On May 27, the joint prevention and control mechanism of the State Council held a press conference. At the meeting, a reporter asked a question. The "Technical Guidelines for Disinfection of the New Coronary Pneumonia Epidemic" stipulates that after a case or asymptomatic infection is hospitalized, terminal disinfection should be carried out in their residence.
However, recent studies have shown that the transmission of the new coronavirus through contact with objects is a very small probability event, which has caused controversy. Is home disinfection necessary?
When is disinfection required?
Is disinfection effective?
Previously, an article titled "Is it necessary to eliminate express delivery and household elimination?"
"Answer from Professor Tang Deliang (Associate) of Columbia University", quoting Professor Deliang Tang from the Department of Environmental Health, School of Public Health, Columbia University, USA.
Tang Deliang said the virus is not a "complete creature" and cannot live alone by itself.
He pointed out that just because the test results came back positive when the surface of the object was confirmed, it should not be inferred that there was a new coronavirus here.
Because the body of the new coronavirus was detected, "just a little fresher".
After the article was published, it quickly sparked widespread discussion. Some analysts believed that the argument side confirmed that "home disinfection" was unnecessary, but the article was subsequently deleted.
The reporter of "Hong Kong 01" asked Tang Deliang for confirmation. He replied that the content quoted in the article was indeed his opinion in a private group, and the relevant quotations were also authorized by him.
He pointed out, "I'm talking about scientific facts, the public understands it, and communication will be easier."
The new coronavirus can stay on surfaces for days, but studies have shown that it is mostly dead virus.
(unsplash @anton-y)
In the article that caused a lot of discussion before, Tang Deliang was quoted as saying that the virus must be parasitized in a living body (host), and the living body can be insects, animals and human bodies, which is why it is impossible for viruses to survive on the surface of ordinary objects.
The survival and replication of the virus also requires the right temperature and humidity, the right pH, and so on.
If the time is extended, "the virus may be alive in the first few seconds after leaving the body, but only in seconds, not minutes."
Mainland mandatory household disinfection provoked Liaoning Dandong re-announcement: unpacked food in refrigerators as medical waste
As for why the virus is detected on various surfaces?
Tang Deliang said that this is a gap in definition. "The existence of a virus we are talking about refers to a live virus that has the ability to replicate. Only a virus in this state can cause transmission and cause new infections."
He emphasized that various methods in the field of biological detection have developed rapidly, and most of the new methods and new technologies are based on the DNA level, which is "sensitive, specific and good", so it can detect the new coronavirus.
But he pointed out that there is a problem in confirming whether there is a live virus on the surface that can replicate and infect others.
Tang Deliang emphasized that just because the test results came back positive, it should not be inferred that there is a new coronavirus here, and the body of the virus was detected.
Most of this is a problem in non-medical laboratories.
Several articles are still from the "Academician" laboratory.
He mentioned in the article that viral contamination in refrigerated transport is also unlikely.
Because refrigeration is indeed a way to preserve the virus, but its conditions are very strict.
Taking his own laboratory as an example, the virus is stored in a liquid nitrogen tank, minus 198, and the virus must be in a special culture medium, which needs to be gradually cooled (one to two degrees per hour); "This process is very troublesome, It also costs money, and if you don’t pay attention, the virus will die. Therefore, it is impossible for general cold chain logistics to meet such conditions.”
Official: It is difficult to determine whether the virus is dead or alive to prevent the spread of the virus
However, in response to a reporter's question on May 27, recent studies have shown that the transmission of the new coronavirus through contact with objects is a very small probability event. Zhang Liubo, chief expert of disinfection at the Chinese Center for Disease Control and Prevention, replied that after the source of infection is isolated, the new crown virus can be prevented. Transmission through the environment, through objects, becomes the focus.
He pointed out that after the new crown patient or asymptomatic infected person leaves, there may be live viruses on the contaminated environment and items, and they need to be terminally disinfected before normal use.
Household disinfection has caused controversy in the mainland. The picture shows a large amount of potion sprayed on the sofa and floor of a household.
(video segment)
Zhang Liubo mentioned that it is sometimes difficult to determine whether a virus is alive or dead, because it is not only related to time, but also to the characteristics of the virus, the number of viruses, the temperature and humidity of the environment at that time, the amount of pollutants, and the amount of sunlight. Many factors such as strength and material characteristics are related, so a scientific judgment must be made.
He emphasized that after the terminal disinfection, it can ensure that there is no live virus in the environment and objects.
He mentioned that terminal disinfection of households is one of the effective measures to prevent the spread of the virus through households.
During the household disinfection operation, in order to ensure the safety of the personnel, family members need to go in after the disinfection is over, and the disinfection team members themselves also need to do personal protection.
"One positive person enters the whole building and kills them"?
In addition, in some places, during the implementation process, the "home disinfection" was increased to "one person positive for the whole building to kill the whole building", which caused widespread controversy.
In this regard, Lei Zhenglong, deputy director of the National Health Commission's Disease Control Bureau and first-level inspector, said that it is required to further strengthen the training of policy documents, technical operation procedures, disinfection methods, and strengthen supervision during the disinfection process.
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