COVID‐19 Vaccination and Health Outcomes Among Adults With an Intellectual Disability in British Columbia, Canada

INTRODUCTION: Early studies demonstrated a higher risk for SARS-CoV-2 virus infection and severe COVID-19 outcomes such as hospitalisation, intensive care unit admission and death among people with an intellectual disability or other chronic conditions. However, the extent to which COVID-19 vaccination has affected the risk of these outcomes remains unclear. METHODS: We conducted a case-control study to examine the association between vaccination and SARS-CoV-2 virus infection risk in people with an intellectual disability and the general population. COVID-19 cases aged 19 years and older confirmed to be infected between 28 January 2020 and 31 December 2021 were obtained from the British Columbia (BC) COVID-19 Integrated Case List, and up to five controls were selected from the province's healthcare client registry matching on sex, age and residential region. COVID-19 vaccination status was determined using the province's immunisation registry. The Community Living BC (CLBC) Registry of supported adults was linked to identify the intellectual disability status of each case and control. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using the conditional logistic regression model. Severe COVID-19 outcomes were ascertained using hospitalisation and death registry databases. Cox regression was used to estimate hazard ratios (HRs) and 95% CIs for the outcomes among COVID-19 cases with and without an intellectual disability. We adjusted for sex, age, residential area and comorbidities. RESULTS: CLBC-supported adults with an intellectual disability were less likely to contract SARS-CoV-2 virus (OR = 0.66, 95% CI 0.61-0.71), and the protective association was stronger when fully vaccinated (OR = 0.40, 95% CI 0.34-0.48). Once infected, adults with an intellectual disability had a higher risk for COVID-19-associated hospitalisation (HR = 1.96, 95% CI 1.60-2.39), ICU admission (HR = 1.61, 95% CI 1.10-2.36) and death (HR = 1.88, 95% CI 1.15-3.07). CONCLUSION: COVID-19 vaccination was effective in reducing the risk of SARS-CoV-2 virus infection among people with an intellectual disability. Safety measures such as prioritised vaccination are important steps for protecting vulnerable people with an intellectual disability from SARS-CoV-2 virus infection, especially as COVID-19 cases with an intellectual disability were more likely to suffer severe health outcomes.