Sergio A. Sánchez-Guerrero, Hematologist, Médica Sur Hospital, Mexico City, Mexico

Background: COVID-19 pandemics arrived to Mexico in March 2020, and in year 2021, a national vaccination program for adult population was implemented. Objectives: The objectives of this study were to assess the outcome of vaccinated patients with hematologic disorders compared to a control group of healthy subjects. Methods: This is a prospective study of 23 patients with various hematologic disorders and 12 healthy individuals who received a complete set of different vaccines (Pfizer, Astra-Zeneca, Moderna, Sinovac or Cansino). Assesment included: Efficacy, adverse effects, and duration of humoral immune response. Statistical analysis was calculated by Chi-square with Yate’s correction. Results: Patients’ group had a 56% female population and a median age of 68 years, whereas the control group included a 75% female population and a median age of 60 years. One patient had hypereosinophilic syndrome and a second one had antiphospholipid antibodies the other patients had several hematologic neoplasias. All the individuals in the control group developed detectable anti-SARS-Cov-2 antibodies by chemoluminiscence testing, but just 70% of patients developed such antibodies (p < 0.1). However, only 50% of patients with chronic lymphocytic leukemia and 33% with myelodysplasia had detectable antibodies (p < 0.05). Immune response decreased substantially within 6 months following vaccination. Conclusion: Patients with hematologic disorders are prone to develop a weaker immune response to SARS-CoV-2 vaccines than healthy people. In any case, this active immunization is just transient.

Keywords: COVID-19. SARS-CoV-2. Vaccines. Hematologic disorders.