RESUMEN
This study investigates COVID-19 outcomes and immune response in chronic myeloid leukemia (CML) patients post-SARS-CoV-2 vaccination, comparing effectiveness of various vaccine options. Data from 118 CML patients (85 in Brazil, 33 in the US) showed similar infection rates prior (14% Brazil, 9.1% US) and post-vaccination (24.7% vs. 27.3%, respectively). In Brazil, AstraZeneca and CoronaVac were the most commonly used vaccine brands, while in the US, Moderna and Pfizer-BioNTech vaccines dominated. Despite lower seroconversion in the Brazilian cohort, all five vaccine brands analyzed prevented severe COVID-19. Patients who received mRNA and recombinant viral vector vaccines (HR: 2.20; 95%CI 1.07-4.51; p < .031) and those that had achieved at least major molecular response (HR: 1.51; 95% CI 1.01-3.31; p < .0001) showed higher seroconversion rates. Our findings suggest that CML patients can generate antibody responses regardless of the vaccine brand, thereby mitigating severe COVID-19. This effect is more pronounced in patients with well-controlled disease.