Donor-directed immunologic safety of COVID-19 vaccination in renal transplant recipients

Therapeutic Myths in Solid Organ Transplantation Infectious Diseases

Infection management in solid organ transplantation poses unique challenges, with a diverse array of potential pathogens and associated antimicrobial therapies. With limited high-quality randomized clinical trials to direct optimal care, therapeutic "myths" may propagate and contribute to suboptimal or excessive antimicrobial use. We discuss 6 therapeutic myths with particular relevance to solid organ transplantation and provide recommendations for infectious diseases clinicians involved in the care of this high-risk population.

Development of donor specific antibodies after SARS-CoV-2 vaccination: What do we know so far?

Vaccination against Coronavirus disease-19 (COVID-19) was pivotal to limit spread, morbidity and mortality. Our aim is to find out whether vaccines against COVID-19 lead to an immunological response stimulating the production of de novo donor specific antibodies (DSAs) or increase in mean fluorescence intensity (MFI) of pre-existing DSAs in kidney transplant recipients (KTRs). This study involved a detailed literature search through December 2^nd, 2023 using PubMed as the primary database. The search strategy incorporated a combination of relevant Medical Subject Headings terms and keywords: "COVID-19", "SARS-CoV-2 Vaccination", "Kidney, Renal Transplant", and "Donor specific antibodies". The results from related studies were collated and analyzed. A total of 6 studies were identified, encompassing 460 KTRs vaccinated against COVID-19. Immunological responses were detected in 8 KTRs of which 5 had increased MFIs, 1 had de novo DSA, and 2 were categorized as either having de novo DSA or increased MFI. There were 48 KTRs with pre-existing DSAs prior to vaccination, but one study (Massa et al) did not report whether pre-existing DSAs were associated with post vaccination outcomes. Of the remaining 5 studies, 35 KTRs with pre-existing DSAs were identified of which 7 KTRs (20%) developed de novo DSAs or increased MFIs. Overall, no immunological response was detected in 452 (98.3%) KTRs. Our study affirms prior reports that COVID-19 vaccination is safe for KTRs, especially if there are no pre-existing DSAs. However, if KTRs have pre-existing DSAs, then an increased immunological risk may be present. These findings need to be taken cautiously as they are based on a limited number of patients so further studies are still needed for confirmation.

Safety and infectious outcomes in pediatric kidney transplant recipients after COVID-19 vaccination: A pediatric nephrology research consortium study

BACKGROUND

Adult kidney transplant recipients (KTRs) fully vaccinated against COVID-19 have substantial morbidity and mortality related to SARS-CoV-2 infection compared with the general population. However, little is known regarding the safety and efficacy of the COVID-19 vaccination series in pediatric KTRs.

METHODS

A multicenter, retrospective observational study was performed across nine pediatric transplantation centers. Eligible KTRs fully vaccinated against COVID-19 were enrolled and data were collected pertaining to SARS-CoV-2 infection incidence and severity, graft outcomes and post-vaccination safety profile, as well as overall patient survival.

RESULTS

A total of 247 patients were included in this investigation with a median age at transplantation of 11 years (IQR 5-15). SARS-CoV-2 infection was observed in 30/110 (27.27%) of fully vaccinated patients, tested post-transplant, within the defined follow-up period. Of these patients, 6/30 (18.18%) required hospitalization and 3/30 (12.12%) required reduction in immunosuppression, with no reported deaths. De novo donor-specific antibodies (DSAs) were found in 8/86 (9.30%) of DSA-tested patients with two experiencing rejection and subsequent graft loss. The overall incidence of rejection and graft loss among the total cohort was 11/247 (4.45%) and 6/247 (3.64%), respectively. A 100% patient survival was observed.

CONCLUSIONS

Observationally, infectious outcomes of SARS-CoV-2 in fully vaccinated pediatric KTRs are excellent, with a low incidence of infection requiring hospitalization and no associated deaths. Though de novo DSAs were observed, there was minimal graft rejection and graft loss reported in the total cohort.

Impact of SARS-CoV-2 Infection on Humoral and Cellular Immunity in a Cohort of Vaccinated Solid Organ Transplant Recipients

The aim of the present study was to determine humoral and T-cell responses after four doses of mRNA-1273 vaccine in solid organ transplant (SOT) recipients, and to study predictors of immunogenicity, including the role of previous SARS-CoV-2 infection in immunity. Secondarily, safety was also assessed. Liver, heart, and kidney transplant recipients eligible for SARS-CoV-2 vaccination from three different institutions in Barcelona, Spain were included. IgM/IgG antibodies and T cell ELISpot against the S protein four weeks after receiving four consecutive booster doses of the vaccine were analyzed. One hundred and forty-three SOT recipients were included (41% liver, 38% heart, and 21% kidney). The median time from transplantation to vaccination was 6.6 years (SD 7.4). In total, 93% of the patients developed SARS-CoV-2 IgM/IgG antibodies and 94% S-ELISpot positivity. In total, 97% of recipients developed either humoral or cellular response (100% of liver recipients, 95% of heart recipients, and 88% of kidney recipients). Hypogammaglobulinemia was associated with the absence of SARS-CoV-2 IgG/IgM antibodies and S-ELISpot reactivity after vaccination, whereas past symptomatic SARS-CoV-2 infection was associated with SARS-CoV-2 IgG/IgM antibodies and S-ELISpot reactivity. Local and systemic side effects were generally mild or moderate, and no recipients experienced the development of de novo DSA or graft dysfunction following vaccination.

COVID-19 infection and vaccination rarely impact HLA antibody profile in waitlisted renal transplant Candidates- a multicenter cohort

Although rare, infection and vaccination can result in antibodies to human leukocyte antigens (HLA). We analyzed the effect of SARS-CoV-2 infection or vaccination on HLA antibodies in waitlisted renal transplant candidates. Specificities were collected and adjudicated if the calculated panel reactive antibodies (cPRA) changed after exposure. Of 409 patients, 285 (69.7 %) had an initial cPRA of 0 %, and 56 (13.7 %) had an initial cPRA > 80 %. The cPRA changed in 26 patients (6.4 %), 16 (3.9 %) increased, and 10 (2.4 %) decreased. Based on cPRA adjudication, cPRA differences generally resulted from a small number of specificities with subtle fluctuations around the borderline of the participating centers' cutoff for unacceptable antigen listing. All five COVID recovered patients with an increased cPRA were female (p = 0.02). In summary, exposure to this virus or vaccine does not increase HLA antibody specificities and their MFI in approximately 99 % of cases and 97 % of sensitized patients. These results have implications for virtual crossmatching at the time of organ offer after SARS-CoV-2 infection or vaccination, and these events of unclear clinical significance should not influence vaccination programs.