Occurrence of Severe SARS-CoV-2 Infection in Fully Vaccinated Solid Organ Transplant Recipients

The present study presents the clinical outcome of SARS-CoV-2 disease in relation to the humoral response in fully vaccinated solid organ transplant (SOT) recipients. Our patient cohort consists of 455 SOT recipients, vaccinated with one of the 2 approved mRNA vaccines. The antibody response was measured 1 month after the second dose, and previously infected patients have been excluded. Of the 449 remaining patients, 15 (3.34%) tested positive, using SARS-CoV-2 polymerase chain reaction. Their mean age was 43.7 ±14.4 years, and median time from transplantation was 7.8 years (1.2-30.2). Eleven patients (73.3%) had been vaccinated with BNT162b2 and 4 (26.7%) with the mRNA1273 vaccine. At the time of infection 9 (60%) patients had a negative (<50 AU/mL) antibody titer, and 6 (40%) had a positive one (>50 AU/mL). Median antibody titer, 27.4± 14.0 days after the second dose, measured at 13 AU/mL (0-7480 AU/mL). Renal function did not appear to be affected by the disease. Τhe mean estimated glomerular filtration rate at diagnosis was 48 ± 15 mL/min, and when in a 29-day (1-101) median follow-up was 53.9± 20.9 mL/min. Of the 15 patients, 7 had mild symptoms and were not hospitalized, and of the remaining 8 (53.3%) who needed hospitalization 7 had severe disease and 2 of them expired. The study confirms the variable and often severe course of coronavirus 2019 infection in SOT recipients, even after their full vaccination, highlighting the need to vaccinate their close relatives and to accelerate the implementation of the booster dose of vaccine.