Myasthenia Gravis (MG) is an autoimmune disorder that can exacerbate for various reasons, including vaccination and infection. This study aimed to investigate the safety of COVID-19 vaccines for MG patients, factors influencing MG exacerbation after COVID-19 infection (MECI), the course and prognosis of MECI, and the impact of COVID-19 vaccine on infected MG patients.Patients were enrolled from the MG database in the Department of Neurology, Xuanwu Hospital, Capital Medical University. Two questionnaires were administered to collect data concerning COVID-19 vaccination (questionnaire 1, Q1) and infection (questionnaire 2, Q2) during two distinct periods. MG exacerbation was defined as an increase of at least two points in the MG activity of daily living (MG-ADL) score. COVID-19 severity was categorized as "hospitalization" or "home management"; Results: During the first data-collecting period, our database registered 1013 adult patients: 273 (26.9%) had received COVID-19 vaccinations and completed Q1, and 8 (2.9%) experienced MG exacerbation after vaccination. During the second data-collecting period, among the newly registered patients, 366 patients completed Q2. Of these, 244 were infected, with 39 (16.0%) experiencing MECI and 21 (8.6%) requiring hospitalization. Multivariate analysis showed that generalized myasthenia gravis was associated with MECI (OR 3.354, 95% CI: 1.423-7.908, p = 0.006). Among the 244 infected patients, 143 had received COVID-19 vaccinations, including 14 who received their booster dose within 6 months before COVID-19 and 129 who were vaccinated more than 6 months before COVID-19. The remaining 101 were unvaccinated. No significant associations were found between COVID-19 vaccination and COVID-19 severity (p = 0.292) or MECI incidence (p = 0.478); Conclusions: COVID-19 vaccines were found to be safe for MG patients in stable condition. Patients with gMG were more susceptible to experiencing MECI. No significant impact of the vaccine on COVID-19 severity or MECI incidence was observed.