*1.5. Diagnosis*

According to the guidelines of the International Society of Heart and Lung Transplantation (ISHLT) concerning patients with cardiothoracic transplant, routine testing of asymptomatic patients is not recommended [17]. An asymptomatic patient who has been in contact with a confirmed case of COVID-19 should be advised to undergo home quarantine for 2 weeks, and testing for SARS-CoV-2 is only indicated if symptoms occur (or otherwise as per local public health guidelines). Testing for SARS-CoV-2 in patients with symptoms of COVID-19 (fever, cough, headaches, myalgia, fatigue, nasal congestion, sudden anosmia, diarrhea, etc.) should be treated like any other patient considered at increased risk of developing severe disease, as per local guidelines [17].

A real-time polymerase chain reaction (RT-PCR), or sequencing of respiratory or blood samples using "primers" based on the viral RNA sequence, indicates whether a person is currently infected. In a study on detection of SARS-CoV-2 in different types of specimens from 205 patients, the virus was detected in 93% (n = 14) of patients where bronchoalveolar lavage fluid was sampled, in 72% (n = 75) of sputum samples, in 63% (n = 5) of nasal swabs, in 46% (n = 6) of bronchoscopic brush biopsies, and in 32% (n = 126) of pharyngeal swabs. Further, in feces specimens, the virus was detected in 29% of cases (n = 44). In blood, SARS-CoV-2 could be detected in only 1% (n = 3), whereas in none of the patients could the virus be detected in urine [18]. Blood samples should be stored for subsequent analysis, for example for antibody testing. Recently, in collaboration between the U.S. Department of Health and Human Services, the U.S. Department of Defense, and the company Cepheid, a new COVID-19 molecular diagnostic test, allowing SARS-CoV-2 detection within 45 min, has been approved by the U.S. Food and Drug Administration (FDA) for point-of-care detection in emergency use for COVID-19. A further benefit of this rapid diagnostic test is that it only requires one minute hands-on time to perform it, reducing the exposure time of the laboratory personnel to potentially virus-containing samples. However, the question remains unanswered as to how this test compares to the widely used RT-PCR test. There have been concerns related to potential false negative results.

Serologic diagnosis by detection of specific antibodies (immunoglobulin M, immunoglobulin G) is currently being introduced. Timelines for the appearance and persistence of these immunoglobulins are currently not well established.

In this paper, we review COVID-19 in solid organ transplant (SOT) recipients, most of whom are under long-term dual- or triple-drug immunosuppressive therapy.
