Objective

We assessed the association of detectable antibody response to COVID-19 vaccination with factors including B-cell depletion in rituximab treated patients.

Methods

A retrospective chart review of rituximab treated adult patients who completed mRNA vaccination for SARS-CoV-2 was conducted. Primary outcome was presence and strength of serologic antibody response to vaccination. Comparisons between those with and without detectable serologic response were calculated using T-tests, Fisher's exact test and Wilcoxon rank sum tests. Negative and positive predictive value was calculated between serologic response and B-cell reconstitution status.

Results

In 56 patients, a significant difference in level of B-cell reconstitution was seen in patients with positive (median, IQR 2 (0.13-10)% of total lymphocyte population) versus negative (median, IQR 0 (0-0)%)(p<0.001) serologic response to vaccination. There was also significant difference in time from last rituximab infusion between patients with positive (median #days, IQR 594 (262, 1163) versus negative (median #days, IQR 138 (68, 197))(p-value <0.001) serologic response to vaccination. 13% (3/24) of patients >12 months since last rituximab exposure, 55% (6/11) of patients 6-12 months from last exposure, and 86% (18/21) of patients <6 months since last exposure did not demonstrate a serologic response to vaccination. Positive predictive value of B-cell reconstitution for COVID-19 serologic response was 91.3%(95%CI: 72%-98.9%) and negative predictive value was 68.8%(95%CI: 41.3%-89%).

Conclusions

B-cell reconstitution and longer time from last rituximab exposure were associated with a positive serologic response to the COVID-19 vaccine. Strategies for maximizing vaccine responsiveness in rituximab treated patients should incorporate assessment of B-cell reconstitution.

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