Here is the day's 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.
Viral load predicts need for ventilator and death risk
When Covid-19 patients are admitted to hospital doctors can estimate their risk of needing mechanical breathing support or dying based on their "viral load," a new study suggest.
The viral load is the amount of virus genetic material obtained by swabbing the back of the nose and throat.
"This risk can be predicted regardless of how sick they are when they are admitted, what other comorbidities they may have, their age or how many days they had symptoms," coauthor Dr Ioannis Zacharioudakis of NYU School of Medicine told Reuters.
His team studied 314 patients, dividing them into three groups according to viral load upon hospital admission.
The group with highest viral levels had 59 per cent higher odds of becoming critically ill or dying than the lowest viral load group.
The data, published on Friday in Annals of the American Thoracic Society, "will have practical implications in our ability to judge which patients will benefit the most from early escalation of care," Dr Zacharioudakis said.
Coronavirus damages red blood cell membranes
The new coronavirus damages the membranes of oxygen-carrying red blood cells, researchers have found.
This contribute to hypoxemia or low blood concentrations of oxygen - common in Covid-19.
Signs of hypoxemia can range from shortness of breath to organ and tissue damage.
Studying blood samples from Covid-19 patients and healthy individuals, researchers found the virus did not appear to affect red cells' ability to pick up oxygen and deliver it throughout the body.
However, patients had "clear damage" to red cell membranes, in particular to a membrane protein responsible for helping the cell survive injuries.
As a result, patients' red cells might be more vulnerable to so-called oxidative stress and other injury, coauthor Angelo D'Alessandro of the University of Colorado Denver said.
Red cells circulate for up to 120 days before the body replaces them with new ones, and they cannot synthesize new components to replace the damaged parts.
This might help explain why some Covid-19 symptoms can last for months, D'Alessandro said.
Heart failure history adds to risks for Covid-19 patients
Another new study has helped quantify the extra risks faced by people with heart failure and coronavirus infections severe enough to require hospitalisation.
Doctors at the Mount Sinai Health System in New York City studied 6,439 hospitalised Covid-19 patients, including 422 with a history of at least one heart failure episode.
Compared to the other patients, those with a history of heart failure had longer average hospital stays of eight days versus six days, the doctors reported on Wednesday in the Journal of the American College of Cardiology.
After accounting for other risk factors, the heart failure patients were more than three times more likely to need mechanical ventilation and nearly twice as likely to die.
If future studies show similar patterns, the researchers conclude, doctors might need to consider using more aggressive therapies in patients with Covid-19 and a history of heart failure.
