[Act-ma_discuss] why you don't want to get covid! Study: Coronavirus Can Persist for Months After Traversing Entire Body

[Amy Hendrickson]

Study: Coronavirus Can Persist for Months After Traversing
Entire Body

Jason Gale/Bloomberg

 

28 december 21

The coronavirus that causes COVID-19, SARS-CoV-2, can spread
within days from the airways to the heart, brain and almost
every organ system in the body, where it may persist for
months, a study found.

In what they describe as the most comprehensive analysis to
date of the virus's distribution and persistence in the body
and brain, scientists at the U.S. National Institutes of
Health said they found the pathogen is capable of
replicating in human cells well beyond the respiratory
tract.

The results, released online Saturday in a manuscript under
review for publication in the journal Nature, point to
delayed viral clearance as a potential contributor to the
persistent symptoms wracking so-called long COVID sufferers.
Understanding the mechanisms by which the virus persists,
along with the body's response to any viral reservoir,
promises to help improve care for those afflicted, the
authors said.

"This is remarkably important work," said Ziyad Al-Aly,
director of the clinical epidemiology center at the Veterans
Affairs St. Louis Health Care System in Missouri, who has
led separate studies into the long-term effects of COVID-19.
"For a long time now, we have been scratching our heads and
asking why long COVID seems to affect so many organ systems.
This paper sheds some light, and may help explain why long
COVID can occur even in people who had mild or asymptomatic
acute disease."

The findings haven't yet been reviewed by independent
scientists, and are mostly based on data gathered from fatal
COVID-19 cases, not patients with long COVID-19 or
"post-acute sequelae of SARS-CoV-2," as it's also called.

Contentious findings

The coronavirus's propensity to infect cells outside the
airways and lungs is contested, with numerous studies
providing evidence for and against the possibility.

The research undertaken at the NIH in Bethesda, Maryland, is
based on extensive sampling and analysis of tissues taken
during autopsies on 44 patients who died after contracting
the coronavirus during the first year of the pandemic in the
U.S.

The burden of infection outside the respiratory tract and
time to viral clearance isn't well characterized,
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 symptom onset. This may
represent infection with 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 patients during their first week of
illness.

"Our results collectively show that while the highest burden
of SARS-CoV-2 is in 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 said.

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 is 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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