Development of COVID-19 Infection in Transplant Recipients After SARS-CoV-2 Vaccination

Monitored COVID-19 vaccine humoral response in immunocompromised solid organ transplant recipients

The SARS-CoV-2 pandemic has resulted in rapid research and vaccine development to help curtail unchecked transmission. However, these studies cannot be applied as easily among every population, such as immunocompromised individuals. In this study, we observed the humoral response of 70 total heart and renal transplant patients to mRNA SARS-CoV-2 vaccinations to help further understand the effectiveness of vaccination in post-transplant patients following second or booster vaccinations. Antibodies were measured by bead technology to detect IgG, as well as IgG/IgM Rapid Cassette tests for confirmation. Immunocompromised patients had a noticeably lower humoral response than non-immunocompromised populations, with an even lower response among Black patients. Our findings also show for the first time various antibody responses to different motifs of the virus, with the lowest being against the S2 motif. A potential link between the duration of immunosuppression and vaccine response was also observed, where patients on immunosuppressants for longer had a stronger response to vaccination compared to recent transplant patients in our study. In addition, younger transplant recipients had a better humoral response to vaccination, and vaccine effectiveness was disproportionate between races. This finding reinforces the continuation of the guidelines for accelerated vaccination schedules for immunocompromised patients.

Factors influencing immunogenicity and safety of SARS-CoV-2 vaccine in liver transplantation recipients: a systematic review and meta-analysis

Background

This review summarizes the factors influencing the efficacy and safety of the COVID-19 vaccine in LTR through meta-analysis, hoping to provide strategies for vaccine use.

Methods

Electronic databases were screened for studies on mRNA vaccines in LTR. The primary outcome was the pooled seroconversion rate, and the secondary outcome was the incidence of adverse events+breakthrough infections. Subgroup analyses were made based on BMI, associated comorbidities, presence of baseline leukopenia, time since transplant, and drugs used.

Result

In total, 31 articles got included. The pooled seroconversion rate after at least two doses of SARS-CoV-2 vaccination was 72% (95% CI [0.52-0.91). With significant heterogeneity among studies I2 = 99.9%, the seroconversion rate was about 72% (95%CI [0.66-0.75]), from the studies reporting two doses of vaccine slightly higher around 75%(95%CI [0.29-1.22]) from studies reporting three doses. The pooled seroconversion rate within the lower to normal BMI group was 74% (95% CI [0.22-1.27], Pi=0.005) against 67% (95% CI [0.52-0.81], Pi=0.000) in the high BMI group. The pooled seroconversion rate in the ''positive leukopenia'' group was the lowest, 59%. Leukopenia could influence the vaccine seroconversion rate in LTR. From the time since transplant analysis after setting seven years as cut off point, the pooled seroconversion rate after at least two doses of COVID-19 vaccination was 53% (95% CI [0.18-0.83], P=0.003, I2 = 99.6%) in <7years group and 83% (95% CI [0.76-0.90], P=0.000 I2 = 95.7%) in > 7years group. The only time since transplantation had reached statistical significance to be considered a risk factor predictor of poor serological response (OR=1.27 95%CI [1.03-1.55], P=0.024). The breakthrough infection rate after vaccination was very low2% (95% CI 0.01-0.03, I2 = 63.0%), and the overall incidence of adverse events, which included mainly pain at the injection site and fatigue, was 18% (95%CI [0.11-0.25], I2 = 98.6%, Pi=0.000).

Conclusion

The seroconversion rate in LTR vaccinated with at least two doses of mRNA COVID-19 vaccine could be significantly affected by the vaccine type, immunosuppressant used, BMI, leukopenia, associated comorbidities, and time since transplantation. Nevertheless, booster doses are still recommended for LTR.

Outcomes and Effects of Vaccination on Sars-Cov-2 Omicron Infection in Kidney Transplant Recipients

BACKGROUND

Kidney transplant recipients (KTRs) are at high risk of COVID-19. Vaccination is significantly effective at preventing infection and reducing infection severity. Omicron infections are less severe than infections by previous strains, but breakthrough disease is more common. Thus, we conducted this study to observe the vaccine efficacy in our KTRs.

METHODS

During the surge in the Omicron variant, beginning in May 2022, we retrieved data from 365 KTRs who had received at least one dose of various COVID vaccines until June 30, 2022. Outcomes of the KTRs (n = 168) after at least the 2nd vaccination were assessed until September 30, 2022, before the border was opened for tourism.

RESULTS

The antibody response in KTRs after the 1st and 2nd doses of SARS-CoV-2 vaccines demonstrated a significant increase from the 1st dose (median: 0.4; IQR: 0.4-8.4 U/mL, P < .001) to the 2nd dose (median: 57.5; IQR: 0.4-799.2 U/mL), and the response rate rose from 32% to 65% (P < .001). SARS-CoV-2 infection was identified in 14/365 (3.8%) patients after at least the 1st dose and 7/187 (3.7%) patients at least 7 days beyond the 2nd dose. Most KTRs had a mild course, but 3 (17%) were hospitalized due to pneumonia.

CONCLUSIONS

Our data demonstrate a lower response rate and anti-S titers after 2nd dose vaccination in KTRs than in the general population, but a lower incidence of SARS-CoV-2 infection after vaccination was observed during the Omicron outbreak. Owing to the breakthrough infections found in ordinarily vaccinated KTRs, we must emphasize the importance of vaccination and boosters to prevent severe illness, hospitalizations, and death among those developing infections.

COVID-19 mortality may be reduced among fully vaccinated solid organ transplant recipients

BACKGROUND

Solid organ transplant (SOT) recipients are at increased risk for morbidity and mortality from COVID-19 due to their immunosuppressed state and reduced immunogenicity from COVID-19 mRNA vaccines. This investigation examined the association between COVID-19 mRNA vaccination status and mortality among SOT recipients diagnosed with COVID-19.

METHODS & FINDINGS

A retrospective, registry-based chart review was conducted investigating COVID-19 mortality among immunosuppressed solid organ transplant (SOT) recipients in a large metropolitan healthcare system in Houston, Texas, USA. Electronic health record data was collected from consecutive SOT recipients who received a diagnostic SARS-CoV-2 test between March 1, 2020, and October 1, 2021. The primary exposure was COVID-19 vaccination status at time of COVID-19 diagnosis. Patients were considered 'fully vaccinated' at fourteen days after completing their vaccine course. COVID-19 mortality within 60 days and intensive care unit admission within 30 days were primary and secondary endpoints, respectively. Among 646 SOT recipients who were diagnosed with COVID-19 at Houston Methodist Hospital between March 2020, and October 2021, 70 (10.8%) expired from COVID-19 within 60 days. Transplanted organs included 63 (9.8%) heart, 355 (55.0%) kidney, 108 (16.7%) liver, 70 (10.8%) lung, and 50 (7.7%) multi-organ. Increasing age was a risk factor for COVID-19 mortality, while vaccination within 180 days of COVID-19 diagnosis was protective in Cox proportional hazard models with hazard ratio 1.04 (95% CI: 1.01-1.06) and 0.31 (0.11-0.90), respectively). These findings were confirmed in the propensity score matched cohort between vaccinated and unvaccinated patients.

