Serologic Status According Severe Acute Respiratory Syndrome Coronavirus 2 in Patients After Orthotopic Heart Transplantation

BACKGROUND: The SARS-CoV-2 pandemic is ongoing. In this context, patients after organ transplantation are especially endangered because of their increased susceptibility to infections. Real effectiveness of vaccinations against SARS-CoV-2 and exposition to the virus in populations after organ transplantation is still being assessed. METHODS: We investigated 371 adult patients (82.7% men, 17.3% women), aged 54 ± 14 years, with a median time from transplantation of 1296 days (interquartile range, 473-400 days) after orthotopic heart transplantation consecutively admitted to the transplant center between February and September 2021. SARS-CoV-2 spike protein antibodies were assessed quantitatively by Elecsys Anti-SARS-CoV-2 S. Data according to past COVID-19 infection and vaccination were compared with the test results. Among the whole group, 59 patients were unvaccinated and had no past COVID-19 infection, 200 patients had a full course of vaccination (2 doses) with an mRNA vaccine, 1 patient had received a viral vector vaccine, 11 patients had had a single dose of an mRNA vaccine, and 99 patients had previously had a COVID-19 infection. Median time from vaccination to antibody assessment was 54 days (interquartile range, 30-76 days). AIM: The aim of this study was to determine exposure to the virus among patients after heart transplantation before vaccination and humoral response to the vaccination and assess the role of antispike antibodies in the prevention of infection. RESULTS: After vaccination, 22.3% had no antibodies (45 patients), 47.3% had titers between 0.8 U/mL [0.82 binding antibody units (BAU)/mL] and 250 U/mL (257.25 BAU/mL; 95 patients), and 30.2% had titers above 250 U/mL (257.25 BAU/mL; 61 patients). After a single dose of vaccine, 63% patients had no antibodies. In the group of unvaccinated patients, 3 patients had titers above 250 U/mL (257.25 BAU/mL; 5.1%) and 12 patients had titers up to 250 U/mL (257.25 BAU/mL; 20.3%). In patients after COVID-19 infection, only 2% did not show antispike antibodies, and in 61.4% the titers were above 250 U/mL (257.25 BAU/mL). In the group of patients infected after the full course of vaccination (4 patients after a single dose and 2 after 2 doses), none of the patients developed antibodies after vaccination. Up to the end of September 2021, none of the patients with antibodies against SARS-CoV-2 developed COVID-19. CONCLUSIONS: The presence of spike protein antibodies may be a relevant marker of effective vaccination. In patients after heart transplantation, exposure to SARS-CoV-2 is high.