Can pets and express delivery spread the new crown? Re-observation of "material passing from person to person"
Recently, my friends in Beijing are a bit distressed. The express delivery to Beijing from other places clearly shows that it has arrived in Beijing, but the express delivery has not been received for several days. The logistics shows that the delivery may be delayed due to abnormal weather.
At this time, someone reminded that because a resident of Haidian, Beijing received a positive nucleic acid test on the package of the express delivery from Xilin Gol, Inner Mongolia, the express delivery had to complete the elimination after entering Beijing.
Whether this statement is reliable or not has yet to be confirmed, but it is not the first time that a positive express has appeared. The disease control departments in Beijing and many other places have issued a reminder: Try to carry out the disassembly outdoors as much as possible.
So, can express packages that test positive infect people?
Another example is that pets may be infected with the new coronavirus, but will it in turn spread to people?
How can we make more precise prevention and control based on scientific research?
"News Weekly" this week's point of view attention: take a closer look at the material transmission.
Can a "positive" express delivery pass from person to person?
This week, news of positive nucleic acid detection of express delivery packages in many places has made the express delivery industry nervous during the peak of Double Eleven.
On Monday, a resident of Zhongguancun Street, Beijing, two weeks after receiving the express delivery, the inner packaging tested positive for nucleic acid. The express was from Xilin Gol, Inner Mongolia; on Wednesday, a resident of Tieling, Liaoning received a package from the United Kingdom, and the surface of the inner packaging also tested positive. .
Local disease control departments issued a reminder that the express delivery process must be eliminated and consumers should try not to bring the outer packaging into the room.
Will "Positive Express" infect people?
How big is the risk?
It has also become a general concern of the public.
Beijing’s Haidian Disease Control Department said that this “positive express” gene fragment in Zhongguancun Street was positive, which can only prove that the package has been contaminated by the virus. As for whether the virus is active and contagious, it cannot be concluded that it needs to be at the top of the country. The laboratory can be trained in order to know.
Zhao Wei, an expert of the Guangdong Provincial Emergency Health Emergency Expert Advisory Committee, Southern Medical University School of Public Health: This nucleic acid test can not only detect positive for live viruses, but if the virus loses its vitality and is not infectious, it can still detect The nucleic acid of the virus, if this express has been transported over a long distance and a long time, the possibility of living coronavirus on its surface is also relatively small.
If it is an experiment conducted by the laboratory through the isolation and culture of the virus, it is the test result of the live virus. Of course, we cannot rule out this possibility.
Professor Zhao Wei has been studying the coronavirus for many years. 18 years ago, his laboratory was commissioned to study the biological characteristics of the SARS virus and found that when the temperature and humidity are suitable, the SARS virus can survive on the surface of a dry object for three days. .
As for how long the new crown virus can survive on express packaging?
Zhao Wei did not conduct special research, but he and his assistant simulated the operation process of this type of experiment to reporters.
Zhao Wei, an expert of the Guangdong Provincial Health Emergency Expert Advisory Committee, Professor of Southern Medical University School of Public Health: Take 5 microliters of this virus liquid and drip each spot on this surface, and make a mark on the surface when taking samples every hour We can use these (extraction methods) like our collection of throat swabs. After taking it, we can use the TCID50 (half tissue culture infectious dose) technology to see the survival of the virus on the express surface.
Zhao Wei told reporters that regarding the survival time of the new coronavirus, the Lancet magazine published a study last year. In an environment with a temperature of 22 degrees Celsius and a humidity of 65%, the new coronavirus can only survive on the surface of printed matter and tissue 3 Hours, it can survive on clothes for 2 days.
Zhao Wei, an expert of the Guangdong Provincial Health Emergency Expert Advisory Committee, Southern Medical University School of Public Health: I think this experiment should reflect the survival time of the virus on some printed materials or paper, including the surface of the box. I think this is more scientific Yes, it is very convincing.
We did similar work during the SARS period. The SARS coronavirus did a lot on the surface of dry objects.
Including some metals, plastics, paper, etc., basically, under normal conditions for three days, its survival time is three days, which should be closer to our current understanding of the new coronavirus.
Since the outbreak of the new crown epidemic, "physical transmission from person to person" has been considered as a mode of virus transmission, but among all kinds of "physical transmission from person to person", only cold chain transmission found a complete chain of evidence in the new outbreaks in Beijing and Qingdao last year.
As for whether express delivery can infect people, Zhang Liubo, the chief expert of disinfection at the China Centers for Disease Control and Prevention, said at a press conference last week that this must meet the three major conditions that express delivery is contaminated, the virus is still alive, and people are contaminated when receiving the delivery.
