From compound risk to common cause: Vaccine hesitancy is associated with overuse of antibiotics

Vaccines and antibiotics are both products of medical science, yet some people avoid recommended vaccines and some people use antibiotics more than is recommended. Taken individually, each of these behaviors represents a major challenge for public health. Yet if the same people who hesitate about vaccines also over-rely on antibiotics, the harmful repercussions for public health would be compounded. Here, we derive predictions from two cognitive models of these behaviors. One model assumes a common cause, exemplified by a naturalness bias against biomedical treatments that is stronger for vaccination than for antibiotics, predicting that use of vaccines and antibiotics should generally be positively correlated. The alternative model is rooted in state-dependent asymmetries towards action versus inaction, predicting the opposite: that higher antibiotic use should be associated with lower vaccine acceptance. Data from a four-country survey (final N=1307) reveals that higher use of antibiotics is associated with lower acceptance of vaccines in the same individuals, supporting the state-dependent model. Thus, decisions that weaken disease prevention are associated with decisions that, via antimicrobial resistance, worsen consequences of disease treatment. Taking state-dependence into account may help guide future research on—and public-health messaging in response to—both prevention and cure challenges.