CONCLUSIONS

This investigation found COVID-19 mortality may be significantly reduced among immunosuppressed SOT recipients within 6 months following vaccination. These findings can inform vaccination policies targeting immunosuppressed populations worldwide.

COVID-19 Breakthrough Infections in Vaccinated Kidney Transplant Recipients

Coronavirus disease 2019 (COVID-19) is associated with increased morbidity and mortality among kidney transplant recipients (KTRs). The administration of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination is the only reliable strategy to prevent COVID-19 and alleviate the severity of COVID-19 in this particular population. The aim of this article was to evaluate the clinical protection by vaccines (breakthrough infections, deaths, and hospitalizations) in KTRs. There were 135 KTRs with COVID-19 breakthrough infections for whom patient-level data were available in PubMed and Web of Science. There was a male predominance (61.4%), 97 were given the standard vaccination regimen, and 38 received three or four doses of the vaccine. The median age was 59.0 (IQR: 49.0−69.0) years. A total of 67 patients were hospitalized, and 10 patients died. In 72.6% of cases, triple-maintenance immunosuppression was employed. The deceased patients were older than the survivors (p < 0.05); an age over 60 years was a risk factor for death (p < 0.05). The KTRs with booster vaccines had a longer time interval from the last vaccine to COVID-19 infection and lower hospitalization rates than the individuals who received the standard vaccination regimen (33.3% vs. 54.8%, p < 0.05). The hospitalized patients were older than the outpatients (p < 0.05). Among 16,820 fully vaccinated or boosted KTRs from 14 centers, there were 633 breakthrough infections (3.58%) and 73 associated deaths (0.41%). The center-level breakthrough infection rates varied from 0.21% to 9.29%. These findings highlight the need for booster doses for KTRs. However, more research is needed to define the long-term effectiveness and immunogenicity of booster doses and to identify methods to boost the protective response to vaccination in these immunocompromised patients.

Outcomes of SARS-CoV-2 Infection in Unvaccinated Compared With Vaccinated Solid Organ Transplant Recipients: A Propensity Matched Cohort Study

BACKGROUND

Solid organ transplant (SOT) recipients are at high risk for complications from coronavirus disease 2019 (COVID-19). Vaccination may mitigate this risk; however, immunogenicity appears to be significantly impaired, with reports of increased risk of breakthrough infection. It is unknown if vaccine breakthrough infections are milder or as severe as infections in unvaccinated patients.

METHODS

We performed a multicenter matched cohort study between March 2020 and September 2021 to assess influence of COVID-19 vaccination on outcomes of COVID-19 infection. Treatment characteristics and disease severity outcomes were compared on the basis of vaccine status; breakthrough infections versus unvaccinated infections. Variable ratio propensity score matching based on age, sex, transplant type, and number of comorbidities, was used to develop the analytic cohort. Logistic regression was used to assess the influence of vaccination status on the selected outcomes.

RESULTS

From a cohort of 511 SOT patients with COVID-19, we matched 77 partially or fully vaccinated patients with 220 unvaccinated patients. Treatment characteristics including use of dexamethasone, remdesivir, and antibiotics did not differ. Vaccinated participants were more likely to receive tocilizumab, 15 of 77 (19.5%) versus 5 of 220 (2.3%), P  < 0.001. Disease severity outcomes including oxygen requirement, mechanical ventilation, and mortality were similar among medically attended vaccine breakthroughs compared with unvaccinated patients.

CONCLUSIONS

SOT recipients who develop medically attended COVID-19 following 1- or 2-dose vaccination seem to have similar disease severity to unvaccinated patients who develop infection. This is consistent with the requirement that SOT recipients need 3 or more vaccine doses and emphasizes the importance of alternate strategies for this population.

Antibody response to the messenger RNA-1273 vaccine (Moderna) in liver transplant recipients

Different reports have shown the clinical and serologic response to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA) vaccines in preventing coronavirus disease 2019 (COVID-19) in the general population, but few studies have examined these responses in transplant recipients. We assessed the vaccine immunogenicity of two doses (100 μg) of the mRNA-1273 vaccine (Moderna) administered with a 28-day interval in liver transplant recipients (LTRs) at follow-up at the Marques de Valdecilla University Hospital. LTRs without a history of COVID-19 infection were tested for SARS-CoV-2 immunoglobulin G (IgG) antibodies directed against the spike protein (S) a median of 43 days after receiving the second Moderna vaccine dose. Clinical data, including immunosuppressive regimen and routine laboratory data, were obtained from the medical record of each patient up to 3 months before the date of the first vaccination. Factors associated with serologic response were evaluated through logistic regression. In total, 129 LTRs who had anti-S results were included. Most patients were men (n = 99; 76.7%) with a median age of 63 years (interquartile range, 56-68). Alcohol (43.4%) and chronic hepatitis C (18.6%) were the most frequent causes of liver transplantation. A positive anti-S IgG response was observed in 113 LTRs (87.6%; 95% confidence interval [CI], 80.8-92.2). A strong inverse relationship between mycophenolate mofetil use and serologic response was found (odds ratio, 0.07; 95% CI, 0.02-0.26; p = 0.001). Conclusion: Most LTRs develop an immunological response to the Moderna SARS-CoV-2 mRNA-based vaccine. An immunosuppressive regimen that includes mycophenolate predicts a weak serologic response.

Breakthrough Infections Following mRNA SARS-CoV-2 Vaccination in Kidney Transplant Recipients

BACKGROUND

The clinical effectiveness of coronavirus disease 2019 (COVID-19) vaccination in kidney transplant (KT) recipients is lower than in the general population.

METHODS

From April to October 2021, 481 KT recipients with COVID-19, included in the Spanish Society of Nephrology COVID-19 Registry, were analyzed. Data regarding vaccination status and vaccine type were collected, and outcomes of unvaccinated or partially vaccinated patients (n = 130) were compared with fully vaccinated patients (n = 351).

