Objectives: The objective of this study is to explore the characteristics of the subset of patients with Hematologic Malignancies (HM) who had little to no change in SARS-CoV-2 spike antibody index value levels after a 3rd mRNA vaccine dose (3 V) and to compare the cohort of patients who did and did not seroconvert post-3V to get a better understanding of the demographics and potential drivers of serostatus.

Study Design: This retrospective cohort study analyzed SARS-CoV-2 spike IgG antibody index values pre- and post- 3 V data on 625 patients diagnosed with HM across a large Midwestern United States healthcare system between October 31, 2019 and January 31, 2022.

Methods: To assess the association between individual characteristics and seroconversion status, patients were placed into two groups based on IgG antibody status pre- and post- the 3 V dose, (-/+) and (-/-). Odds ratios were used as measures of association for all categorical variables. Logistic regressions were used to measure the association between HM condition and seroconversion.

Results: HM diagnosis was significantly associated with seroconversion status (P = .0003) with patients non-Hodgkin lymphoma 6 times the odds of not seroconverting compared to multiple myeloma patients (P = .0010). Among the participants who were seronegative prior to 3 V, 149 (55.6%) seroconverted after the 3 V dose and 119 (44.4%) did not.

Conclusion: This study focuses on an important subset of patients with HM who are not seroconverting after the COVID mRNA 3 V. This gain in scientific knowledge is needed for clinicians to target and counsel these vulnerable patients.