Transplant patients are at an elevated risk for infections. Therefore, infection prevention plays a pivotal role in their care. Two different approaches were chosen to determine their vaccination status and motivation. The vaccination rate was determined by analyzing the patients' vaccination cards based on German vaccination recommendations. The vaccinations were categorized into standard, indicated, and risk-dependent vaccinations. The vaccination motivation was determined through a semi-structured interview using a self-developed questionnaire as an interview guide. Both parts were analyzed separately. A total of 126 patients were included in the study. In 115 (91.3%) patients, vaccination cards were available, 64.3% had complete standard and 0.9% indicated vaccinations. In the risk-dependent vaccinations category, 49.6% of participants had at least one of the additional vaccinations. The vaccination rate against hepatitis B was significantly higher in kidney than in liver transplant recipients (88.1% vs. 55.4%, Χ2 = 13.7, p < 0.001, n = 107). Vaccination confidence correlated significantly with willingness to vaccinate (r = 0.362, p < 0.001, n = 123). In conclusion, only a few transplant patients have complete vaccination protection. Further patient education is needed to increase patients' confidence in vaccinations and to motivate them.

Central nervous system (CNS) infections in kidney transplant recipients (KTRs) remain poorly characterized, with current evidence largely derived from isolated case reports over the past two decades. This multicenter study aims to systematically delineate the epidemiology, clinical profiles, and outcomes of CNS infections in a large KTR cohort.

We conducted a retrospective analysis of 3,602 KTRs across three transplant centers in China (May 2004-July 2024). CNS infections were defined by: 1) neurological symptoms/signs, and 2) microbiological confirmation via cerebrospinal fluid (CSF) analysis, including metagenomic next-generation sequencing (mNGS) and routine microbiologic testing (bacterial and fungal cultures).

CNS infections were diagnosed in 0.53% of KTRs (19/3602), with symptom onset occurring 2-121 months post-transplantation. Etiologies included bacterial (47%, 9/19), viral (32%, 6/19), and fungal (21%, 4/19) pathogens. Notably, 79% of cases (15/19) were exclusively identified by mNGS, whereas conventional cultures failed detection. Presenting symptoms included headache (79%) and altered mental status (42%). Mortality reached 42% (8/19) within 9-22 days of diagnosis; among survivors, 73% (8/11) exhibited neurological sequelae.

CNS infections in KTRs are rare but characterized by rapid progression and high fatality rate. While the risk of CNS infections persists throughout the post-transplant period, 1-6 months after transplantation is a higher-incidence period of CNS infections. KTRs with neurological symptoms (particularly headache and elevated CSF pressure) should undergo CSF mNGS which is critical in diagnosing such infections.

Immunocompromised individuals, hemato-oncologic diseases or post-transplantation included, are, due to impaired immune response, at increased risk for severe and prolonged COVID-19. Observational Studies showed that SARS-CoV-2 RNAemia has been associated with poorer prognosis and higher disease severity.

The aim of this study was to investigate the occurrence of RNAemia and its association with anti-SARS-CoV-2 antibodies in immunocompromised COVID-19 patients. Risk factors for RNAemia were included in the analysis.

A retrospective study was conducted in 55 immunocompromised patients tested positive for SARS-CoV-2, who received treatment with monoclonal antibodies (mAb) between December 2021 and March 2022. Serological and virological tests were performed before mAb administration and clinical data were collected from electronic health records.

Out of 55 patients, 35 % showed SARS-CoV-2 RNAemia. RNAemia was present in the 2 reported fatal cases. It was associated with negative testing for anti-receptor binding domain (RBD) IgG, anti-S2 domain of spike protein (S2) IgG and a lower leukocyte count. No association was found between previous COVID-19 vaccinations and the risk for RNAemia in immunocompromised patients.

The study underscores the importance of humoral response in controlling SARS-CoV-2 replication. RNAemia can serve as a potential biomarker for disease severity in immunocompromised individuals. Therefore, it should be considered in clinical settings for appropriate therapy decisions. Further research is needed to evaluate the pathophysiology and implications of RNAemia in immunodeficient patients with COVID-19.

Patients with cirrhosis and liver transplant recipients are at increased risk of infections. Malnutrition, multiple hospital admissions, immune dysfunction related to cirrhosis, and immunosuppressive agents used for liver transplantation predispose the recipient to various life-threatening infections. Some of these infections are preventable with vaccines. With the COVID-19 pandemic, there has been an accelerated research in vaccination technology and platforms, which in turn may also improve awareness of physicians regarding this healthy and often ignored aspect of management of patients with cirrhosis and transplant recipients. The organ transplant candidates should complete the recommended vaccination schedule as early as possible (especially patients with compensated cirrhosis) or at least during their pretransplant work-up so as to prevent or reduce the severity of various infections.

The global pandemic caused by the highly contagious SARS-CoV-2 virus led to the emergency approval of COVID-19 vaccines to reduce rising morbidity and mortality. However, limited research exists on evaluating the impact of these vaccines on immunocompromised individuals, such as recipients of living donor liver transplantation, highlighting the need for further studies to better understand their effectiveness in this specific population.

From June 2021, we followed up on the effectiveness of the vaccine for patients taking immunosuppressive drugs after living-donor liver transplantation (LDLT). A total of 105 immunocompromised individuals participated, of which 50 patients with hepatitis B were taking antiviral drugs. Patients were assessed to analyze how the combination of immunosuppressive and antiviral drugs affected the efficacy of the BNT162b2, mRNA-1273, and ChAdOx1 nCoV-19 COVID-19 vaccines.

