Abstract Details

Various vaccines are implicated in rare demyelinating events. Although influenza is the most commonly-implicated vaccine, an increasing number of CNS inflammatory events are linked to SARS-CoV-2 vaccines.

We aim to determine the prevalence and clinical characteristics of iatrogenic CNS inflammation associated with vaccinations at a tertiary neuroimmunology clinic and compare the frequency of these events before and after the COVID-19 pandemic. 

We analyzed consecutive patients seen over 4 years (2017-2021) at a tertiary neuroimmunology clinic who were screened for iatrogenic CNS inflammation secondary to vaccinations. In patients with suspected iatrogenic events, the Naranjo Adverse Drug Reaction Probability Scale was used to score the probability of vaccine-related events as doubtful, possible, probable, or definite.

In total, 419 patients were seen over 4 years and were screened. Eleven cases were identified, and the total prevalence was 2.6% (82% female, average age 56+/- 18 years). Most events (10, 91%) were scored as probable. The following disease phenotypes were identified: multiple sclerosis relapse (6, 55%), optic neuritis (1, 9%), monophasic MOGAD (1, 9%), transverse myelitis relapse (1, 9%), seropositive NMOSD (1, 9%), and autoimmune encephalitis (1, 9%). The vaccines included influenza (n=4), SARS-CoV-2 mRNA (n=3), swine flu (n=1), and HPV (n=1). Two patients were exposed simultaneously to multiple vaccines (tetanus, MMR, and VZV; tetanus, hepatitis A, and meningococcal vaccines). Spontaneous resolution occurred in 36% of events, complete response to corticosteroids/immunotherapy in 46%, partial response in 9%, and unresponsiveness in 9%. Finally, 8 patients (73%) had relapsing disease and 3 patients (27%) had monophasic disease.

Post-vaccination iatrogenic CNS inflammation is a rare but distinct neuroimmunological disease spectrum mostly involving spontaneous recovery or responsiveness to corticosteroids. We did not identify an excess of SARS-CoV-2 vaccine-related events. The rare occurrence and predominantly favorable prognosis suggest the benefit of vaccination outweighs the neurological risks, especially during the COVID-19 pandemic.