Background: Limited literature examines the uptake of COVID-19 vaccines and outcomes in the Canadian asthma population.

Objectives: To examine COVID-19 vaccination rates and related adverse health outcomes in youths and young adults with prevalent asthma compared to those with diabetes, allergic rhinitis (AR), eczema (EZ), and the general population.

Methods: We assembled longitudinal cohorts of Ontario residents aged 12-35 years using population-based health administrative databases from Mar 2020 to Oct 2022. Chronic disease cohorts were defined with ICD-10 codes. Poisson regressions were used to compare vaccination rates between the study groups. Logistic regression was used to calculate the odds of cardiac events adjusting for confounders and vaccination status.

Results: 5.1 million individuals were included in this study and 18.2% had prevalent asthma, 31.1% with AR, 51.4% with EZ and <1.5% with type 1 diabetes. The COVID-19 vaccine rates were 80.0%, 81.5%, 80.0% and 85.2%, in those with asthma, AR, EZ and diabetes respectively.  Generally, those with diabetes and either asthma, AR, or EZ had higher odds of cardiac events (OR=3.44, 95%CI: 3.20, 3.70). The odds of cardiac events were nearly doubled if they had received at least one dose of COVID-19 vaccine compared to those who were not vaccinated and without any of these health conditions. Similar odds of cardiac outcomes were observed after adjusting for interactions of vaccination status and disease prevalence.

Conclusions: Our study quantified rates of COVID-19 vaccine uptake and potential adverse outcomes such as a cardiac event in youths and young adults with asthma compared with those with other chronic conditions.