Live-virus shedding was detected in 18 patients who had undergone hematopoietic stem cell transplants or chimeric antigen receptor (CAR) T-cell therapy and in 2 patients with lymphoma.
The finding was reported Dec. 1 in a research letter in the New England Journal of Medicine.
Individuals who are otherwise healthy when they get COVID-19 are “no longer infectious after the first week of illness,” said lead author Mini Kamboj, MD, chief medical epidemiologist, Memorial Sloan Kettering Cancer Center, New York.
“We need to keep an open mind about how [much] longer immunocompromised patients could pose an infection risk to others,” she added.
Dr. Kamboj said in an interview that her team’s previous experience with stem cell transplant recipients had suggested that severely immunocompromised patients shed other viruses (such as respiratory syncytial virus, parainfluenza, and influenza) for longer periods of time than do healthy controls.
Based on their latest findings, the investigators suggest that current guidelines for COVID-19 isolation precautions may need to be revised for immunocompromised patients. Even if only a small proportion of patients with cancer who have COVID-19 remain contagious for prolonged periods of time, “it’s a residual risk that we need to address,” Dr. Kamboj said.
Dr. Kamboj also suggested that physicians follow test-based criteria to determine when a patient undergoing transplant can be released from isolation.
Shedding of viable virus
For this study, the investigators used cell cultures to detect viable virus in serially collected nasopharyngeal and sputum samples from 20 immunocompromised patients who had COVID-19 (diagnosed with COVID-19 between March 10 and April 20).
Patients had lymphoma (n = 8), multiple myeloma (n= 7), acute leukemia/myelodysplastic syndrome (n = 4), and chronic leukemia (n = 1). There were 16 patients who had undergone transplant, 2 who had received CAR T-cell therapy, and 2 who had received other therapy.
There were 15 patients receiving active treatment or chemotherapy, and 11 developed severe COVID-19 infection.
In total, 78 respiratory samples were collected.
“Viral RNA was detected for up to 78 days after the onset of symptoms,” the researchers reported, “[and] viable virus was detected in 10 of 14 nasopharyngeal samples (71%) that were available from the first day of laboratory testing.”
Five patients were followed up, and from these patients, the team grew virus in culture for up to 61 days after symptom onset. Two among this small group of five patients had received allogenic hematopoietic stem cell transplantation and one patient had been treated with CAR T-cell therapy within the previous 6 months. This patient remained seronegative for antibodies to the coronavirus.
For 11 patients, the team obtained serial sample genomes and found that “each patient was infected by a distinct virus and there were no major changes in the consensus sequences of the original serial specimens or cultured isolates.” These findings were consistent with persistent infection, they noted.
The authors have disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.