The
placenta may have a way to protect itself and the fetus from
infection with the coronavirus, a small study suggests.
Researchers studied 24 women who gave birth between July 2020 and
April 2021. Eight had symptomatic COVID-19 in the second trimester,
eight were sick from the virus in the third trimester, and eight
were not infected during pregnancy. When COVID-19 occurred in
pregnancy, particularly during the third trimester, placenta cells
appeared to "shed" a surface protein called ACE2 that the virus uses
to break into cells and infect them, leaving fewer gateways for
entry. Women who had COVID-19 in the third trimester had high levels
of an enzyme called ADAM17 that is known to help ACE2 release itself
from the cell surface, the researchers reported in The American
Journal of Pathology.
The placenta may be sensing the maternal COVID-19 infection "and
possibly putting in place this mechanism to help shed off ACE2,
prevent SARS-CoV-2 from invading the placenta and passing on to the
fetus," said Elizabeth Taglauer of Boston Medical Center. Earlier
studies have shown that placental cells become infected in only
about 7% to 20% of pregnancies where the mother has COVID-19,
Taglauer said. When the virus does somehow get into the placenta, it
rarely reaches the fetus, she added. Her team plans further studies
of "protection pathways" that may be keeping the virus out of
placental cells and away from fetal blood vessels.
COVID vaccines safe in rheumatic, musculoskeletal diseases
COVID-19 vaccines appear to be safe for people with rheumatic and
musculoskeletal diseases and are likely to trigger flares - a sudden
worsening of symptoms - in less than 5% of cases, researchers have
found.
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The findings were based on data from 5,121 patients in 30 countries.
Severe flares occurred in fewer than 1% of patients after
vaccination, they found. Overall, flares were more likely to occur
in patients with active disease, according to a report published in
Annals of the Rheumatic Diseases. "However, it is important to note
that flares can occur as part of the ... disease, and the observed
percentages of flare would be compatible with the natural history of
the disease rather than necessarily caused by vaccines against
SARS-CoV-2," said Dr. Pedro Machado of University College London.
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The average study participant was 72 years old, and most were women.
Many had inflammatory joint diseases, connective tissue diseases or
vasculitis and were receiving various combinations of
disease-modifying antirheumatic drugs, immunosuppressants, and other
medications.
Most had received the Pfizer/BioNTech vaccine (70%), followed by
shots from AstraZeneca (17%) and Moderna (8%). "Our findings should
provide reassurance to rheumatologists, other health professionals
and vaccine recipients, and promote confidence in the safety of
COVID-19 vaccination in people with inflammatory rheumatic
diseases," Dr. Machado said.
Peer-review does not lead to major changes in "preprints"
Two studies published on Tuesday in PLoS Biology suggest that papers
posted on so-called preprint servers before undergoing formal peer
review do not change significantly before publication in medical
journals.
One study compared more than 180 reports posted during the first
four months of the pandemic on the preprint servers medRxiv and
bioRxiv to the versions eventually published in peer-reviewed
journals. Roughly 83% of COVID-related papers and 93% of non-COVID-related
papers did not change from their preprint to final published
versions, they found. When the researchers did identify changes, in
the majority of cases those changes did not qualitatively change the
conclusions of the paper, they said.
The other study used machine learning to analyze the relationships
between nearly 18,000 preprints on the bioRxiv server and their
published versions. Most manuscripts had only modest changes in
wording during the peer-review and publication process, the
researchers found.
Click for a Reuters graphic on vaccines in development.
(Reporting by Nancy Lapid; Additional reporting by Marilynn Larkin;
Editing by Bill Berkrot)
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