Vaccines may curb new virus mutations; teens use soft drinks to fake
positive COVID-19 tests
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[July 08, 2021]
By Nancy Lapid
(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 vaccines may be curbing new virus mutations
Along with preventing illness and deaths, COVID-19 vaccines may also be
curbing the "rampant evolution" of the new coronavirus by limiting new
mutations that allow it to evade antibodies, researchers believe. As
part of a larger study, they closely analyzed gene sequences in virus
samples obtained from 30 COVID-19 patients who had not been vaccinated
and 23 vaccinated individuals with so-called breakthrough cases of
COVID-19. In particular, they looked at genes associated with the spike
the virus uses to break into cells. The spikes are targeted by the
antibodies unleashed by current treatments and vaccines. The more the
spike mutates, or changes, the less likely the antibodies will be fully
effective. Compared to virus samples from unvaccinated patients, samples
from vaccine breakthrough patients showed significantly fewer mutations
on the spike, researchers from data analytics company nference reported
on Monday on medRxiv ahead of peer review. The more people get infected,
the more opportunities the virus has to mutate as it makes copies of
itself inside the body. It is possible that by suppressing the number of
copies made in vaccinated people, the chances to mutate are reduced as
well, the authors suggest. "This study presents the first known evidence
that COVID-19 vaccines are fundamentally restricting the ... escape
pathways accessible to SARS-CoV-2," they concluded.
Some teens are faking positive COVID-19 tests
Teenagers have figured out how to use soft drinks to fake a positive
COVID-19 test, and the authors of a new study warn schools and other
groups to be aware. As of July 1, videos uploaded to social media under
the search term #fakecovidtest, featuring young people applying various
liquids to rapid antigen COVID-19 tests, had been viewed millions of
times, according to the British news website inews.co.uk. That report ,
and others, prompted University of Liverpool researchers to study the
effects of applying soft drinks and artificial sweeteners to the test
swabs. All four sweeteners tested produced negative results on rapid
COVID-19 tests, as did spring water. But 10 of 14 soft drinks produced
positive or weakly positive results, with no apparent link between the
test results and the soft drinks' ingredients, the researchers reported
on Monday on medRxiv ahead of peer review. Since March, UK schools have
asked pupils without symptoms to test twice weekly, the authors note. A
positive test can result in an entire class having to isolate at home.
Based on their findings, they advise, testing "should be performed first
thing in the morning, prior to the consumption of any food or drinks,
and supervised where feasible."
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A medical worker administers a dose of the "Comirnaty" Pfizer-BioNTech
COVID-19 vaccine to a patient at a coronavirus disease (COVID-19)
vaccination center installated in front of Paris town hall, France,
July 7, 2021. REUTERS/Sarah Meyssonnier
Rapid COVID-19 tests are generally reliable
Used properly, "rapid antigen" COVID-19 tests that give fast results
are generally reliable, a new study suggests. The tests have "good"
sensitivity, or the ability to correctly identify patients who are
infected with the coronavirus, and "excellent" specificity, or the
ability to correctly identify people who are not infected, UK
researchers reported in The Lancet Microbe. Unlike gold-standard PCR
tests, which involve complex lab equipment and highly trained staff,
rapid antigen tests can be processed on the spot. The researchers
evaluated six commercially available tests. Compared to PCR, their
accuracy at diagnosing infection varied from 65% to 89% and rose
above 90% in patients with high viral loads. The researchers warn
that correct use of the tests is essential, which may happen less
often with members of the public than when administered by trained
healthcare workers. Although PCR-based testing is more accurate,
they conclude, the rapid tests' "versatility in terms of cost and
portability," and their usefulness in disrupting transmission from
infected asymptomatic individuals who would otherwise go undetected
"could outweigh the risk of missing positive cases."
(Reporting by Nancy Lapid and Megan Brooks; Editing by Bill Berkrot)
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