Before and after the vaccinations, patients were monitored to establish differences between immunosuppressed patients and those additionally taking antiviral drugs. In immunocompromised patients taking antiviral drugs for hepatitis B, we confirmed that the effect of the COVID-19 vaccine was reduced when compared to immunocompromised patients. Interestingly, 23 patients (11 without and 12 additionally with hepatitis B drug administration) encountered breakthrough infections, and although there was a minor discrepancy in vaccine efficacy among the patients taking antiviral drugs for hepatitis B, it did not reach statistical significance.

Additional COVID-19 vaccination is recommended for patients taking immunosuppressive drugs and hepatitis B antiviral drugs after LDLT.

Solid organ transplant (SOT) candidates and recipients are a fragile population, in which the presence of a pre-transplant disease leading to organ insufficiency and the post-transplant immunosuppressive treatment expose them to an increased risk of infectious diseases. The best intervention to guarantee efficient prevention of infections, with optimal cost-benefit ratio, is represented by vaccination programs; however, the response to vaccines needs that the immune system maintains a good function. This is even more relevant at paediatric age, when specific immunological conditions make transplant candidates and recipients particularly vulnerable. Paediatric patients may be naïve to most infections and may have incomplete immunization status at the time of transplant listing due to their age. Moreover, the unaccomplished development of a mature immune system and the immunosuppressive regimen adopted after transplant might affect the efficacy of post-transplant vaccinations. Therefore, every effort should be made to obtain the widest vaccination coverage before the transplantation, whenever possible. This review reports the most relevant literature, providing information on the current approach to the vaccinations in paediatric SOT candidates and recipients.

Observational studies of coronavirus disease 2019 (COVID-19) among transplant candidates and recipients remain important as immunocompromised patients formed a very small proportion of patients included in COVID-19 trials and large database analyses. We discuss methods that have been used in such analyses to evaluate the impact of vaccination on the risk of symptomatic COVID-19 in such patients and on the probability of developing post-acute sequelae of severe acute respiratory syndrome coronavirus 2 after the onset of infection. We also propose future directions for research and discuss the methods that will be useful to conduct such investigations. The study design and analytical issues that we consider have the potential to be helpful not only for COVID-19 research but also for other infections as well.

Heart transplantation (HT) is the definitive treatment for eligible patients with end-stage heart disease. A major complication of HT is allograft rejection which can lead to graft dysfunction and death. The guiding principle of chronic immunosuppression therapy is to prevent rejection of the transplanted organ while avoiding oversuppression of the immune system, which can cause opportunistic infections and malignancy. The purpose of this review is to describe immunosuppressive management of the HT recipient-including agent-specific pharmacology and pharmacokinetics, outcomes data, adverse effects, clinical considerations, and recent guideline updates. We will also provide recommendations for medical prophylaxis of immunosuppressed patients based on the most recent clinical guidelines. Additionally, we highlight the importance of medical therapy adherence and the effect of social determinants of health on the long-term management of HT. HT recipients are a complex and high-risk population. The objective of this review is to describe basic pharmacotherapy in HT and implications for nurses and pharmacists.

Torque Teno Virus (TTV), first discovered in 1997, is a non-pathogenic, highly prevalent virus with a notable presence in the human virome. TTV has garnered attention as a potential indicator of immunocompetence in recipients of solid organ transplants. In this review, we discuss the role of TTV as a potential marker for immunosuppression optimization, prediction of graft rejection, and as an indicator of opportunistic infections. We discuss TTV's behavior over the course of time after transplantation, TTV's implications in different immunosuppressive regimens, and potential utility in vaccinations. The review synthetizes findings from various studies depicting its potential clinical utility for future personalized patient care.

(1) Background: Vulnerable populations including transplant recipients are jeopardised by COVID-19. Herein, we report on B and T cell responses among liver and kidney organ recipients at our centre. (2) Methods: 23 liver and 45 kidney (14 thereof combined kidney/pancreas) transplanted patients were vaccinated with two doses of BNT162b2 followed by a booster dose of mRNA-1273 in 28 non-responders 4 months thereafter. Anti-SARS-CoV-2-Ig was measured by specific ELISA and virus neutralisation assay; T cell responses were measured by a spike protein-specific IFN-γ release assay. (3) Results: Compared to controls, B and T cell responses were weak in transplant recipients, particularly in those without prior exposure to SARS-CoV-2. Within this group, only 15% after the first and 58.3% after the second vaccination achieved seroconversion. A total of 14 out of 28 vaccination non-responders achieved a seroconversion after a third dose. Vaccination side effects were more frequent in healthy controls. The use of mycophenolate was associated with reduced anti-SARS-CoV-2-Ig production. (4) Conclusions: Our data confirm that vaccination responses are insufficient after standard vaccination in liver and kidney transplant recipients and are affected to a variable degree by specific immunosuppressants, particularly mycophenolate. Monitoring vaccination success and re-vaccinating those who are unresponsive seems prudent to achieve sufficient titres. Overall, prospective large-scale, multinational, multicentre studies or high-quality meta-analyses will be needed to generate personalised vaccination strategies in order to achieve protective immunity in high-risk, hard-to-immunize populations.

