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UPDATE: A #coronavirus patient is considered contagious as long as they carry "replication-competent" virus. Based on limited CDC data, patients with severe immune impairment are thought to be contagious for up to 20 days after onset of COVID19 symptoms. This may soon be revised:
We've known that patients with weakened immune systems can remain contagious for up to twice as long as those without immune impairment (20 days vs. 10 days) and these findings have informed transmission-based precautions around the country.
But 20 days may be insufficient.
But 20 days may be insufficient.
A new study of immunocompromised #COVID patients found that some remain potentially contagious far longer than previously thought: 15% had replication-competent virus after 20 days.
Key finding: 1 patient grew virus in culture 61 days after symptom onset. https://www.nejm.org/doi/full/10.1056/NEJMc2031670
Key finding: 1 patient grew virus in culture 61 days after symptom onset. https://www.nejm.org/doi/full/10.1056/NEJMc2031670
These unique patients received allogeneic hematopoietic stem-cell transplants or CAR T-cell therapy within the previous 6 months & remained negative for antibodies to coronavirus. Their immune systems were severely compromised, which likely allowed virus to continue replicating.
Many people have weakened immune systems, but specific treatments (stem cell transplant) can produce defects in the immune system that allow #coronavirus to fester. With time, we'll create subcategories of patients with bespoke treatment, transmission, and quarantine guidelines.
Takeaway: For most of the pandemic, we've believed that severely immunocompromised patients remain infectious no longer than 20 days after symptom onset. We now know that a subset of these patients can shed viable coronavirus for 2 months. Isolation precautions should be updated.
