By Nancy Lapid
Aug 28 (Reuters) - The following is a roundup of some of the
latest scientific studies on the novel coronavirus and efforts
to find treatments and vaccines for COVID-19, the illness caused
by the virus.
COVID-19 reinfection seen in U.S. patient
A case of coronavirus reinfection has been documented in a
U.S. patient from Reno, Nevada, according to doctors. The
25-year-old man tested positive for the virus in April after
showing mild illness and then got sick again in late May,
developing more severe COVID-19 symptoms. Doctors and Nevada
public health officials said they were able to show through
sophisticated testing that the virus associated with each
instance of infection represented genetically different strains.
Their report, released on Friday, is undergoing peer review by
the Lancet medical journal. Last week, three reinfections were
reported - one in Hong Kong and two in Europe. Unlike the Nevada
case, the second infections in those patients were milder than
the first. Reinfection "may represent a rare event," the Nevada
researchers wrote. But, they said, the findings implied that
initial exposure to the virus may not result in full immunity
for everyone who has been infected by it. (https://reut.rs/2QyWYn8;
https://bit.ly/2EGVbK0)
Saliva samples preferable for COVID-19 testing
Letting patients provide saliva samples for COVID-19 tests
is easier and safer than swabbing the back of the nose and
throat for samples to test, and the results are equally
reliable, Yale University researchers said. Writing on Friday in
the New England Journal of Medicine, they compared saliva and
nasopharyngeal swab samples from 70 U.S. hospitalized COVID-19
patients and 495 asymptomatic healthcare workers, using
gold-standard laboratory methods. In both groups, the saliva
tests and the nasopharyngeal swab tests showed similar
sensitivity for detecting the virus. For healthcare workers,
unlike the collection of nasopharyngeal samples, collection of
saliva samples by patients does not present a risk of infection
and alleviates demands for supplies of swabs and personal
protective equipment, the researchers said. In a separate study
on Friday in the journal Annals of Internal Medicine, Canadian
researchers employed an experimental saliva test kit and found
that it might miss some mild or asymptomatic infections. But
they agreed with the Yale researchers about the advantages of
saliva tests and said they "may be of particular benefit for
remote, vulnerable or challenging" patients. (https://bit.ly/32DkSnf;
https://bit.ly/31EIV5X)
Accuracy of faster COVID-19 tests is unclear
It is hard to know whether so-called point-of-care COVID-19
tests, which provide results in a couple of hours rather than
days as some other tests do, are accurate, according to a
research review. The authors of the review, published on
Wednesday by the Cochrane Library, focused on two types of rapid
point-of-care tests: antigen tests, which identify proteins on
the virus using disposable devices, and molecular tests, which
detect viral genetic material using portable or table-top
devices. Altogether, they reviewed 22 studies from around the
world that compared point-of-care tests to gold-standard
so-called RT-PCR laboratory tests. Three-quarters of the studies
did not follow the point-of-care test manufacturers'
instructions, they found. There also was little information
about study participants, so it was not possible to tell if the
results could be applied to people with no symptoms, mild
symptoms or severe symptoms. And studies often were at risk for
bias, or did not detail their methods. "The evidence currently
is not strong enough and more studies are urgently needed to be
able to say if these tests are good enough to be used in
practice," the research team led by Jonathan Deeks of the
University of Birmingham in Britain wrote. (https://bit.ly/3loR9XA)
New studies add to data on COVID-19 in children
Children are far less likely than adults to get severe cases
of COVID-19, British doctors found. At 138 hospitals in Britain,
through June, less than 1% of COVID-19 patients were children,
and 99% survived. Those who died had serious underlying health
conditions. "We can be quite sure that COVID in itself is not
causing harm to children on a significant scale," said Malcolm
Semple of the University of Liverpool, co-author of research
published on Thursday in BMJ. While children's risk for severe
COVID-19 is low, Black children and obese children experienced
higher risks. A separate study published on Monday in the
journal JAMA Pediatrics suggests the proportion of U.S. children
with asymptomatic COVID-19 may be low. At 28 hospitals, more
than 33,000 children were tested during ear, nose and throat
appointments or procedures. None were suspected of having the
virus. Fewer than 1% were asymptomatically infected. Even
without symptoms, infected children can shed virus for weeks,
Korean doctors said on Friday in the JAMA Pediatrics. (https://reut.rs/2YIGaPb;
https://bit.ly/34IfGRm; https://bit.ly/34DHZRb;
https://bit.ly/3lqsSAo; https://bit.ly/34UgNhh)
Open https://tmsnrt.rs/3a5EyDh in an external browser for a
Reuters graphic on vaccines and treatments in development.
(Reporting by Nancy Lapid, Kate Kelland and Deena Beasley;
Editing by Will Dunham)