Background: Acute transverse myelitis (ATM) has been reported as a potential risk of COVID-19 vaccination.
Objectives: To investigate the association between acute transverse myelitis (ATM) after the COVID-19 vaccination.
Methods: We performed self-controlled case series (SCCS) study using the large-linked database on the COVID-19 vaccine registry and national claims database. The COVID-19 vaccination data were obtained for approximately 42 million vaccinees who were older than 18 years of age from February 26, 2021, to August 31, 2022, in the Korea Disease Control and Prevention Agency. Claims data included 51 million people in the National Health Insurance Service between January 1, 2002, to August 31, 2022. We defined ATM patients have both an ATM code (ICD-10 code: G37.3) and an ATM-related procedures code (e.g., cerebral spinal fluid analysis). Patients with a history of ATM or ATM-related disease (e.g., acute disseminated encephalomyelitis or neuromyelitis optica) were excluded to include only new ATM cases. COVID-19 infection could influence the incidence of ATM, patients that had COVID-19 within 28 days prior to diagnosis with ATM were also excluded. The observation period was 270 days after the first dose of the COVID-19 vaccine between February 26, 2021, to December 4, 2021, considering a follow-up period. Exposures were the COVID-19 vaccines approved in South Korea. The incidence rate ratio (IRR) and 95% confidence interval (CI) were estimated using the conditional Poisson regression for the risk period in 1–42 days after COVID-19 vaccination compared with the control period which non-risk period within the observation period. We conducted subgroup analyses by gender, age, and vaccination brand shortly before the ATM diagnosis and sensitivity analyses that changed the risk period to 1–21 days and 1–28 days and the observation period to 90 days and 180 days.
Results: A total of 159 ATM patients were included in the SCCS analysis. Among them, 82 (51.6%) were male, and the mean age was 55±18 years. The number of events in the risk period was 85 and the number of events in the control period was 74. IRR was 2.44 (95% CI: 1.79–3.34) for the ATM risk within 1–42 days after COVID-19 vaccination. The IRR was significantly increased in the subgroup and sensitivity analyses. IRR by vaccination brand shortly before the ATM diagnosis was 3.33 (95% CI: 1.82–6.08) for ChAdOx1nCov‐19; 2.03 (95% CI: 1.34–3.09) for BNT162b2; 2.57 (95% CI: 1.14–5.97) for mRNA-1273; 3.33 (95% CI: 0.30–36.44) for Ad26.COV2.S.
Conclusions: This SCCS study showed an increased ATM risk after COVID-19 vaccination within 1–42 days. We found an association between ATM and both viral vector and mRNA vaccines. Physicians should be alert to allow ATM early diagnosis, and continuous monitoring is needed.
