COVID-19 Vaccine-triggered Relapsing Immune Dysregulation: An Observational Study with Four-year Follow-up.

Background: Vaccination against COVID-19 infection became mandatory because of the field situation during the pandemic. Purpose: Vaccine efficacy and safety need many field years of study; time constraints due to the pandemic limited the same. A hospital-based study was done in South India among patients who presented with immune-mediated disorders in temporal correlation with COVID-19 vaccination. Methods: The study period was 20 months, from March 2020 to November 2021. There were a total of 3,235 patients with neurological issues seen in two tertiary institutions, catering predominantly to patients from lower socio-economic strata in South India. A total of 1,007 (31.12%) patients had received COVID-19 vaccination (single dose in 511 [50.7%] and both doses in 496 [49.3%]). The general prevalence of primary demyelinating disease was compared with the background of vaccine-induced demyelination. Chi-square test was utilised for determining the association between neurological sequelae and the type of vaccine administered. Results: Eighteen patients had neurological sequelae, and 16 had a monophasic pattern. Recurrent autoimmunity was seen in two patients who took the Sputnik vaccine. Comparing the prevalence of primary multiple sclerosis (MS) versus vaccine-induced demyelination, there was a statistically significant difference ( Conclusion: Vaccination is an effective public health intervention. However, in susceptible individuals, it can probably trigger a recurrent and multisystem event by immune dysregulation. The association is an observation-based postulate that needs a longer, larger follow-up. As per this study, it is non-fatal and remits permanently.