RESULTS

Clinical picture was similar and survival analysis showed no differences between groups: 21.7% of fully vaccinated patients and 20.8% of unvaccinated or partially vaccinated died (P = 0.776). In multivariable analysis, age and pneumonia were independent risk factors for death, whereas vaccination status was not related to mortality. These results remained similar when we excluded patients with partial vaccination, as well as when we analyzed exclusively hospitalized patients. Patients vaccinated with mRNA-1273 (n = 213) showed a significantly lower mortality than those who received the BNT162b2 vaccine (n = 121) (hazard ratio: 0.52; 95% confidence interval, 0.31-0.85; P = 0.010).

CONCLUSIONS

COVID-19 severity in KT patients has remained high and has not improved despite receiving 2 doses of the mRNA vaccine. The mRNA-1273 vaccine shows higher clinical effectiveness than BNT162b2 in KT recipients with breakthrough infections. Confirmation of these data will require further research taking into account the new variants and the administration of successive vaccine doses.

The effect of COVID 19 vaccination on kidney recipients

BACKGROUND

Nearly one year from the onset of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, safe and effective vaccines began distribution around the world. This study aimed to assess the rate of COVID-19 disease among vaccinated kidney transplant patients and the types of symptoms found within them.

DESIGN

This cross-sectional study was performed at the transplant ward and Organ Procurement Unit of Sina Hospital, Tehran, Iran. As a sample size, 159 cadavers' kidney recipients received two doses of the Sinopharm SARS-CoV-2 vaccine. The required data were collected using a checklist via conducting a face-to-face interview.

RESULTS

The mean age of the vaccinated participants was 49.44 ± 13.87 years old. There were 73 (45.91%) vaccinated cases of SARS-CoV-2 infection during the study period, 18 cases (12.6%) occurred among fully vaccinated individuals, and 53 cases (33.3%) were among individuals who had received only one dose of vaccine. 45% of the fully vaccinated patients (received 2 doses vaccine) contracted SARS-CoV-2 from their families; 35% were infected through participation in social events (35%). There was a significant difference in disease severity levels between the fully vaccinated group and the one-dose vaccinated (p < 0.023). The severe disease occurred in 2 patients after vaccination, who were subsequently admitted to the hospital. There was a significant difference between the number of kidney transplant days and infection with SARS-CoV-2 before (P = 0.15) and after vaccination (p < 0.015).

CONCLUSION

Even after vaccination, kidney recipients are still at the risk of contracting SARS-CoV-2. In addition to these results, the efficacy of vaccination in preventing death caused by SARS-CoV-2 was confirmed.

Tacrolimus-resistant SARS-CoV-2-specific T cell products to prevent and treat severe COVID-19 in immunosuppressed patients

Solid organ transplant (SOT) recipients receive therapeutic immunosuppression that compromises their immune response to infections and vaccines. For this reason, SOT patients have a high risk of developing severe coronavirus disease 2019 (COVID-19) and an increased risk of death from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. Moreover, the efficiency of immunotherapies and vaccines is reduced due to the constant immunosuppression in this patient group. Here, we propose adoptive transfer of SARS-CoV-2-specific T cells made resistant to a common immunosuppressant, tacrolimus, for optimized performance in the immunosuppressed patient. Using a ribonucleoprotein approach of CRISPR-Cas9 technology, we have generated tacrolimus-resistant SARS-CoV-2-specific T cell products from convalescent donors and demonstrate their specificity and function through characterizations at the single-cell level, including flow cytometry, single-cell RNA (scRNA) Cellular Indexing of Transcriptomes and Epitopes (CITE), and T cell receptor (TCR) sequencing analyses. Based on the promising results, we aim for clinical validation of this approach in transplant recipients. Additionally, we propose a combinatory approach with tacrolimus, to prevent an overshooting immune response manifested as bystander T cell activation in the setting of severe COVID-19 immunopathology, and tacrolimus-resistant SARS-CoV-2-specific T cell products, allowing for efficient clearance of viral infection. Our strategy has the potential to prevent severe COVID-19 courses in SOT or autoimmunity settings and to prevent immunopathology while providing viral clearance in severe non-transplant COVID-19 cases.

Safety and Efficacy of the COVID-19 Vaccine in Kidney Transplant Recipients

Background: Kidney transplant recipients appear to be at high risk for critical coronavirus disease 2019 (COVID-19) illness. They are considered a priority for COVID-19 vaccination. Only a few studies report on the safety and efficacy of the COVID-19 vaccine in these patients.

Methods: In this prospective observational study, we measured anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) spike-specific IgG post first and second COVID-19 mRNA vaccines in 113 kidney transplant recipients and compared them to 62 healthy volunteers.

Result: After the first COVID-19 vaccine, SARS-CoV-2-specific antibodies were undetectable in 38.9% of kidney transplant recipients, and after the second, it remained undetectable in 12.4%. SARS-CoV-2-specific antibodies were significantly lower in kidney transplant recipients. The average antibody titer after the first vaccine was 1243.6±4137.5 in kidney transplant recipients compared to 20012.2±44436.4 in the controls after the first dose (P=0.002), and 7965.5±12431.3 versus 82891.3±67418.7, respectively, after the second dose (P <0.001). The immune response to the COVID-19 vaccine seemed to be influenced by mycophenolate dose in kidney transplant recipients and pre-vaccination infection.

Conclusion: Kidney transplant recipients are prone to have attenuated antibody responses (anti-spike IgGs) to mRNA COVID-19 vaccines. Patients on mycophenolate mofetil (2 gm daily) had significantly lower SARS-CoV-2 spike-specific IgG levels as compared to patients on no or reduced dose of mycophenolate. Hence, kidney transplant recipients need to continue all infection control precautionary measures against COVID-19 infection and should be considered a priority for a third COVID-19 vaccine.

Predictive factors of a viral neutralizing humoral response after a third dose of COVID-19 mRNA vaccine

Kidney transplant recipients (KTRs) have reduced ability to mount adequate antibody response after two doses of the COVID-19 mRNA vaccine. French health authorities have allowed a third booster dose (D3) for KTRs, but their response is heterogeneous and tools able to discriminate the responders are lacking. Anti-RBD IgG titers (chemiluminescence immunoassay), spike-specific cellular responses (IFN-γ-releasing assay, IGRA), and in vitro serum neutralization of the virus (the best available correlate of protection), were evaluated 7-14 days after the second dose (D2) of BNT162b2 vaccine in 93 KTRs. Among the 73 KTRs, whose serum did not neutralize SARS-CoV-2 in vitro after D2, 14 (19%) acquired this capacity after D3, and were considered as "responders." Exploratory univariate analysis identified short time from transplantation and high maintenance immunosuppression as detrimental factors for the response to D3. In addition, any of the presence of anti-RBD IgGs and/or positive IGRA after D2 was predictive of response to D3. By contrast, none of the KTRs with both a negative serology and IGRA responded to D3. In summary, routinely available bioassays performed after D2 allow identifying KTRs that will respond to a booster D3. These results pave the way for the personalization of vaccination strategy in KTRs.

