INTRODUCTION
Since the initial outbreak in Wuhan, China, in December 2019, the
Coronavirus Disease 2019 (COVID-19) has spread across the world,
prompting a global pandemic. The disease caused by severe acute
respiratory syndrome coronavirus 2 (SARS-CoV-2) was seen as a pulmonary
and infectious problem (1).
The other conditions initially identified as risk factors for a severe
course of COVID-19 were cardiovascular disease, diabetes, and
hypertension. Only later in the process came the realization that kidney
disease is a leading risk factor for death. Ultimately, it appeared that
the population of patients with chronic kidney disease (CKD), especially
those treated with dialysis or transplantation, is one of the
highest-risk groups for hospitalization and death (2, 3, 4). Dialysis
and transplant patients represent a vulnerable population as all of them
suffer from multiple pre-existing medical conditions. COVID-19 causes
substantial mortality in both dialysis and kidney transplant population
due to their underlying chronic kidney disease and a high prevalence of
comorbid conditions such as hypertension, diabetes mellitus, and
cardiovascular disease (5, 6). Immunosuppressive treatment is also a
precondition for a more severe course of the disease. However, the
potential effect of its long-term use is a matter of debate (7, 8). Some
argue that the transplant patients might be at a higher risk of severe
infection resulting from their impaired immune system, while others
speculate that immunosuppressive therapy might be protective as it could
address the COVID-19 induced cytokine storm (9, 10, 11, 12, 13).
Large European data became available later, after the first wave. Recent
data show that CKD patients are at a higher risk than those with other
known risk factors, including chronic heart and lung disease. According
to the European Renal Association COVID-19 registry which included 4,298
kidney failure patients, 28-day mortality was 20% in 3,285 patients
receiving dialysis and 19.9% in 1,013 recipients of a transplant (7).
The ERACODA database (1,073 patients) reported a 28-day case fatality
rate of 25% in 768 dialysis patients and 21.3% in 305 kidney
transplant recipients during the first wave (5). Other reports based on
regional or national registries have also suggested lower mortality in
kidney transplant patients than in hemodialysis patients (14, 15).
COVID-19 reported case fatality rates vary greatly between countries
owing to differences in public health policy, case ascertainment, and
testing capacity. During the pandemic, a substantial number of patients
died while waitlisted, due to dramatic reductions in organ donation and
transplantation, reaching as high as 80% in some countries of the
European Union (4, 16). The early days of the pandemic came with plenty
of unknowns affecting the healthcare community’s ability to prepare for
and perform transplants. At the beginning, hospitals were limiting
surgical procedures to emergencies only in an effort to free up staff
for COVID-19 patients and to preserve scarce resources such as personal
protective equipment. Testing capacity was also limited. Additionally,
there was an effort to avoid the risk of further infections which could
arise from admitting more patients into hospitals than necessary.
Transplants from deceased donors were limited to urgent situations only;
while living donation programs were suspended amid the lockdown and fear
of infection. However, it was shown that during the outbreak, the risk
of being infected by SARS-CoV-2 was more than 4 times lower for kidney
transplant recipients than for hemodialysis patients, mainly because
transplant patients can be managed at home, while hemodialysis still
mostly takes place in hospital settings (4, 17). In-center hemodialysis
patients were at a higher risk for COVID-19 related mortality,
independently from the known risk factors such as obesity, ischemic
heart disease and lung disease (2). Data from Spain and Italy have shown
a 30% mortality of dialysis patients (18, 19). Recently published
French data showed that the 30-day Covid-19-related mortality was
significantly higher in kidney transplant recipients (KTRs) compared to
non-transplant patients (17.9% vs 1.4%, P=0.038) (20).