Abstract P187: Comparative Analysis Of Covid-19 Vaccine Efficacy In Heart Transplant Recipients On Standardized Immunotherapy Regimens

Abstract

Background: International data on COVID-19 infection in immunosuppressed populations is limited. Heart transplant (OHT) recipients requiring immunotherapy are at risk for potentially increased complications with COVID-19 infection, including long-covid and oxidative stress during initial infection. The availability of vaccination and temporal trends in this population has not been well described. We report outcomes in immunosuppressed patients during the initial years of the COVID pandemic. Methods: All patients who underwent heart transplantation at Mayo Clinic in Florida were reviewed from March 2019 to October 2021. Patients were divided into two groups: those diagnosed with COVID-19 (based on a positive SARS-CoV-2 RT-PCR) and those not. A p value of 0.05 was considered significant using the Chi-squared test. Results: A total of 98 patients were reviewed. Of these, 49 were COVID-19-positive (CP), and 49 were negative (CN). The cohort was well matched, with a median age of 58 years (49 - 65) in both groups. 20 females in the CP group and 9 in the CN group. Diabetic status (p = .07), history of hypertension (p=.5), BMI (p=.41), GFR (p=.19), and ejection fraction (p=.29) were not significantly different between the two groups. Immunosuppression was not significantly different for CP or CN patients, with a median trough tacrolimus level of 7.68 vs. 8.70 (p = .26). The median time from transplant to CP was 384 days (237 - 677). The CN group’s median follow-up after transplant was 947 days (737 - 1191). CP hospitalization rate was 24% (5 Pfizer, 3 unvaccinated, 4 Moderna) with only 1 death. Hospitalized patients’ markers of inflammation were: IL6 19.2 (12-48), D-dimer 1408 (763 - 2227), and CRP 54 (20 - 90). The CP group was more vaccinated than the CN group (92% vs. 78%, p = .025). More CP patients received the Pfizer vaccine compared to Moderna (p = .018). Conclusion: We found that patients after OHT on similar immunotherapy regimens did not carry the same risk of contracting Covid-19 despite being vaccinated. CP patients were generally infected in the first 1.5 years after OHT. This may indicate an increased infection rate due to a weakened immune system or lack of bivalent boosters before 2022. Vaccine efficacy in this population should be evaluated in larger studies.