Coronavirus can persist for months after traversing entire body, reveals research

By Jason Gale

The burden of infection outside the respiratory tract and time for viral clearance isn’t well characterised, particularly in the brain, wrote Daniel Chertow, who runs the NIH’s emerging pathogens section, and his colleagues.

The group detected persistent SARS-CoV-2 RNA in multiple parts of the body, including regions throughout the brain, for as long as 230 days following onset of symptoms. This may represent infection with a defective virus, which has been described in persistent infection with the measles virus, they said.

In contrast to other Covid-19 autopsy research, the NIH team’s post-mortem tissue collection was more comprehensive and typically occurred within about a day of the patient’s death. 

Culturing Coronavirus
The NIH researchers also used a variety of tissue preservation techniques to detect and quantify viral levels, as well as grow the virus collected from multiple tissues, including lung, heart, small intestine and adrenal gland from deceased Covid-19 patients during their first week of illness.

“Our results collectively show that while the highest burden of SARS-CoV-2 is on the airways and lung, the virus can disseminate early during infection and infect cells throughout the entire body, including widely throughout the brain,” the authors stated.

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The researchers posit that infection of the pulmonary system may result in an early “viremic” phase, in which the virus is present in the bloodstream and seeded throughout the body, including across the blood-brain barrier, even in patients experiencing mild or no symptoms. One patient in the autopsy study was a juvenile who likely died from unrelated seizure complications, suggesting infected children without severe Covid-19 can also experience systemic infection, they said.

Immune Response
The less-efficient viral clearance in tissues outside the pulmonary system may be related to a weak immune response outside the respiratory tract, the authors said.

SARS-CoV-2 RNA was detected in the brains of all six autopsy patients who died more than a month after developing symptoms, and across most locations evaluated in the brain in five, including one patient who died 230 days after symptom onset.

The focus on multiple brain areas is especially helpful, said Al-Aly at the Veterans Affairs St. Louis Health Care System. 

“It can help us understand the neurocognitive decline or ‘brain fog’ and other neuropsychiatric manifestations of long Covid,” he said. “We need to start thinking of SARS-CoV-2 as a systemic virus that may clear in some people, but in others may persist for weeks or months and produce long Covid -- a multifaceted systemic disorder.”

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