Background and Objectives: Underpowered immune response to vaccines against SARS-CoV-2 was observed in solid organ transplant (SOT) recipients. A novel combination of monoclonal antibodies tixagevimab-cilgavimab (TGM/CGM) received authorization as pre-exposure prophylaxis (PrEP) in those with reduced response to vaccine. We aimed to evaluate the response rate to COVID-19 vaccination in kidney transplant (KT), compared to liver transplant (LT) recipients, and the efficacy and safety of PrEP with TGM/CGM. Material and Methods: Between March and November 2022, adult KT and LT recipients who had completed the vaccination schedule (3 doses) were tested for anti-SARS-CoV-2 antibodies titer. SOT recipients with anti-SARS-CoV-2 titer ≥ 100 IU/mL were considered protected against infection, while those with titer < 100 UI/mL were defined non-protected. Patients with inadequate response were invited to PrEP. Results: In total, 306 patients were enrolled [KT:197 (64.4%), LT:109 (35.6%)]. After the complete scheme of vaccination, 246 (80.3%) patients developed a protective titer, while 60 (19.6%) did not have a protective titer. KT recipients had a lower rate of protective anti-COVID-19 titer compared to LT patients [149 (75.6%) vs. 97 (89.0%), p = 0.004]. Recipients with non-protective anti-COVID-19 titer received mainly tacrolimus-based regimen associated with mycophenolate mofetil (MMF) (70%) e steroids (46.7%) as maintenance immunosuppression, while those treated with everolimus were associated with higher protective titer. Of 35 (58.3%) patients who received PrEP, within 12 months, 6 (17.1%) (all KT) developed pauci-symptomatic COVID-19 disease, while 15/25 (60%) of non-responders, who did not receive the prophylaxis, developed COVID-19 disease. After PrEP, hospitalization rate was lower (2.8% vs. 16%), and no adverse events, neither graft loss nor rejection, were observed. Conclusions: Despite complete COVID-19 vaccination, SOT recipients might be not protected from the SARS-CoV-2 infection, especially after KT. In non-protected SOT patients, the subsequent pre-exposure prophylaxis with combination of monoclonal antibodies (TGM/CGM) might be an efficacy and safe strategy to prevent COVID-19 severe disease and hospitalization.

Solid organ transplantation (SOT) candidates and recipients are at increased risk for morbidity and mortality from vaccine-preventable infections. Children are at particular risk given that they may not have completed their primary immunization series at time of transplant or have acquired natural immunity to pathogens from community exposures. Multiple society guidelines exist for vaccination of SOT candidate and recipients, although challenges remain given limited safety and efficacy data available for pediatric SOT recipients, particularly for live-vaccines. After transplant, individual patient nuances regarding exposure risks and net state of immunosuppression will impact timing of immunizations. The purpose of this review is to provide readers with a concise, practical, expert-opinion on the approach to vaccinating the SOT candidate and recipient and to supplement existing guidelines. In addition, pediatric-specific knowledge gaps in the field and future research priorities will be highlighted.

Solid organ transplant (SOT) recipients are at high risk for complications from coronavirus disease 2019 (COVID-19). SOT recipients mount lower immunological responses to vaccines than general population and are at high risk for breakthrough COVID-19 infections. Passive immunotherapy in the form of anti-Spike monoclonal antibodies (MoAbs) may be an alternative for the prophylaxis and treatment of COVID-19 in these patients. SARS-CoV-2 has evolved by accumulating resistance mutations that have escaped the neutralizing action of most MoAbs. However, MoAbs directed at more conserved epitopes and that maintain effector functions could maintain efficacy in the treatment of these patients. According to published data, SOT recipients with low anti-spike antibody responses to vaccination could benefit from the use of MoAbs in pre-exposure prophylaxis, in the treatment of COVID-19 mild to moderate and severe COVID-19 with less than 15 days of symptom duration and low oxygen requirements. Combination therapy could be more effective than monotherapy for the treatment of mild-to-moderate SARS-CoV-2 infection.

The mRNA-based vaccine was released as a COVID-19 prophylactic; however, its efficacy in organ transplant recipients is unknown. This study aimed to clarify this in liver transplant recipients.

Herein, liver transplant recipients from two hospitals who received vaccines were included. Immunoglobulin-G antibodies against the spike and nucleocapsid proteins were measured chronologically after the second, third, and fourth vaccine doses.

Antibody levels in 125 liver transplant recipients and 20 healthy volunteers were analyzed. The median age at transplant was 35 (interquartile range 1, 53) years, and the period between transplant and the first dose was 15.2 ± 7.7 years. After the second and third doses, 89.1% and 100% of recipients displayed a positive humoral response, respectively. Anti-spike antibodies after the second dose were significantly reduced at 3 and 6 months, compared to that at 1 month (26.0 [5.4, 59.5], 14.7 [6.5, 31.4] vs. 59.7 [18.3, 164.0] AU/mL, respectively, p < 0.0001). However, a booster vaccine significantly elevated anti-spike antibodies in LT recipients (p < 0.0001) as well as in healthy controls (p < 0.0001). Additionally, the decay rate was comparable between the transplant recipients and controls (2.1 [0.8, 4.5] vs. 2.7 [1.1, 4.1] AU/mL/day, p = 0.9359). Only 4.0% of vaccinated transplant recipients were positive for anti-nucleocapsid antibodies.

Liver transplant recipients can acquire immunity similar to that of healthy people through vaccination against SARS-CoV-2. The antibody decay rate is the same, and booster vaccinations should be administered similarly to that in healthy individuals.

To estimate the prevalence of patients with an immunocompromising condition at risk for COVID-19, estimate COVID-19 prevalence rate (PR) and incidence rate (IR) by immunocompromising condition, and describe COVID-19-related healthcare resource utilization (HCRU) and costs.

Using the Healthcare Integrated Research Database (HIRD), patients with ≥1 claim for an immunocompromising condition of interest or ≥2 claims for an immunosuppressive (IS) treatment and COVID-19 diagnosis during the infection period (1 April 2020-31 March 2022) and had ≥12 months baseline data were included. Cohorts (other than the composite cohort) were not mutually exclusive and were defined by each immunocompromising condition. Analyses were descriptive in nature.

