We read with interest the article by Allen et al. about four patients experiencing bifacial muscle weakness with paresthesias within 3 weeks after vaccination with a vector-based SARS-CoV-2 vaccine being classified as Guillain-Barre syndrome (GBS) variant [1]. Three patients profited from intravenous immunoglobulins (IVIGs) or steroids, and one recovered without treatment [1]. It was concluded that neurologists should stay vigilant for GBS in patients having been vaccinated with a SARS-CoV-2 vaccine [1]. The study is appealing but raises comments.

Development of a GBS in response to a SARS-CoV-2 vaccination is rare but has been previously reported [2,3,4,5]. Post-SARS-CoV-2 vaccination GBS has been found in a 32yo male who developed GBS, subtype acute, inflammatory, demyelinating polyneuropathy (AIDP), eight days after the first dose of a vector-based SARS-CoV-2 vaccine [2]. This patient had a previous history of AIDP 14 years earlier from which he recovered completely. He profited from two IVIG cycles and plasmapheresis but is still handicapped and currently undergoing immune-adsorption [2]. A second case refers to a 69yo female who developed AIDP 39d after the first dose of a vector-based SARS-CoV-2 vaccine and 15d after having been tested positive for SARS-CoV-2. In a 86yo female GBS was diagnosed one day after having received the first dose of an mRNA-based SARS-CoV-2 vaccine [3]. She recovered only partially under IVIGs [3]. A further patient with SARS-CoV-2 vaccination associated GBS concerns a 82yo female who developed GBS two weeks after the first dose of an mRNA-based SARS-CoV-2 vaccine [4]. Since she had not undergone nerve conduction studies, no GBS subtype could be defined. GBS. Seven patients with SARS-CoV-2 vaccination associated GBS were reported from India (table 1). All of these patients had cranial nerve involvement [5]. The VAERS registry does not list GBS as an adverse reaction to SARS-CoV-2 vaccinations. 

A further limitation of the study is that the outcome of the four presented cases was not described in detail. We should be told if IVIGs or steroids were beneficial and if four patients recovered completely or incompletely.

Another limitation of the study is that patient four did not undergo nerve conduction studies (NCSs). Diagnosing GBS according to the validated Brighton criteria requires application of NCSs. For diagnosing GBS according to the Brighton criteria CSF cell counts <50 cells/ml are required. 

Overall, the interesting study has some limitations, which challenge the results and their interpretation.