1.INTRODUCTION
Since December 2019, COVID-19 infection caused by severe acute respiratory syndrome type 2 coronavirus (SARS-CoV-2) has rapidly spread worldwide, posing significant challenges to public health systems in various countries around the world. SARS-CoV-2 has undergone multiple rounds of variation since the outbreak. As of March 31, 2023, it has caused more than 6.8 million deaths worldwide, and the total medical costs and other economic setbacks caused by the prevention and treatment of COVID-19 are unprecedented. In addition, long-term chronic epidemics of the disease, as well as various anti-epidemic measures have caused a large number of psychological and social problems among the population, exacerbating social instability, particularly in less developed countries[1].Presently, there are few specific drugs against this highly contagious ribonucleic acid virus, and widespread vaccination in the population is considered one of the effective  interventions to substantially reduce morbidity and mortality and end the virus epidemic [2].As of 31 March 2022, more than 13 billion vaccine doses have been administered all over the world(https://covid19.who.int.). Multiple large randomized controlled trials and real-world studies have demonstrated the safety and efficacy of COVID-19 vaccines in the general population[3, 4]. However, the safety of COVID-19 vaccination for some patients with specific diseases, especially autoimmune diseases, has not been confirmed. Because these patients often have immune dysfunction and are immunocompromised by long-term use of immunosuppressants, they tend to be excluded from vaccine RCTs trial participant selection[5].
ANC is a large group of autoimmune diseases characterized by an inappropriate immune response, in which the body mistakenly recognizes the nervous system as an immune target[6], causing neurological damage, which often progresses or repeatedly exacerbates, resulting in disability or death. Common conditions include multiple sclerosis (MS), myasthenia gravis (MG), Guillain-Barre syndrome (GBS), neuromyelitis optica spectrum disorder (NMOSD) and chronic inflammatory demyelinating polyneuropathy (CIDP) , etc. Infection is the most common cause of exacerbation in ANC[7],SARS-CoV-2 may activate neuroinflammatory pathways[8], and severe pneumonia rates and mortality are higher in ANC patients infected with SARS-CoV-2[9].In addition, immunosuppressive therapy (IST) also increases the chance of severe pneumonia post-infection in ANC patients. For these reasons, vaccination is necessary to protect these patients from SARS-CoV-2 infection. Paradoxically, the vaccine itself contains weakened or inactivated parts (antigens) of specific organisms that can trigger immune responses and induce antigen production in the body, and in general, this weakened version does not cause disease in healthy people receiving the vaccine, but immune abnormalities and hypo immunity are prevalent in people with autoimmune neurological diseases, and the vaccine may elicit or aggravate autoimmune diseases[10].Since the COVID-19 pandemic, multiple studies have reported that vaccines induce autoimmune diseases or exacerbate pre-existing conditions[11, 12], however, more studies suggest that vaccination is safe for patients with neuroimmune diseases[2, 13, 14]. These contradictory conclusions fuelled the hesitancy of patients with autoimmune diseases to vaccinate; Therefore, in the context of the long-term epidemic of COVID-19, it is essential to clarify the risks and benefits of post-inoculation for these patients.
Due to the lack of direct safety evidence for SARS-CoV-2 vaccination in ANC patients, we conducted a systematic review and single-arm meta-analysis based on various eligible safety studies in ANC patients after vaccination to more fully assess the safety of SARS-CoV-2 vaccination in patients with autoimmune neurological diseases, eliminate these patients’ hesitancy to vaccinate through evidence-based medicine, and improve the protection rate of vulnerable populations.