This week's roundup of some of the latest scientific studies on the coronavirus and efforts to find treatments and vaccines for COVID-19 compares the morbidity of this disease to seasonal influenza, warns of risks associated with the spaces we live in and confirms that canines can help with virus detection.
COVID-19 far more deadly than seasonal flu
COVID-19 is three times more deadly than seasonal influenza, according to researchers in France who compared 89,530 patients hospitalized with COVID-19 early this year with 45,819 patients hospitalized with flu between December 2018 and February 2019.
The death rate was 16.9% versus 5.8%, which is "particularly striking when reminded that the 2018-2019 flu season had been the worst in the past five years in France in terms of the number of deaths," Dr. Catherine Quantin, from Dijon University Hospital, said in a news release.
More patients with COVID-19 landed in intensive care units (16.3% versus 10.8%) and the average ICU stay was nearly twice as long (15 days versus eight days), her team reported in The Lancet Respiratory Medicine. COVID-19 patients were also more likely to need mechanical ventilation and to suffer lung failure.
In another study published on Wednesday in The BMJ, U.S. researchers found people being hospitalized for COVID-19 carried higher risks of organ failure and death, and increased health resource use, compared to people hospitalized for the flu.
Narrow hallways present higher infection risks
An unmasked coronavirus-infected person walking fast down a narrow corridor leaves a long stream of virus-laden droplets trailing behind, a new computer simulation suggests. Even if social distancing guidelines are followed, it might still be risky to follow someone down a narrow corridor, researchers advised in a report published in Physics of Fluids.
"The transmission of COVID-19 is highly influenced by the airflow," said co-author Xiaolei Yang of the Chinese Academy of Sciences in Beijing. "A slight change of airflow can significantly alter the virus spreading pattern," he said.
Such changes can be caused by a minor difference in corridor width, walking speed, indoor architectural structure, temperature, humidity or other factors. Staying 6 feet (1.83 meters) behind the person in front of you "is not enough for narrow corridors, and wearing a face mask is recommended even if you do not see people around," he said.
In addition, the viral droplets behind a walking person tend to hover at waist height, so short kids are exposed to higher risk than adults, he added. "When you are with a child, you may want to hold him or her in your arms."
Dogs can sniff out COVID-19
In the preliminary study published in PLoS One, dogs who sniffed swab samples of armpit sweat could tell which samples came from COVID-19 patients and which were from people who tested negative for the new coronavirus. That study was conducted in March.
More recently, the researchers have validated the findings in additional trials, said study leader Dominique Grandjean of Alfort Veterinary School in France. Dogs can identify infected individuals with 85% to 100% accuracy and rule out infection with 92% to 99% accuracy, Grandjean said.
"It takes one-tenth of a second for a trained dog to say 'yes' or 'no,'" he said. Training requires three to eight weeks depending on whether the dog is already trained for odor detection. COVID-19-detecting dogs have already been deployed in airports in the United Arab Emirates, Grandjean said.
Immune system can self-attack with COVID-19
Antibodies are supposed to attack invading germs, but severely ill COVID-19 patients have so-called autoantibodies that mistakenly attack not just their own tissues and organs but even virus-fighting proteins produced by the immune system, new research shows.
Scientists studied 194 COVID-19 patients, including 55 with severe disease, plus a control group of 30 people without the virus. In the sickest patients, they found a high frequency of autoantibodies created by the immune system causing injury to the central nervous system, blood vessels and connective tissues like cartilage, ligaments and tendons. They also found a high prevalence of autoantibodies that interfere with substances involved in the functioning of the immune system itself, including cytokines and other "immunomodulatory" proteins.
"The surprising extent of autoantibody reactivities" in these patients indicates that these mistakenly targeted antibodies are "an intrinsic aspect" of COVID-19. The report was posted on medRxiv ahead of peer review.