The Impact of Vaccination on Incidence and Outcomes of SARS-CoV-2 Infection in Patients with Kidney Failure in Scotland

BACKGROUND

Patients with kidney failure requiring KRT are at high risk of complications and death following SARS-CoV-2 infection, with variable antibody responses to vaccination reported. We investigated the effects of COVID-19 vaccination on the incidence of infection, hospitalization, and death from COVID-19 infection.

METHODS

The study design was an observational data linkage cohort study. Multiple health care datasets were linked to ascertain all SARS-CoV-2 testing, vaccination, hospitalization, and mortality data for all patients treated with KRT in Scotland from the start of the pandemic over a period of 20 months. Descriptive statistics, survival analyses, and vaccine effectiveness were calculated.

RESULTS

As of September 19, 2021, 93% (n=5281) of the established KRT population in Scotland had received two doses of an approved SARS-CoV-2 vaccine. Over the study period, there were 814 cases of SARS-CoV-2 infection (15.1% of the KRT population). Vaccine effectiveness rates against infection and hospitalization were 33% (95% CI, 0 to 52) and 38% (95% CI, 0 to 57), respectively. Within 28 days of a SARS-CoV-2-positive PCR test, 9.2% of fully vaccinated individuals died (7% patients on dialysis and 10% kidney transplant recipients). This compares to <0.1% of the vaccinated general Scottish population admitted to the hospital or dying due to COVID-19 during that period.

CONCLUSIONS

These data demonstrate that a primary vaccine course of two doses has limited effect on COVID-19 infection and its complications in patients with KRT. Adjunctive strategies to reduce risk of both COVID-19 infection and its complications in this population are urgently required.

Infection or a third dose of mRNA vaccine elicits neutralizing antibody responses against SARS-CoV-2 in kidney transplant recipients

Transplant recipients, who receive therapeutic immunosuppression to prevent graft rejection, are characterized by high coronavirus disease 2019 (COVID-19)-related mortality and defective response to vaccines. We observed that previous infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but not the standard two-dose regimen of vaccination, provided protection against symptomatic COVID-19 in kidney transplant recipients. We therefore compared the cellular and humoral immune responses of these two groups of patients. Neutralizing anti-receptor-binding domain (RBD) immunoglobulin G (IgG) antibodies were identified as the primary correlate of protection for transplant recipients. Analysis of virus-specific B and T cell responses suggested that the generation of neutralizing anti-RBD IgG may have depended on cognate T-B cell interactions that took place in germinal center, potentially acting as a limiting checkpoint. High-dose mycophenolate mofetil, an immunosuppressive drug, was associated with fewer antigen-specific B and T follicular helper (TFH) cells after vaccination; this was not observed in patients recently infected with SARS-CoV-2. Last, we observed that, in two independent prospective cohorts, administration of a third dose of SARS-CoV-2 mRNA vaccine restored neutralizing titers of anti-RBD IgG in about 40% of individuals who had not previously responded to two doses of vaccine. Together, these findings suggest that a third dose of SARS-CoV-2 mRNA vaccine improves the RBD-specific responses of transplant patients treated with immunosuppressive drugs.

Real-world Effectiveness of the Pfizer-BioNTech BNT162b2 and Oxford-AstraZeneca ChAdOx1-S Vaccines Against SARS-CoV-2 in Solid Organ and Islet Transplant Recipients

BACKGROUND

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

METHODS

We linked 4 national registries to retrospectively identify laboratory-confirmed SARS-CoV-2 infections and deaths within 28 d in England between September 1, 2020, and August 31, 2021, comparing unvaccinated adult SOT recipients and those who had received 2 doses of ChAdOx1-S or BNT162b2 vaccine. Infection incidence rate ratios were adjusted for recipient demographics and calendar month using a negative binomial regression model, with 95% confidence intervals. Case fatality rate ratios were adjusted using a Cox proportional hazards model to generate hazard ratio (95% confidence interval).

RESULTS

On August 31, 2021, it was found that 3080 (7.1%) were unvaccinated, 1141 (2.6%) had 1 vaccine dose, and 39 260 (90.3%) had 2 vaccine doses. There were 4147 SARS-CoV-2 infections and 407 deaths (unadjusted case fatality rate 9.8%). The risk-adjusted infection incidence rate ratio was 1.29 (1.03-1.61), implying that vaccination was not associated with reduction in risk of testing positive for SARS-CoV-2 RNA. Overall, the hazard ratio for death within 28 d of SARS-CoV-2 infection was 0.80 (0.63-1.00), a 20% reduction in risk of death in vaccinated patients (P = 0.05). Two doses of ChAdOx1-S were associated with a significantly reduced risk of death (hazard ratio, 0.69; 0.52-0.92), whereas vaccination with BNT162b2 was not (0.97; 0.71-1.31).

CONCLUSIONS

Vaccination of SOT recipients confers some protection against SARS-CoV-2-related mortality, but this protection is inferior to that achieved in the general population. SOT recipients require additional protective measures, including further vaccine doses, antiviral drugs, and nonpharmaceutical interventions.

Immunological Biomarkers in Blood to Monitor the Course and Therapeutic Outcomes of COVID-19

BACKGROUND

The COVID-19 pandemic has posed a great challenge to the medical community because little is known about its clinical course, therapeutic options, and laboratory monitoring tools for diagnosis, prognosis, and surveillance. This review focuses on immune biomarkers that can be measured in peripheral blood in a clinical laboratory under routine conditions to monitor the innate immune system response in the acute phase, as well as the adaptive immune response established both after infection and vaccination.

METHODS

A PubMed search was performed covering January 2020 to June 2021 to extract biomarkers suitable for monitoring the immune response and outcome of COVID-19 and therapeutic interventions, including vaccination.

RESULTS

To monitor the innate immune response, cytokines such as interleukin-6 or acute phase reactants such as C-reactive protein or procalcitonin can be measured on autoanalyzers complemented by automated white blood cell differential counts. The adaptive immune response can be followed by commercially available enzyme-linked immune spot assays to assess the specific activation of T cells or by monitoring immunoglobulin A (IgA), IgM, and IgG antibodies in serum to follow B-cell activation. As antigens of the SARS-CoV-2 virus, spike and nucleocapsid proteins are particularly suitable and allow differentiation between the immune response after infection or vaccination.

