Results from a nationally representative survey of U.S. adults have shown that after adjusting for demographic and healthcare utilization characteristics, coverage levels for influenza and pneumococcal vaccines were significantly higher among priority adults who were recent or past CAM users compared to adults who had never used a CAM therapy. Among non-priority adults, adjusted coverage levels for influenza, pneumococcal, and hepatitis B vaccines were significantly higher among recent or past CAM users when compared to never CAM users. Additionally, adults using chiropractic services had higher vaccination coverage levels compared to never CAM users.
Results from this study are somewhat unexpected considering findings from previous studies have shown that parents with an alternative medical orientation were significantly less accepting of immunizations for their children [22, 23]. A national survey of parents of children aged ≤ 6 years found that when compared to parents with a conventional medical orientation, parents with an alternative medical orientation were significantly less likely to believe immunizations are important (89.4% vs. 75.5%, respectively) and more likely to choose to opt out of an immunization for their child (11.2% vs. 24.9%, respectively) . In a study of parents of school children, parents claiming vaccine exemptions for their children were more likely than parents of vaccinated children to report use of CAM professionals by their immediate family members (79.6% vs. 51.2%, respectively) . It could be that parents are more cautious of vaccination for their children because the hypothesized risks for children's immunizations are more publicized and more severe  than those for adult immunizations. Also, parents may be more averse to risks that are involuntary (e.g., school entry laws), and risks to children (that cause greater fear or dread than risks to adults) [25, 26].
Our results suggest that, similar to previous studies, respondents use CAM as supplemental rather than alternative health care [4, 27]. Recent and past CAM users in our study were significantly more likely to have more doctor visits than non-CAM users. Because CAM users tend to have more doctor visits, they likely have more contact with physicians which provide more opportunities to be immunized. The positive association between CAM use and immunization coverage among priority adults also suggests that even if CAM users are receiving negative information regarding immunizations from their CAM providers, it is not affecting their receipt of immunizations at this time.
The difference in hepatitis B vaccination coverage levels between recent and non-CAM users was relatively small (i.e. 4–6 percentage points for priority and non-priority adults) and remained significant among non-priority adults after adjusting for demographic and healthcare utilization characteristics. The finding that CAM users had higher vaccination coverage levels for hepatitis B has several possible explanations. First, CAM users might be more concerned about their general health and wellness  and therefore more likely to get all immunizations. Another possible reason could be that CAM providers request their patients to receive the hepatitis B vaccination to protect themselves from liability in light of publicized hepatitis B outbreaks among alternative medicine practices in which CAM procedures required injections [28, 29]. Notably, many CAM therapies are available for persons with hepatitis B or hepatitis C disease, and HIV. Thus populations at high risk for hepatitis B infection might already be aware of the healing opportunities CAM therapies may provide. In addition, hepatitis B is a sexually transmitted disease and thus those at risk for hepatitis B may also be at risk for other STDs (e.g., HIV, chronic vaginal symptoms). Studies have shown that persons with some STDs use CAM therapies to alleviate symptoms before they are diagnosed [30, 31].
This study was subject to several limitations. The definition of CAM use was wide and included therapies that some may consider mainstream and not alternative, such as yoga or special diets like Atkins. The inclusion of these more common and mainstream therapies could have lessened the difference seen in vaccination coverage between CAM users and non-CAM users. Thus, the actual difference may be larger than observed. Immunization status was self-reported and not verified by a medical provider; however, a previous study found that self-report of influenza and pneumococcal vaccinations are highly sensitive, with moderate to low specificity, respectively . Due to the cross sectional nature of the study we could not assess a temporal relationship and therefore we are not able to establish causal relationships. It is unknown if vaccinated respondents received their vaccines prior to or after initiating a CAM therapy.