Characteristics and risk factors of COVID-19 breakthrough infections in Idiopathic Inflammatory Myopathies: Results from the COVAD study

Objectives: To explore prevalence, characteristics and risk factors of COVID-19 breakthrough infections (BIs) in idiopathic inflammatory myopathies (IIM) using data from the COVID-19 Vaccination in Autoimmune Diseases (COVAD) study.

Methods: A validated patient self-reporting e-survey was circulated by the COVAD study group to collect data on COVID-19 infection and vaccination in 2022. BIs were defined as COVID-19 occurring ≥14 days after 2 vaccine doses. We compared BIs characteristics and severity among IIMs, other autoimmune rheumatic and non-rheumatic diseases (AIRD, nrAID), and healthy controls (HC). Multivariable Cox regression models assessed the risk factors for BI, severe BI and hospitalisations among IIMs.

Results: Among 9449 included response, BIs occurred in 1447 (15.3%) respondents, median age 44 years (IQR 21), 77.4% female, and 182 BIs (12.9%) occurred among 1406 IIMs. Multivariable Cox regression among IIMs showed age as a protective factor for BIs [Hazard Ratio (HR)=0.98, 95%CI=0.97-0.99], hydroxychloroquine and sulfasalazine use were risk factors (HR=1.81, 95%CI=1.24-2.64, and HR=3.79, 95%CI=1.69-8.42, respectively). Glucocorticoid use was a risk factor for severe BI (HR=3.61, 95%CI=1.09-11.8). Non-White ethnicity (HR=2.61, 95%CI=1.03-6.59) was a risk factor for hospitalisation. Compared to other groups, patients with IIMs required more supplemental oxygen therapy (IIM=6.0% versus AIRD=1.8%, nrAID=2.2%, and HC=0.9%), intensive care unit admission (IIM=2.2% versus AIRD=0.6%, nrAID, and HC=0%), advanced treatment with antiviral or monoclonal antibodies (IIM=34.1% versus AIRD=25.8%, nrAID=14.6%, and HC=12.8%), and had more hospitalisation (IIM=7.7% versus AIRD=4.6%, nrAID=1.1%, and HC=1.5%).

Conclusion: Patients with IIMs are susceptible to severeCOVID-19 BI. Age and immunosuppressive treatments were related to the risk ofBIs.