Patients with lymphoma, especially those treated with anti-CD20 monoclonal antibodies (MoAb), suffer high COVID-19-associated morbidity and mortality. The goal of this study was to assess the ability of lymphoma patients to generate a sufficient humoral response after two injections of BNT162b2 Pfizer vaccine and to identify factors impacting the response.
Antibody titers were measured with the SARS-CoV-2 IgG II Quant (Abbott©) assay in blood samples drawn from lymphoma patients 4±2 weeks after the 2nd vaccine dose. The cutoff for a positive response was set at 50AU/ml.
Positive serological responses were observed in 51% of the 162 patients enrolled in this cross-sectional study. In a multivariate analysis, an interval of <12 months between the last anti-CD20 MoAb dose and the second vaccine dose [OR 31.3 (8.4-116.9), p<0.001] and presence of active lymphoma [OR 4.2 (2.1-8.2), p=0.006] were identified as negative response predictors. The rate of seropositivity increased from 3% in patients vaccinated within 45 days from the last MoAb administration to 80% in patients vaccinated >1 year after this therapy. The latter percentage was equal to that of patients never exposed to MoAbs.
Lymphoma patients, especially those recently treated with anti-CD20 MoAbs, fail to develop sufficient humoral response to BNT162b2 vaccine. While a serologic response is not the only predictor of immunity, its low level could make this population more vulnerable to COVID-19, which implies the urge for a different vaccination schedule for such patients.
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