A New England Journal of Medicine study yesterday of cancer patients with COVID-19 demonstrated viral RNA shedding for up to 78 days and live virus for up to 61 days, suggesting extended infectiousness in patients whose immune system is suppressed.
Live-virus shedding in patients who are not immunocompromised is well-documented, but little is known about how long immunocompromised patients—including those receiving cancer treatments—are contagious. The presence of viral RNA does not always correlate with transmissibility, and previous studies have demonstrated lengthy periods of viral RNA shedding after patients are no longer infectious.
Scientists at Memorial Sloan Kettering Cancer Center collected respiratory samples from 20 cancer patients receiving immune-suppressing therapy from Mar 10 to Apr 20. Nasopharyngeal samples were tested for SARS-CoV-2, the virus that causes COVID-19, using reverse-transcription polymerase chain reaction (RT-PCR). Viral culture of positive swabs was used to assess the presence of infective particles and whole-genome sequencing was conducted for viral samples.
Of the 20 patients, 15 were receiving active treatment or chemotherapy and 11 had severe COVID-19. Viral RNA was detected in the cancer patients up to 78 days after the onset of symptoms (interquartile range [IQR], 24 to 64 days). Viable virus was detected in 71% of initial nasopharyngeal samples and grew in cultures from five patients up to 61 days after symptom onset.
Whole-genome sequencing of viral samples suggested persistent infection with a single viral strain.
“Patients with profound immunosuppression after undergoing hematopoietic stem-cell transplantation or receiving cellular therapies may shed viable SARS-CoV-2 for at least 2 months. The current guidelines for COVID-19 isolation precautions may need to be revised for immunocompromised patients,” the study authors wrote.