CONCLUSIONS

Routine immune monitoring of COVID-19 is feasible in clinical laboratories with commercially available instruments and reagents. Strategies such as whether biomarkers reflecting the response of the innate and adaptive immune system can be used to make predictions and assist in individualizing therapeutic interventions or vaccination strategies need to be determined in appropriate clinical trials. Promising preliminary data are already available based on single-center reports and completed or ongoing vaccination trials.

Third dose of the BNT162b2 vaccine in heart transplant recipients: Immunogenicity and clinical experience

BACKGROUND

The repeated waves of the COVID-19 pandemic have highlighted the necessity to optimize vaccine responses in immunocompromised populations. We investigated the safety and immunogenicity of a third, booster, dose of the Pfizer BNT162b2 vaccine in heart transplant (HT) patients.

METHODS

The cohort comprised 96 adult HT patients who received a third homologous dose of the BNT162b2 vaccine 168 days after the second dose. The vaccine-induced antibody responses of both receptor-binding domain (RBD) IgG and neutralizing antibodies were assessed in all patients, with a positive antibody response being defined as the presence of either IgG anti-RBD or neutralizing antibodies. For a subset of patients, T cell response was also studied.

RESULTS

The third dose was associated with a low rate of adverse events, mostly mild pain at the injection site. No serious adverse events were recorded, and there were no episodes of rejection. At 18 days following the third dose of the vaccine, the positive antibody response increased from 23% to 67%, with a corresponding increase in neutralizing capacity. The third dose elicited SARS-CoV-2 neutralization titers >9-fold and IgG anti-RBD antibodies >3-fold of the range achieved after the two primary doses. Mycophenolate use, lower eGFR and higher C-reactive protein were independently associated with a reduced likelihood of generating an immune response. Importantly, a specific T-cell response following the third dose was evident in the majority of transplant recipients.

CONCLUSIONS

An homologous third booster dose of the BNT162b2 vaccine gave overall consistent tolerability and a good safety profile, while eliciting humoral and cellular immune responses.

SARS-CoV-2 in Kidney Transplant Recipients: A Systematic Review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global healthcare crisis. Kidney transplant (KTx) patients and the patients with chronic kidney disease are two of the most vulnerable populations to the risks of coronavirus disease 2019 (COVID-19). A systematic literature search on PubMed and Web of Science was conducted. We analyzed published case reports, case series and articles on COVID-19’s clinical presentation, management, outcomes and vaccination among kidney transplant recipients. A total of 33 studies were included in the study, which included 1676 KTx recipients and 108 waiting list patients infected with COVID-19. These studies reported the clinical presentation, management and immunosuppressive adjustment among the KTx recipients. The remaining studies focused on other aspects, such as vaccination and transplantation, during the COVID-19 pandemic. Mortality due to COVID-19 was observed to be the highest for KTx recipients, followed by patients on hemodialysis, and lowest in the general population. There is no definitive treatment of COVID-19 yet, and managing transplant patients is enigmatic of this: the treatment is based on symptom management. There is an urgent need for guidelines on managing kidney transplant recipients and immunosuppressive adjustments for the course of COVID-19 treatment.

SARS-COV-2 vaccination with BNT162B2 in renal transplant patients: Risk factors for impaired response and immunological implications

Solid organ transplant patients are at a higher risk for poor CoronaVirus Disease-2019 (COVID-19)-related outcomes and have been included as a priority group in the vaccination strategy worldwide. We assessed the safety and efficacy of a two-dose vaccination cycle with mRNA-based COVID-19 vaccine (BNT162b2) among 82 kidney transplant outpatients followed in our center in Rome, Italy. After a median of 43 post-vaccine days, a SARS-CoV-2 anti-Spike seroprevalence of 52.4% (n = 43/82) was observed. No impact of the vaccination on antibody-mediated rejection or graft function was observed, and no significant safety concerns were reported. Moreover, no de novo HLA-donor-specific antibodies (DSA) were detected during the follow-up period. Only one patient with pre-vaccination HLA-DSA did not experience an increased intensity of the existing HLA-DSA. During the follow-up, only one infection (mild COVID-19) was observed in a patient after receiving the first vaccine dose. According to the multivariable logistic regression analysis, lack of seroconversion after two-dose vaccination independently associated with patient age ≥60 years (OR = 4.50; P = .02) and use of anti-metabolite as an immunosuppressant drug (OR = 5.26; P = .004). Among younger patients not taking anti-metabolites, the seroconversion rate was high (92.9%). Further larger studies are needed to assess the best COVID-19 vaccination strategy in transplanted patients.

Antibody response after a booster dose of SARS-CoV-2 vaccine in liver transplant recipients and those with chronic liver diseases

INTRODUCTION AND OBJECTIVES

Lower antibody (Ab) responses after SARS-CoV-2 vaccination have been reported in liver transplant (LT) recipients and those with chronic liver diseases (CLD). The role of a booster dose in those with poor responses to initial vaccination is not well defined.

METHODS

In this prospective study, we determined antibody (Ab) response to spike protein after a booster dose in LT recipients and those with chronic liver diseases (CLD) with and without cirrhosis after they had a poor response to an initial standard regimen.

RESULTS

Of the 80 patients enrolled, 45 had LT, and 35 had CLD (18 with cirrhosis). A booster dose was given at a median of 138.5 days after the completion of the standard regimen. After the booster dose, 58 (73%, 31 LT, 27 CLD) had good response (≥250 U/mL), and 22 (28%, 14 LT, and 8 CLD) had poor response (7 undetectable and 15 with low Ab levels). No patient had any serious adverse events. The antibody responses were lower in those who had undetectable Ab (80 U/mL) than those who had low levels of Ab (0.80-249 U/mL) after the standard vaccination regimen (42% vs. 87%, p=0.0001). The antibody responses after homologous and heterologous booster doses were similar.

CONCLUSIONS

We have shown that a booster dose will enhance Ab responses in LT recipients and those with CLD who had poor responses after an initial vaccine regimen.

Predictive Factors for Humoral Response After 2-dose SARS-CoV-2 Vaccine in Solid Organ Transplant Patients

Background

A weak immunogenicity has been reported in solid organ transplant (SOT) recipients after 2 doses of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine. The aim of this retrospective study was to identify the predictive factors for humoral response in SOT patients.

