Safety and immunogenicity of
 mRNA COVID
 ‐19 vaccine in inpatients with muscular dystrophy

Introduction/Aims Due to muscular weakness and cardiopulmonary dysfunction, patients with muscular dystrophy (MD) have an increased risk of serious complications from coronavirus disease 2019 (COVID-19). Although vaccination is recommended, COVID-19 vaccination safety and immunogenicity in these patients are unknown. We investigated reaction frequency, post-vaccine antibody titers after two mRNA COVID-19 vaccine doses, and clinical predictors of antibody response among patients with MD. METHODS: We recruited 171 inpatients with MD receiving two BNT162b2 mRNA COVID-19 vaccine doses from seven hospitals. Blood samples were obtained from 53 inpatients before the first dose and 28-30 days after the second dose, and antibody titers were measured. RESULTS: Overall, 104 (60.8%) and 115 (67.6%) patients experienced side effects after the first and second doses, respectively. These were generally mild and self-limited. Multiple logistic regression analysis showed that a bedridden state was associated with reduced side effects (OR: 0.29, 95% CI: 0.12-0.71). The antibody titers of all participants changed from negative to positive after two vaccine doses. The geometric mean titer (GMT) of the inpatients was 239 (95% CI: 159.3-358.7). Older age (RR=0.97, 95% CI: 0.95-0.99) and bedridden state (RR=0.27, 95% CI: 0.14-0.51) were associated with a lower antibody titer. Patients with myotonic dystrophy type 1 (DM1) had a lower GMT than patients with other MDs (RR=0.42, 95% CI: 0.21-0.85). DISCUSSION: COVID-19 vaccination is safe and immunogenic in inpatients with MD. Patients with DM1 appear to have a poorer COVID-19 antibody response than those with other MDs. This article is protected by copyright. All rights reserved.