EXPERIMENTAL AND CLINICAL TRANSPLANTATION

The COVID-19 pandemic has disrupted health systems worldwide, including solid-organ donation and transplant programs.^1,2 Early in the outbreak period, transplant societies recommended suspending living kidney transplant programs, with deceased donor kidney transplant suggested to be reserved for lifesaving cases.^3,4 The cost of this decision was a decrease in transplant numbers. The number of transplant procedures decreased 17% in 2020 compared with 2019.⁵ Because of the lifesaving nature of heart, liver, and lung transplant, these activities continued in patients with an expected survival of <6 months.⁶ The main concerns for both donors and recipients were (1) the probability of COVID-19 transmission from living or deceased donors to recipients during transplant, (2) the probability of COVID-19 positivity in a recipient just before or after transplant, and (3) the effect of COVID-19 on donor and organ survival in the early period after transplantation. After the start of the pandemic, the benefit-to-risk ratio for delaying elective transplantation became another concern. In this situation, the question was how best to proceed with lifesaving transplants while balancing the risks posed by COVID-19.⁷ As widespread testing for transplant donors and recipients became available, transplant rates began to increase. However, patients who are on wait lists for kidney transplant have a higher risk of hospitalization and death compared with patients who are transplanted. Although the risk of COVID-19 infection from an infected living or deceased donor remains unclear at this time, data obtained thus far have resulted in some recommendations. However, no significant associations have been found between organ transplantation and SARSCoV- 2 transmission, except for lung transplant.³ Since the beginning of the pandemic, the transplantation center at Ba?kent University, after initial assessments of the course of COVID-19 in transplant patients, has carefully continued renal and hepatic transplant activities, but with some interruptions. Routine donor screening worldwide during the COVID-19 era include the following measures: (1) all organ transplant donor candidates (living or deceased) should be screened for COVID-19; (2) the history of the donor candidate should be evaluated in terms of COVID-19 (if possible, by an investigation of official data); (3) to evaluate the radiological lung involvement of the donor candidates, chest radiographs and, if necessary, computed tomography should be used; (4) living donor candidates should be informed to use protective measures (face masks, maintaining distance, and hand hygiene) for at least 2 weeks before the transplant procedures; (5) patients should self-quarantine for 14 days before the procedures operation (recommended by some authorities but is not mandatory); and (6) living donor candidates should be encouraged to complete their primary vaccination schedule at least 2 weeks before transplant. In addition to the measures mentioned above, experiences at the Ba?kent University Transplantation Center since the beginning of the pandemic resulted in some practical recommendations for COVID-19 safe organ donation.

Living Donor Screening Before Transplant

Ba?kent University recommendations will be presented in terms of 4 topics based on clinical requirements: (1) living donors without a known COVID-19 history, (2) living donors with a known COVID-19 history, (3) SARS-CoV-2 polymerase chain reaction (PCR)-positive living donor candidates (diagnosed during the screening procedure), and (4) living donors who have close contact with a SARS CoV-2-positive person. The recommendations were based on clinical requirements and data from available guidelines, literature, and the Ba?kent University Transplantation Center’s experience.

Living donors without a known COVID-19 history

The history of the donor candidate should be evaluated in terms of COVID-19 (by means of official data investigation and/or history obtained from candidate). Testing with PCR and lung imaging should be ordered in addition to evaluation of the donor for potential contact and disease symptoms within 48 to 72 hours (preferably within the last 24 hours) prior to surgery. Transplantation from living donors with positive PCR during screening is not recommended.

Living donors with a known COVID-19 history

Donor candidates who had COVID-19 at least 21 days before the operation and have 2 negative PCRs tests are eligible for organ donation. A decision to conduct the transplant procedure should be made by considering the benefits versus the risks. The potential risk of perioperative morbidity and mortality in the first 6 to 8 weeks following COVID-19 for the candidate should be considered.^8,9

SARS-CoV-2 polymerase chain reaction-positive living donor candidates (diagnosed during the screening procedure)

