Dermatomyositis; This literature-non-study case was reported in a literature article and describes the occurrence of DERMATOMYOSITIS (Dermatomyositis) in a  patient of an unknown age and gender who received SPIKEVAX NOS (SPIKEVAX NOS) for COVID-19 prophylaxis.      No Medical History information was reported.    On an unknown date, the patient received dose of SPIKEVAX NOS (SPIKEVAX NOS) (unknown route) 1 dosage form. On an unknown date, the patient experienced DERMATOMYOSITIS (Dermatomyositis) (seriousness criterion medically significant). At the time of the report, DERMATOMYOSITIS (Dermatomyositis) outcome was unknown.        The action taken with SPIKEVAX NOS (SPIKEVAX NOS) (Unknown) was unknown.   For SPIKEVAX NOS (SPIKEVAX NOS) (Unknown), the reporter considered DERMATOMYOSITIS (Dermatomyositis) to be related.    This case referred to patient 1 out of 4 patients who received Moderna vaccine and developed symptoms.  No concomitant medications were provided.  In this study, retrospective review was performed on patients treated between 01-Mar-2020, and 31-Oct-2022, for dermatomyositis (DM).  Ninety-eight patients treated for dermatomyositis were included. In total 12/98 patients experienced DM symptoms (either incident or relapse) following either infection or vaccination.  Symptoms described during disease onset following vaccination or infection included proximal muscle weakness, rash and dysphagia. Of the 12 who developed incident disease or relapse, 7 patients developed symptoms post infection and 8 developed symptoms post-vaccination (3 patients had symptoms following both infection and vaccination). 4 out of 8 patients received Moderna vaccine.  The mean onset of symptoms following COVID-19 infection was 3.2 days (median 0.5) and following COVID-19 vaccination was 5.75 days. All patients were seropositive with one or more of the antibodies NXP-2, MDA5, Anti-TIF-1-gamma, Jo1, MI2, Ku, and SSA-52 kd. 9/12 patients had a positive myositis specific antibody and the remaining 3/12 had myositis-associated antibodies. There was no predominant vaccine associated with the development of post vaccination DM symptoms.  The majority of patients with post-vaccination or infection symptoms were treated with a combination of glucocorticoids, IVIG (5 patients), mycophenolate mofetil (4 patients), hydroxychloroquine (2 patients), and methotrexate (2 patients); these treatments were new treatments for the patients after they started with DM symptoms.  The author concluded that this retrospective review revealed a strong temporal relationship between dermatomyositis symptoms and COVID-19 infection or vaccination in 12.2 percent of all DM patients evaluated in the clinic during the pandemic.   This case was linked to US-MODERNATX, INC.-MOD-2023-744013, US-MODERNATX, INC.-MOD-2023-744007, US-MODERNATX, INC.-MOD-2023-744021 (E2B Linked Report).  Company Comment  This literature non-study case concerns a patient of unknown age and gender, with no medical history information reported, who experienced the unexpected and serious (due to medically significant) event of Dermatomyositis (DM), which occurred after vaccination with SPIKEVAX COVID-19 VACCINE NOS vaccine. Dose number and vaccination schedule were not provided. As described by the author's, patients presented with a relapse or new diagnosis of DM after immunization; however, the benefit provided by the vaccine is superior compared to the fatal complications of SARS-Cov-2 and that studying populations with new onset disease following infection and vaccination should be further pursued and may allow for insights into the immune dysregulation that triggers DM. No further information about the events was provided. The benefit-risk relationship of SPIKEVAX COVID-19 VACCINE NOS is not affected by this report.; Sender's Comments:  US-MODERNATX, INC.-MOD-2023-744013:Same Report US-MODERNATX, INC.-MOD-2023-744007:Same Report US-MODERNATX, INC.-MOD-2023-744021:Same Report