Methods

Three hundred and ninety-three SOT patients from our center with at least 4 wk of follow-up after 2 doses of mRNA-based vaccine were included in this study. Anti-SARS-Cov-2 spike protein antibodies were assessed before and after vaccination.

Results

Anti-SARS-CoV-2 antibodies were detected in 34% of the patients: 33.7% of kidney transplant patients, 47.7% of liver transplant patients, and 14.3% of thoracic transplant patients (P = 0.005). Independent predictive factors for humoral response after vaccination were male gender, a longer period between transplantation and vaccination, liver transplant recipients, a higher lymphocyte count at baseline, a higher estimated glomerular filtration rate and receiving the tacrolimus + everolimus ± steroids combination. Conversely, the nondevelopment of anti-SARS-CoV-2 antibodies after vaccination was associated with younger patients, thoracic organ recipients, induction therapy recipients, and tacrolimus + mycophenolic acid ± steroids recipients.

Conclusions

The immunosuppressive regimen is a modifiable predictive factor for humoral response to SARS-CoV-2 vaccine.

Breakthrough COVID-19 after SARS-CoV-2 vaccination in solid organ transplant recipients: An analysis of symptomatic cases and monoclonal antibody therapy

BACKGROUND

Solid organ transplant (SOT) recipients are at increased risk for complications from SARS-CoV-2 infection. Little is known regarding clinical course and outcomes of breakthrough COVID-19 in the fully vaccinated SOT population. We sought to describe our cohort of SOT recipients who developed symptomatic breakthrough COVID-19 after full vaccination.

METHODS

We conducted a retrospective review of SOT recipients diagnosed with COVID-19 at least 14 days after completing SARS-CoV-2 vaccination. Patients were analyzed according to those presenting with mild-to-moderate and severe COVID-19, respectively. We described presenting characteristics, COVID-19 therapy, and analyzed outcomes including emergency department (ED) visits, hospitalization, and intensive care unit (ICU) admission.

RESULTS

Thirty-five patients met inclusion criteria. These had a mean age of 60.8 years and kidney transplant was the most common SOT type. Five patients presented with severe COVID-19 at diagnosis, all requiring hospitalization without ICU admission. From the 30 patients who presented with mild-to-moderate infection, 28 received casirivimab-imdevimab. Four of these 28 (14.3%) had an ED visit, with one requiring hospital admission (3.4%). No patients required ICU admission.

CONCLUSION

Breakthrough COVID-19 may occur in SOT recipients after full vaccination, though they appear to have acceptable outcomes. Anti-spike monoclonal antibody therapy for eligible SOT patients may have mitigated clinical progression and improved the outcomes. Further study with large cohorts is warranted. This article is protected by copyright. All rights reserved.

Solid organ transplantations and COVID-19 disease

Tens of thousands of people worldwide became infected with severe acute respiratory syndrome coronavirus-2. Death rate in the general population is about 1%-6%, but this rate rises up to 15% in those with comorbidities. Recent publications showed that the clinical progression of this disease in organ recipients is more destructive, with a fatality rate of up to 14%-25%. We aimed to review the effect of the pandemic on various transplantation patients. Coronavirus disease 2019 (COVID-19) has not only interrupted the lives of waiting list patients’; it has also impacted transplantation strategies, transplant surgeries and broken donation chains. COVID-19 was directly and indirectly accountable for a 73% surplus in mortality of this population as compared to wait listed patients in earlier years. The impact of chronic immunosuppression on outcomes of COVID-19 remains unclear but understanding the immunological mechanisms related to the virus is critically important for the lifetime of transplantation and immune suppressed patients. It is hard to endorse changing anti-rejection therapy, as the existing data evaluation is not adequate to advise substituting tacrolimus with cyclosporine during severe COVID-19 disease.

COVID-19 in Immunocompromised Patients: A Systematic Review

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) was first identified as a novel coronavirus in Wuhan, Hubei province, central China, in December 2019, and is responsible for the 2019-to-present pandemic. According to the most recent data released by the World Health Organization, more than 200 million people have been infected by SARS-CoV-2 so far, and more than 4 million people died worldwide. Although our knowledge on SARS-CoV-2 and COVID-19 is constantly growing, data on COVID-19 in immunocompromised patients are still limited. The aim of the present systematic review is to describe clinical picture, disease severity, proposed treatment regimen, and response to vaccination in patients with different types and severity of immunosuppression.

COVID-19 in Patients with Glomerular Disease: Follow-Up Results from the IRoc-GN International Registry

Background

The acute and long-term effects of severe acute respiratory syndrome coronavirus 2 infection in individuals with GN are still unclear. To address this relevant issue, we created the International Registry of COVID-19 infection in GN.

Methods

We collected serial information on kidney-related and -unrelated outcomes from 125 GN patients (63 hospitalized and 62 outpatients) and 83 non-GN hospitalized patients with coronavirus disease 2019 (COVID-19) and a median follow-up period of 6.4 (interquartile range 2.3-9.6) months after diagnosis. We used logistic regression for the analyses of clinical outcomes and linear mixed models for the longitudinal analyses of eGFR. All multiple regression models were adjusted for age, sex, ethnicity, and renin-angiotensin-aldosterone system inhibitor use.

Results

After adjustment for pre-COVID-19 eGFR and other confounders, mortality and AKI did not differ between GN patients and controls (adjusted odds ratio for AKI=1.28; 95% confidence interval [CI], 0.46 to 3.60; P=0.64). The main predictor of AKI was pre-COVID-19 eGFR (adjusted odds ratio per 1 SD unit decrease in eGFR=3.04; 95% CI, 1.76 to 5.28; P<0.001). GN patients developing AKI were less likely to recover pre-COVID-19 eGFR compared with controls (adjusted 6-month post-COVID-19 eGFR=0.41; 95% CI, 0.25 to 0.56; times pre-COVID-19 eGFR). Shorter duration of GN diagnosis, higher pre-COVID-19 proteinuria, and diagnosis of focal segmental glomerulosclerosis or minimal change disease were associated with a lower post-COVID-19 eGFR.

Conclusions

Pre-COVID-19 eGFR is the main risk factor for AKI regardless of GN diagnosis. However, GN patients are at higher risk of impaired eGFR recovery after COVID-19-associated AKI. These patients (especially those with high baseline proteinuria or a diagnosis of focal segmental glomerulosclerosis or minimal change disease) should be closely monitored not only during the acute phases of COVID-19 but also after its resolution.

