Seroconversion rates in kidney transplant recipients following SARS-CoV-2 vaccination and its association with immunosuppressive agents: a systematic review and meta-analysis

Seroconversion in liver and intestine transplant patients after one, two or three doses of adenoviral vector vaccines against SARS-CoV-2. Single center experience in Argentina

BACKGROUND

The capacity of different anti-SARS-CoV-2 vaccines to elicit immune response is not equivalent in the healthy population compared to chronically immunosuppressed patients. Most of the reports available to assess the effects of anti-SARS-CoV-2 vaccines on solid organ transplant recipients (SOTR) were performed using mRNA-based vaccines.

OBJECTIVE

This study aims to assess the seroconversion rate in a cohort of liver and liver- intestinal transplant patients after vaccination with the non-replicative vector-based vaccines after transplantation used in our country, Argentina (rAd26-rAd5 (Sputnik V) and ChAdOx11 nCoV-19 (AZD1222) (Astra Zeneca-Oxford).

METHODS

One hundred and three (103) liver and liver-intestinal transplant recipients were enrolled. Patients with previous PCR-confirmed COVID19 were excluded, therefore 77 were finally included for analysis; 75 were liver transplant recipients, 1 was a combined liver-intestine and 1 a multivisceral transplant. All received their first vaccine dose between March and June 2021; 66,2% males, and the mean age was 56,3 years. All patients have a post-transplant follow up longer than 1 year (mean 6.6 years, median 5 years, range 1-23 years). Immune response after first, second and third doses were determined using three different spike (S)-S commercial ELISA kits and an in-house made anti nucleocapsid-protein (N) ELISA.

RESULTS

Following the three doses, 57.1 % (44/77) of the patients seroconverted, while 33/77 (42.9 %) did not present anti-SARS-CoV-2 antibodies. The seroconversion rate was different for each dose. We found that 5/27 (18.5 %) of transplant patients seroconverted after a single dose; 18/29 pts (62.0 %) had anti-SARS-Cov-2 antibodies after the second doses; and 18/21 pts (85.7 %) reached the seroconversion after the third doses. The proportion of seroconversion was significantly increased in the second doses regardless the response observed after the first doses (p = 0.012, Fisher's exact test), particularly when two doses of ChAdOx11 vaccine was administrated (p = 0.040, Chi-square). However, the comparisons of seroconversion rate between Sputnik V and ChAdOx11 vaccines showed no differences after the different vaccination doses. No significant statistical difference in patient́s gender, age, comorbidities, type of vaccine, post-transplant, or maintenance immunosuppressive therapy was found between responders and non-responders.

CONCLUSION

Despite having a lower seroconversion rate compared to the general population, viral-vector vaccines benefit SOTR patients increasing the seroconversion rate using at least two doses of vaccine. These results support the concept of developing tailor-made vaccination guidelines for this specific population. This analysis provides further support to safety and efficacy of viral-vector vaccines in liver and liver-intestine transplant patients.

Heterologous Versus Homologous COVID-19 Boosters: Immune Response Outcomes in Renal Transplant Recipients

We aimed to investigate the immune responses to homologous and heterologous COVID-19 booster vaccinations in renal transplant recipients (RTRs) and to identify factors affecting these responses. In this prospective multicenter observational study, we measured the antibody kinetics of 90 RTRs using the chemiluminescent microparticle immunoassay method. The mean age of participants was 45.2 ± 11.4 years, with 35.6% being female. On the 42nd day after the first vaccine dose, the median antibody level was 16.7 (IQR 2.5-249.5) AU/mL, and the seropositivity rate was 60% (n = 36). Mycophenolic acid (MFA) (OR: 0.087, 95% CI: 0.024-0.311) and ACE inhibitor use (OR: 0.203, 95% CI: 0.052-0.794) were identified as independent factors affecting seropositivity. Patients who received the Pfizer/BioNTech booster had significantly higher antibody levels compared to those who received the CoronaVac/Sinovac booster (p = 0.021). Additionally, a significantly higher rate of COVID-19 positivity was observed among patients who received the CoronaVac/Sinovac booster (p = 0.031). Heterologous COVID-19 booster vaccination is significantly more effective than homologous inactivated booster vaccination in enhancing immune responses and preventing new infections in RTRs. MFA and ACE inhibitor usage were independent factors affecting seropositivity. Additional COVID-19 vaccine doses are needed in this patient group.

Living During COVID-19 While Immunocompromised: A Patient and Physician Perspective from France

This article is co-authored by a kidney transplant recipient and her nephrologist. By sharing her personal experience of the coronavirus disease 2019 (COVID-19) pandemic, the patient illustrates the concerns of immunocompromised patients during this unprecedented health crisis. She describes the difficulties encountered at work, the omnipresent protective measures, and the need for appropriate information. The nephrologist, who follows a cohort of over 1700 kidney transplant recipients, recounts the medical team's struggle to protect their vulnerable patients against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as a veritable succession of hopes and disappointments. She describes the management of immunosuppression in kidney transplant recipients, the deployment of the COVID-19 vaccination program with the finding of poor immune responses in many patients including those receiving immunosuppressant drugs after kidney transplant, and the first use of prophylactic monoclonal antibodies. From both the patient's and the physician's perspectives, the COVID-19 pandemic has required continuous adaptation.

Humoral response to SARS-CoV-2 mRNA vaccine on in ABO blood type incompatible kidney transplant recipients treated with low-dose rituximab

We aimed to evaluate the humoral response after the second and third doses of SARS-CoV-2 mRNA vaccine in ABO blood type incompatible kidney transplant (KT) recipients treated with rituximab. This retrospective study conducted between June 2021 and June 2022 included 131 KT recipients and 154 nontransplant controls who had received mRNA vaccines. We compared the seropositivity (anti-SARS-CoV-2 spike IgG antibody titer ≥ 0.8 U/mL) after the second and third vaccinations. Furthermore, we evaluated the impact of pretransplant vaccination for seropositivity. Of the 131 KT recipients, 50 had received the third dose of mRNA vaccine. The antibody titer was significantly increased after the third dose of mRNA vaccine. The seropositivity rate after the third dose of mRNA vaccine increased from 36 to 70%. We observed no significant difference in seropositivity after the third dose of mRNA vaccine in ABO incompatibility, rituximab use, mycophenolate mofetil use, and age at KT. Of the nine recipients who had received the second or third dose of the mRNA vaccine prior to the KT, eight of the recipients were seropositive both before and after the KT. Our results suggest that ABO incompatibility or rituximab use was not significantly associated with seropositivity.