Hantavirus infection-related acute inflammatory demyelinative polyradiculoneuropathy: A case report and literature review.

RATIONALE: Hemorrhagic fever with renal syndrome (HFRS) is a common infectious disease in China. As a complication of post-Hantavirus infection, Guillain-Barre syndrome (GBS) was rarely previously reported. Here, we described a case of acute inflammatory demyelinative polyradiculoneuropathy secondary to Hantavirus infection in spring of 2023. We also made a summary of the clinical features from previous reported cases. PATIENT CONCERNS: A young male patient complained a fever with headache, who was subsequently diagnosed with HFRS with positive serum Hantavirus antibody IgM. Two weeks later, he presented sustained back pain, obvious numbness located in 4 extremities, chest and abdomen, facial dyskinesia and 4 extremities muscle weakness. DIAGNOSIS, INTERVENTIONS, AND OUTCOMES: He was rapidly diagnosed with GBS by typical cerebrospinal fluid change and the electromyography examination presentation, which was verified associated with hantavirus infection. He was treated with intravenous immunoglobulin infusion followed by rehabilitation treatment. He got a complete recovery within 4 months after disease onset. LESSONS: GBS was an uncommon manifestation of Hantavirus infection. GBS should be considered when acute limb weakness happens in cases with HFRS. A multidisciplinary team could make a rapid diagnosis and optimal treatment when nervous system disorders occurred.

Adverse Events Following COVID-19 Vaccination in Adolescents: Insights From Pharmacovigilance Study of VigiBase.

BACKGROUND: During coronavirus disease 2019 (COVID-19) pandemic, several COVID-19 vaccines were licensed with fast-track procedures. Although these vaccines have demonstrated high immunogenicity, there has been concerns on the serious adverse events (AEs) following COVID-19 vaccination among adolescents. We aimed to analyze comparative safety of COVID-19 vaccination in adolescents. METHODS: In this pharmacovigilance study, we performed a disproportionality analysis using VigiBase, the World Health Organization's global individual case safety report (ICSR) database. To compare serious AEs reported following COVID-19 vaccines vs. all other vaccines in adolescents aged 12-17 years, ICSRs following any vaccines on adolescents aged 12-17 years were included, defining cases as reports with the AEs of interest, with all other AEs as non-cases. The AEs of interest were myocarditis/pericarditis, multisystem inflammatory syndrome/Kawasaki disease (MIS/KD), anaphylaxis, Guillain-Barré syndrome (GBS), and immune thrombocytopenia (ITP). We conducted a disproportionality analysis to estimate reporting odds ratio (ROR) with 95% confidence interval (CI) for each AE of interest, adjusted for sex by using logistic regression. RESULTS: Of 99,735 AE reports after vaccination in adolescents, 80,018 reports were from COVID-19 vaccinated adolescents (52.9% females; 56.3% America). The AEs of interest were predominantly reported as serious AE (76.1%) with mRNA vaccines (99.4%). Generally, higher reporting odds for the AEs were identified following COVID-19 vaccination in adolescents; myocarditis/pericarditis (2,829 reports for the COVID-19 vaccine vs. 35 for all other vaccines, adjusted ROR [aROR], 19.61; 95% CI, 14.05-27.39), and MIS/KD (104 vs. 6, aROR, 4.33; 95% CI, 1.89-9.88). The reporting odds for anaphylaxis (515 vs. 165, aROR, 0.86; 95% CI, 0.72-1.02), GBS (94 vs. 40, aROR, 0.64; 95% CI, 0.44-0.92) and ITP (52 vs. 12, aROR, 1.12; 95% CI, 0.59-2.09) were not significantly higher following COVID-19 vaccination. CONCLUSION: In this study, there were disproportionate reporting of immune-related AEs following COVID-19 vaccination. While awaiting definitive evidence, there is a need to closely monitor for any signs of immune-related AEs following COVID-19 vaccination among adolescents.

Guillain-Barré Syndrome After COVID-19 Infection in Korea: A Case Series.

Guillain-Barré syndrome (GBS) is an autoimmune-driven condition characterized by acute polyneuropathy, often emerging as a sequel to prior infections or vaccinations. This study presents the first reported cases of GBS emerging after the full recovery from coronavirus disease 2019 (COVID-19) infection in Korea. Despite experiencing mild acute COVID-19 symptoms, these patients faced substantial weakness attributed to GBS, significantly affecting their daily lives. The timely administration of intravenous immunoglobulin treatment halted the progression of symptoms, underscoring the critical importance of early intervention. These cases highlight the potential for neurological complications associated with COVID-19 and underscore the necessity for continuous monitoring and timely medical care.

