Hypogammaglobulinemia is associated with reduced antibody response after anti-SARS-CoV-2 vaccination in MS patients treated with antiCD20 therapies.

Background: COVID-19 vaccination is highly recommended to multiple sclerosis (MS) patients. Little is known about the role of patients' clinical and demographic characteristics in determining antibody response.

Methods: We evaluated safety and efficacy of anti-SARS-CoV-2 vaccines on 143 included MS patients. Then, we analyzed antibody titer in a subgroup, assessing clinical and demographic variables associated with protection and antibody titer.

Results: After completing the vaccination cycle, the rate of local adverse events was similar after the first and second dose. A higher proportion of systemic AEs was reported after the second dose (65.7% vs 24.5% after the first dose). Antibody response was evaluated in 97 patients. Higher EDSS (OR 0.6, 95% CI 0.4-0.9, p = 0.006) and treatment with antiCD20 (OR 0.02, 95% CI 0.003-0.098, p 0.001) were associated with a lower chance of having an efficacious response. Higher weight was associated with higher Ab titer (β = 15.2, 95% CI 2.8-27.6, p = 0.017), while treatment with antiCD20 with lower titers (β =  - 1092.3, 95% CI - 1477.4 to - 702.2, p < 0.001). In patients treated with antiCD20, hypogammaglobulinemia (β - 543, 95% CI - 1047.6 to - 39.1, p = 0.036) and treatment duration (β - 182, 95% CI - 341.4 to - 24.3, p = 0.027) were associated with lower Ab titer.

Conclusion: Our study confirms that COVID-19 vaccination in MS patient is safe and effective in preventing symptomatic COVID-19 and should be recommended to all patients. Moreover, we suggest a possible role of hypogammaglobulinemia in reducing Ab response in patients treated with antiCD20 therapies.