SARS-CoV-2 Vaccine Mandates for Patients on the Kidney Transplant Waitlist

Measures to Increase Immunogenicity of SARS-CoV-2 Vaccines in Solid Organ Transplant Recipients: A Narrative Review

Purpose of review: To review the data on the immunogenicity of COVID-19 vaccines, administered by different strategies, in solid organ transplant recipients (SOTRs). Recent findings: COVID-19 booster vaccines were given to SOTRs as a widespread practice in many transplant centers, mostly as the third and/or fourth dose in an extended vaccine series, with a significantly improved humoral response compared with the initial two-dose scheme. However, one-third of SOTRs remained unresponsive, despite these boosters. Next steps: Vaccination with standard dosing remains the most feasible strategy for attaining protection against COVID-19. Additional booster doses and temporarily holding or reducing mycophenolate mofetil/mycophenolic acid may provide immunogenicity to vaccines, according to recent studies demonstrating some efficacy with these measures. Preexposure prophylaxis with monoclonal antibodies showed benefit in immunocompromised patients but is no longer recommended by the National Institutes of Health (NIH) due to diminished efficacy against Omicron and recent variants. Screening for the presence and titers of SARS-CoV-2-specific antibodies in SOTRs is not recommended in most clinical settings. T cell-based techniques are needed to evaluate vaccine efficacy and risk of infection. As SARS-CoV-2 continues to evolve, new vaccines based on conservative protein component/complexes of the COVID virus, in addition to its spike protein, are warranted to offer prolonged protection.

International Practices on COVID-19 Vaccine Mandates for Transplant Candidates

Background

The coronavirus disease 2019 (COVID-19) pandemic created unprecedented challenges for solid organ transplant centers worldwide. We sought to assess an international perspective on COVID-19 vaccine mandates and rationales for or against mandate policies.

Methods

We administered an electronic survey to staff at transplant centers outside the United States (October 14, 2021-January 28, 2022) assessing the reasons cited by transplant centers for or against implementing a COVID-19 vaccine mandate. Each responding center was represented once in the analysis.

Results

Respondents (N=90) represented 27 countries on five continents. Half (51%) of responding transplant center representatives reported implementing a COVID-19 vaccine mandate, 38% did not, and 12% were unsure. Staff at centers implementing a vaccine mandate cited efficacy of pretransplant vaccination versus post-transplant vaccination, importance for public health, and minimizing exposure of other patients as rationale for the mandate. Of centers with a mandate, the majority (81%) of the centers mandate vaccination regardless of prior SARS-CoV-2 infection status and regardless of prevaccination spike-protein antibody titer or other markers of prior infection. Only 27% of centers with a vaccine mandate for transplant candidates also extended a vaccine requirement to living donor candidates. Centers not implementing a vaccine mandate cited concerns for undue pressure on transplant candidates, insufficient evidence to support vaccine mandates, equity, and legal considerations.

Conclusions

The approach to pretransplant COVID-19 vaccination mandate policies at international transplant centers is heterogeneous. International transplant centers with a vaccine mandate were more willing to extend vaccine requirements to candidates' support persons, cohabitants, and living donors. Broader stakeholder engagement to overcome vaccine hesitancy across the world is needed to increase the acceptance of pretransplant COVID-19 vaccination to protect the health of transplant patients.