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.
Placental infection may be more likely in early pregnancy
The coronavirus that causes COVID-19 rarely infects the placenta, but new research suggests that when such an infection does occur it is more likely to happen early in pregnancy.
Analyzing 12 placentas from healthy women, ranging in gestational age from 5 weeks to 36 weeks, researchers found that the cells in the placenta that become infected with the coronavirus have the surface protein ACE2, which the virus uses as a gateway for entry.
Late in pregnancy, the ACE2 proteins are positioned on cells in a way that does not expose them to the virus circulating in the mother's blood, possibly protecting the placenta from infection, said study coauthor Dr. Drucilla Roberts of the Massachusetts General Hospital in Boston.
This "protective" positioning pattern was less often seen in early gestation placentas, when ACE2 was typically present over the entire cell circumference, the study found. That suggests "increased vulnerability of the early placenta to infection," Roberts said.
"As more pregnant women recover from first trimester SARS-CoV-2 infection, it is important to remain vigilant to possible placental infection" and transmission from mother to fetus, the researchers said in a report published in Journal of Infectious Diseases. How often that happens, and effects on the fetus and newborn remain unknown, they added.
COVID-19 patients face low risk of new heart failure
Patients hospitalized with COVID-19 may develop heart failure even if they do not have a previous history of heart disease or cardiovascular risk factors, although the risk is low, according to a study published on Monday in the Journal of the American College of Cardiology.
Among 6,439 hospitalized COVID-19 patients, doctors found 37 patients (0.6%) with no history of heart failure who developed new cases during their hospitalization - including eight in their 40s, on average, who had no previous cardiovascular disease or risk factors.
It is not clear yet whether new-onset heart failure in these patients is an indirect effect of critical illness or a direct effect of the virus invading the heart, said study coauthor Dr. Anu Lala of the Icahn School of Medicine at Mount Sinai in New York, in a statement.
"Importantly," she added, "though symptoms of heart failure - particularly shortness of breath - can mimic symptoms associated with COVID-19, being alerted to the findings of this study may prompt clinicians to monitor for signs of congestion more consistent with heart failure than COVID-19 alone."
Hepatitis C drugs work synergistically with remdesivir
Combining Gilead Sciences' antiviral drug remdesivir - the current standard of care for hospitalized COVID-19 patients - with oral drugs used to treat hepatitis C virus (HCV) might be more effective than remdesivir alone, laboratory experiments suggest.
Four HCV drugs that work synergistically with remdesivir "are especially interesting," said Gaetano Montelione of Rensselaer Polytechnic Institute in Troy, New York.
In test tube experiments, these HCV drugs increased remdesivir's antiviral activity as much as 10-fold, his team reported on Monday in Cell Reports.
The drugs - simeprevir, grazoprevir, paritaprevir, and vaniprevir - inhibit a protein in the coronavirus called PLpro, while remdesivir, which is given intravenously, targets viral polymerase proteins.
Drug companies are developing oral drugs that target the same viral proteins as remdesivir. If those become available, Montelione said, it may be possible to offer them in combination with a hepatitis C drug for use at home, before COVID-19 patients become so ill that they need to be hospitalized.
"So far all of the research has been performed in cells," he noted, "and this approach must undergo further testing, perhaps first in animals, and then in clinical trials."
(Reporting by Nancy Lapid; Editing by Bill Berkrot)