AIMS: To evaluate antibody response to mRNA vaccine, identify subgroups with poor response and to determine long-term antibody durability in hematological patients. MATERIALS AND METHODS: We have vaccinated 292 patients with all hematological malignancies with a third dose of mRNA COMIRNATY vaccine with a 12-month follow-up period in our center in Ostrava, Czech Republic. RESULTS: Antibody response for the whole cohort exceeded 74% through the whole 12-month follow-up. Lowest seroconversion was observed in CLL cohort (20/41, 48.8%), patients who received anti-CD20 therapy < 6 months before vaccination (8/30, 26.7%) and BTK inhibitors (3/6, 50.0%). On the contrary, patients with chronic myeloproliferative neoplasms and acute leukemia performed comparably with healthy population (33/33; 100% and 12/13; 92.3%, respectively). We have seen better results if the time interval between anti-CD20 therapy and additional vaccine dose was longer than 6 months (5/8 patients achieved seroconversion on 4th booster dose after previous failure). Also, 36 patients received a 4th dose of vaccine as a booster with measurable increase in protective antibodies in 50% (18/36). CONCLUSIONS: Additional doses show promise for a well-timed revaccination even in poor responders. To our knowledge, no study comparable to our work in terms of follow-up length, vaccine consistency or variety of hematological malignancies and/or treatment has been reported yet. Our findings shed more light on long-term antibody response to mRNA vaccines against SARS-CoV-2 in patients with hematological cancer and bring important data for the evaluation of possible vaccine failure and scheduling of subsequent doses.

• Keywords
• COVID‐19, Cancer, Leukemia, Lymphoma, Myeloma, Vaccination,
• MeSH
• Time Factors MeSH
• COVID-19 * prevention & control   immunology   MeSH
• Adult MeSH
• Hematologic Neoplasms * immunology   therapy   MeSH
• Middle Aged MeSH
• Humans MeSH
• mRNA Vaccines MeSH
• Follow-Up Studies MeSH
• Antibodies, Viral * blood   immunology   MeSH
• SARS-CoV-2 * immunology   MeSH
• Immunization, Secondary * MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• COVID-19 Vaccines * immunology   administration & dosage   MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic MeSH
• Names of Substances
• mRNA Vaccines MeSH
• Antibodies, Viral * MeSH
• COVID-19 Vaccines * MeSH