Weak antibody response to three doses of mRNA vaccine in kidney transplant recipients treated with belatacept

Poor responses to mRNA COVID-19 vaccine have been reported after 2 vaccine injections in kidney transplant recipients (KTRs) treated with belatacept. We analyzed the humoral response in belatacept-treated KTRs without a history of SARS-CoV-2 infection who received three injections of BNT162b2-mRNA COVID-19 vaccine. We also investigated vaccine immunogenicity in belatacept-treated KTRs with prior COVID-19 and characterized symptomatic COVID-19 infections after the vaccine in belatacept-treated KTRs. Among the 62 belatacept-treated KTRs (36 [58%] males), the median age (63.5 years IQR [51-72]), without COVID-19 history, only four patients (6.4%) developed anti-SARS-CoV-2 IgG with low antibody titers (median 209, IQR [20-409] AU/ml). 71% were treated with mycophenolic acid and 100% with steroids in association with belatacept. In contrast, in all the 5 KTRs with prior COVID-19 history, mRNA vaccine induced a strong antibody response with high antibody titers (median 10 769 AU/ml, IQR [6410-20 069]) after two injections. Seroprevalence after three-vaccine doses in 35 non-belatacept-treated KTRs was 37.1%. Twelve KTRs developed symptomatic COVID-19 after vaccination, including severe forms (50% of mortality). Breakthrough COVID-19 occurred in 5% of fully vaccinated patients. Administration of a third dose of BNT162b2 mRNA COVID-19 vaccine did not improve immunogenicity in KTRs treated with belatacept without prior COVID-19. Other strategies aiming to improve patient protection are needed.

SARS-CoV-2 infection in liver transplant recipients: A complex relationship

The recent manuscript reviewed investigations involving liver damage in coronavirus disease 2019 (COVID-19) patients, and COVID-19 in patients with previous chronic hepatological diseases, such as patients with liver graft. The literature presents several conflicting results concerning the anti-SARS-CoV-2 response in patients with solid organ transplants, in liver transplant recipients. Therefore, we would like to humbly state a few points for consideration involving liver transplant recipients and COVID-19, such as the time since transplantation, comorbidities, and immunosuppressive regimens.

Discordance Between SARS-CoV-2-specific Cell-mediated and Antibody Responses Elicited by mRNA-1273 Vaccine in Kidney and Liver Transplant Recipients

Supplemental Digital Content is available in the text.

Severe acute respiratory syndrome coronavirus 2–specific cell-mediated immunity (SARS-CoV-2-CMI) elicited by mRNA-based vaccines in solid organ transplant (SOT) recipients and its correlation with antibody responses remain poorly characterized.

Serological Response to the BNT162b2 COVID-19 mRNA Vaccine in Adolescent and Young Adult Kidney Transplant Recipients

BACKGROUND

Initial reports in adult kidney transplant recipients (KTR) indicate low immunogenicity after 2 doses of the BNT162b2 COVID-19 mRNA vaccine. We describe the immunogenicity of this vaccine compared to the serologic response in naturally infected COVID-19 positive adolescent and young adult KTR.

METHODS

For this prospective observational study, the study group included 38 KTR who received 2 doses of the tested vaccine, and the control group included 14 KTR who had a previous polymerase chain reaction-confirmed COVID-19 infection.

RESULTS

The mean age was 18 ± 3 y. Positive serologic responses were observed in 63% and 100% of the study and control groups, respectively (P = 0.01). Antibody titers were almost 30-fold higher in the control than the study group (median [interquartile range (IQR)]: 2782 [1908-11 000] versus 100.3 [4.7-1744] AU/mL, P < 0.001), despite the longer time from the COVID-19 infection to serologic testing compared to time from vaccination (median [IQR]: 157.5 [60-216] versus 37 [20.5-53] d, P = 0.011). Among vaccinated patients, higher proportions of those seronegative than seropositive were previously treated with rituximab (50% versus 8%, P = 0.01). Time from the second vaccine dose to serologic testing was longer in seropositive than seronegative patients (median [IQR]: 24.5 [15-40] versus 46 [27-56] d, P = 0.05). No patient developed symptomatic COVID-19 disease postvaccination.

CONCLUSIONS

The BNT162b2 COVID-19 mRNA vaccine yielded higher positive antibody response in adolescent and young adult KTR than previously reported for adult KTR. Antibody titers after vaccination were significantly lower than following COVID-19 infection. Longer time may be required to mount appropriate humoral immunity to vaccination in KTR.

Update on Coronavirus 2019 Vaccine Guidelines for Transplant Recipients

The coronavirus disease 2019 (COVID-19) vaccine and its utility in solid organ transplantation need to be timely revised and updated. These guidelines have been formalized by the experts—the apex technical committee members of the National Organ and Tissue Transplant Organization and the heads of transplant societies—for the guidance of transplant communities. We recommend that all personnel involved in organ transplantation should be vaccinated as early as possible and continue COVID-19–appropriate behavior despite a full course of vaccination. For specific guidelines of recipients, we suggest completing the full schedule before transplantation whenever the clinical condition permits. We also suggest a single dose, rather than proceeding unvaccinated for transplant, in case a complete course is not feasible. If vaccination is planned before surgery, we recommend a gap of at least 2 weeks between the last dose of vaccine and surgery. For those not vaccinated before transplant, we suggest waiting 4 to 12 weeks after transplant. For the potential living donors, we recommend the complete vaccination schedule before transplant. However, if this is not feasible, we suggest receiving at least a single dose of the vaccine 2 weeks before donation. We suggest that suitable transplant patients and those on the waiting list should accept a third dose of the vaccine when one is offered to them. We recommend that organs from a deceased donor with suspected/proven vaccine-induced thrombotic thrombocytopenia should be avoided and are justified only in cases of emergency situations with informed consent and counseling.

COVID-19 en receptores de trasplante renal: ¿qué hemos aprendido tras 18 meses de pandemia?

La infección por el SARS-CoV-2 (COVID-19) ha supuesto un importante impacto en la actividad trasplantadora en nuestro país. En su condición de paciente inmunodeprimido y con frecuentes comorbilidades, era esperable que la mortalidad y el riesgo de complicaciones asociadas a la COVID-19 en el receptor de trasplante renal (TR) fueran mayores en comparación con la población general, si bien la información al respecto en los primeros meses de la pandemia era muy limitada. Desde marzo de 2020 hemos mejorado rápidamente nuestro conocimiento acerca de la epidemiología, características clínicas y manejo de la COVID-19 post-trasplante. La presente revisión pretende recopilar la información disponible a julio de 2021 en respuesta a una serie de cuestiones relevantes: ¿cómo se manifiesta clínicamente la infección por SARS-CoV-2 en receptores de TR?, ¿cuáles son sus factores pronósticos?, ¿es más grave la COVID-19 en el contexto del TR respecto a los pacientes inmunocompetentes?, ¿de qué opciones de tratamiento antiviral disponemos actualmente para el receptor de TR?, ¿cuál es la experiencia disponible con los tratamientos inmunomoduladores? y, por último, ¿son eficaces las vacunas frente a la COVID-19 basadas en ARN mensajero en esta población?. A pesar de los avances realizados aún son varios los aspectos que debemos mejorar en nuestro abordaje de la infección por SARS-CoV-2 en el ámbito específico del TR.

