The mediating effect of health literacy on COVID-19 vaccine confidence among a diverse sample of urban adults in Boston and Chicago

Abstract

Background: A high rate of COVID-19 vaccination is critical to reduce morbidity and mortality related to infection and to control the COVID-19 pandemic. Understanding the factors that influence vaccine confidence can inform policies and programs aimed at vaccine promotion. We examined the impact of health literacy on COVID-19 vaccine confidence among a diverse sample of adults living in two major metropolitan areas.

Methods: Questionnaire data from adults participating in an observational study conducted in Boston and Chicago from September 2018 through March 2021 were examined using path analyses to determine whether health literacy mediates the relationship between demographic variables and vaccine confidence, as measured by an adapted Vaccine Confidence Index (aVCI).

Results: Participants (N = 273) were on average 49 years old, 63 % female, 4 % non-Hispanic Asian, 25 % Hispanic, 30 % non-Hispanic white, and 40 % non-Hispanic Black. Using non-Hispanic white and other race as the reference category, Black race and Hispanic ethnicity were associated with lower aVCI (-0.76, 95 % CI -1.00 to -0.50; -0.52, 95 % CI -0.80 to -0.27, total effects from a model excluding other covariates). Lower education was also associated with lower aVCI (using college or more as the reference, -0.73 for 12th grade or less, 95 % CI -0.93 to -0.47; -0.73 for some college/associate's/technical degree, 95 % CI -1.05 to -0.39). Health literacy partially mediated these effects for Black and Hispanic participants and those with lower education (indirect effects -0.19 and -0.19 for Black race and Hispanic ethnicity; 0.27 for 12th grade or less; -0.15 for some college/associate's/technical degree).

Conclusions: Lower levels of education, Black race, and Hispanic ethnicity were associated with lower scores on health literacy, which in turn were associated with lower vaccine confidence. Our findings suggest that efforts to improve health literacy may improve vaccine confidence, which in turn may improve vaccination rates and vaccine equity.

Clinical trials number: NCT03584490.

Keywords: COVID-19; Health disparities; Health literacy; SARS-CoV-2; Vaccine acceptance; Vaccine hesitancy.

Fig. 1

Baseline Distribution of Health Literacy (Health LiTT) in Sample Note. Histogram of health literacy as measured by Health LiTT. By definition, T scores have a mean of 50 and standard deviation of 10, relative to the reference sample. A T score of 55 is the cutoff for adequate health literacy. There is wide range of scores in this sample, although a ceiling effect is apparent at the top end of the scale.

Fig. 2

Baseline Distribution of Scores on Adapted Vaccine Confidence Index (VCI) Note. Histogram of adapted VCI scores in our sample. Most participants have a ratio greater than 1.0, in the direction of greater vaccine confidence.

Fig. 3

Path Analysis Model from a lavaan Latent Variable Analysis Note. Model illustrating the mediation of Race and Ethnicity and Education on vaccine confidence through health literacy. All path lines are significant with p < 0.05, except for the direct and indirect effects of Asian Race and the direct effect of Hispanic ethnicity on aVCI. Estimates are standardized path coefficients. Mediated effects are the product of a and b coefficients (a*b).