Due to concerns about an inadequate protective antibody response and the possibility of pathogenic global immune system activation, which might cause relapse, patients with severe aplastic anemia (SAA) frequently do not receive vaccinations against viruses. 

In 50 SAA patients who had previously received immunosuppressive therapy (IST), researchers assessed the effect of the COVID-19 immunization on hematological indices and disease status as well as the humoral and cellular responses to vaccination. Prior to and after the completion of the vaccine series, there was no discernible variation in the hemoglobin (P = 0.52), platelet count (P = 0.67), absolute lymphocyte (P = 0.42), or neutrophil (P = 0.98) counts. 

Three individuals (6%) experienced relapse following immunization or a gradual drop in counts necessitating treatment. Even in patients taking ciclosporin (10/11, 90.1%), a decrease in an in-vitro Angiotensin II Converting Enzyme (ACE2) binding and neutralization assay allowed for the detection of humoural response in 90% (28/31) of instances. Comparing the spike-specific T-cell responses between 10 control participants and 27 SAA patients indicated qualitatively comparable CD4+ Th1-dominant vaccination responses. Patients on or off ciclosporin medication at the time of immunization did not have a different response in CD4+ (P = 0.77) or CD8+ (P = 0.74) T-cell responses. 

Our findings show that genuine relapse after immunization is uncommon, and suitable cellular and humoral responses occur in SAA previously treated with IST.

Reference: onlinelibrary.wiley.com/doi/10.1111/bjh.18456