Of the 16,873,161 patients in the source population, 2.7% (n = 458,049) were immunocompromised (IC). The COVID-19 IR for the composite IC cohort during the study period was 101.3 per 1000 person-years and the PR was 13.5%. The highest IR (195.0 per 1000 person-years) and PR (20.1%) were seen in the end-stage renal disease (ESRD) cohort; the lowest IR (68.3 per 1000 person-years) and PR (9.4%) were seen in the hematologic or solid tumor malignancy cohort. Mean costs for hospitalizations associated with the first COVID-19 diagnosis were estimated at nearly $1 billion (2021 United States dollars [USD]) for 14,516 IC patients, with a mean cost of $64,029 per patient.

Immunocompromised populations appear to be at substantial risk of severe COVID-19 outcomes, leading to increased costs and HCRU. Effective prophylactic options are still needed for these high-risk populations as the COVID-19 landscape evolves.

Donor-derived transmission of infections is a rare complication of kidney transplant. Hepatitis A virus (HAV) is a common cause of acute viral hepatitis worldwide, but donor-derived transmission to organ recipients has been reported in the literature only twice previously. The timeline for HAV incubation and clearance in transplant recipients is not well understood.

In 2018, 2 kidneys and a liver were procured from a deceased donor resident of Kentucky, one of many states that was experiencing an HAV outbreak associated with person-to-person transmission through close contact, primarily among people who reported drug use. Both kidney recipients, residents of Virginia, subsequently developed acute HAV infections. We report the results of an investigation to determine the source of transmission and describe the clinical course of HAV infection in the infected kidney recipients.

The liver recipient had evidence of immunity to HAV and did not become infected. The donor and both kidney recipients were found to have a genetically identical strain of HAV using a next-generation sequencing-based cyber molecular assay (Global Hepatitis Outbreak Surveillance Technology), confirming donor-derived HAV infections in kidney recipients. At least 1 kidney recipient experienced delayed development of detectable hepatitis A anti-IgM antibodies. By 383 and 198 d posttransplant, HAV RNA was no longer detectable in stool specimens from the left and right kidney recipients, respectively.

Adherence to current guidance for hepatitis A vaccination may prevent future morbidity due to HAV among organ recipients. http://links.lww.com/TXD/A548.

SARS-CoV-2 vaccination is the standard of care for the prevention of COVID-19 disease. Although vaccination triggers both humoral and cellular immune response, COVID-19 vaccination efficacy is currently evaluated by measuring antibodies only, whereas adaptative cellular immunity is unexplored. Our aim is to test humoral and cell-mediated response after three doses of BNT162b vaccine in two cohorts of fragile patients: Common Variable Immunodeficiency (CVID) patients and Kidney Transplant Recipients (KTR) patients compared to healthy donors. We enrolled 10 healthy controls (HCs), 19 CVID patients and 17 KTR patients. HC BNT162b third dose had successfully mounted humoral immune response. A positive correlation between Anti-Spike Trimeric IgG concentration and neutralizing antibody titer was also observed. CVID and KTR groups showed a lower humoral immune response compared to HCs. IFN-γ release induced by epitopes of the Spike protein in stimulated CD4+ and CD8+ T cells was similar among vaccinated HC, CVID and KTR. Patients vaccinated and infected showed a more efficient humoral and cell-mediated response compared to only vaccinated patients. In conclusion, CVID and KTR patients had an efficient cell-mediated but not humoral response to SARS-CoV-2 vaccine, suggesting that the evaluation of T cell responses could be a more sensitive marker of immunization in these subjects.

Background and Objectives: Solid organ transplant (SOT) recipients have a higher risk of suffering from severe Coronavirus (COVID-19) compared to the general population. Studies have shown impaired immunogenicity of mRNA vaccines in this high-risk population; thus, SOT recipients have been prioritized globally for primary and booster doses. Materials and Methods: We analyzed 144 SOT recipients who had previously received two doses of BNT162b2 or mRNA1273 vaccine, and who were subsequently vaccinated with a booster dose of the mRNA1273 vaccine. Humoral and cellular immune responses were measured 1 and 3 months after the second dose, and 1 month after the third dose. Results: One month after the second dose, 33.6% (45/134) of patients displayed a positive antibody response with a median (25th, 75th) antibody titer of 9 (7, 161) AU/mL. Three months after the second dose, 41.8% (56/134) tested positive with a median (25th, 75th) antibody titer of 18 (7, 251) AU/mL. After the booster dose, the seropositivity rate increased to 69.4% (93/134), with a median (25th, 75th) titer of 966 (10, 8027) AU/mL. The specific SARS-CoV-2 T-cell response was assessed in 44 randomly selected recipients 3 months after the second dose, and 11.4% (5/44) of them had a positive response. Following the third dose, 42% (21/50) tested positive. Side effects after the third dose were mild, with pain at the injection site being the most frequent adverse effect, reported by 73.4% of the recipients. Conclusion: Our study shows a mild delayed increase in antibody titer, three months after primary vaccination compared to one month after. It also shows a robust augmentation of humoral and specific T-cell responses after the booster dose, as well as the safety and tolerability of the mRNA vaccines in SOT recipients.

Direct acting antivirals and monoclonal antibodies reduce morbidity and mortality associated with severe acute respiratory syndrome coronavirus 2 infection. Persons at higher risk for disease progression and hospitalized patients with coronavirus disease-2019 (COVID-19) benefit most from available therapies. Following an emphasis on inpatient treatment of COVID-19 during the early pandemic, several therapeutic options were developed for outpatients with COVID-19. Additional clinical trials and real-world studies are needed to keep pace with the evolving pandemic.

