B-cell count is the only factor associated with serological response to tozinameran in patients with multiple sclerosis (MS), a new study published in the journal JAMA Network found. The optimum cutoff for a serological response is a B-cell count of at least 40/μL.

Therefore, MS patients treated with rituximab should receive the tozinameran vaccine as soon as possible and treatment with rituximab should be delayed until B-cell levels are at 40/μL. At this point, patients may receive a second dose of the vaccine. 

Treatments that deplete B-cells, such as rituximab, are often used to treat MS. However, these impair the body’s response to vaccines.

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Here, a team of researchers led by Joachim Burman MD, PhD, from the Department of Medical Sciences at Uppsala University in Sweden conducted a prospective cohort study to identify factors associated with a favorable response to tozinameran.

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The researchers evaluated 67 people with MS who are being (60 people) or will be (7 people) treated with rituximab. 

The results showed that the proportion of patients with a positive vaccine response to tozinameran increased with the number of B cells they had. This was the only factor associated with this outcome.

Other potential factors affecting the outcome that the researchers investigated were the sex and age of the patients, the number of rituximab infusions they had previously received and the time since the last rituximab treatment, the accumulated dose of rituximab, any past COVID-19 infection, CD19+ B-cell count before vaccination, and CD4+ and CD8+ T-cell counts.

According to the authors, the same approach used here may help assess response to other vaccines in patients treated with other B-cell depleting therapies, however, more studies are needed to confirm this.

Tozinameran is more widely known as the Pfizer-BioNTech COVID-19 vaccine.


Tolf A, Wiberg A, Müller M, et al. Factors associated with serological response to SARS-CoV-2 vaccination in patients with multiple sclerosis treated with rituximab. JAMA Netw Open. 2022;2;5(5):e2211497. doi:10.1001/jamanetworkopen.2022.11497