Zhang Liubo, chief expert of disinfection at the Chinese Center for Disease Control and Prevention: The first condition should be that the express delivery is contaminated when it is received or when it is shipped.
Second, when this express arrived in our hands, the virus on this was still alive.
Of course the third one, when we received this express, people were contaminated.
Therefore, if we are to prevent, we will start from these three aspects.
Zhao Wei, an expert of the Guangdong Provincial Health Emergency Expert Advisory Committee, Southern Medical University School of Public Health, said: The possibility of spreading to people through positive express delivery is theoretically possible.
However, through the way we spread it and the time the virus survives on the surface of dry objects, on the whole, the possibility of spreading to us through positive express delivery is relatively small.
In Zhao Wei’s view, in most cases, the public does not need to be overly nervous when picking up and disassembling express delivery. However, for express delivery from overseas and medium-to-high-risk areas, it is necessary to maintain sufficient vigilance and take necessary disinfection, hand washing, etc. measure.
Zhao Wei, an expert of the Guangdong Provincial Emergency Health Emergency Expert Advisory Committee, Professor of the School of Public Health of Southern Medical University: When placing an order, we try to avoid looking for those (commodities) in the medium-to-high-risk areas if the (express delivery) comes from the medium- and high-risk areas. , The disease control department’s suggestion, we all still have to abide by it as much as possible, so that it can indeed reduce the possibility of our infection.
If we limit it to the scope of express delivery from medium to high risk sources, I think it will not add a lot of burden to our ordinary people.
How should pets be accurately quarantined?
Express parcels tested positive, causing people to worry about material transmission.
At the same time, how should pets be treated in epidemic prevention and control?
Not long ago, when a pet dog was subjected to epidemic prevention and isolation by its owner, the so-called harmless treatment was carried out by the epidemic prevention personnel, which aroused widespread concern. Animals also have the right to life and need to be respected and protected. They should be accompanied by people. When pets are in close contact under certain circumstances, what kind of prevention and control measures should be used to make people feel more at ease?
Chengdu is affected by the new round of epidemics, among which Gongdongyuan Community, which has been upgraded to a high-risk area, has implemented closed management.
Some residents said that they could not take care of the pets they had in their homes after being quarantined, and they hope to get help.
With such a demand, the street staff organized a "love team" composed of 3 volunteers and 1 epidemic prevention staff. Holding the keys provided by the residents, they came to home to kill the enclosed area. , And then feed food to the single pet inside.
In dealing with pets involved in the epidemic, many provinces and cities in China have adopted flexible methods.
For example, on Tuesday, the Changping District Government stated that it would provide two solutions for door-to-door feeding and centralized surrogacy; Shijiazhuang Xiaoguozhuang faced 30,000 “left-behind animals” during the epidemic at the beginning of the year, and sent more than a dozen people to serve as “temporary feeding”. In another example, cities such as Shanghai and Beijing have also released humanized plans for special management during this special period earlier.
With the gradual cooling of the climate, sudden outbreaks of the epidemic have ushered in many regions.
This has brought new challenges to the normalized epidemic prevention status, and also brought a lot of inconvenience to the lives of many people. Miss Fu who lives in the risky community of Shangrao No. 1 Middle School in Jiangxi is one of them.
During the period of quarantine, home surveillance recorded images of anti-epidemic personnel entering the home and beating the pet dog with a stick. Later, the relevant department announced that the pet dog had been treated innocuously.
Such behavior is a violation of private property, and the temperature of treating life in the face of the epidemic has also dropped a lot.
This incident triggered thinking about how to prevent and control with pets during the epidemic.
Lu Hongzhou, member of the National Health Commission’s Disease Prevention and Control Expert Committee: There is no need to take too strict measures in areas where there is no epidemic. There have been reports in our country, including Hong Kong, including our mainland. After human infection, the virus is transmitted to pets, dogs, There have been reports of cases of cats, but these infected pets, so far, there is no evidence that they have the disease, and they have not transmitted the virus to humans.
Lu Hongzhou also pointed out that even if there is currently no case to confirm whether the new crown virus can circulate between people and pets living together, the World Health Organization has stated in 2020 that according to experimental evidence from Denmark, the new crown virus will be transmitted from human to mink. It was passed back to humans by the mink.
Therefore, we still cannot completely let go of our vigilance, and we should not neglect pet detection or even quarantine observation during flow observation.
Lu Hongzhou, a member of the Expert Committee of Disease Prevention and Control of the National Health Commission: We have an animal protection law, and there is a very good relationship between the owner and the pet. We need to talk about science and prevention of the spread of diseases.
