Here is a brief roundup 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.

Coronavirus antibodies in breast milk may protect infants

Breast milk from infected mothers may contain antibodies to the novel coronavirus that could be protective for babies, a study suggests. "Nursing mothers who are infected with the novel coronavirus should continue to breastfeed throughout their COVID-19 illness and beyond, because (other researchers) have shown transmission does not occur via milk, and we have determined that antibodies are almost certainly there, and may protect their babies from infection," Rebecca Powell of The Icahn School of Medicine at Mount Sinai in New York, who led the study, told Reuters. Her team's report, posted on Friday on the preprint server medRxiv, has not yet been peer-reviewed or published in a medical journal.

Mysterious children's illness could be connected to coronavirus

A rare, life-threatening condition is developing in some children after exposure to the new coronavirus that researchers are calling "Pediatric Multi-System Inflammatory Syndrome Potentially Associated with COVID-19." Doctors are seeing clusters of children, some very young, with the disorder, which can attack multiple organs, impair heart function and weaken heart arteries. British physicians reporting on Thursday in The Lancet said the children initially have a fever, rash, conjunctivitis, lower-limb swelling, pain in arms and legs, and "significant" gastrointestinal symptoms, even without testing positive for the coronavirus. The syndrome, while rare, can rapidly progress to critical illness requiring mechanical ventilation.

Coronavirus may survive in sperm

Chinese researchers who tested the sperm of 38 men infected with COVID-19 found that six of them, or 16%, had the new coronavirus in their semen, suggesting a small chance that the virus, formally known as SARS-CoV-2, could be sexually transmitted, scientists said. Some of the men were already recovering from their illness.

"If it could be proved that SARS-CoV-2 can be transmitted sexually... (that) might be a critical part of the prevention," doctors at China's Shangqiu Municipal Hospital wrote in the medical journal JAMA Network Open on Thursday, adding that more research is needed.

Virus spread affected more by public health measures than by climate

Temperature and latitude do not appear to be associated with the spread of the novel coronavirus, and humidity levels have only a weak effect, according to data collected in March from 144 regions of the world. By contrast, public health measures like social distancing, school closures and sheltering at home do make a difference and were strongly associated with reduced epidemic growth, Dr. Peter Juni at the University of Toronto and colleagues found in a report published on Friday in CMAJ (Canadian Medical Association Journal).

"The important effect of public health interventions needs to be weighed carefully against potential economic and psychosocial harms when deciding when and how to lift restrictions," Juni's team concluded in their report.

Poor nasal swab technique may explain some false negatives

Part of the reason for some false negative coronavirus tests – tests that do not detect the virus in someone who is actually infected – may be that the test sample was not collected properly by the person using the nasopharyngeal swab, Canadian researchers say. They reanalyzed specimens from patients with confirmed or suspected COVID-19 whose test results had been negative or unclear and found less human DNA than they expected to see. Correct use of nasopharyngeal swabs to obtain a high-quality specimen "requires training and expertise as it involves the insertion of the swab to ... a depth of roughly 7 centimeters (2.76 inches), followed by rotation and withdrawal," Zabrina Brumme of Simon Fraser University in Burnaby, British Columbia and colleagues say. Their study, posted on Friday on the preprint server medRxiv, has not yet been peer-reviewed or published in a medical journal.

Hydroxychloroquine fails to show benefit in some

In a large observational study of hospitalized coronavirus patients, hydroxychloroquine – an old malaria drug championed by U.S. President Donald Trump as a "game-changer" in the fight against the virus – neither lessened patients’ need for breathing assistance nor their risk of death, according to a report published on Thursday in The New England Journal of Medicine.

"We didn't see any association between getting this medicine and the chance of dying or being intubated," lead researcher Dr. Neil Schluger, of New York-Presbyterian Hospital and Columbia University Irving Medical Center, told Reuters. "The patients who got the drug didn't seem to do any better." Patients in the study were not randomly assigned to receive hydroxychloroquine or a placebo, the researchers noted, and so randomized trials, the gold standard for tests of new therapies, should continue.