(585) Impact of the SarsCov2 Booster Dose on Clinical Events in Heart Transplant Patients in Galicia. INMU TC Study

PURPOSE: Heart transplant (HT) patients have a higher risk of severity after SARS-CoV-2 (COVID-19) infection than general population. Serological response to the initial vaccination regimen is lower. The clinical impact of the booster vaccination regimen in HT patients is unknown. The INMU_TC study analyze the immunogenicity after the COVID19 vaccination schedule and the clinical impact in patients with HT in Galicia. PURPOSE: : To analyze the clinical events related to COVID-19 infection after receiving the booster dose in a population of patients with CT. METHODS: Prospective observational study. HT recipients followed in the Galician Health System who had received a booster dose of COVID-19 vaccine according to the regional protocol were consecutively included. Serum anti-SARS-COV2 IgG concentration was determined between 14-30 days after the last vaccination dose. A value ≥33 BAU/ml was considered positive. COVID-19 clinical events were recorded. RESULTS: : We included 275 HT recipients, median age 64.5 years (IQR:55.1-70.7), and 21.8% female. Median time since HT was 7.4 years (IQR:2.5-14.9). Of these, 41 patients (14.9%) had COVID-19 after the booster dose, with an incidence rate of 300.6 per 1000 patient-year. Fourteen patients (34.2% of those infected) required hospital admission, and 4 died from the infection (9.8%). No significant differences were found between infected and non-infected patients after the third dose, except for renal function, more deteriorated in infected patients (creatinine 1.8±1.6 vs 1.4±0.8; p=0.008) and treatment with RAASi (12(29.3%) vs 123(52.6%); p=0.005). There were no significant differences in immunosuppression. A higher percentage of patients with infection, admission, and death had a negative serologic test. Serum concentration of antiSARSCoV2 IgG was lower in infected patients (735.8±895.0 vs 1318.1±847.9; p<0.001) and in patients requiring admission (266.9±581.8 vs 1282±862.2; p<0.001). Patients admitted to ICU and those who died had undetectable titers (<4.81 BAU/ml). CONCLUSION: HT patients with COVID-19 after the booster vaccine dose had lower serum concentration of anti-SARS-COV2 IgG, being even lower in those who presented a more unfavorable evolution. These data could suggest the importance of monitoring the response to vaccination in these patients in order to evaluate other therapeutic options.