Differences in serologic response to COVID-19 infection or vaccination were reported in adult kidney transplant recipients (KTR) compared to non-immunocompromised patients. This study aims to compare the serologic response of naturally infected or vaccinated pediatric KTR to that of controls.

Thirty-eight KTR and 42 healthy children were included; aged ≤18 years, with a previously confirmed COVID-19 infection or post COVID-19 vaccination. Serological response was measured by anti-spike protein IgG antibody titers. Response post third vaccine was additionally assessed in KTR.

Fourteen children in each group had previously confirmed infection. KTR were significantly older and developed a 2-fold higher antibody titer post-infection compared to controls [median (interquartile range [IQR]) age: 14.9 (7.8, 17.5) vs. 6.3 (4.5, 11.5) years, p = 0.02; median (IQR) titer: 1695 (982, 3520) vs. 716 (368, 976) AU/mL, p = 0.03]. Twenty-four KTR and 28 controls were vaccinated. Antibody titer was lower in KTR than in controls [median (IQR): 803 (206, 1744) vs. 8023 (3032, 30,052) AU/mL, p < 0.001]. Fourteen KTR received third vaccine. Antibody titer post booster in KTR reached similar levels to those of controls post two doses [median (IQR) 5923 (2295, 12,278) vs. 8023 (3034, 30,052) AU/mL, p = 0.37] and to KTR post natural infection [5282 AU/mL (2583, 13,257) p = 0.8].

Serologic response to COVID-19 infection was significantly higher in KTR than in controls. Antibody level in KTR was higher in response to infection vs. vaccination, contrary to reports in the general population. Response to vaccination in KTR reached levels comparable to controls only after third vaccine.

To date, no comprehensive marker to monitor the immune status of patients is available. Given that Torque teno virus (TTV), a known human virome component, has previously been identified as a marker of immunocompetence, it was retrospectively investigated whether TTV viral load may also represent a marker of ability to develop antibody in response to COVID-19-BNT162B2 vaccine in solid organ transplant recipients (SOT). Specifically, 273 samples from 146 kidney and 26 lung transplant recipients after successive doses of vaccine were analyzed. An inverse correlation was observed within the TTV copy number and anti-Spike IgG antibody titer with a progressive decrease in viremia the further away from the transplant date. Analyzing the data obtained after the second dose, a significant difference in TTV copy number between responsive and nonresponsive patients was observed, considering a 5 log₁₀ TTV copies/mL threshold to discriminate between the two groups. Moreover, for 86 patients followed in their response to the second and third vaccination doses a 6 log₁₀ TTV copies/mL threshold was used to predict responsivity to the booster dose. Although further investigation is necessary, possibly extending the analysis to other patient categories, this study suggests that TTV can be used as a good marker of vaccine response in transplant patients.

The effectiveness of vaccines against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.529 Omicron variant in immunosuppressed solid organ and islet transplant (SOT) recipients is unclear.

National registries in England were linked to identify SARS-CoV-2 positive tests, noninjury hospitalization within 14 d, and deaths within 28 d between December 7, 2020, and March 31, 2022 in adult SOT recipients. Incidence rate ratios (IRRs) for infection, and hospitalization or death, were adjusted for recipient demographics and calendar month for the Omicron-dominant period (December 20, 2021, to March 31, 2022). Mortality risk following SARS-CoV-2 infection was adjusted for recipient demographics and dominant variant using a Cox proportional-hazards model for the entire time period.

During the Omicron-dominant period, infection IRRs (95% confidence intervals) were higher in those receiving 2, 3, and 4 vaccine doses than in unvaccinated patients (1.25 [1.08-1.45], 1.46 [1.28-1.67], and 1.79 [1.54-2.06], respectively). However, hospitalization or death IRRs during this period were lower in those receiving 3 or 4 vaccine doses than in unvaccinated patients (0.62 [0.45-0.86] and 0.39 [0.26-0.58], respectively). Risk-adjusted analyses for deaths after SARS-CoV-2 infection between December 7, 2020, and March 31, 2022, found hazard ratios (95% confidence intervals) of 0.67 (0.46-0.98), 0.46 (0.30-0.69), and 0.18 (0.09-0.35) for those with 2, 3, and 4 vaccine doses, respectively, when compared with the unvaccinated group.

In immunosuppressed SOT recipients, vaccination is associated with incremental, dose-dependent protection against hospitalization or death after SARS-CoV-2 infection, including against the Omicron variant.

SARS-CoV-2 vaccines are recommended pre-transplantation, however, waning immunity and evolving variants mandate booster doses. Currently there no data to inform the optimal timing of booster doses post-transplant, in patients primed pre-transplant. We investigated serial serological samples in 204 transplant recipients who received 2 or 3 SARS-CoV-2 vaccines pre-transplant. Spike protein antibody concentrations, [anti-S], were measured on the day of transplantation and following booster doses post-transplant. In infection-naïve patients, post-booster [anti-S] did not change when V3 (1^st booster) was given at 116(78-150) days post-transplant, falling from 122(32-574) to 111(34-682) BAU/ml, p=0.78. Similarly, in infection-experienced patients, [anti-S] on Day-0 and post-V3 were 1090(133-3667) and 2207(650-5618) BAU/ml respectively, p=0.26. In patients remaining infection-naïve, [anti-S] increased post-V4 (as 2^nd booster) when given at 226(208-295) days post-transplant, rising from 97(34-1074) to 5134(229-5680) BAU/ml, p=0.0016. Whilst in patients who had 3 vaccines pre-transplant, who received V4 (as 1^st booster) at 82(49-101) days post-transplant, [anti-S] did not change, falling from 981(396-2666) to 871(242-2092) BAU/ml, p=0.62. Overall, infection pre-transplant and [anti-S] at the time of transplantation predicted post-transplant infection risk. As [Anti-S] fail to respond to SARS-CoV-2 booster vaccines given early post-transplant, passive immunity may be beneficial to protect patients during this period.

