A large-scale multinational study investigating the association between mental illness and COVID-19 vaccination uptake found generally minimal differences in vaccination rates between individuals with and without mental illness.

The study, published in Nature Communications, analyzed data from 325,298 participants across seven cohort studies in the COVIDMENT consortium and 8,080,234 individuals from Swedish national registers.

Uptake of the first dose of the COVID-19 vaccine by September 30, 2021, was 85.1% in the COVIDMENT cohorts and 84.6% in the Swedish register population. In the COVIDMENT cohorts, 82.4% of individuals with mental illness received the first dose compared to 86.8% of those without mental illness. In the Swedish register population, 78.5% of individuals with mental illness were vaccinated versus 85.0% without.

Individuals with substance use disorder had the lowest vaccination rates, with a 16% lower uptake compared to those without mental illness. Individuals with a specialist diagnosis of mental illness but who were not using psychiatric medication had a 9% lower uptake, and slightly higher vaccination rates were observed among individuals with depression and bipolar disorder.

The study's strengths include its large sample size, multinational design, and the use of both self-reported and register-based data. However, limitations such as potential selection bias in the cohort studies and residual confounding due to unmeasured factors like healthcare engagement were noted.

Conflict of interest disclosures can be found in the study.