Common public screening methods unreliable; student athletes may need heart test after Covid-19

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 screening in public venues is unreliable

Covid-19 screening tests used at airports, schools, and other public places are not particularly effective, a large analysis shows. Researchers synthesized the evidence from 22 studies of various screening methods, including taking people's temperature, asking about symptoms, travel history and exposure to infected or possibly infected people, and combinations of those and other approaches.

All of these, as well as repeated screening, had low "sensitivity," meaning poor ability to identify those with Covid-19, and low "specificity," that is, they could not reliably identify those without Covid-19. The specificity measure tended to be more accurate in places with low infection rates.

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With these popular screening methods, "a high proportion of infected individuals may be missed and go on to infect others, and some healthy individuals may be falsely identified as positive, requiring confirmatory testing and potentially leading to the unnecessary isolation of these individuals," the researchers wrote on Tuesday in a review for The Cochrane Library.

"Given the poor sensitivity of existing approaches, our findings point to the need for greater emphasis on other ways that may prevent transmission such as face coverings, physical distancing, quarantine, and adequate personal protective equipment for frontline workers."

Cardiac MRI may be in order for athletes after Covid-19

When college athletes recover from Covid-19 and are ready to return to sports, it might be wise to first make sure the new coronavirus has not left them with myocarditis, an inflammation of the heart that has turned up in some patients even after only mild or asymptomatic illness. At Ohio State University, doctors performed cardiovascular magnetic resonance imaging (MRI) studies on 26 student athletes, women and men, who had recovered from Covid-19.

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None had been hospitalized, and 12 reported having only mild symptoms. Their electrocardiograms looked normal, and ultrasound examinations showed no heart abnormalities. But the MRIs detected myocarditis in four of the athletes - two of whom had no symptoms.

And 12 athletes had heart tissue scarring, although they had not had any of the typical signs of a heart attack. In a paper published on Friday in JAMA Cardiology, the doctors conclude that while larger studies are needed, MRI may be a good way to evaluate athletes after Covid-19 recovery and to guide safe competitive sports participation.

Previous Covid-19 not linked with childbirth complications

For otherwise healthy women giving birth, previous exposure to the novel coronavirus appears not to impact labor and delivery, a new study suggests. From early April to early July, researchers at Copenhagen University Hospital tracked 1,361 women in labor, 1,236 of their partners and 1,342 of their newborns. None of the women were currently sick with Covid-19, but 2.9 per cent of them and 3.8 per cent of their partners had antibodies to the coronavirus, indicating previous infections. Only about half of those with antibodies reported having had any symptoms.

"No associations between previous Covid-19 disease and obstetric- or neonatal complications were found," the study authors reported on Tuesday in a paper posted on medRxiv in advance of peer review. They did find that having a partner with Covid-19 antibodies was a significant predictor that the woman who gave birth would also have antibodies, reinforcing how contagious the disease is with close contact.

The mothers in the study were generally young nonsmokers with a healthy weight. Those who did have Covid-19 antibodies had not had serious cases that required hospitalization. "Our results and conclusion may therefore not directly be applied to other populations" such as new mothers who are obese, frequent smokers or those who had severe Covid-19, they noted.