(1204) Increased Antibody Response to a Five-Dose Regime of Covid-19 Vaccine in Lung Transplant Patients

There is an increased mortality risk in COVID-19 infected lung transplant (LTx) patients . SARS-CoV-2-specific IgG antibody response after vaccination is impaired in LTx patient, most likely due to intensive immunosuppressive therapy. Whether a five-dose regime of COVID-19 vaccines in LTx patients results in an increased antibody response is not known. Therefore we studied the serological IgG antibody response, and risk factors for non-response after a five-dose regime of COVID-19 vaccines. In this single center retrospective cohort study, IgG antibody response were assessed after 2-5 mRNA-based COVID-19-vaccine in all vaccinated LTx patients between February 2021 and September 2022. Vaccine response was defined as an IgG level above 300 BAU/ml. Antibody responses due to COVID-19 infection were excluded from the analysis. Mann-Whitney U-test and chi-squared test were used to compare clinical parameters and outcomes between responders and non-responders. Of 294 LTx patients IgG antibody responses after 2-5 vaccinations were analyzed. IgG antibody response to COVID-19 vaccination was found in 15% of the LTx patients after 2 vaccines, in 38% after 3 vaccines, in 49% after 4 vaccines and in 59% after 5 vaccines. 246/492 (50%) of the vaccinated individuals tested positive for SARS-CoV-2 during the study period. The COVID-19 related mortality was 1,4 % (4/294), all 4 patients were non-responders. Factors associated with COVID-19 vaccine response are shown in table 1. For the total group COVID-19 related hospitalization was not significantly higher in non-responders (p = 0.208). Risk factors associated with non-response to COVID-19 vaccines were renal impairment, defined as EGFR < 60 ml/min/1,73 m2 (p = 0.007) and older age (p = 0.009). A five-dose regime of COVID-19 vaccines in LTx patients increases the IgG antibody levels and results in a vaccine response in 59% of the LTx population. Therefore, continuing to vaccinate LTx patients without a response seems to be beneficial.