Pathway of nCoV infection

Paul Hunter, professor of medicine at the University of East Anglia and non-permanent advisor to the World Health Organization (WHO), said it is difficult to determine how people are infected with nCoV, even though the virus has infected 107. million people in the world.

For example, a person may touch the counter top of the counter that a Covid-19 patient has touched, but also in contact with the supermarket clerk or the child of the person infected with classmates. Therefore, determining the mode of infection is difficult. However, after a year, studies have revealed more evidence of the pathway of nCoV transmission.

Sift through the contact surface

Theoretically, nCoV can be transmitted through the surface of common objects. Recently, however, some scientists believe that this has been emphasized more than necessary. In a study published in the Lancet Medical journal in July 2020, Emanuel Goldman, a microbiologist at Rutgers School of Medicine in New Jersey, gave advice from several governments to disinfect residual surfaces. at restrictions. According to him, most experiments take place in the laboratory with large amounts of virus, not quite the same reality. He commented that the trend of disinfecting furniture with strong detergents is not enough, but at the same time advises people to wash their hands often.

The Nature editorial published in early February states that surface-borne nCoV contamination is rare. WHO and health agencies need to better explain their recommendations on how to prevent the epidemic.

According to Professor Hunter, nCoV can be spread by contact with a contaminated surface, but demonstrating has many challenges. The best studies on this have been done since the beginning of the pandemic before the virus spread to a point where it was difficult to determine a path of transmission.

In February 2020, scientists examined the surfaces of objects at Wuhan Hospital, which treated the large number of Covid-19 patients at the time. They found the virus on mice, trash cans, bed rails, doorknobs, and even the soles of healthcare workers’ shoes. Another study published in the New England Journal of Medicine found that the virus can live up to 72 hours on plastic and steel, 8 hours in copper and 4 hours on cardboard.

However, after a year of living with the pandemic, epidemiologists have yet to find clear evidence of a CoV infection caused by exposure to a contaminated surface. As of July 2020, WHO noted this could be the route of infection but there have been no reports of any specific cases of the disease in this way.

American people wear a mask when going out to avoid COV infection. Image:NY Times

Sift through drops

Scientists generally agree that nCoV is spread through droplets between close contacts. When you cough or sneeze, thousands of tiny droplets of saliva that cannot be seen with the naked eye will shoot out. They can fly as far as 1 meter before they touch the ground or 2 meters if they cough hard.

The smallest droplets of water will continue to fly in the air for a while. The larger droplets are the main means by which the virus is transmitted to humans. If these drops come into contact with your face, you risk getting sick.

Singing or speaking out loud is also risky because of the high amount of air. In March 2020, of the 121 members of the choir in Skagit, Washington, 53 had Covid-19 and two died. At that time, the number of cases in the West Coast of the United States was still relatively small. Professor Hunter said droplet infection mainly occurs when many people gather in enclosed spaces, not socially isolated.

Airborne transmission

Whether or not nCoV is airborne is a controversial question. The smallest droplets from a person infected with the virus can stay in the air for hours. That means you can get nCoV even without close contact. The bacteria that cause tuberculosis and the viruses that cause measles and chickenpox usually spread this way

At the beginning of the pandemic, most scientists were still skeptical about the possibility of the virus being transmitted through the air. However, by the summer of 2020, 239 scientists from 32 countries wrote letters to WHO, urging the agency to take the problem more seriously. Now, experts from WHO and the US Agency for Disease Control and Prevention have recognized this possibility but ranked at low risk.

According to a study published in May 2020 in the journal Nature Research, the genetic material of nCoV was found in air samples at two hospitals in Wuhan. They show up in restrooms and rooms where a doctor has a mask removed. This finding reinforces evidence of the ability of viruses to be in the air and underscores the role of keeping the room airy, but does not answer the question of whether a person can get sick this way. Viruses may be dead or decomposed into small particles.

Another investigation at a restaurant in Guangzhou, China, found traces of nCoV in the air conditioning system. The restaurant became a target of investigation after one customer infects 9 other people while eating there.

The WHO guidelines in November 2020 say: “Airborne infections can occur in certain settings, especially indoors, where people are crowded and where people are exposed to the virus. with others over long periods of time such as restaurants, choirs, gymnasiums, nightclubs, offices or places where religious services are performed.

In 2020, German Chancellor Angela Merkel recommends opening windows as an effective and inexpensive anti-epidemic.

Mai Dung (Follow Telegraph)


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