With interest we read the article by Koike, H., & Katsuno, M. [1] about considerations on the relation between SARS-CoV-2 and Guillain-Barre syndrome (GBS) and the effect of SARS-CoV-2 vaccination on the prevalence of SARS-CoV-2 associated GBS (SAG) [1]. The authors plea for vaccinations if the overall benefit outweighs the risk [1]. The review is appealing but raises the following comments and concerns. GBS manifests not only as acute, inflammatory, demyelinating polyneuropathy (AIDP), acute, motor axonal neuropathy (AMAN), or acute, motor and sensory axonal neuropathy (AMSAN), but also as Miller-Fisher syndrome (MFS), mono- or polyneuritis cranialis, (MNC/PNC), as cervico, pharyngo-cervico-brachial (PCB) variant, or as Bickerstaff encephalitis (BFE) [2]. Though the latter are infrequently reported, they should not be neglected in terms of prevalence figures. We do not agree with the statement that SARS-CoV-2 associated GBS is rare [1]. In a recent review, 300 patients with SAG were collected [Finsterer, submitted]. In this data set, all age groups were affected (7-94y) and there was male preponderance. Latency between onset of COVID-19 and onset of SAG ranged between -10 and 90 days. The most common GBS subtype in this cohort was AIDP (n=171), followed by AMAN (n=24), AMSAN (n=16), MFS (n=8), MNC/PNC (n=3), PCB (n=1), and BFE (n=0) [Finsterer, submitted]. Only in one patient was SARS-CoV-2 RNA detected in the CSF. Most patients received intravenous immunoglobulins (IVIG) (n=241), followed by plasmapheresis (n=28), and steroids (n=7).

Most patients achieved only incomplete recovery (n=163). Seventeen patients died. It should be also considered that many patients with SAG go either undetected or are not published, why the prevalence of SAG is supposedly higher than usually estimated. 

The authors do not consider that SARS-CoV-2 vaccinations itself are not harmless and can cause GBS [3]. In a recent review about post-vaccination GBS, 19 cases have been collected as per the end of June 2021 [Finsterer, submitted]. These patients aged 20-86y and there was gender balance. All patients developed post-SARS-CoV-2 vaccination GBS (PSVG) after the first vaccine dose. Most frequently the ASZ vaccine was given (n=14), followed by the Pfizer vaccine (n=4), and the J&J vaccine (n=1) [Finsterer, submitted]. Most PSVG patients benefited from IVIG (n=13), Six patients required artificial ventilation. Nine patients achieved partial recovers and only 1 patient complete recovery.

Concerning the effect of SARS-CoV-2 vaccinations on the prevalence of GBS, no valid data have been published yet. In a recent review about the number of publications and number of SAG patients reported in the second half of 2020 and the first half of 2021 (after introduction of SARS-CoV-2 vaccinations) it could be shown that the number of SAG patients declined from 192 to 75, thus by 61% [submitted]. Whether this reduction is attributable to a vaccination effect or other factors remains speculative, but a benefit of vaccinations with regard to the prevalence of SAG cannot be excluded.

Overall, the benefit risk ratio regarding SARS-CoV-2 vaccinations is higher than one but we should find out which patients are at risk to develop GBS. A risk factor so far identified is previous GBS.