Researchers investigated if COVID-19 occurred in patients with neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) and reported a number of such cases, thus reinforcing the need for further research to be conducted to evaluate COVID-19 vaccine efficacy among patients with NMOSD and MS.

Anti-CD20 is a class of immunosuppressants widely used to treat NMOSD and MS. The data shows that they work by reducing the rate of relapse and disability accumulation. When the COVID-19 vaccines first became available, patients with MS on anti-CD20 therapies were prioritized.

“As anti-CD20 therapies exposure is associated with COVID-19 severity and with lower anti-spike humoral immunity after vaccination, we aimed to assess whether COVID-19 had occurred among previously vaccinated patients and determine the characteristics of these patients,” the researchers wrote in the study published in the Multiple Sclerosis Journal.

Continue Reading

They carried out their study using the French database COVISEP and identified 1650 patients with MS and 67 patients with NMOSD. They then identified all cases of COVID-19 (n=460). 

Read more about NMOSD etiology

The results demonstrated that 16 patients with MS became infected with COVID-19 after receiving their first dose of the vaccine. In addition, the researchers discovered that 17 patients with MS and 1 aquaporin-4 positive patient with NMOSD were diagnosed with COVID-19 after receiving 2 doses of the BNT162b2 vaccine. 

The concern reported was the low immunogenicity of COVID-19 vaccines among patients treated with anti-CD20. The French health authority recommendation is that a third dose should be given 4 weeks after the second dose among patients treated with anti-CD20. 

“Our results reinforce this recommendation, even if we cannot be sure that this third dose would guarantee the same protection as vaccinated non-immunocompromised patients,” the researchers wrote.

“These preliminary findings stress the need for a prospective clinical and biological follow-up on COVID-19 vaccine efficacy among this population exposed to immunosuppressive therapies, and further studies are needed to assess the impact of prior vaccination on COVID-19 severity among immunocompromised patients.”


Januel E, De Seze J, Vermersch P, et al. Post-vaccine COVID-19 in patients with multiple sclerosis or neuromyelitis optica. Mult Scler. Published online December 21, 2021. doi:10.1177/13524585211049737