(Reuters) – 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.

COVID-19 often undiagnosed in frontline hospital workers

A high proportion of COVID-19 infections among U.S. healthcare personnel appear to go undetected, according to a report on Monday in the Morbidity and Mortality Weekly Report of the U.S. Centers for Disease Control and Prevention. Between April and June, among more than 3,000 frontline workers in 12 states, roughly 1 in 20 had antibody evidence of a previous COVID-19 infection, but 69% of those infections had never been diagnosed. Among those with antibodies to the novel coronavirus, about one-third did not recall having symptoms in the preceding months, nearly half did not suspect that they had been infected, and some two-thirds had never had a positive COVID-19 test. Infections among frontline healthcare personnel may be going undetected, the study authors say, because some infections may be only minimally symptomatic or asymptomatic and also because personnel with symptoms may not always have access to testing. COVID-19 antibodies were less common among workers who reported using a face covering for all patient encounters and more common among those who reported a shortage of personal protective equipment. The researchers call for more frequent testing of healthcare personnel and universal use of face coverings in hospitals. (bit.ly/2DizVKk)

Virus may impair heart’s beating, contracting

Following recent reports that the new coronavirus can invade heart muscle cells comes the discovery that infected cells show impairments in function. In test tube experiments, researchers infected “myocytes,” or heart muscle cells, with the new coronavirus and found that before the infected cells die, they progressively lose their “electrophysiological and contractile properties.” This means they have trouble transmitting the electrical impulses that regulate heartbeats and shortening or lengthening their fibers so the heart can expand and contract to pump blood. In a paper posted online Sunday on bioRxiv ahead of peer review, the researchers note that their test tube experiments likely do not exactly replicate what happens with cells in the body, and more research is needed to confirm their findings. Still, they say, their results suggest that cardiac symptoms in COVID-19 patients are likely a direct effect of the virus and warn that “long-term cardiac complications might be possible … in patients who recover from this illness.” (bit.ly/31KM0Ba)

Eye symptoms common in children with COVID-19

Children with COVID-19 often have nonserious eye symptoms like itching, discharge, or pink eye, a study from China suggests. Among 216 children hospitalized with COVID-19 in Wuhan, the epicenter of the outbreak there, 23% had these kinds of eye issues, doctors found. Eye problems were more common in children with other symptoms such as cough or fever. In all cases, the eye problems were mild and eventually went away either without treatment or with “minimal” eye drops, researchers reported in JAMA Ophthalmology. It is reassuring that most of the children had other symptoms first, said Dr. Douglas Fredrick, chief of pediatric ophthalmology at the Mount Sinai Health system in New York City, who was not involved in the study. If conjunctivitis, or pink eye, were always among the first symptoms, “we’d be more worried that children could spread this by pink eye from one child to another,” he told Reuters. Still, he said, the study doesn’t completely rule out that type of transmission. (bit.ly/3gtuZjn)

Cell phone activity may predict COVID-19 spread

Cell phone use patterns suggest that when people stay home, coronavirus infection rates go down, researchers say. For a study published on Monday in JAMA Internal Medicine, they analyzed publicly available de-identified cell phone activity and location data collected between January and May from 2,740 counties across the United States. After mid-February, when the coronavirus outbreak began, cell phone activity declined significantly in workplaces, stores and restaurants, and mass transit stations and increased in homes – with the greatest initial changes seen in areas with higher rates of COVID-19. Two weeks after cell phone activity shifted away from workplaces and retail locations, the counties with the most pronounced changes had the lowest rates of new COVID-19 cases. “Perhaps reassuringly,” the researchers said, cell phone activity at grocery stores and in areas classified as parks was not strongly associated with rates of growth in COVID-19 cases. They speculate that publicly available cell phone location data might help health offices better predict COVID-19 growth rates and inform decision about where to implement shutdowns and reopenings. (bit.ly/32EBdYB)

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