Update on SARS-CoV-2 Vaccination for Kidney Transplant Recipients

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has had a significant impact on transplantation, with mortality rates in transplant recipients ranging from 10% to 20% (1). Although some antiviral and anti-inflammatory therapies for COVID-19 have become available, they need to be given within a short time window during the course of illness to be effective (2, 3). Thus, the recent US Food and Drug Administration (FDA) Emergency Use Authorization of highly efficacious mRNA-based SARS-CoV-2 vaccines by Pfizer/BioNTech and Moderna provides hope for reducing infection rates (4).

Both the Pfizer/BioNTech and Moderna vaccines were rigorously evaluated in >70,000 individuals and found to have an efficacy of 94.1%−95% in phase 3 placebo-controlled trials (5, 6). Local and systemic adverse events, such as fever, chills, and headache, occurred and were more common after the second dose (5, 6). Immunocompromised patients, including kidney or kidney-pancreas transplant recipients, were not included in the two large trials, and therefore, safety and efficacy data are lacking. Nevertheless, despite the lack of vaccine data, the Centers for Disease Control and Prevention (CDC) Advisory Committee on Immunization Practices (ACIP) stated that immunocompromised patients can receive the vaccine after being counseled regarding risks and benefits, lack of data, and the potential for lower efficacy (7).

Experts with the American Society of Transplantation (AST) have reviewed the available information for the safety and efficacy of mRNA vaccination and recommended that transplant candidates, recipients, and their household contacts receive the vaccine when it is available to them (8). This is consistent with recommendations from other transplant societies, such as the Canadian Society of Transplantation (CST) and The Transplantation Society (TTS) (9). Although mRNA vaccines have not specifically been tested in kidney or kidney-pancreas transplant recipients, mRNA technology has been used in investigational vaccines for cancer and other infectious diseases. Given the relatively high mortality from COVID-19 in transplant patients, it is clear that the benefits of vaccination outweigh any theoretical risks of systemic or off-target effects, such as graft dysfunction. The efficacy of the vaccine is likely to be lower in transplant recipients than outlined in the trials; however, it is also likely that patients with a functioning transplant will derive at least partial benefit.

The AST guidance also outlines issues regarding timing of vaccination in relation to transplant immunosuppression in order to maximize immune responses (8). Vaccines should be given prior to transplant when possible. In the post-transplant setting, the SARS-CoV-2 vaccine can be given starting 1 month after transplant, although a longer time period is suggested if T or B cell ablation is given. It is also suggested to wait to start the vaccination series 90 days after developing COVID-19 or receipt of convalescent plasma or monoclonal antibody. Since no vaccine co-administration studies are available, it is reasonable to avoid giving other vaccines within 14 days of a SARS-CoV-2 vaccine. Importantly, since vaccination is a 2-dose series, deferring transplant to complete vaccination doses is not suggested as a routine (Table 1).

Table 1.

Recommendations for giving the SARS-CoV-2 vaccine in patients with kidney and kidney-pancreas transplants

View Table

The prioritization of kidney or kidney-pancreas transplant recipients is likely to occur in phase 1c, as defined by the CDC (7), in which several groups of high-risk individuals are noted. Some transplant recipients who are healthcare workers or other essential workers or reside in long-term care facilities may receive the vaccine sooner. A state-defined prioritization and distribution scheme, as well as vaccine availability, will likely define when transplant recipients are vaccinated. In addition, several other types of SARS-CoV-2 vaccines are under review or being developed and may become available in the future. The AST guidelines are updated as new information becomes available and provide an excellent “go-to” resource for transplant professionals on SARS-CoV-2 vaccination.