ANTIBODY RESPONSES AND SAFETY OF THE COMMERCIALLY AVAILABLE VACCINES AGAINST SARS-COV-2 VIRUS IN ALLOGRAFTED PATIENTS: REAL WORLD DATA FROM A SINGLE CENTER

Abstract

Objective: Patients (pts) who have undergone allogeneic stem cell transplantation (alloSCT) are at high-risk for life-threating complications post SARS-CoV-2 infection, and the mortality rates has been reported of approximately 30-35%. The currently available vaccines proved their effectiveness in the general population by reducing the severity of the COVID-19 infection however, scant data exist regarding the safety and efficacy of the commercially available vaccines in allografted pts. Methodology: After a median of 2,7 (0,3-6,7) ys post alloSCT, 20 pts received within a median of 42 days, 2 vaccines of either Pfizer (n=17) or combinations of Pfizer with Moderna (n=2) or AstraZeneca (n=1). Off immunosuppression without evidence of active GvHD were 14 pts, 1 was only on Cyclosporine (CSP) while 5 were on steroids plus CSP or MMF or Ibrutinib for GvHD treatment. Automated commercial chemiluminescence immunoassay (CLIA) against spike (S1/S2) protein was used for antibody responses detection. Results: During vaccination program no side effect grade ≥3 (including allergy, thrombosis, heart dysfunction or laboratory abnormalities) was reported. The commonest complains were fatigue (20%), bony pain (10%) and fever <38.5 oC (10%). Satisfactory antibody responses were observed in 66% and 95% of pts after the 1st and 2nd dose respectively. Importantly, active GvHD and intensive immunosuppression, did not negatively affect the antibody responses. None of the vaccinated pts developed COVID infection Conclusion: Our retrospective study although with small number of patients and with short term follow-up, in agreement with others, confirms that the current commercially available vaccines against SARS-CoV-2 are safe and highly effective in producing effective humoral responses in allografted patients. Prospective studies with longer follow-up are needed to elucidate the proper timing and the number of necessary doses for a safe and effective approach in preventing severe COVID-19 infection