaccination) have documented that parents who delay or refuse vaccinating their children in general tend to be college educated, higher income, white populations, and also tend to have lifestyles that include CAM use and alternative diets.14,71–73 Perhaps not coincidentally, CAM is associated with higher income and higher education,74 which may partially explain the inverse education relationship we observed. Lastly, we found that foreign-born children had higher odds of vaccination compared with US-born children. Although we are unaware of studies examining the relationship of nativity/citizenship and influenza vaccination in US children, a recent study of Mexican adults in California found that higher influenza vaccine uptake diminishes after the first generation postmigration.75 Furthermore, a study of other vaccines found that having a foreign-born or noncitizen mother was associated with reduced odds or vaccination.76 More research is needed in these areas.

I find it particularly interesting that Mexican immigrants want the flu vaccine, so much so that they have a higher flu vaccine uptake than native Americans, but that by the first generation flu vaccine uptake falls to be indistinguishable from that of other native-born Americans.

Of course, one of the problems with this study is the classic “chicken or the egg” question. Is it using alternative medicine that causes parents to refuse to vaccinated or do parents who already have a reluctance to vaccinate tend to gravitate towards alternative therapies? From my perspective, I tend to think it’s more the latter than the former. Parents who are already vaccine-averse like the message promoted by CAM practitioners and their openness to not vaccinating. Of course, then these CAM practitioners themselves promote antivaccine views and “support” not vaccinating, thus creating a negative feedback loop that shuts down any thought of vaccinating. My only surprise from this study is that, if this study is to be believed, the effect is weaker than I would have predicted.

I started this post by referring to this as a “Well, duh!” study, and so it is. That doesn’t mean it’s pointless, worthless, or a waste of verbiage. It’s not. It tells us something important: Namely that CAM and antivaccine beliefs go hand-in-hand. Whether it’s because CAM practitioners’ are antivaccine and influence parents or because parents who are already vaccine-averse or antivaccine seek out CAM practitioners, CAM and vaccines do not go together.