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.
“Pocket” in virus’ spike protein could be treatment target
The spike protein on the novel coronavirus that helps it break into healthy cells has a tiny "pocket" that could make it vulnerable to antiviral drugs, researchers have discovered.
Using a powerful imaging technique called electron cryo-microscopy, they studied the molecular structure of the virus and found the pocket, with a small molecule, linoleic acid (LA), buried inside.
LA molecules are critical to the immune functions "that go haywire in Covid-19," coauthor Imre Berger from the Max Planck-Bristol Centre for Minimal Biology in the UK said in a news release. "And the virus that is causing all this chaos, according to our data, grabs and holds on to exactly this molecule - basically disarming much of the body's defenses."
In a paper published on Monday in Science, researchers note that common-cold-causing rhinoviruses have a similar pocket, and drugs that fit into the pocket by mimicking fatty acids like LA have lessened symptoms in human clinical trials.
This suggests, they say, that drugs developed to target the pocket on the coronavirus spike protein might help eliminate Covid-19.
Most people infected with the new coronavirus will have symptoms, according to researchers who reviewed data from nearly 80 studies of individuals with positive PCR tests for Covid-19. Overall, just 20 per cent remained asymptomatic.
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Five of the studies provided enough data for the researchers to examine the spread of the disease. Compared to Covid-19 patients with symptoms, patients who never developed symptoms were 65 per cent less likely to transmit the virus to others, the researchers reported on Tuesday in the journal PloS Medicine.
"A minority of people has truly asymptomatic SARS-CoV-2 infection and, if they are less infectious than people with symptoms, they probably account for a relatively small proportion of all transmission," coauthor Dr. Nicola Low of the University of Bern told Reuters. "Most people will go on to develop symptoms and there is a substantial amount of transmission during the pre-symptomatic phase," Low said.
That means prevention measures to reduce transmission, including face covering, social distancing, physical barriers and widespread testing and contact tracing to find and isolate contagious people remains necessary.
The average time from when a heart attack starts to when treatment begins has gotten longer during the pandemic, and researchers attribute most of the delay to patients' fears of contracting Covid-19 if they go to a hospital.
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In a study published in the American Journal of Emergency Medicine, doctors in China found the average time from symptom onset to first contact with a healthcare provider was about an hour longer in January to April 2020 than during the same period in 2019.
And this year, after arrival at the hospital, the time until a blocked artery was reopened was 22 minutes longer - and more heart attack patients died, the authors say.
Coauthor Dr. Ming-Wei Wang from Affiliated Hospital of Hangzhou Normal University told Reuters patients need to understand the importance of getting to a hospital quickly, and Covid-19 screening at hospitals should be hastened for patients with chest pain.
Dr. Aditya Kapoor from India's Sanjay Gandhi Postgraduate Institute of Medical Sciences, who was not involved in the study, said other studies have found similar delays. "Resource and manpower allocation to Covid-19 treatment, lockdown restrictions, and patient apprehensions related to hospital visits all play an important role," he said.
Living with a human who has Covid-19 raises the risk that dogs and cats will be infected with the new coronavirus, according to a French study.
Blood tests performed on 34 cats and 13 dogs belonging to patients who had recovered from Covid-19 found antibodies to the virus, indicating likely past infection, in 21 per cent of the pets - 8 cats and 2 dogs.
By comparison, among 38 pets in households with no known Covid-19, only one cat tested positive, according to a report of the study posted on bioRxiv on Tuesday ahead of peer review.
"We cannot definitively prove that all the 10 positive animals were infected with SARS-CoV-2," the authors said, adding that it is not known whether infected pets can spread the virus back to humans. "While viral shedding from pets does not appear sufficient for transmission to humans or other animals encountered during walks, for people in closer contact, precautionary measures should be considered."
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