There may be 3 situations regarding the PCR test results. (1) For patients with COVID-19 shown within 21 days before the operation, transplantation should be avoided due to the risks for both candidate and recipient. Transplantation should be avoided due to the risk of transmission to the recipient and the potential risk of perioperative morbidity and mortality for the donor candidate. (2) For patients who are recovered from COVID-19 within 21 to 90 days before the operation, the decision for surgery should be made by weighing the benefits and the risks. The risk of transmission of the disease is considered very low, since PCR positivity may not indicate active disease and contagiousness in candidates whose complaints have completely passed. However, careful consideration should be made because of the possibility of reinfection, particularly in the presence of new variants. The potential risk of perioperative morbidity and mortality in the first 6 weeks after a positive SARSCoV- 2 test for candidates should be kept in mind. (3) For patients who have recovered from COVID-19 at least 90 days before the operation, repeated positive PCR tests >90 days after the initial infection should be considered as potentially true positives as it may reflect reinfection. Transplantation should be avoided due to the risk for both candidate and recipient.

Living donors who had close contact with a COVID-19 patient

For donor candidates who had close contact with a COVID-19 patient, the transplant should be postponed for 14 days. Candidates who are asymptomatic during this period are eligible for transplantation. Negative PCR results (2 negative test results) at the end of the period is mandatory.

Deceased Donor Screening Before Transplant

Recommendations from the Ba?kent University are presented in terms of 3 topics based on clinical requirements regarding deceased donors: (1) deceased donors without a known COVID-19 history, (2) deceased donors with a known COVID-19 history, and (3) deceased donors with a SARS-CoV-2 PCR positive result (diagnosed during the screening procedure)

Deceased donors without a known COVID-19 history

The history of the deceased donor candidate should be evaluated in terms of COVID-19 (by means of official data investigation and/or history obtained from the donor’s relatives). Donors should be screened epidemiologically, including for known contacts, and by clinical history of known or suspected COVID-19 infection and COVID-19 vaccination history. PCR testing of nasopharyngeal specimens should be performed within 72 hours prior to recovery of organ (preferably as soon as possible to the operation). Two negative results are not mandatory but preferred. For deceased donors, radiological findings alone should not be considered as evidence of COVID-19; the PCR test results and the donor’s clinical history should be evaluated together.

Deceased donors with a known COVID-19 history

Donors who are at least 21 days past the onset of COVID-19 and have complete resolution of symptoms and negative PCR tests are eligible to be donors. A deceased donor with a normal immune system, had asymptomatic or mild symptoms of COVID-19, and have completely resolved symptoms can be a donor in cases of urgent need for transplant. However, transplant can occur at least 10 to 14 days after diagnosis and if the PCR test is negative (for nonpulmonary organs). A lower respiratory tract sample should be obtained for lung donors.^10,11

Deceased donors with a SARS-CoV-2 polymerase chain reaction-positive result (diagnosed during the screening procedure)

If the deceased donor has recovered clinically but still shows a positive test, the urgency of the transplant and the possible mortality of the recipient should be considered before proceeding with the transplant. The safety of the recipient should be evaluated on a case-by-case basis. No test is 100% sensitive or specific and both false positive and false negative results may occur.

Pretransplant Recipient Screening

All potential organ recipients should be screened for COVID-19 before organ procurement by PCR test. Patients with active COVID-19 and/or signs or symptoms of other respiratory illnesses are generally deferred for transplant. Screening for COVID-19 is by nasopharyngeal swab. For patients with active COVID-19 infection, the optimal deferral period is not known. We suggest waiting until all symptoms have resolved and at least 2 PCR tests for SARSCoV- 2 show negative results.

General Measures

Preventive measures for organ transplant recipients are similar to those defined for the general population. All transplant candidates are eligible for COVID-19 vaccination, unless contraindicated. Priority should be given to vaccination of all transplant recipient candidates as a global policy to perform safer transplant activities.

The benefit-to-risk ratio for an individual living donor and transplant candidate should always be taken into consideration when making the final decision to perform a transplant. The priority of COVID-19 vaccination of recipient candidates is crucial. Although the immunogenicity and efficacy of COVID-19 vaccines are uncertain in transplant candidates, the potential for benefit from vaccination likely outweighs this uncertainty.¹² Timing of screening must be as close as possible to organ procurement.

Volume: 20 Issue: 8 August 2022 - Supplement - 4

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