Response to “Nerve conduction studies support the classification of SARSCoV-2 associated Guillain-Barre subtypes”

We read with interest the comments made by Finsterer et al.¹ on our previously published case report “Guillain–Barré syndrome after coronavirus disease 2019 vaccine: A temporal association”.² We understand that the comments made are interesting points of discussion.

The main point questioned by Finsterer et al., the diagnosis of Guillain-Barré syndrome (GBS) as a temporal association, not necessarily causal, can be elucidated due to several components. First, due to the time the article was written, in which there were not as many cases reported in the literature as currently, as correctly described in the letter “In a recent review of the neurological side effects of SARS-CoV-2 vaccines, 300 cases of SC2VaG were described”.¹ Second, due to limited diagnostic resources in the case, a public hospital in southern Brazil. The absence of diagnostic tests, such as those mentioned by Finsterer et al. (electroneuromyography, investigation of cytokines, chemokines and glial markers in the CSF), are factors that must be highlighted before defining the causality of the association. Added to the two previous points is the sensitivity to the moment of the pandemic in which the article was produced. The beginning of an important vaccination campaign, in the midst of the growth of anti-vaccine groups, inspires caution when associating causality without the possibility of ruling out, through more elaborate tests, other causes. Finally, the level of evidence that a case report has in comparison to other scientific productions is highlighted. Then, for a reliable correlation between the SARS-CoV-2 vaccine and GBS, studies with a higher level of evidence are necessary, such as randomized clinical trials and systematic reviews.³

Furthermore, it is noteworthy that the delay between the onset of symptoms and diagnosis was due to the patient having interpreted the initial changes as of psychiatric origin, taking 2 months to seek the medical service of reference in the region. Thus, there is a consensus among us authors that the delay in diagnosis and treatment, as well highlighted by Finsterer et al., may have been one of the factors that led to worse outcome. The authors also emphasize that the findings of the patient's neurological physical examination are those described in the article, so, those not mentioned, such as the involvement of several pairs of cranial nerves, were not present.

Therefore, for all the reasons mentioned above and despite the interesting and pertinent comments made by Finsterer et al., the authors adopted a more cautious approach and, thus, defined the case as a temporal association, not necessarily a causal one.

None declared.

All authors are in agreement with the content of the manuscript. All authors participated in the data acquisition and analysis, and contributed to the drafting of the manuscript.

All informed consent was obtained from the subject(s) and/or guardian(s). Approval of the research protocol: N/A. Registry and the Registration No. of the study/trial: N/A. Animal Studies: N/A.