Effect of Disease-Modifying Therapies on Clinical Efficacy of COVID-19 Inactivated Vaccination among People with Multiple Sclerosis

BACKGROUND: Immunogenicity data shows blunted responses to COVID-19 vaccination among people with MS (pwMS) on certain disease-modifying therapies (DMTs). Still, it is unclear how this data may translate into the clinic. OBJECTIVE: To assess the effect of DMTs and other factors on the clinical efficacy of inactivated vaccination in reducing COVID-19 incidence and severity. METHODS: This cohort study was designed and conducted in Isfahan, Iran, from April until December 2021. We used multivariable Poisson regression to compare COVID-19 incidence, multivariable cox regression to compare COVID-19-free survivals, and an ordinal logistic model to compare COVID-19 severity between vaccinated pwMS on different DMTs. RESULTS: A total of 617 pwMS were included in the final analysis. The cumulative incidence of all probable COVID-19 was 18.48%. 7/114 (6.14%) of the COVID-19 cases – all among the ones receiving fingolimod or anti-CD20 therapies (aCD20) – required hospitalization due to COVID-19, one of whom who was on fingolimod died and the rest recovered without complications. Analyses showed higher post-vaccination COVID-19 incidence and severity in pwMS on fingolimod and aCD20. CONCLUSION: The observed results justify further vaccination of pwMS on injectable and oral DMTs other than S1PR modulators and aCD20, and stresses the importance of personalized vaccination scheduels, post-vaccination serological screening, earlier and more frequent booster administerations, and reservation of COVID-19 treatment resources for pwMS on S1PR modulators and aCD20.