COVID-19 vaccines may trigger flares in rare inflammatory muscle diseases

<p><strong>OBJECTIVES:</strong> Disease flares in the post COVID-19 vaccination period represent a prominent concern, though risk factors are poorly understood. We studied these flares among patients with idiopathic inflammatory myopathies (IIMs) and other autoimmune rheumatic diseases (AIRDs).</p><p><strong>METHODS:</strong> The COVAD-1 and -2 global surveys were circulated in early 2021 and 2022 respectively, and we captured demographics, comorbidities, AIRDs details, COVID-19 infection history, and vaccination details.Flares of IIMs were defined as a. patient self-reported, b. immunosuppression (IS) denoted, c. clinical sign directed, and d. with &gt;7.9-point MCID worsening of PROMISPF10a score. Risk factors of flares were analyzed using regression models.</p><p><strong>RESULTS:</strong> Of 15165 total respondents, 1278 IIMs (age 63 years, 70.3% female, 80.8% Caucasians), and 3453 AIRDs were included. Flares of IIM were seen in 9.6%, 12.7%, 8.7%, and 19.6% patients by definitions a-d respectively with a median time to flare of 71.5 (10.7-235) days, similar to AIRDs. Patients with active IIMs pre-vaccination (OR:1.2; 95%CI:1.03-1.6, p = 0.025) were prone to flares, while those receiving Rituximab (OR:0.3; 95%CI:0.1-0.7, p = 0.010) and Azathioprine (OR:0.3, 95%CI:0.1-0.8, p = 0.016) were at lower risk. Female gender and comorbidities predisposed to flares requiring changes in immunosuppression. Asthma (OR: 1.62; 95%CI: 1.05-2.50, p = 0.028) and higher pain VAS (OR: 1.19; 95%CI: 1.11-1.27, p &lt; 0.001) were associated with disparity between self-reported and IS-denoted flares.</p><p><strong>CONCLUSION:</strong> A diagnosis of IIMs confers an equal risk of flares in the post COVID-19 vaccination period to AIRDs, with active disease, female gender, and comorbidities conferring a higher risk. Disparity between patient and physician reported outcomes represents a future avenue for exploration.</p>