July 14 (Reuters) - Here 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.
New findings shed light on why chronic lung diseases that block the airways - such as chronic bronchitis, emphysema and pulmonary fibrosis - increase patients' risks for severe Covid-19.
The diseases cause genetic changes in the epithelial cells that line the airways, making the cells more vulnerable to attack from the coronavirus, researchers reported on Wednesday (July 14) in Nature Communications.
Laboratory studies of these cells found changes in their molecular makeup that likely make it easier for the virus to enter the body, make copies of itself, and trigger out-of-control immune responses that fill the lungs with fluid and cause severe organ damage.
The researchers, led by Nicholas Banovich at Translational Genomics Research Institute in Phoenix, were only able to examine cells from lung-disease patients without Covid-19 but said their "study highlights crucial areas for future research."
Anaemia, a blood disorder characterized by a low red blood cell count, should probably be added to the list of risk factors for poorer Covid-19 outcomes, according to researchers who studied 374 Covid-19 survivors who were hospitalized and then released, with tests showing the virus was gone from their systems.
They found that 104 patients needed to be rehospitalized, and rates of moderate or severe anaemia (as indicated by levels of haemoglobin, a protein in red blood cells that carries oxygen) were higher among the readmitted patients in the year before their Covid-19 diagnosis and while they were sick with the coronavirus.
The study, published in iScience, cannot prove that anaemia caused or contributed to the readmissions.
Still, the research team from data analytics company nference in Cambridge, Massachusetts said the "robust association" of anaemia with rehospitalization calls for research into whether anaemia treatments might be beneficial in some cases.
Survivors of mild cases of Covid-19 do not need to be screened later for heart problems, researchers advise.
They performed cardiovascular magnetic resonance imaging on 74 healthcare workers who had recovered six months earlier from mild or asymptomatic coronavirus infections, and on 75 uninfected individuals matched for age, sex, and ethnicity.
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According to a report published on Tuesday in European Heart Journal: Cardiovascular Imaging, there were no differences between the survivor group and the control group in any parameters of heart structure or function or in lab tests that would suggest heart disease.
The researchers, led by George Joy of Barts Heart Center in London, conclude, "Our study provides societal reassurance for the cardiovascular health of working-aged individuals with convalescence from mild SARS-CoV-2."
"Screening asymptomatic individuals following mild diseases is not indicated."
The Alpha, Beta and Gamma variants of the novel coronavirus increased patients' risks of hospitalization and death by 60 per cent compared to earlier forms of the virus, and the Delta variant was even more virulent, according to researchers who studied more than 211,000 patients in Canada diagnosed with Covid-19 between Feb. and June 2021.
Alpha, Beta and Gamma - first seen in the UK, South Africa and Brazil - more than doubled the risk of needing intensive care, even though the patients were generally younger and healthier than those infected earlier in the pandemic.
With the Delta variant, first identified in India and now becoming dominant in many countries, "risks of hospitalization and death more than doubled, and risk of ICU admission more than tripled" compared to earlier SARS-CoV-2 strains, said Dr. David Fisman of the University of Toronto, who co-authored a report posted on Monday on medRxiv ahead of peer review.
He told Reuters his team did find an overall downward trend in disease severity over time, likely because of vaccinations.