The coronavirus disease 2019 (COVID-19) pandemic presented unique challenges to patients with decompensated cirrhosis awaiting transplant, with respect to accessing medical facilities for routine clinic visits, imaging, laboratory workup, or endoscopies. There was a delay in organ procurement that led to a decrease in the number of liver transplants (LTs) and an increase in the morality of waitlisted patients at the beginning of the pandemic. LT numbers later equalized to pre-pandemic numbers due to combined efforts and adaptability of transplant centers as well as dynamic guidelines. Due to being immunosuppressed, the demographics of LT patients were at an increased risk of infection. Although there is a higher rate of mortality and morbidity in patients with chronic liver disease, LT itself is not a risk factor for mortality in COVID-19. There was no difference in overall mortality in LT patients compared to non-LT patients, and mortality risk factors were the same: age, hypertension, diabetes, obesity, and chronic kidney disease. The most common causes of death were respiratory complications. Liver-related deaths were reported in 1.6% of patients. The optimal timing of liver transplantation post-infection depends on various factors, such as the severity of liver injury, the presence of comorbidities, and the progression of the underlying liver disease. There is not enough data available on COVID-19 cholangiopathy and the number of cases that will be seen in the future that will require LT. There are some concerns of lower immunogenicity of COVID-19 vaccines in LT patients but available evidence suggests that the vaccines are safe and well-tolerated.

Solid-organ transplant recipients (SOTRs) have a higher risk of coronavirus disease 2019 (COVID-19) complications and death and a less powerful and lasting response to vaccines and to natural infection. In Colombia, this population was prioritized in the National Vaccination Plan against COVID-19 and received vaccines from different platforms. The aim of this study was to estimate the effectiveness of the complete vaccination schedule and of the vaccine booster for COVID-19 administered to SOTRs in Colombia.

A nested-cohort was assembled within the population-based ESPERANZA cohort and included the subset of 16 y and older SOTRs (n = 6963); the follow-up period spanned March 11, 2021, to May 11, 2022. The vaccine effectiveness was estimated with Cox proportional-hazards models so that the overall effectiveness of the complete vaccination schedule, the vaccine booster, each used vaccine, and the homologous and heterologous schedules were estimated, adjusting by the main confounders.

The overall effectiveness of being fully vaccinated was 73.7% (95% confidence interval [CI], 68.9%-77.0%) to prevent COVID-19 infection, 83.7% (95% CI, 78.7%-87.5%) to prevent hospitalization, and 92.1% (95% CI, 88.8%-94.4%) to prevent death due to COVID-19. Similarly, the effectiveness of the vaccine booster was 76.7% (95% CI, 70.6%-81.5%), 86.9% (95% CI, 79.4%-91.6%), and 94.5% (95% CI, 89.8%-97.1%) to prevent confirmed COVID-19 infection, hospitalization, and death due to COVID-19, respectively. In both cases, there were no statistically significant differences across age groups.

Findings from this work show a high protection of vaccination against infection, hospitalization, and death due to COVID-19 in SOTRs, which increases with the vaccine booster.

Solid organ transplant (SOT) recipients have shown suboptimal antibody response following COVID-19 vaccination. Several risk factors for the diminished response have been identified including immunosuppression and older age, but the influence of different comorbidities is not fully elucidated.

This case-control study consisted of 420 Danish adult SOT recipients and 840 sex- and age-matched controls, all vaccinated with a third homologous dose of either BNT162b2 (Pfizer-BioNTech) or mRNA-1273 (Moderna) vaccine. The primary outcome was differences in humoral immune response. The secondary outcome was breakthrough infections. Additionally, we looked for factors that could predict possible differences between the two groups.

Response rate increased from 186/382 (49%) to 275/358 (77%) in SOT recipients and remained on 781/790 (99%) to 601/609 (99%) in controls following a third vaccine dose. SOT recipients had significantly lower median antibody concentrations after third dose compared to controls (332.6 BAU/ml vs 46,470.0 BAU/ml, p <0.001). Lowest median antibody concentrations were seen in SOT recipients with liver disease (10.3 BAU/ml, IQR 7.1-319) and diabetes (275.3 BAU/ml, IQR 7.3-957.4). Breakthrough infections occurred similarly frequent, 150 (40%) among cases and 301 (39%) among controls (p = 0.80).

A third COVID-19 vaccine dose resulted in a significant increase in humoral immunogenicity in SOT recipients and maintained high response rate in controls. Furthermore, SOT recipients were less likely to produce antibodies with overall lower antibody concentrations and humoral immunity was highly influenced by the presence of liver disease and diabetes. The prevalence of breakthrough infections was similar in the two groups.

Compared with the general population, the immune response to COVID-19 mRNA vaccines is lower in adult kidney transplant recipients (KTRs). However, data is limited for pediatric KTRs. In this study, we aimed to assess humoral and cellular immune responses to the COVID-19 mRNA vaccine in pediatric KTRs.

This multicenter, prospective, case-control study included 63 KTRs (37 male, aged 12-21 years), 19 dialysis patients, and 19 controls. Humoral (anti-SARS-CoV2 IgG, neutralizing Ab (nAb)) and cellular (interferon-gamma release assay (IGRA)) immune responses were assessed at least one month after two doses of BNT162b2 mRNA vaccine.

