Guillain–Barré syndrome after SARS-CoV-2 vaccination in a patient with previous vaccine-associated Guillain–Barré syndrome

We eagerly read the article by Ling et al. about a 63 years old male with a history of arterial hypertension, hyperlipidemia, diabetes, nephrolithiasis, anxiety disorder, and Guillain-Barre syndrome(GBS) after an influenza vaccination 22 years earlier, who developed a second GBS 11 days after the first dose of a vector-based SARS-CoV-2 vaccine(Astra Zeneca)[1] Within a follow-up of three months the patient partially recovered after treatment with initially immunoglobulins followed by plasma exchange.[1] It was concluded that the case does not imply a causal relation between the vaccination and GBS.[1] The study is appealing but raises concerns that require discussion.
We do not agree with the statement “No convincing evidence has shown that SARS-CoV-2 vaccination causes GBS”.[1] In a recent review about the neurological complications of SARS-CoV-2 vaccinations, 389 cases with SARS-CoV-2 vaccination associated GBS have been listed.[2] Given these data, the first key point “Guillain–Barré syndrome(GBS) has very rarely been described after vaccination against SARS-CoV-2,[1] is not plausible.
We also do not agree with the third key point “More cases of GBS have been reported after SARS-CoV-2 infection than after vaccination”.[1] As per the end of June 2021 at least 300 patients with SARS-CoV-2 infection associated GBS have been reported.[Finsterer et al. submitted] As per the end of September 2021 389 SARS-CoV-2 vaccination associated cases with GBS have been published.[2]
It should be explained how the cause of the electrophysiological findings shown in figure 1 was differentiated from the previous GBS or from diabetic polyneuropathy. Since results of nerve conduction studies (NCSs) frequently do not change considerably after clinical recovery from a GBS, it is conceivable that the findings shown in figure 1 are simply residual findings from the first GBS. It should be mentioned if the patient had undergone NCS between the first and second GBS. It is also crucial to know the duration of diabetes and the HbA1c values over time. As NCS studies were interpreted as mixed axonal and demyelinating it is conceivable that, at least, partially, they are attributable to diabetic polyneuropathy.
Missing is the exclusion of an acute SARS-CoV-2 infection. Results of PCR tests for SARS-CoV-2 during hospitalisation were not provided.[1]
It should be specified which subtype of GBS was diagnosed in the index patient. AIDP, AMAN, or AMASN? Knowing the subtype is essential, as treatment may vary considerably between the subtypes.
It should be specified what is meant by non-invasive mechanical ventilation. Oxygen supplementation via face mask, non-invasive positive pressure ventilation(NIPPV), continuous positive airway pressure (CPAP), or bi-level positive pressure(BIPAP)?
Missing is a discussion about other patients with SARS-CoV-2 vaccination induced GBS with a history of previous GBS.[3]