Global and Regional Burden of Vaccine-Associated Transverse Myelitis and Potentially Associated With Vaccines From 1967 to 2023: An Analysis of the International Pharmacovigilance Data

Abstract

Limited data on the potential safety risk of vaccine-associated transverse myelitis (TM) is available. Thus, we aimed to identify the global burden and clinical features of vaccine-associated TM to facilitate tailored monitoring of potential adverse vaccine reactions. This study used data from the World Health Organization pharmacovigilance database, which contains over 35 million reports from over 140 countries. We extracted individual case safety reports from 1967 to 2023. To investigate the potential association between 19 vaccines and TM, we calculated global reporting counts, reported odds ratios (ROR) with 95% confidence intervals (CI), and information components (IC) with IC_0.25 based on the Bayesian model. We identified 2305 reports (male, n = 999 [43.34%]) of vaccine-associated TM from 4007 reports of all-cause TM. Since the first report in 2010, the cumulative number of vaccine-associated TM reports has steadily increased, with a significant increase after 2020 due to the emergence of COVID-19 mRNA vaccines. Most vaccines were associated with TM (ROR, 42.62 [95% CI, 28.02–64.82]; IC, 4.46 [IC_0.25, 3.75]), albeit with varying levels of signal. Typhoid vaccines had the highest signal with TM reports (ROR, 42.62 [28.02–64.82]; IC, 4.46 [3.75]), followed by hepatitis A (ROR, 38.04 [30.13–48.03]; IC, 4.90 [4.51]), influenza (ROR, 31.55 [28.17–35.32]; IC, 4.80 [4.62]), encephalitis, papillomavirus, and hepatitis B vaccines. Age- and sex-specific analyses indicated that the risk of vaccine-associated TM increased with age and to be more susceptible among males through ROR. The rate of fatal adverse outcomes of vaccine-associated TM was 0.22%. This study highlights a potential signal detection between vaccines and the onset of TM, with vaccine-associated reports comprising over half of all reported TM cases in the database. Although the incidence remains low, clinicians should remain vigilant for TM symptoms following vaccination, particularly in older adults where the risk appears to be higher. While our findings do not permit for causal inference, given the increasing trend of vaccine-associated TM reports after 2020, continued pharmacovigilance and further research are needed to ensure timely detection and management of potential risks while maintaining the benefits of immunization.