Guillain-Barré syndrome after COVID-19 vaccination: A systematic review and analysis of case reports.

INTRODUCTION: Cases of Guillain-Barré Syndrome (GBS) have been believed to be associated with the novel COVID-19 infection, and also with the following vaccines developed against the infection. Our work aims to investigate the incidence of GBS after COVID-19 vaccination, and describe its clinical characteristics and potential confounders. METHODS: An electronic search was conducted through four databases: PubMed, Scopus, medRxiv, and Google Scholar for all case reports and case series describing after COVID-19 vaccine administration. All published articles from inception until November 1st, 2022 were included. Differences between groups were assessed using Pearson chi-square test. Modified Erasmus GBS Outcome Score (mEGOS) for the ability to walk after GBS was calculated for all cases with sufficient clinical data, and Kaplan-Meier survival analysis was performed to study the effect of vaccine type on the relationship between vaccination time and complication of GBS. RESULTS: About 103 studies describing 175 cases of GBS following COVID-19 vaccination were included. The Acute Inflammatory Demyelinating Polyradiculoneuropathy subtype was the most reported subtype with 74 cases (42.29%). The affected age group averaged around 53.59 ±18.83 years, with AMSAN occurring in a rather older group (63.88 ±20.87 years, p=0.049). The AstraZeneca vaccine was associated with AIDP (n=38, 21.71%) more than other vaccines, p=0.02. The bilateral facial palsy subtype was mostly linked to adenoviral vector vaccinations, accounting for an average of 72% of the total BFP cases. Dysesthesias was the most reported sensory complication (60%, p=0.349). Most GBS patients survived (96%, p=0.036), however, most patients had low mEGOS scores (4 ±3.57, p<0.01). On average, patients developed GBS at 13.43 ±11.45 days from vaccination (p=0.73), and survival analysis for complication of GBS into mechanical ventilation or walking impairment yielded a severely increased probability of complication after 25 days (p<0.01). Intravenous immunoglobulins (p=0.03) along with rehabilitation (p=0.19) were the most commonly used treatment. CONCLUSION: This work investigates the incidence of Guillain-Barré Syndrome after COVID-19 vaccination. Most cases occurred after receiving the AstraZeneca or Pfizer vaccines, and despite low mortality rates, ambulation was compromised in most patients. A higher risk of GBS complication is associated with an onset later than 12-13 days, particularly with Pfizer, AstraZeneca, and Moderna vaccines. No specific predisposing or prognostic factor was identified, and the relation between the COVID-19 vaccines and GBS remain unclear.

Guillain-Barré syndrome and COVID-19 vaccination: a systematic review and meta-analysis.

BACKGROUND: Case-reports/series and cohorts of Guillain-Barré syndrome (GBS) associated with COVID-19 vaccination have been reported. METHODS: A systematic review and meta-analysis of cohort studies of GBS after COVID-19 vaccination was carried out. Incidence and incidence rate ratio for a number of vaccine doses and risk of GBS, also considering the specific vaccine technology, were calculated in a random-effects model. RESULTS: Of 554 citations retrieved, 518 were discarded as irrelevant. We finally included 15 studies. The random effect model yielded, regardless of the vaccine technology, 1.25 (95%CI 0.21; 2.83) GBS cases per million of COVID-19 vaccine doses, 3.93 (2.54; 5.54) cases per million doses for adenovirus-vectored vaccines and 0.69 (0.38; 1.06) cases per million doses for mRNA vaccines. The GBS risk was 2.6 times increased with the first dose. Regardless of the vaccine technology, the GBS risk was not increased but disaggregating the data it was 2.37 (1.67; 3.36) times increased for adenovirus-vectored vaccines and 0.32 (0.23; 0.47) for mRNA vaccines. Mortality for GBS after vaccination was 0.10 per million doses and 4.6 per GBS cases. CONCLUSIONS: Adenovirus-vectored vaccines showed a 2.4 times increased risk of GBS that was about seven times higher compared with mRNA-based vaccines. The decreased GBS risk associated with mRNA vaccines was possibly due to an elicited reduction of infections, including SARS-CoV-2, associated with GBS during the vaccination period. How adenovirus-vectored COVID-19 vaccines may trigger GBS is unclear and further studies should investigate the relationship between vaccine technologies and GBS risk.

