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Disclosures: Tolf reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
May 17, 2022
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MS patients treated with rituximab may receive COVID-19 vaccine as soon as possible

Disclosures: Tolf reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
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Rituximab-treated patients with MS may be vaccinated for COVID-19 as soon as possible, researchers reported in JAMA Network Open.

Andreas Tolf, MD, of the department of medical sciences at Uppsala University in Sweden, and colleagues conducted a prospective cohort study from Jan. 21 to Dec. 1, 2021, and analyzed data from 67 participants with planned or ongoing treatment with rituximab.

Source: Adobe Stock.
Source: Adobe Stock.

Researchers assessed serological vaccine responses by measuring quantitation of anti-spike IgG antibodies and anti-receptor-binding domain (RBD) IgG antibodies, as well as their neutralizing capacities.

Among the 60 patients currently receiving rituximab (49 women; mean age, 43 years), the median disease duration for MS was 9 years (range, 1-29 years), and the median drug dose was 2,750 mg (range, 500-10,000 mg). Vaccine responses were determined before vaccination with tozinameran and 6 weeks after.

Researchers established cutoff values for anti-spike IgG (264 binding antibody units/mL) and anti-RBD IgG (506 units/mL) to determine the proportion of patients who had a positive response, indicated by an increased number of B cells. A cutoff for B-cell count of at least 40/µL was associated with an optimal serological response.

Six months after the last rituximab infusion, data on B-cell counts were available for 48 patients, and 29 (60%) had a B-cell count of at least 10/µL. Of those 29 patients, 26 (90%) had positive results for anti-spike IgG antibodies, 21 (72%) for anti-RBD IgG antibodies, and 27 (93%) developed antibodies with greater than 90% inhibition of angiotensin-converting enzyme 2.

“These results favor early vaccination without considering time from last infusion or B-cell count because some patients generated a functional serological response anyway, and T-cell responses appeared to develop independently of B-cell count,” the authors wrote. “The results also suggest that an additional vaccine dose may be considered when the B-cell count reaches 40/µL to ensure that as many patients as possible will generate an adequate vaccine response.”