Humoral response to heterologous prime‐booster vaccination in heart transplant recipients aged 18–70 years primed with a viral vector SARS‐CoV‐2 vaccine

Abstract

Solid organ transplant recipients have demonstrated a blunted immune response to standard 2‐dose vaccination against SARS‐CoV‐2. This study sought to determine the humoral response to heterologous booster vaccination (viral vector vaccine dose 1 and 2 + mRNA booster). Heart transplant recipients, aged 18 to 70 years of age who initially received two doses of the viral vector ChAdOx1 nCoV‐19 vaccine followed by a BNT162b2 mRNA booster were recruited. A detectable antibody response in the absence of prior SARS‐CoV‐2 was the primary outcome measured. This was defined as an anti‐spike titre of ≥0.8 U/mL on the Elecsys anti‐SARS‐CoV‐2 S immunoassay. A total of 80 heart transplant patients (mean age 49 ± 13 years, 28% female) were included. Blood samples were drawn at a median of 30 (IQR 28‐33) days after the BNT162b2 mRNA booster. The frequency of a detectable antibody response increased from 37.5% ( n = 30) after dose 2 to 56% ( n = 45) post dose 3 ( p < 0.001). A non‐detectable antibody response was significantly more common in recipients with a shorter time interval from transplantation ( p < 0.001), lower likelihood of cardiac allograft vasculopathy (p = 0.003) and in those prescribed a triple versus dual immunosuppressant regime ( p = 0.009) and a tacrolimus versus cyclosporine basedregimen ( p = 0.007). Despite heterologous prime‐booster vaccination 44% of this vulnerable population ultimately continue to have no detectable antibodies.

Measures to Increase Immunogenicity of SARS-CoV-2 Vaccines in Solid Organ Transplant Recipients: A Narrative Review

“…A study in Thailand showed that KTRs who received two doses of this vaccine had a response rate of 33.33% [ 90 ]. A Mexican study of liver transplant recipients showed an antibody positivity of 89.2% with BNT162b2 (Pfizer-BioNTech), 60% with ChAdOx1 nCOV-19 (Oxford-AstraZeneca), 76.9% with CoronaVac (Sinovac, Life Sciences, Beijing, China), 55.6% Ad5-nCov (Cansino, Biologics, Tianjin, China), and 68.2% Gam-COVID-Vac (Sputnik V, Gamaleya National Centre of Epidemiology and Microbiology, Russia), but did not specify the dosing of each vaccine [ 91 ]. Another study of HTRs showed an antibody response in 37.5% of patients after two doses of ChAdOx1 and 56% after the third dose with BNT162b2 (Pfizer-BNT) [ 92 ].…”