Guillain-Barré syndrome following primary cytomegalovirus infection in a patient with liver transplantation.

We present the case of a man in his 60s with a 5-month medical history of deceased donor liver transplantation, who developed Guillain-Barré syndrome (GBS) secondary to a primary cytomegalovirus (CMV) infection. This was confirmed by molecular tests and serology antibodies that ruled out other frequent aetiologies. Therapy with intravenous immunoglobulin and valganciclovir was started and the patient gradually improved over the weeks. GBS is the most common aetiology of paralysis worldwide, and it is an autoimmune-mediated neuropathy that is frequently caused by a preceding infection. Few cases of GBS have been reported in the context of liver transplant recipients, and those related to CMV infection are extremely rare. This case highlights the importance of considering GBS as a possible differential diagnosis in patients with solid organ transplantation, and it contributes to the knowledge of other infrequent aetiologies of this condition.

Post-marketing active surveillance of Guillain Barré Syndrome following COVID-19 vaccination in persons aged ≥12 years in Italy: A multi-database self-controlled case series study.

BACKGROUND: Recently published studies have reported association of COVID-19 vaccine ChAdOx1-S (Vaxzevria) with Guillain Barré Syndrome (GBS). Less is known about the safety of other COVID-19 vaccines with respect to GBS outcome. This study investigated the association of COVID-19 vaccines with GBS in more than 15 million persons aged ≥12 years in Italy. METHODS: Study population was all individuals aged ≥12 years who received at least one dose of COVID-19 vaccines, admitted to emergency care/hospital for GBS from 27 December 2020-30 September 2021 in Italy. Identification of GBS cases and receipt of at least one dose of mRNA-1273 (Elasomeran), BNT162b2 (Tozinameran), ChAdOx1-S (Vaxzevria) and Ad26.COV2.S (Janssen) through record linkage between regional health care and vaccination registries. Relative Incidence (RI) was estimated Self-controlled case series method adapted to event-dependent exposure using in the 42-day exposure risk period after each dose compared with other observation periods. RESULTS: Increased risk of GBS was found after first (RI = 6.83; 95% CI 2.14-21.85) and second dose (RI = 7.41; 2.35-23.38) of mRNA-1273 and first dose of ChAdOx1-S (RI = 6.52; 2.88-14.77). Analysis by age found an increased risk among those aged≥60 years after first (RI = 8.03; 2.08-31.03) and second dose (RI = 7.71; 2.38-24.97) of mRNA-1273. The first dose of ChAdOx1-S was associated with GBS in those aged 40-59 (RI = 4.50; 1.37-14.79) and in those aged ≥ 60 years (RI = 6.84; 2.56-18.28). CONCLUSIONS: mRNA-1273 and ChAdOx1-S vaccines were associated with an increased risk of GBS however this risk resulted in a small number of excess cases. Limitations were loss of GBS outpatient cases and imprecision of the estimates in the subgroup analysis due to a low number of events.

Clinical and laboratory findings in scrub typhus associated Guillain-Barré syndrome in South Korea.

BACKGROUND AND AIMS: Scrub typhus is an endemic disease in the fall season that occurs in a limited number of places known as the Tsutsugamushi Triangle. Peripheral neuropathy is a common complication of scrub typhus. Herein, we encountered several patients with ascending paralysis after scrub typhus infection, who were diagnosed with Guillain-Barré syndrome (GBS). We aimed to investigate the clinical and laboratory characteristics of patients who developed GBS after scrub typhus. METHODS: Patients were retrospectively recruited from six nationwide tertiary centers in South Korea from January 2017 to December 2021. Patients who had been clinically diagnosed with GBS and confirmed to have scrub typhus via laboratory examination and/or the presence of an eschar before the onset of acute limb paralysis were included. The GBS-associated clinical and electrophysiological characteristics, outcomes, and scrub typhus-associated features were collected. RESULTS: Of the seven enrolled patients, six were female and one was male. The median time from scrub typhus infection to the onset of limb weakness was 6 (range: 2-14) days. All patients had eschar on their bodies. Four patients (57.1%) were admitted to the intensive care unit and received artificial ventilation for respiratory distress. At 6 months, the median GBS disability score was 2 (range, 1-4) points. INTERPRETATION: Patients with scrub typhus-associated GBS have a severe clinical presentation and require intensive treatment with additional immunotherapies. Therefore, GBS should be included in the differential diagnosis when peripheral neuropathies develop during scrub typhus treatment. Notably, scrub typhus is associated to GBS.

