ABSTRACT
Background: Patients (Pts) with hematologic malignancies (HM) are at greater risk of severe morbidity and mortality caused by COVID19 and show a lower response to the two-dose COVID19 mRNA vaccine series. The primary vaccine series now includes a third dose of the COVID19 vaccine (3V) for immunocompromised Pts. The objective of this study was to explore the characteristics of HM patients who had no change in SARS-CoV-2 spike protein titer levels post 3V (-/-) to gain a better understanding of the drivers of serostatus. Methods: This retrospective cohort study analyzed Pt data on SARS-CoV-2 spike IgG antibody titers pre- and post- 3V across the healthcare system. This study included 268 fully vaccinated HM Pts diagnosed with HM between October 31, 2019 and January 31, 2022 and had a negative serostatus prior to 3V. Post 3V titers were obtained 21 days after 3V. Demographics, association between characteristics and seroconversion status, and odds ratios were all assessed (table). Results: Pts with Non-Hodgkin lymphoma (NHL) had 6 times the odds of not seroconverting compared to multiple myeloma (MM) (CI 1.88 - 19.12, P = .0010). NHL also have about 14 times the odds of not seroconverting compared to Pts diagnosed with other HM conditions, which included: neoplasms of uncertain behavior and disorders of white blood cells (CI 1.72 - 112.44, P = .0021). 90% of seronegative Pts showed no spike IgG antibody reaction to 3V as indicated by pre- and post- 3V index values. Demographics, previous COVID19 infection, and vaccine type were not significantly associated with seroconversion. Conclusions: HM patients who are not seroconverting after 3V, suggest a prioritized population for continued increased behavioral precautions, additional vaccination efforts, including a fourth dose of an mRNA COVID19 vaccine, as well as passive immunity boosting through monoclonal and polyclonal antibodies.