Why are some coronovirus asymptomatic – and why are they so contagious?



Just how contagious is Covid-19 contracted – yet shows no symptoms – and what makes them asymptomatic while others suffer greatly from the disease?

This study, published this week in the medical journal JAMA Internal Medicine, provides a theory for the first question. 303 patients with COVID-19 were isolated at a treatment center in South Korea. Of them, 110 (36%) were asymptomatic and 21 (19%) developed symptoms during isolation.

“The ability of transmission from asymptomatic people to control the spread of SESVID-19 has been cited as an important factor, but the clinical course and viral load of asymptomatic people with SARS-CoV-2 infection. There is limited information about, “the researchers wrote.
They found: “Many individuals with SARS-CoV-2 infection remained asymptomatic for a long time, and the viral load was similar to that of symptomatic patients,” the scientists concluded. “Therefore, infected individuals should be isolated regardless of symptoms.”

The study was led by Seungje Lee, an associate professor at Sunchunyung University College of Medicine in South Korea, reviewed it, and carried out the first epidemic; Researchers analyzed swabs taken from the group between 6 March and 26 March.


‘Many individuals with SARS-CoV-2 infection remained asymptomatic for a long time, and the viral load symptom was similar in patients.’

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said that in his 40 years of dealing with viral outbreaks, he had never seen anything like COVID-19, especially in a singular way that brought about the greatest public health Helped. Crisis in a generation.
“I have been dealing with viral outbreaks for the last 40 years. I have not seen a single virus – that is, a pathogen – there is a limit where 20% to 40% of people have no symptoms, ”he said on the novel and a recent House Committee on Energy on the coronavirus epidemic. told.
The World Health Organization currently estimates that 16% of people with COVID-19 are asymptomatic and can transmit coronaviruses, while other data suggest that 40% of coronavirus viruses are due to carriers not displaying symptoms of the disease.
According to the study of “viral shedding” dynamics, according to the Centers for Disease Control and Prevention, infectivity of asymptomatic individuals relative to those who are symptomatic is 75% – how much of the virus is transmitted through talk or breathing.
Not everyone responds similarly to COVID-10 infection. These Chinese researchers wrote, “Different host immune responses to SARS-CoV-2 infection may partly explain why men and women, young and elderly, infected with this virus have different disease severity.”
So why are some people asymptomatic while others are not? “SARS-CoV-2, a virus causing Coronavirus disease 2019 (COVID-19), uses angiotensin-converting enzyme 2 (ACE2) as a cell receptor to invade human cells,” he said. said.
Those ACE2 receptors or “gates” are more prevalent in older people and are thicker than younger ones. For example, there may be some way to explain why people over the age of 60 have not been affected as badly by the virus.
Exposure to other coronaviruses, which can give people “T-cell immunity” to the same virus, is achieving a low viral load of COVID-19 and other lucky genetic variations that may also contribute to some people being infected. Are no less severe or symptomatic.
There is currently no vaccine for COVID-19, although many companies say they have progressed with the tests. However, unlike influenza virus, for which there are many vaccines, people have generally not been immune to COVID-19 for many generations.
related: Feeling loose about masks? think again. If everyone wore a mask today, how many lives could be saved

The public has been confused about the number of asymmetric people and how contagious they are.

MarketWatch photo illustration / iStockphoto

But a strong immune response to infection with a virus such as COVID-19 can sometimes bite both ways. Case in point: Doctors and members of the public were taken aback by how strong, healthy people suffered from the 1918 influenza.
Doctors today said that “cytokine storm”, is a process where the immune system in healthy people reacts so strongly to injury to the body and eventually damage organs and, in the most severe cases, organ failure.
A hallmark of some viruses: the growth of immune cells and their active compounds (cytokines) effectively turned the body against itself, causing lung inflammation, severe respiratory distress, and secondary bacterial pneumonia.
According to a recent report by Deutsche Bank DB, “There is a big difference between Spanish flu and COVID-19 distribution of deaths.”
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“For COVID-19, the elderly are the most hurt, but in 1918 the young working-age population was severely affected.
“In fact, among 25-34-year-olds in the United States, mortality from pneumonia and influenza that year was 50% higher than for 65-74-year-olds. A notable difference for Kovid-19,” Deutsche Bank said.


Asymptomatic transmission is the ‘Kovid-19 Epidemic Heel of Epidemic Control’.


– Monica Gandhi, Deborah Yoko and Diane Havalir, scientists at the University of California, San Francisco

Public-health officials have advised people to keep a distance of six feet from each other. Facial masks are designed to prevent the wearer, who may be infected with COVID-19, but have very mild or no symptoms, spreading invisible droplets to another person and thus infecting them as well.
It does not matter whether a person is ill or not. According to a May 28 editorial in the New England Journal of Medicine, asymmetric transmission is “the heel of COVID-19 epidemic control through public health-related strategies”. It stated that SARS-CoV-1, SARS-CoV- More than 2 is contagious.
A recent study of coronovirus outbreaks in a skilled nursing facility noted editorials by researchers Monica Gandhi, Deborah Yoko, and Diane Havelir at the University of California, San Francisco, that “strongly demonstrate that our current approaches are inadequate.”
They said those symptoms included high genetic relatedness, mainly transmission via respiratory drops, and low frequency of respiratory symptoms (fever, cough and shortness of breath), five days after exposure to both infections. Middle ones develop.
This University of San Francisco, San Francisco study stated that there is an excessive load of SARS-CoV-2 in the upper respiratory tract even among pre-symptomatic patients, which distinguishes it from SARS-CoV-1, where replication is predominantly It occurs from Lower respiratory tract. ”
“Despite the deployment of similar control interventions, the symptoms of the two epidemics have increased dramatically in different directions,” he said. “Within 8 months, SARS was controlled after infecting approximately 8,100 individuals in limited geographic areas of SARS-COV-1.”
Governments around the world are struggling to stop the spread of the epidemic. (An epidemic is a disease that infects areas or a community.) The “Spanish flu” from 1918 to 1919 and the Black Death from 1347 to 1351 were two of the most extreme epidemics ever recorded.
As of Saturday, COVID-19, a disease caused by the virus SARS-CoV-2, had infected at least 19.4 million people globally and 4.9 million people in the US, making it more than 721,762 people worldwide and fewer Less than 161,365 people were killed. Data collected by Johns Hopkins University.
The stock market has been on a wild ride in recent months. Dow Jones Industrial Index DJIA,
+ 0.17%
And the S&P 500 SPX,
+ 0.06%
Friday ended as investors awaited two rounds of fiscal stimulus; Nasdaq Composite Comp,
-0.87%
The 7-day win streak came to an end.


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