Autoreactive T cells target peripheral nerves in Guillain-Barré syndrome.

Guillain-Barré syndrome (GBS) is a rare heterogenous disorder of the peripheral nervous system, which is usually triggered by a preceding infection, and causes a potentially life-threatening progressive muscle weakness1. Although GBS is considered an autoimmune disease, the mechanisms that underlie its distinct clinical subtypes remain largely unknown. Here, by combining in vitro T cell screening, single-cell RNA sequencing and T cell receptor (TCR) sequencing, we identify autoreactive memory CD4+ cells, that show a cytotoxic T helper 1 (TH1)-like phenotype, and rare CD8+ T cells that target myelin antigens of the peripheral nerves in patients with the demyelinating disease variant. We characterized more than 1,000 autoreactive single T cell clones, which revealed a polyclonal TCR repertoire, short CDR3ß lengths, preferential HLA-DR restrictions and recognition of immunodominant epitopes. We found that autoreactive TCRß clonotypes were expanded in the blood of the same patient at distinct disease stages and, notably, that they were shared in the blood and the cerebrospinal fluid across different patients with GBS, but not in control individuals. Finally, we identified myelin-reactive T cells in the nerve biopsy from one patient, which indicates that these cells contribute directly to disease pathophysiology. Collectively, our data provide clear evidence of autoreactive T cell immunity in a subset of patients with GBS, and open new perspectives in the field of inflammatory peripheral neuropathies, with potential impact for biomedical applications.

SARS-CoV-2 Vaccination and Neuroimmunological Disease: A Review.

Importance: The temporal association between the occurrence of neurological diseases, many autoimmune diseases, and vaccination against SARS-CoV-2 has been topically interesting and remains hotly debated both in the medical literature and the clinic. Given the very low incidences of these events both naturally occurring and in relation to vaccination, it is challenging to determine with certainty whether there is any causative association and most certainly what the pathophysiology of that causation could be. Observations: Data from international cohorts including millions of vaccinated individuals suggest that there is a probable association between the adenovirus-vectored vaccines and Guillain-Barré syndrome (GBS). Further associations between other SARS-CoV-2 vaccines and GBS or Bell palsy have not been clearly demonstrated in large cohort studies, but the possible rare occurrence of Bell palsy following messenger RNA vaccination is a topic of interest. It is also yet to be clearly demonstrated that any other neurological diseases, such as central nervous system demyelinating disease or myasthenia gravis, have any causative association with vaccination against SARS-CoV-2 using any vaccine type, although it is possible that vaccination may rarely trigger a relapse or worsen symptoms or first presentation in already-diagnosed or susceptible individuals. Conclusions and Relevance: The associated risk between SARS-CoV-2 vaccination and GBS, and possibly Bell palsy, is slight, and this should not change the recommendation for individuals to be vaccinated. The same advice should be given to those with preexisting neurological autoimmune disease.

Lessons learned from annotation of VAERS reports on adverse events following influenza vaccination and related to Guillain-Barré syndrome.

BACKGROUND: Vaccine Adverse Events ReportingSystem (VAERS) is a promising resource of tracking adverse events following immunization. Medical Dictionary for Regulatory Activities (MedDRA) terminology used for coding adverse events in VAERS reports has several limitations. We focus on developing an automated system for semantic extraction of adverse events following vaccination and their temporal relationships for a better understanding of VAERS data and its integration into other applications. The aim of the present studyis to summarize the lessons learned during the initial phase of this project in annotating adverse events following influenza vaccination and related to Guillain-Barré syndrome (GBS). We emphasize on identifying the limitations of VAERS and MedDRA. RESULTS: We collected 282 VAERS reports documented between 1990 and 2016 and shortlisted those with at least 1,100 characters in the report. We used a subset of 50 reports for the preliminary investigation and annotated all adverse events following influenza vaccination by mapping to representative MedDRA terms. Associated time expressions were annotated when available. We used 16 System Organ Class (SOC) level MedDRA terms to map GBS related adverse events and expanded some SOC terms to Lowest Level Terms (LLT) for granular representation. We annotated three broad categories of events such as problems, clinical investigations, and treatments/procedures. The inter-annotator agreement of events achieved was 86%. Incomplete reports, typographical errors, lack of clarity and coherence, repeated texts, unavailability of associated temporal information, difficulty to interpret due to incorrect grammar, use of generalized terms to describe adverse events / symptoms, uncommon abbreviations, difficulty annotating multiple events with a conjunction / common phrase, irrelevant historical events and coexisting events were some of the challenges encountered. Some of the limitations we noted are in agreement with previous reports. CONCLUSIONS: We reported the challenges encountered and lessons learned during annotation of adverse events in VAERS reports following influenza vaccination and related to GBS. Though the challenges may be due to the inevitable limitations of public reporting systems and widely reported limitations of MedDRA, we emphasize the need to understand these limitations and extraction of other supportive information for a better understanding of adverse events following vaccination.

