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MG Expert Series: Impact of COVID-19 on MG Patients and Safety of Vaccines

MG Expert Series: Impact of COVID-19 on MG Patients and Safety of Vaccines

EMR data supports that COVID-19 Outcomes are worse in patients with Myasthenia Gravis who are older or have trouble swallowing


There is a concern that persons living with myasthenia gravis (MG) may be more vulnerable or have worse outcome due to COVID-19 infection. Our colleagues examined outcomes of COVID-19 infection in patients with myasthenia gravis and compared to those without myasthenia gravis by using Optum®’s electronic health record database of more than 700 hospitals.i Patients were included if they had laboratory confirmed COVID-19 with positive SARS-CoV-2 PCR test between March 1, 2020 and Jan 31, 2021.


MG patients were identified based on diagnostic medical codes. Among those without MG, rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and multiple sclerosis (MS) were further identified with corresponding diagnostic codes. Through this process, 5 groups of patients namely MG, RA, SLE, MS and Non-MG groups were identified. Outcomes of COVID-19 infection including hospitalization, ICU admission, ventilator use and death were compared between groups, adjusted for age, sex, race, comorbidities, treatments, presence of swallowing and breathing difficulties and month of COVID-19 diagnosis.


A total of over 400,000 individuals were included, with 377 individuals in the MG group and over 97% of patients falling into the non-MG group without any of the aforementioned conditions. Compared to Non-MG group, individuals in the MG group were older, more frequently Caucasian and had higher prevalence of comorbidities. MG patients with COVID-19 infection were more frequently hospitalized (38%) compared to RA, SLE, MS, and non-MG groups (26%, 24%, 24%, 14% respectively).


Risk of ICU admission in the MG group was higher than the other groups after adjusting for covariates. Ventilator use (3.7%) and death (10.5%) were more frequent in the MG group compared to the non-MG group, however, these differences were not significant after adjusting for covariates. Within the MG group, age 75 years or older and trouble swallowing were significantly associated with the risk of death after accounting for other differences. Symptomatic treatment, chronic immunosuppressive therapy or IVIg within the 6 months prior to COVID-19 infection did not affect the outcomes significantly in the MG group.


This study used a large population-based dataset to compare COVID-19 infection outcome between MG and other disease groups as well as identifying risk factors for worse outcome among MG patients. The authors acknowledge limitations of the study including a retrospective study, unknown validity of using diagnostic code to identify MG patients, inability to identify MG disease severity or dose of medications. The study findings nonetheless can further guide decision making and counseling on vaccination, maintenance treatment, and initiation of new treatments during pandemic.


Safety of COVID-19 vaccines in persons with MG


People with autoimmune diseases are often concerned about disease exacerbation triggered by a vaccination. In the observational study conducted by Farina et al.ii, 104 subjects with MG who had received at least one dose of SARS-CoV-2 vaccine were evaluated to see if vaccination worsened MG symptoms. MG worsening was defined as reoccurrence of MG symptoms lasting at least 24 hours within the 4 weeks after SARS-CoV-2 infection or vaccination. MGFA classification and post intervention status (PIS) classification was used to measure symptoms before and after vaccination. Data was gathered from medical records and interviews.


Among 104 subjects, 94% had at least two doses and 64% had the third “booster” dose. 79% had acetylcholine receptor antibody, 8.6% had MuSK antibody and 11.5% were antibody negative. At the time of vaccination, most patients (83.6%) had minimal or no MG symptoms and at least 80% of the patients were taking immunotherapy. The mean disease duration was 16 years and patients were followed for 91 days in average.


The most frequent symptoms after COVID-19 vaccination were pain and fever. MG symptoms worsening was observed in eight cases (7.7%), more frequently in those with MuSK antibody. Most of the worsening was considered mild and spontaneously resolved in 75% of cases. Overall, there were no differences in disease severity class when MGFA-PIS was compared before vaccination and at the last follow up.


This study supports the safety and tolerability of COVID-19 vaccination. Limitations of this study include its retrospective design, which may result in underreporting of symptoms. Still, the very low numbers of reported complications in this population are reassuring and in-line with what is expected given the safety of other vaccines for patients with MG. The cohort measured in this study had a rather long disease duration and most of the subjects had well controlled MG symptoms, so the generalizability of this data may be limited.


[1]Kim Y, Li X, Huang Y, Kim M, Shaibani A, Sheikh K, Zhang GQ, Nguyen TP. COVID-19 Outcomes in Myasthenia Gravis Patients: Analysis From Electronic Health Records in the United States. Front Neurol. 2022 Mar 28;13:802559. doi: 10.3389/fneur.2022.802559. PMID: 35418937; PMCID: PMC8996116.

[1]Farina A, Falso S, Cornacchini S, Spagni G, Monte G, Mariottini A, Massacesi L, Barilaro A, Evoli A, Damato V. Safety and tolerability of SARS-Cov-2 vaccination in patients with myasthenia gravis: A multicenter experience. Eur J Neurol. 2022 Apr 7. doi: 10.1111/ene.15348. Epub ahead of print. PMID: 35390184.

[1]Law N, Davio K, Blunck M, Lobban D, Seddik K. The Lived Experience of Myasthenia Gravis: A Patient-Led Analysis. Neurol Ther. 2021 Dec;10(2):1103-1125. doi: 10.1007/s40120-021-00285-w. Epub 2021 Oct 23. PMID: 34687427; PMCID: PMC8540870.

[1]Nowak RJ, Coffey CS, Goldstein JM, Dimachkie MM, Benatar M, Kissel JT, Wolfe GI, Burns TM, Freimer ML, Nations S, Granit V, Smith AG, Richman DP, Ciafaloni E, Al-Lozi MT, Sams LA, Quan D, Ubogu E, Pearson B, Sharma A, Yankey JW, Uribe L, Shy M, Amato AA, Conwit R, O'Connor KC, Hafler DA, Cudkowicz ME, Barohn RJ; NeuroNEXT NN103 BeatMG Study Team. Phase 2 Trial of Rituximab in Acetylcholine Receptor Antibody-Positive Generalized Myasthenia Gravis: The BeatMG Study. Neurology. 2021 Dec 2;98(4):e376–89. doi: 10.1212/WNL.0000000000013121. Epub ahead of print. PMID: 34857535; PMCID: PMC8793103.

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