Comparing Humoral and Cellular Adaptive Immunity during Convalescent Phase of COVID-19 in Hemodialysis Patients and Kidney Transplant Recipients

Evaluation of the Humoral and Cellular Immune Response Post COVID-19 Infection in Kidney Transplant Recipients

Kidney transplantation is a major risk factor for severe forms of coronavirus disease 2019 (COVID-19). The dynamics and the persistence of the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in this immunocompromised population remain largely unknown. This study aimed to evaluate the persistence of humoral and cellular immune response in kidney transplant recipients (KTRs) and to establish whether immunosuppressive therapy influenced long-term immunity in this population. We report here the analysis of anti-SARS-CoV-2 antibodies and T cell-mediated immune responses in 36 KTRs compared to a control group who recovered from mild COVID-19. After a mean time of 5.22 ± 0.96 months post symptom onset for kidney transplant recipients, 97.22% of patients and 100% of the control group displayed anti-S1 immunoglobulin G SARS-CoV-2 antibodies (p > 0.05). No significant difference was reported in the median of neutralizing antibodies between the groups (97.50 [55.25-99] in KTRs vs. 84 [60-98] in control group, p = 0.35). A significant difference in SARS-CoV-2-specific T cell reactivity was found in the KTRs compared to the healthy controls. The levels of IFNγ release after stimulation by Ag1, Ag2 and Ag3 were higher in the control group compared to the kidney transplant group (p = 0.007, p = 0.025 and p = 0.008, respectively). No statistically significant correlation between humoral and cellular immunity was found in the KTRs. Our findings indicated that humoral immunity persisted similarly for up to 4 to 6 months post symptom onset in both the KTRs and the control group; however, T cell response was significantly higher in the healthy population compared to the immunocompromised patients.

Assessing T-Cell Immunity in Kidney Transplant Recipients with Absent Antibody Production after a 3rd Dose of the mRNA-1273 Vaccine

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.

Molnupiravir When Used Alone Seems to Be Safe and Effective as Outpatient COVID-19 Therapy for Hemodialyzed Patients and Kidney Transplant Recipients

Background: Molnupiravir demonstrated an in vitro antiviral activity against positive-sense RNA viruses, including SARS-CoV-2. The study aimed to present the results of outpatient molnupiravir use in kidney transplant recipients and hemodialysis patients during the first months of 2022 in Poland. Methods: The retrospective observational cohort study at one kidney transplant center included 36 patients diagnosed with COVID-19 with an automated nucleic acid amplification test on nasopharyngeal swab specimens. All patients received molnupiravir for home-based therapy at a dose of 800 mg every 12 h orally for 5 days. Both kidney transplant recipients (n = 16) and hemodialysis patients (n = 20) presented a lot of comorbidities with a Charlson comorbidity index of 4.1 and 5.1, respectively. Results: Patients presented with fever, cough, and weakness followed by muscle and joint pain. Five kidney transplant recipients experienced acute kidney injury with a rise in serum creatinine level from 0.4 to 1.9 mg/dL. No serious side effects of molnupiravir therapy or interactions with immunosuppressive medications were observed. Symptoms of COVID-19 improved rapidly or resolved within 24–48 h of starting treatment. Conclusion: The study suggests the safety and efficacy of molnupiravir therapy alone early after the onset of SARS-CoV-2 infection, but further investigations should be performed to confirm our preliminary results. To the best of the authors’ knowledge, it is the first published report on molnupiravir use in end-stage kidney disease (ESKD) patients on hemodialysis and the third concerning kidney transplant recipients.

Immunity after COVID-19 Recovery and Vaccination: Similarities and Differences

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is associated with a robust immune response. The development of systemic inflammation leads to a hyperinflammatory state due to cytokine release syndrome during severe COVID-19. The emergence of many new SARS-CoV-2 variants across the world deteriorates the protective antiviral immunity induced after infection or vaccination. The innate immune response to SARS-CoV-2 is crucial for determining the fate of COVID-19 symptomatology. T cell-mediated immunity is the main factor of the antiviral immune response; moreover, SARS-CoV-2 infection initiates a rapid B-cell response. In this paper, we present the current state of knowledge on immunity after COVID-19 infection and vaccination. We discuss the mechanisms of immune response to various types of vaccines (nucleoside-modified, adenovirus-vectored, inactivated virus vaccines and recombinant protein adjuvanted formulations). This includes specific aspects of vaccination in selected patient populations with altered immune activity (the elderly, children, pregnant women, solid organ transplant recipients, patients with systemic rheumatic diseases or malignancies). We also present diagnostic and research tools available to study the anti-SARS-CoV-2 cellular and humoral immune responses.

Duration of SARS-CoV-2 shedding and infectivity in the working age population: a systematic review and meta-analysis

BACKGROUND

During the COVID-19 pandemic, working age individuals have been implicated in sustaining the resurgence of SARS-CoV-2 infections, and multiple outbreaks have been observed in several occupational settings. In this regard, Occupational Physicians play a crucial role in the management of infected workers, particularly in the safe return-to-work of subjects after clinical resolution. To this end, knowledge of the duration of the infective phase in the working age population is essential, taking into account previous evidence suggesting that PCR positivity does not coincide with virus viability.

METHODS

A systematic review and meta-analysis, searching major scientific databases, including PubMed/MEDLINE, Scopus and Web of Science, were performed in order to synthesize the available evidence regarding the mean and maximal duration of infectivity compared to the mean and maximal duration of viral RNA shedding. A subgroup analysis of the studies was performed according to the immunocompetent or immunocompromised immune status of the majority of the enrolled individuals.

RESULTS

Twenty studies were included in the final qualitative and quantitative analysis (866 individuals). Overall, a mean duration of RT-PCR positivity after symptom onset was found equal to 27.9 days (95%CI 23.3-32.5), while the mean duration of replicant competent virus isolation was 7.3 days (95%CI 5.7-8.8). The mean duration of SARS-CoV-2 shedding resulted equal to 26.5 days (95%CI 21.4-31.6) and 36.3 days (95%CI 21.9-50.6), and the mean duration of SARS-CoV-2 infectivity was 6.3 days (95%CI 4.9-7.8) and 29.5 days (95%CI 12.5-46.5), respectively considering immunocompetent and immunocompromised individuals. The maximum duration of infectivity among immunocompetent subjects was reported after 18 days from symptom onset, while in immunocompromised individuals it lasted up to 112 days.

CONCLUSIONS

These findings suggest that the test-based strategy before return-to-work might not be warranted after 21 days among immunocompetent working age individuals, and could keep many workers out of occupation, reducing their livelihood and productivity.