Guillain-Barré syndrome and SARS-CoV-2 infection: a systematic review and meta-analysis on a debated issue and evidence for the 'Italian factor'.

BACKGROUND AND PURPOSE: The association between Guillain-Barré syndrome (GBS) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is debated. This study reappraises, after three pandemic years, the epidemiological data and the features of GBS in SARS-CoV-2 patients. METHODS: A systematic review and meta-analysis of case reports/series and cohort studies published between 1 January 2020 and 19 April 2023 was performed. RESULTS: In all, 209 case reports/series (304 patients) and 26 cohort studies were included. The risk of GBS in northern Italy during the first pandemic wave was 2.85 times increased (95% confidence interval [CI] 1.54; 5.25) whereas in some countries the risk during the first pandemic year was 0.17 times reduced (risk ratio 0.83, 95% CI 0.75; 0.93). The incidence of GBS in SARS-CoV-2 Italian hospitalized cohorts was 8.55 per 1000 (95% CI 5.33; 12.49) with an estimated incidence of 0.13 GBS per 1000 in the SARS-CoV-2 infected population. In European cohorts the pooled rate of GBS with SARS-CoV-2 infection was 61.3% of the total. GBS patients with SARS-CoV-2 infection showed more frequently, but not differently from non-infected patients, the classical clinical presentation and the demyelinating subtype. Cranial nerves were more frequently involved in SARS-CoV-2 infected patients. CONCLUSIONS: An increased risk of GBS occurred in northern Italy during early COVID-19 pandemic. The recognition of the 'Italian factor' reconciles contrasting results of the epidemiological studies. The slightly reduced GBS risk in other countries and the relatively high frequency of GBS associated with SARS-CoV-2 infection can be explained by the adopted health measures that decreased the circulation of other GBS infective antecedents.

Neuromuscular diseases associated with COVID-19 vaccines: a systematic review and pooled analysis of 258 patients.

BACKGROUND: Neuromuscular diseases (NMD) emerged as one of the main side effects of the COVID-19 vaccination. We pooled and summarized the evidence on the clinical features and outcomes of NMD associated with COVID-19 vaccination. METHODS: We comprehensively searched three databases, Medline, Embase, and Scopus, using the key terms covering "Neuromuscular disease" AND "COVID-19 vaccine", and pooled the individual patient data extracted from the included studies. RESULTS: A total of 258 NMD cases following COVID-19 have been reported globally, of which 171 cases were Guillain-Barré syndrome (GBS), 40 Parsonage-Turner syndrome (PTS), 22 Myasthenia Gravis (MG), 19 facial nerve palsy (FNP), 5 single fiber neuropathy, and 1 Tolosa-Hunt syndrome. All (100%) SFN patients and 58% of FNP patients were female; in the remaining NMDs, patients were predominantly male, including MG (82%), GBS (63%), and PTS (62.5%). The median time from vaccine to symptom was less than 2 weeks in all groups. Symptoms mainly appeared following the first dose of vector vaccine, but there was no specific pattern for mRNA-based. CONCLUSION: COVID-19 vaccines might induce some NMDs, mainly in adults. The age distribution and gender characteristics of affected patients may differ based on the NMD type. About two-thirds of the cases probably occur less than 2 weeks after vaccination.

Biological analysis of the potential pathogenic mechanisms of Infectious COVID-19 and Guillain-Barré syndrome.

