Symptoms Potentially Related to Small Fiber Neuropathy (SFN) and Anticovid Vaccines: An International Journal of Medical Toxicology and Drug Experience

ABSTRACT

Introduction: SFN is a relatively rare condition related to finer fibers of peripheral nervous system. A specific diagnostic procedure is necessary to reach a correct diagnosis.The most frequently reported symptoms are pain (described as burning or a sensation of intense heat, as "aching cold", "pinpricks", "electric shocks),paraesthesia (spontaneous sensations of tingling,numbness,itching),dysesthesia and allodynia. Some published papers hypothesized a correlation between SFN and anticovid vaccine. Objective: Study target was to analyze the adverse events following immunization (AEFI) reported in our ASL (resident population 1,221,857, ¼ regional population) potentially linked to the SFN symptoms. Methods: Data relating to AEFI were extrapolated from the National Pharmacovigilance Network (NPN), while data referring to administered doses were extracted from the ASL QlinkView platform. Results: From 27 December 2020 to 26 April 2022, 624 reports, relating to vaccines anticovid AEFI, were received and recorded in the NPN. 2.109 AEFI were described in these reports. Administered vaccines Comirnaty (346/624 sheets;1.164/2.109AEFI;2.092.042/ 3.028.781 total administered doses), the most reported AEFI were related to general pathologies pain, wheal or erythema at the injection site, headache, fever, asthenia, nausea, malaise, tachycardia, muscle pain, fatigue, joint pain (25% of 1.164 AEFI). Other described symptoms other pains, burning, itching, paraesthesia, tingling, numbness, allodynia, potentially linked to SFN (17.3% of 1.164 AEFI);Spikevax (112/624 sheets;392/2.109 AEFI;607.626/ 3.028.781 doses),the most reported AEFI, like Comirnaty, were related to the injection site (26% of 392 AEFI), while the potentially symptoms related to SFN were the 20.2% of 392 AEFI;Vaxzevria (146/624 sheets;512/2.109 AEFI;298.188/3.028.781 doses), the most reported AEFI, related to general pathologies, were the 33% of 512 AEFI, while potentially symptoms related to SFN were the 18.8%. Finally, as regards the Janssen vaccine (10/624 sheets;32/2.109 AEFI;30.702/3.028.781 doses), the most described events, related to general pathologies, are the 47% of the 32 AEFI, while 31% are potentially linked to the of SFN symptoms. No AEFI was reported related to the 223 doses about Novavax vaccine. The causality assessment was defined correlatable about 37 records (6% of 624 records). 12/37 records describe potentially linked to SFN symptoms (6 Vaxzevria (1%), 3 Comirnaty (0.5%) and 3 Spikevax (0.5%)). Conclusion: The analysis about AEFI reported in our ASL related to anticovid vaccines underlined the existence of symptoms potentially linked to SFN, although only in a few cases it was evaluated a causality assessment to vaccination. Just a specific diagnostic procedure can confirm the diagnosis and the correlation. Therefore, the correlation between SFN and vaccine needs larger-scale studies and insights for a correct evaluation.