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 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://graphics.reuters.com/HEALTH-CORONAVIRUS/yxmvjqywprz/index.html for a Reuters graphic on vaccines and treatments in development.
(Reporting by Nancy Lapid, Kate Kelland and Deena Beasley; Editing by Will Dunham)