(B-301) Risk of Autoimmune Disease after COVID-19 vaccination: A modified Self-controlled case series study

Background: Growing evidence suggests that autoimmune disease may be a safety concern with COVID-19 mRNA vaccines, but data on other vaccine platforms remain limited.

Objectives: We aim to assess the relative incidence (RI) of autoimmune disease across different COVID-19 vaccine platforms using the modified self-controlled case series (SCCS) design.

Methods: We identified patients with autoimmune disease between March 21 and December 31, 2021 from Taiwan’s National Health Insurance Research Database and linked them to the COVID-19 vaccination database. The post-vaccination risk period was defined as the 14 days following vaccination day 1, and the remaining time was defined as the reference period. The observation period ended on December 31, 2021, or was censored at the date of death for deceased cases. To avoid recurrences of an event are not independent, we only included the first occurrence of autoimmune disease. As physicians assess patients’ health before vaccination, we included unvaccinated cases and employed modify SCCS to account for event decreasing probability of exposure. The model was estimated using an unbiased estimating equation and optimized by maximizing the Poisson pseudo-likelihood through iterative reweighting of observations.

Results: For the mRNA platform, we identified 993,335 cases, and RI of the post-exposure 14 days risk period was 2.92 (95% CI, 2.86-2.97); for the virus-vector platform, we identified 5,978 cases, and RI of the post-exposure 14 days risk period was 2.28 (95% CI, 2.12-2.44); for the protein subunit platform, we identified 3,891 cases, and RI of the post-exposure 14 days risk period was 1.23 (95% CI, 1.10-1.38).

Conclusions: COVID-19 vaccination may increase the risk of autoimmune disease, underscoring variations in risk across different vaccine platforms. These findings provide a foundation for future vaccine development and head-to-head comparisons.