The Effectiveness of Bivalent mRNA Omicron Containing Booster Vaccines Among Patients with Hematological Neoplasms

Purpose: Last year was characterized by an escape phenomenon of the SARS-CoV-2 virus generating novel variants, mainly the omicron sub-lineages BA.2.12.1, BA.4 and BA.5, which have confirmed resistance to the acquired immune response developed following first-generation mRNA vaccines. Given the ability to use mRNA technology to respond quickly to variant strains, novel bivalent vaccines against novel omicron variants were generated. In the current work, we evaluated the efficacy and safety of novel bivalent mRNA Omicron-containing booster vaccines among patients with hematological neoplasms, including both lymphoproliferative and myeloid malignancies. Patients and Methods: The cohort contains all patients with hematological neoplasms that are insured by the second-largest healthcare organization in Israel. The primary outcome was Covid-19 related hospitalization or mortality. During the study period, 472 patients were infected with omicron. We compared the outcome of 70 patients who received the bivalent mRNA booster to 402 who didn’t.Results: Fewer bivalent recipients needed Covid-19–related hospitalization (2 of 70 [2.9%]) in comparison to the non-vaccinated cohort (42 of 402 [10.4%]) with p-value=0.0304. This represents an 89% relative risk reduction in Covid-19–related hospitalization in patients with hematological neoplasms. The median duration of hospitalization was 7 days for the non-vaccinated group and 4 for the vaccinated group. We have not observed a statistically significant increase in ischemic stroke rates due to the Bivalent mRNA Omicron-containing booster vaccine.Conclusion: We conclude that our results support that the bivalent omicron-containing vaccine mRNA booster has a protective effect in preventing and shortening hospitalization in patients with hematological neoplasms with an acceptable safety profile.Fuding: A grant from KSM- Maccabi Research and Innovation Center supported this study.Declaration of Interests: The authors have no conflict of interest.Ethics Approval: receiving approval from the institution’s ethical committee. Maccabi Healthcare Services Helsinki committee has approved the study.