Among COVID-19 naïve KTRs (n = 46), 76.1% tested positive for anti-SARS-CoV-2 IgG, 54.3% for nAb, and 63% for IGRA. Serum levels of anti-SARS-CoV-2 IgG and nAb activity were significantly lower in KTRs compared to dialysis and control groups (p < 0.05 for all). Seropositivity in KTRs was independently associated with shorter transplant duration (p = 0.005), and higher eGFR (p = 0.007). IGRA titer was significantly lower than dialysis patients (p = 0.009). Twenty (43.4%) KTRs were positive for all immune parameters. Only four of 11 seronegative KTRs were IGRA-positive. COVID-19 recovered KTRs had significantly higher anti-SARS-CoV-2 IgG and nAb activity levels than COVID-19 naïve KTRs (p = 0.018 and p = 0.007, respectively).

The humoral and cellular immune responses to SARS-CoV-2 mRNA BNT162b2 vaccine are lower in pediatric KTRs compared to dialysis patients. Further prospective studies are required to demonstrate the clinical efficacy of the mRNA vaccine in KTRs. This prospective study was registered in ClinicalTrials.gov (NCT05465863, registered retrospectively at 20.07.2022). A higher resolution version of the Graphical abstract is available as Supplementary information.

The vulnerable population of kidney transplant recipients (KTRs) are low responders to COVID-19 vaccines, so specific immune surveillance is needed. The interferon-gamma (IFN-γ) release assay (IGRA) is effective in assessing T cell-mediated immunity. We assessed SARS-CoV-2-directed T cell responses in KTRs with absent antibody production after a third dose of the mRNA-1273 vaccine, using two different IGRAs. A cohort of 57 KTRs, who were actively followed up, received a third dose of the mRNA-1273 vaccine. After the evaluation of humoral immunity to SARS-CoV-2, 14 seronegative patients were tested with two commercial IGRAs (SD Biosensor and Euroimmun). Out of 14 patients, one and three samples were positive by IGRAs with Euroimmun and SD Biosensor, respectively. The overall agreement between the two assays was 85.7% (κ = 0.444). In addition, multivariate linear regression analysis showed no statistically significant association between the IFN-γ concentration, and the independent variables analyzed (age, gender, years since transplant, total lymphocytes cells/mcl, CD3+ cells/mcl, CD3+ CD4+ cells/mcl, CD3+ CD8+ cells/mcl, CD19+ cells/mcl, CD3-CD16+CD56+ cells/mcl) (p > 0.01). In a vulnerable setting, assessing cellular immune response to complement the humoral response may be advantageous. Since the two commercial IGRAs showed a good agreement on negative samples, the three discordant samples highlight the need for further investigations.

Pneumococcal infections remain a common global cause of significant morbidity and mortality. The first recommendations for adult pneumococcal vaccination, published in South Africa in 1999, contained information only on the 23-valent polysaccharide vaccine (PPV23). With the introduction of the 13-valent pneumococcal conjugate vaccine (PCV13) for use in adults and the perceived uncertainty that most clinicians had regarding use of these vaccines in adults, these vaccine recommendations were updated in 2022. A Working Group, which consisted of individuals in various fields of medical practice in South Africa, who were from different areas of the country, and included clinicians from both the public and private sectors, was assembled to revise the recommendations. The expertise of the participants varied widely, dependent on their training and specialty, and encompassed different organ systems, disease conditions, and/or practice types. Each participant was allocated a different section, based on their expertise, for which they were required to do an extensive review of the current literature and write their section. The entire working group then reviewed the complete document several times, following additional comments and recommendations. This update contains recommendations for the use of both PPV23 and PCV13, either alone, or in sequence, both in vaccine naïve and in previously vaccinated individuals. It includes both age and risk categories, and encompasses the elderly (≥65 years), as well as younger adults (<65 years) with comorbid conditions or with high-risk conditions and/or immunocompromise. It is hoped that this review and its associated vaccine recommendations will clarify for clinicians, from all spheres of practice in South Africa, how, where, and when pneumococcal vaccines should be used in adults, with the ultimate goal of significantly increasing the appropriate use of these vaccines, in order to decrease the substantial morbidity and mortality associated with pneumococcal infections in adults in South Africa. Furthermore, it is hoped that this review of local epidemiological data and the manner in which this information was interpreted in the development of these local vaccine recommendations, could be used as an example for other regions of the world, to tailor their recommendations to locally available epidemiological data.

Vaccination against SARS-CoV2 represents a key weapon to prevent COVID-19, but lower response rates to vaccination have frequently been reported in solid organ transplant recipients. The aim of our study was to evaluate the rate of seroconversion to SARS-CoV-2 mRNA vaccines in a cohort of kidney transplant recipients and the potential role of the different immunosuppressive regimens. We conducted an observational retrospective cohort study in kidney transplant patients vaccinated for COVID-19. For each patient, we evaluated IgG anti-S-RBD SARS-CoV-2 titers immediately before the administration of first COVID-19 vaccination dose, 20 days after the first dose and 40 days after the second dose. Moreover, we evaluated the type of immunosuppressive treatment and the incidence of vaccine breakthrough SARS-CoV-2 infection. We enrolled 121 kidney transplant patients vaccinated for COVID-19. At the time of administration of the first vaccine dose, all patients had a negative antibody titer; only 4.1% had positive antibody titers 20 days after the first dose. More than half patients 62 (51%) had protective antibody titers 40 days after the second dose. A total of 18 Solid Organ Transplant Recipients (SOTRs) (14.9%) got a SARS-CoV-2 breakthrough infection during the study period. With regard to immunosuppressive regimen, patients on mycophenolate-based regimen (48.7%) showed the lowest antibody response rates (27.5%) compared to other regimens. Our study confirms that kidney transplant patients show a poor response to two doses of COVID-19 vaccination. Moreover, in our study the use of mycophenolate is significantly associated with a non-response to COVID-19 m-RNA vaccines.

