Breakthrough infections can lead to long COVID; genes may explain
critical illness in young, healthy adults
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[October 28, 2021]
By Nancy Lapid
(Reuters) - The following is a summary of
some recent studies on COVID-19. They include research that warrants
further study to corroborate the findings and that have yet to be
certified by peer review.
Breakthrough infections can lead to long COVID
The persistent syndrome of COVID-19 after-effects known as long COVID
can develop after "breakthrough" infections in vaccinated people, a new
study shows. Researchers at Oxford University in the UK reviewed data on
nearly 20,000 U.S. COVID-19 patients, half of whom had been vaccinated.
Compared to unvaccinated patients, people who were fully vaccinated -
and in particular those under age 60 - did have lower risks for death
and serious complications such as lung failure, need for mechanical
ventilation, ICU admission, life-threatening blood clots, seizures, and
psychosis. "On the other hand," the research team reported on medRxiv on
Tuesday ahead of peer review, "previous vaccination does not
appear to protect against several previously documented outcomes of
COVID-19 such as long COVID features, arrhythmia, joint pain, Type 2
diabetes, liver disease, sleep disorders, and mood and anxiety
disorders." The absence of protection from long COVID "is concerning
given the high incidence and burden" of these lasting problems, they
added.
Genes may explain critical COVID-19 in young, healthy adults
A gene that helps the coronavirus reproduce itself might contribute to
life-threatening COVID-19 in young, otherwise healthy people, new
findings suggest. French researchers studied 72 hospitalized COVID-19
patients under age 50, including 47 who were critically ill and 25 with
non-critical illness, plus 22 healthy volunteers. None of the patients
had any of the chronic conditions known to increase the risk for poor
outcomes, such as heart disease or diabetes. Genetic analysis identified
five genes that were significantly "upregulated," or more active, in the
patients with critical illness, of which the most frequent was a gene
called ADAM9. As reported on Tuesday in Science Translational Medicine,
the researchers saw the same genetic pattern in a separate group of 154
COVID-19 patients, including 81 who were critically ill. Later, in lab
experiments using human lung cells infected with the coronavirus, they
found that blocking the activity of the ADAM9 gene made it harder for
the virus to make copies of itself. More research is needed, they say,
to confirm their findings and to determine whether it would be
worthwhile to develop treatments to block ADAM9.
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A computer image created by Nexu Science Communication together with
Trinity College in Dublin, shows a model structurally representative
of a betacoronavirus which is the type of virus linked to COVID-19,
better known as the coronavirus linked to the Wuhan outbreak, shared
with Reuters on February 18, 2020. NEXU Science Communication/via
REUTERS
Pregnant women get sub-par benefit from first vaccine
dose
Women who get the first dose of an mRNA COVID-19 vaccine while
pregnant or breastfeeding need the second dose to bring their
protective benefit up to normal, according to a new study.
Researchers compared immune responses to the mRNA vaccines from
Moderna Inc or Pfizer Inc and partner BioNTech SE in 84 pregnant
women, 31 breastfeeding women, and 16 similarly-aged nonpregnant,
non-lactating women. After the first shot, everyone developed
antibodies against the coronavirus. But antibody levels were lower
in women who were pregnant or breastfeeding. Other features of the
immune response also lagged in the pregnant and lactating women
after the first dose but "caught up" to normal after the second
shot. In a report published last week in Science Translational
Medicine, the researchers explained that in order for a mother's
body to nurture the fetus, "substantial immunological changes occur
throughout pregnancy." The new findings suggest that pregnancy
alters the immune system's response to the vaccine. Given that
pregnant women are highly vulnerable to complications from COVID-19,
"there is a critical need" for them to get the second dose on
schedule, the researchers said.
Coronavirus found to infect fat cells
Obesity is a known risk factor for more severe COVID-19. One likely
reason may be that the virus can infect fat cells, researchers have
discovered. In lab experiments and in autopsies of patients who died
of COVID-19, they found the virus infects two types of cells found
in fat tissue: mature fat cells, called adipocytes, and immune cells
called macrophages. "Infection of fat cells led to a marked
inflammatory response, consistent with the type of immune response
that is seen in severe cases of COVID-19," said Dr. Catherine Blish
of Stanford University School of Medicine, whose team reported the
findings on bioRxiv on Monday ahead of peer review. "These
data suggest that infection of fat tissue and its associated
inflammatory response may be one of the reasons why obese
individuals do so poorly when infected with SARS-CoV-2," she said.
(Reporting by Nancy Lapid; Editing by Bill Berkrot)
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