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The B-cell–depleting multiple sclerosis (MS) drug ocrelizumab has been associated with decreased vaccine seroconversion, including from SARS-CoV-2 vaccination. For patients receiving B-cell–depleting therapy, it has been suggested that vaccines be administered in the weeks before the next dose. However, B cells typically remain depleted through the 6-month retreatment interval, and it remains unclear whether waiting to time the vaccine dose has improved seroconversion rates. In this study, investigators evaluated ocrelizumab serum concentration at the time of first mRNA SARS-CoV-2 vaccination to determine whether a correlation with seroconversion existed.
Fifty-three patients on ocrelizumab received their first vaccine, followed by a second dose 42 days later. Of these, 15% seroconverted at 42 days and 40% seroconverted at 70 days. At time 0, 66% of patients had undetectable serum B-cell counts. SARS-CoV-2 seroconversion at 70 days correlated inversely with ocrelizumab serum concentration at time of first vaccination. Seroconversion occurred in 88% with ocrelizumab concentrations <0.1 g/mL, some of whom also had detectable B-cell counts.
van Kempen ZLE et al. Ocrelizumab concentration is a good predictor of SARS-CoV-2 vaccination response in patients with multiple sclerosis. Ann Neurol 2022 Oct 17; [e-pub]. (https://doi.org/10.1002/ana.26534)
Comment
This small cohort study suggests vaccine seroconversion is more likely to occur when ocrelizumab concentration is lowest. This evidence would support timing of vaccination close to the next 6-month ocrelizumab dose. However, this cohort had an unexpectedly high incidence of detectable B cells. When flexibility is possible, vaccines can be administered a month before the next dose. Larger studies will need to reproduce this finding and determine vaccine response durability. The latest guidance on COVID-19 vaccination for patients with MS is provided here.