Health Disparities
Decomposition of influenza and pneumococcal vaccine uptake among immigrant and non-immigrant older adults in Canada: a cross-sectional analysis of data from the Canadian Longitudinal Study on Aging (CLSA) Ji Yoon Kim* Ji Yoon Kim Giorgia Sulis Alton Russell Seungmi Yang Jesse Papenburg Ananya Banerjee Patricia Li
Background: Immigrant older adults in Canada have lower uptake of influenza and pneumococcal vaccines than non-immigrant older adults. However, the contributions of sociodemographic, health-related, healthcare access, and environmental factors to these disparities remain understudied. Therefore, we decomposed vaccination disparities by immigrant status to assess the contributions of these factors to the disparities.
Methods: Using data from the Canadian Longitudinal Study on Aging, we analyzed self-reported influenza and pneumococcal vaccination among adults aged 65 years and older. Logistic regression models were used to estimate the odds of vaccination in immigrant and non-immigrant participants and the non-linear Oaxaca-Blinder decomposition method was used to assess the contributions of covariates to the disparities in vaccinations by immigrant status.
Results: For influenza vaccination, differences in covariate distributions (i.e., covariate effect) accounted for -50% of the disparity, suggesting that vaccination rates would be higher for immigrants compared to non-immigrants by half of the observed disparity if distribution of covariates were to be the same between immigrants and non-immigrants. Differences in covariate effects (i.e., coefficient effect) accounted for 150% of the disparity. For pneumococcal vaccination, differences in covariate distributions accounted for 37% of the disparity and the remaining 63% were attributed to coefficient effects. The relative contributions of specific covariates varied between the two vaccines.
Conclusions: Our findings suggest that equalizing covariate distributions could reverse disparities in influenza vaccination rates and reduce pneumococcal disparities by 37%. Future research should identify additional modifiable factors and develop vaccine-specific strategies to address disparities.