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.
Hong Kong man has first documented Covid-19 reinfection
A 33-year-old man who had recovered from a severe case of Covid-19 in April was infected again four months later in the first documented instance of human reinfection, University of Hong Kong researchers said on Monday. In August, after returning from a trip to Europe, he was diagnosed again - but with a different strain of the virus. While the first infection landed him in the hospital, the second produced no symptoms. Genetically, the first virus was closely related to strains collected in March/April while the second was closely related to strains collected in July/August, the researchers wrote in a report seen by Reuters. "Our findings suggest that SARS-CoV-2 may persist in the global human population as is the case for other common-cold associated human coronaviruses," they said in a statement. "Since the immunity can be short lasting after natural infection, vaccination should also be considered for those with one episode of infection," researchers said. "Patients with previous Covid-19 infection should also comply with epidemiological control measures such as universal masking and social distancing," they added. The report has been accepted for publication in Clinical Infectious Diseases.
Low oxygen in Covid-19 pneumonia linked to vascular widening
Widened small blood vessels in the lungs appear to be linked with the low oxygen levels seen in Covid-19 respiratory failure, a small study suggests. Researchers made the discovery by injecting saline with tiny microbubbles into the veins of 18 critically ill Covid-19 patients and tracked the bubbles using ultrasound. Normally, the bubbles would travel through the heart and enter the lungs, but would not get through the lungs because they would not fit through the capillaries. In more than 80% of these patients, however, the bubbles passed through the lungs and reached the blood vessels of the brain, which means the lung's capillaries were abnormally dilated, researchers reported earlier this month in the American Journal of Respiratory and Critical Care Medicine. The more bubbles that made their way beyond patients' lungs, the lower their oxygen levels, researchers said. This "may explain the disproportionate low oxygen levels seen in many patients with Covid-19 pneumonia," coauthor Dr. Hooman Poor of the Mount Sinai - National Jewish Health Respiratory Institute in New York City told Reuters. Researchers should consider testing drugs that would cause these patients' pulmonary blood vessels to constrict, he suggested. An editorial published in the journal on Friday points out that with dilated pulmonary blood vessels, a higher-than-usual volume of blood flows into the brain, which "raises the question of whether increased neurologic complications of Covid-19 could be related" to the dilation observed by the researchers.
Genetic “barcodes” may help monitor coronavirus mutations
"Genetic barcodes" can help track how the new coronavirus spreads and mutates, researchers said on Saturday in the International Journal of Infectious Diseases. Based on the organization, or sequence, of the genetic code of the virus, the researchers identified 11 distinct SARS-CoV-2 "barcodes" that represent different clades, or lineages, descended from a common viral ancestor. "We were able to assign approximately 94% of the global sequenced genomes to one of the clades," Arnab Pain of King Abdullah University of Science and Technology in Saudi Arabia told Reuters. Different continents have different variations, his team found. The subtle differences in the genetic sequences represented by the barcodes may affect virus infectivity or illness severity, he noted. Most of the genetic profiles available for the study were from North America and Europe, with Covid-19 cases from other regions under-represented. The researchers plan to regularly update the barcodes. "This is a dynamic process, and some virus clades/subclades may eventually die-off in the future, and new clades may form," Pain said. "We will continue to monitor the viral mutations in the global scenario and share our observations with the scientific community."