BNT162b2 mRNA COVID-19 vaccine three-dose safety and risk of COVID-19 in patients with myasthenia gravis during the alpha, delta, and omicron waves

COVID-19 affects the respiratory parenchyma and may potentially contribute to the tendency of myasthenia gravis (MG) patients to develop respiratory failure. It is, therefore, important to study the safety of vaccines against SARS-CoV-2 and to assess the risk of COVID-19 in MG patients. The safety of the three-dose BNT162b2 mRNA vaccine and outcomes of COVID-19 during the alpha, delta, and omicron waves were studied in MG patients as well as the rate of exacerbations and safety for a period of up to 6 weeks from each vaccine dose and patient morbidity and mortality during COVID-19 compared to the general population. 430 vaccine doses were administered across 150 patients. Thirteen patients (8.7%) complained of exacerbation within 6 weeks of each vaccine dose. Both MG onset rate and exacerbation rate were similar to previous years. MG exacerbation rate among fifteen patients who had COVID-19 was significantly higher (40%) compared to the rate following vaccination. During the alpha and delta waves, COVID-19 mortality and severe disease were significantly higher (26.7%) compared to the general population (0.96%). All of them were unvaccinated and had generalized MG. During the omicron wave, all the MG patients who contracted COVID-19 were vaccinated and had mild disease. We concluded that COVID-19 is hazardous for generalized MG patients, while the vaccination did not raise the risk for either exacerbation or new onset of MG and was associated with a reduced risk for severe COVID-19. Hence, it is recommended for generalized MG patients to get vaccinated. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00415-022-11303-8.