Background: Guillain-Barré syndrome (GBS) is a medical condition characterized by the immune system of the body attacking the peripheral nerves, including those in the spinal nerve roots, peripheral nerves, and cranial nerves. It can cause limb weakness, abnormal sensations, and facial nerve paralysis. Some studies have reported clinical cases associated with the severe coronavirus disease 2019 (COVID-19) and GBS, but how COVID-19 affects GBS is unclear. Methods: We utilized bioinformatics techniques to explore the potential genetic connection between COVID-19 and GBS. Differential expression of genes (DEGs) related to COVID-19 and GBS was collected from the Gene Expression Omnibus (GEO) database. By taking the intersection, we obtained shared DEGs for COVID-19 and GBS. Subsequently, we utilized bioinformatics analysis tools to analyze common DEGs, conducting functional enrichment analysis and constructing Protein-protein interaction networks (PPI), Transcription factors (TF) -gene networks, and TF-miRNA networks. Finally, we validated our findings by constructing the Receiver Operating Characteristic (ROC) curves. Results: This study utilizes bioinformatics tools for the first time to investigate the close genetic relationship between COVID-19 and GBS. CAMP, LTF, DEFA1B, SAMD9, GBP1, DDX60, DEFA4, and OAS3 are identified as the most significant interacting genes between COVID-19 and GBS. In addition, the signaling pathway of NOD-like receptors is believed to be essential in the link between COVID-19 and GBS.

Relation between Guillain-Barré syndrome and Covid-19: Case-Series.

Approximately two-thirds of the Guillain-Barré syndrome (GBS) cases are preceded by upper respiratory tract infection or enteritis. There has been previous documentation of a clear association between Covid-19 and GBS. Covid-19 can affect the nervous tissue either through direct damage or through triggering a host immune response with subsequent development of autoimmune diseases such as GBS. Covid-19 can affect the host`s immune system through the activation and interaction of the T-and B-lymphocytes with subsequent production of antibodies that cross-react with the gangliosides. Depending on the nature of the neuronal autoimmune destruction, the affected individual may have either a demyelinating or axonal subtype of GBS. These subtypes differ not only in symptoms but also in the likelihood of recovery. This report presents two cases of GBS that developed after the respiratory symptoms of Covid-19. Their neurological features indicated demyelination, axonal damage, irritation of spinal nerve roots, and impaired sensory and motor transmission with additional facial nerve palsy in the second-studied case. This case report highlights the relationship between GBS and Covid-19 infection.

Association Between Guillain-Barré Syndrome and COVID-19 Infection and Vaccination: A Population-Based Nested Case-Control Study.

BACKGROUND AND OBJECTIVES: Existing data regarding occurrence of Guillain-Barré syndrome (GBS) after coronavirus disease 2019 (COVID-19) infection and vaccination are inconclusive. We aimed to assess the association between GBS and both severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and COVID-19 vaccine. METHODS: We conducted a nested case-control study in a cohort of 3,193,951 patients aged 16 years or older, without a diagnosis of prior GBS, from the largest health care provider in Israel. Participants were followed from January 1, 2021, until June 30, 2022, for the occurrence of GBS. Ten randomly selected controls were matched to each case of GBS on age and sex. We assessed both SARS-CoV-2 infection and COVID-19 vaccine administration in the prior 6 weeks in cases and controls. RESULTS: Overall, 76 patients were diagnosed with GBS during follow-up and were matched to 760 controls. A positive test for SARS-CoV-2 was detected in 9 (11.8%) cases and 18 (2.4%) controls. An administration of COVID-19 vaccine was detected in 8 (10.5%) cases (all Pfizer-BioNTech [BNT162b2] vaccine) and 136 (17.9%) controls (134 Pfizer-BioNTech vaccine). Multivariable conditional logistic regression models showed that the odds ratio for GBS associated with SARS-CoV-2 infection and COVID-19 vaccine administration was 6.30 (95% CI 2.55-15.56) and 0.41 (95% CI 0.17-0.96), respectively. The results were similar when exposure to SARS-CoV-2 infection or COVID-19 vaccine administration was ascertained in the prior 4 and 8 weeks, although did not reach statistical significance for COVID-19 vaccine at 4 weeks. DISCUSSION: Our study suggests that SARS-CoV-2 infection is associated with increased risk of GBS, whereas Pfizer-BioNTech COVID-19 vaccine is associated with decreased risk of GBS.