Review of Early Immune Response to SARS-CoV-2 Vaccination Among Patients With CKD

The effects of the coronavirus disease-2019 (COVID-19) pandemic, particularly among those with chronic kidney disease (CKD), who commonly have defects in humoral and cellular immunity, and the efficacy of vaccinations against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are uncertain. To inform public health and clinical practice, we synthesized published studies and preprints evaluating surrogate measures of immunity after SARS-CoV-2 vaccination in patients with CKD, including those receiving dialysis or with a kidney transplant. We found 35 studies (28 published, 7 preprints), with sample sizes ranging from 23 to 1140 participants and follow-up ranging from 1 week to 1 month after vaccination. Seventeen of these studies enrolled a control group. In the 22 studies of patients receiving dialysis, the development of antibodies was observed in 18% to 53% after 1 dose and in 70% to 96% after 2 doses of mRNA vaccine. In the 14 studies of transplant recipients, 3% to 59% mounted detectable humoral or cellular responses after 2 doses of mRNA vaccine. After vaccination, there were a few reported cases of relapse or de novo glomerulonephritis, and acute transplant rejection, suggesting a need for ongoing surveillance. Studies are needed to better evaluate the effectiveness of SARS-CoV-2 vaccination in these populations. Rigorous surveillance is necessary for detection of long-term adverse effects in patients with autoimmune disease and transplant recipients. For transplant recipients and those with suboptimal immune responses, alternate vaccination platforms and strategies should be considered. As additional data arise, the NephJC COVID-19 page will continue to be updated (http://www.nephjc.com/news/covid-vaccine).

Discordant Virus-Specific Antibody Levels, Antibody Neutralization Capacity, and T-cell Responses Following 3 Doses of SARS-CoV-2 Vaccination in a Patient With Connective Tissue Disease

We report a patient with connective tissue disease who developed modest severe acute respiratory syndrome coronavirus 2 receptor binding domain–specific antibody levels and a lack of neutralization capacity, despite having received 3 mRNA coronavirus disease 2019 vaccines and holding anti-B-cell therapy for >7 months before vaccination. The patient developed virus-specific T-cell responses.

Severe COVID-19 by SARS-CoV-2 Lineage B.1.1.7 in Vaccinated Solid-Organ Transplant Recipients: New Preventive Strategies Needed to Protect Immunocompromised Patients

BACKGROUND

Solid-organ transplant (SOT) recipients are at a high risk of severe COVID-19, and are priority for vaccination. Here, we describe three cases of severe COVID-19 caused by SARS-CoV-2 B.1.1.7 lineage in vaccinated SOT recipients.

METHODS

Three SOT patients were hospitalized in the Policlinico Hospital of Bari (southern Italy) and underwent nasopharyngeal swabs for molecular detection of SARS-CoV-2 genes and spike protein mutations by real-time PCR. One sample was subjected to whole-genome sequencing.

RESULTS

One patient was a heart transplant recipient and two were kidney transplant recipients. All were hospitalized with severe COVID-19 between March and May 2021. Two patients were fully vaccinated and one had received only one dose of the BNT162b2 mRNA vaccine. All the patients showed a high viral load at diagnosis, and molecular typing revealed the presence of B.1.1.7 lineage SARS-CoV-2. In all three cases, prolonged viral shedding was reported.

CONCLUSIONS

The three cases pose concern about the role of the B.1.1.7 lineage in severe COVID-19 and about the efficacy of COVID-19 vaccination in immunocompromised patients. Protecting immunocompromised patients from COVID-19 is a challenge. SOT recipients show a suboptimal response to standard vaccination, and thus, an additive booster or a combined vaccination strategy with mRNA, protein/subunit, and vector-based vaccines may be necessary. This population should continue to practice strict COVID-19 precautions post-vaccination, until new strategies for protection are available.

Interpreting and addressing suboptimal immune responses after COVID-19 vaccination in solid-organ transplant recipients

Transplant recipients were excluded from the initial clinical trials determining safety and efficacy of the landmark COVID-19 vaccines. Further, there is increasing evidence that immunosuppressed transplant recipients have a blunted antibody response to COVID-19 vaccination. In a concerning report by Sattler et al. in this issue of the JCI, kidney transplant recipients not only lacked a humoral response following two doses of Pfizer BNT162b2, but also displayed substantial impairment of the cellular response to SARS-CoV-2 antigens. This Commentary addresses potential strategies for transplant providers to evaluate and augment vaccine immunogenicity given the likelihood that COVID-19 will remain a world-wide threat to the health of transplant recipients.

Implications of defective immune responses in SARS-CoV-2 vaccinated organ transplant recipients

Organ transplant patients have poor immune responses to COVID-19 vaccines; thus designing vaccine strategies to protect this vulnerable population from SARS-CoV-2 infection is crucial.

[COVID-19 vaccination in dialysis and kidney transplant patients]

Au cours de la COVID-19, la dialyse et la transplantation rénale ont été identifiées comme d’importants facteurs de risque de développer une forme sévère de la maladie. La réponse immunitaire humorale post-infection est durable. Cependant, après vaccination, celle-ci apparaît plus limitée, tant en termes de taux de réponse (séropositivité post-vaccination) qu’en termes de taux quantitatif d’anticorps. Alors que les patients dialysés ont un taux de réponse de 80–95 % en fonction des études, la réponse est particulièrement faible chez les patients transplantés rénaux, avec des taux de séropositivité de 30–50 %, et notamment s’ils sont traités par bélatacept (environ 5 % de réponse). Ces éléments ont poussé à proposer des schémas vaccinaux alternatifs en France, avec notamment l’utilisation d’une 3^e injection de vaccin ARNm. Malgré ces résultats, de nombreuses questions sur la vaccination des insuffisants rénaux restent en suspens, concernant notamment la qualité des réponses cellulaires (encore peu étudiées), la durabilité des réponses post-vaccinales, et surtout l’efficacité clinique des vaccins.