Conclusion
Vaccines currently routinely recommended to the general population in the U.S.* have not been shown to cause small fiber neuropathy (SFN).
Epidemiological Evidence
The 2012 report by the Institute of Medicine (IOM), now called the National Academy of Medicine (NAM), found no relevant studies of quality in the literature assessing SFN and varicella or influenza vaccines 1. No relevant studies of quality have been published since this report.
Proposed Biological Mechanism
SFN encompasses the heterogeneous group of disorders that damage the small subsets of sensory and autonomic nerve fibers with little to no large fiber involvement 2. One mechanism that could contribute to SFN is molecular mimicry, which refers to the possibility that similar epitopes shared between self-peptides and foreign peptides (introduced via infection or immunization) inadvertently cause the activation of autoreactive T or B cells, leading to autoimmunity. However, the IOM concluded that there was no mechanistic evidence for an association between SFN and varicella or influenza vaccines, as the publication reviewed provided no evidence beyond a temporal association 1.
* These conclusions do not necessarily consider vaccines recommended only for special populations in the United States such as Yellow Fever vaccine (international travelers) or Smallpox vaccine (military personnel), or vaccines no longer recommended to the public such as the Janssen (J&J) COVID-19 vaccine.
References
1. Institute of Medicine. In: Stratton K, Ford A, Rusch E, Clayton EW, eds. Adverse Effects of Vaccines: Evidence and Causality. Washington (DC): National Academies Press (US); 2012.
2. Gibbons CH. Small fiber neuropathies. Continuum (Minneap Minn) 2014; 20(5 Peripheral Nervous System Disorders): 1398-412.
