COVID-19 vaccination coverage and the effect on regional disparities in morbidity and mortality among older people in Sweden, 2021–2023

AIMS: The COVID-19 pandemic had substantial impacts on mortality and morbidity, even after the rollout of vaccinations. These impacts however, varied considerably across regions. We examined regional disparities in COVID-19 mortality and hospitalizations among older people in Sweden from January 2021 to August 2023 and assessed the role of vaccination coverage in shaping these disparities. METHODS: Using full-population data on people in Sweden born in 1955 or earlier, we created a nested case-control study. Conditional logistic regressions with county fixed effects were estimated across three periods of vaccination rollout (Doses 1-2, 3-4, and 5-6). County fixed effects were compared across models with and without vaccination adjustment. Further, the benefits of vaccination coverage corresponding to the most successful regions were evaluated with potential impact fractions (PIFs). RESULTS: Across counties, the final shares of vaccinated individuals ranged from 94% to 98% for Doses 1 and 2, 90% to 96% for Dose 3, 80% to 91% for Dose 4, 65% to 83% for Dose 5, and 13% to 47% for Dose 6. In models without vaccination adjustments, COVID-19 mortality ranged from -56% to +75% relative to an average county, and hospitalizations from -45% to +51%. Vaccination adjustment had little impact on the disparities. Overall PIFs were 8% to 11% for mortality and 7% to 8% for hospitalizations, with greater PIFs in urban counties.