To date, reports addressing the antibody response following mRNA SARS-CoV-2 vaccination in lung transplant (LTX) recipients are limited. Thus, the aim of this clinical study was to investigate the efficacy and safety of the vaccines in LTX recipients compared to controls.

An open-label, nonrandomized prospective study was conducted at Tohoku University Hospital. LTX recipients and controls who received either the BNT162b2 vaccine or the mRNA-1273 vaccine were recruited, and SARS-CoV-2 IgG was measured before and after vaccination. The adverse events were reviewed. Predictors of negative serology after vaccination were evaluated with logistic regression.

Forty-one LTX recipients and 24 controls were analyzed. Although all controls had a positive antibody response to a SARS-CoV-2 mRNA vaccine, antibody response was found in 24.4% of LTX recipients (p < .0001). The amount of SARS-CoV-2 IgG following the 2nd dose significantly climbed to 6557 AU/mL in controls, whereas the increase in IgG in LTX recipients was 8.3 AU/mL (p < .0001). Fewer LTX recipients developed systemic fever than controls (p < .0001) despite equivalent overall adverse event percentages in both groups. A higher plasma concentration of mycophenolate was a significant predictor of negative serology (p = .032).

An impaired antibody response to mRNA vaccines was significantly found in LTX recipients compared to controls and was associated with the plasma concentration of mycophenolate. While repeating mRNA vaccination may be one of the strategies to improve antibody response given the safety of the vaccines, emerging data on humoral immune responses based on immunosuppression regimens in LTX recipients should be studied (jRCT1021210009).

Several population groups display an increased risk of severe disease and mortality following SARS-CoV-2 infection. These include those who are immunocompromised (IC), have a cancer diagnosis, human immunodeficiency virus (HIV) infection or chronic inflammatory disease including autoimmune disease, primary immunodeficiencies, and those with kidney or liver disease. As such, improved understanding of the course of COVID-19 disease, as well as the efficacy, safety, and benefit-risk profiles of COVID-19 vaccines in these vulnerable groups is paramount in order to inform health policy makers and identify evidence-based vaccination strategies. In this review, we seek to summarize current data, including recommendations by national health authorities, on the impact and benefit-risk profiles of COVID-19 vaccination in these populations. Moving forward, although significant efforts have been made to elucidate and characterize COVID-19 disease course and vaccine responses in these groups, further larger-scale and longer-term evaluation will be instrumental to help further guide management and vaccination strategies, particularly given concerns about waning of vaccine-induced immunity and the recent surge of transmission with SARS-CoV-2 variants of concern.

Infection risk and COVID-19 outcomes make SARS-CoV-2 vaccination essential forsolid-organ transplant recipients. Reports of immune activation after vaccination causing graft failure raise concerns, but data are limited. Here, we document graft function, donor-derived-cell-free-DNA(dd-cfDNA), and donor-specific antibodies (DSA) in solid-organ renal transplant recipients after vaccination. Retrospective demographics, graft function, and immunologic parameters were collected in 96 renal transplant patients one month after their second vaccine dose. For-cause biopsies were performed based on clinician judgment. Similar proportions of subjects experienced increases (39.6 %) and decreases (44.8 %) in serum creatinine in the post-vaccination period, p = 0.56. Similar proportions of subjects experienced increases (23 %) and decreases (25 %) in serum ddcfDNA in the post-vaccination period, p = 0.87. Post-vaccination changes in serum creatinine and ddcfDNA (r(95) = -0.04, p = 0.71), serum creatinine and cumulative DSA MFI (r(95) = 0.07, p = 0.56), and ddcfDNA and cumulative DSA MFI(r(95) = 0.13, p = 0.21) were not significantly correlated. Five subjects had increased cumulativeDSA MFI, but there were no de novo cases. Biopsies on three subjects confirmed pre-existing diagnoses. Our study found minimal evidence ofdonor-directed immunologic activity post-vaccination, and all immunologic changesdid not correlate to graft dysfunction. We believe these findings do not amount to evidence ofpost-vaccination deleterious donor-directed activation. SARS-CoV-2 vaccination is immunologically safe and should continue for renal transplant recipients.

The coronavirus disease 2019 (COVID-19) pandemic has had a major global impact on solid organ transplantation (SOT). An estimated 16% global reduction in transplant activity occurred over the course of 2020, most markedly impacting kidney transplant and living donor programs, resulting in substantial knock-on effects for waitlisted patients. The increased severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection risk and excess deaths in transplant candidates has resulted in substantial effort to prioritize the safe restart and continuation of transplant programs over the second year of the pandemic, with transplant rates returning towards prepandemic levels. Over the past 2 y, COVID-19 mortality in SOT recipients has fallen from 20%-25% to 8%-10%, attributed to the increased and early availability of SARS-CoV-2 testing, adherence to nonpharmaceutical interventions, development of novel treatments, and vaccination. Despite these positive steps, transplant programs and SOT recipients continue to face challenges. Vaccine efficacy in SOT recipients is substantially lower than the general population and SOT recipients remain at an increased risk of adverse outcomes if they develop COVID-19. SOT recipients and transplant teams need to remain vigilant and ongoing adherence to nonpharmaceutical interventions appears essential. In this review, we summarize the global impact of COVID-19 on transplant activity, donor evaluation, and patient outcomes over the past 2 y, discuss the current strategies aimed at preventing and treating SARS-CoV-2 infection in SOT recipients, and based on lessons learnt from this pandemic, propose steps the transplant community could consider as preparation for future pandemics.