We need to find a balance between the two. In the absence of evidence that pets can transmit the virus to people, I think at this time, we just need to isolate this pet. We need to monitor and we need to strictly enforce it. Quarantine, after how long we have proved that pets are not infectious and no longer carry the virus, we should lift the quarantine. I think this is a scientific attitude.
What is "space-time companion"
During the entire epidemic prevention and control process, as everyone understands the virus, some prevention and control measures are being dynamically adjusted, but in this process, the virus is also changing. For example, the delta mutant is extremely contagious. It may be that the past concept of close connection is no longer practical, so a new word: time and space companions appear, what does this word mean?
Beginning on October 17, the local epidemic involving more than 20 provinces, autonomous regions, and municipalities stabilized this week, which lasted more than a month, and many provinces affected by the epidemic were effectively controlled.
In this round of the epidemic, the new concept of “time and space companion” appeared in front of people.
Ms. Chen, who lives in Chengdu, Sichuan, became the first local "experiencer".
"Time and Space Companion" Ms. Chen: I am now in the green code. After the nucleic acid check and the report, I changed to the yellow code. At that time, I was a little panicked on November 2nd. I thought my code was yellow. It's not that there was a BUG. The relevant staff called and said that I should have a track that overlaps with the confirmed case, so I don't panic, so I will do the nucleic acid normally and watch it at home for the time being.
Such epidemic prevention measures are currently being implemented in many places.
On Monday, a resident in Dalian, Liaoning, was isolated at home because he was a “time and space companion”; a middle school teacher in Zhengzhou, Henan was also isolated from home and could not return to school.
Like Ms. Chen, they both found their health code changed from "green" to "yellow".
"Time and Space Companion" Ms. Chen: Our company is in Tianfu Square, and the office of the confirmed case is also in Tianfu Square. It's actually not very far away, it should be a few hundred meters.
In Chengdu, where Ms. Chen lives, “time-space companion” is defined as: the same time-space grid with her phone number and the confirmed number at 800 meters by 800 meters, staying together for more than 10 minutes, and accumulative staying on either party’s number in the last 14 days If the duration exceeds 30 hours, the number found in this way is the time-space companion number.
Under these conditions, there were 82,000 "space-time companions" who were screened out together with Ms. Chen.
"Time and Space Companion" Ms. Chen: I definitely can't go to work after I turn into a yellow code. What was required at the time was to do two nucleic acids within three days, and the results of the two nucleic acids must be negative, so that it is temporarily safe. Before the two results came out, you couldn't go anywhere. I was still working at home for a week, which is equivalent to ten days without going out.
Prior to the "time and space companions", the personnel who are investigating the risk of new crown virus infection are managed as close contacts.
The "Guidelines for the Determination and Management of Close Contacts" issued by the National Health Commission mentions that in the determination principles of close contacts and sub-close contacts, most of them are in the same space and in the same field.
Compared with the space-time companions, the latter expands further in space.
Professor Qian Hua, the head of the Laboratory of Indoor Environment and Health of Southeast University, said that the transmission of aerosols in a closed indoor environment is stronger than that of droplets. In his research, he found that the delta strain can still pass more than 5 meters away. The case of aerosol transmission.
Qian Hua, head of the Laboratory of Indoor Environment and Health, Southeast University: You stay in a poorly ventilated place, stay in a well-ventilated place, and stay outdoors. These three risks are completely different.
In a confined space, the risk is definitely high. As long as there is a ventilated room, the aerosol concentration will drop very quickly. The outdoor risk is relatively small, but it is not zero.
When we prevent and control, we may think that there are some impacts in response to the fact that we should rely on a higher gear, one step forward, and put it to such a large distance. But from a precise point of view, I think the same building should be enough. Eight hundred meters is equivalent to a relatively large range.
In Qian Hua's view, the concept of "time and space companions" means that, in the face of the rapid spread of the Delta strain, the circulation department has difficulty in accurately locating close contacts, and has adopted an insurance move.
In fact, at present, there is no unified definition and management method for "time and space companions" in China.
Where it has been clearly defined, the management methods are also different.
With the advancement of normalized prevention and control, more scientific and precise prevention and control methods can minimize the impact on production and life, and this also puts forward higher requirements for participants, not only accurate but also "temperature".
Qian Hua, head of the Laboratory of Indoor Environment and Health, Southeast University: It should be convenient for the operator, because the base station can immediately know that this person has been here and can quickly find these people.
But it is not detailed enough, there is no problem with the same building, and no problem with being in the same room.
On the basis of understanding the way it spreads, it is best if you can achieve good results at a relatively small cost.
In other words, if you want to make it bigger, it will definitely be defensive, but our economic life and the lives of our people are too expensive to bear, so precision protection has always been emphasized.
In fact, it means that we need to judge it more scientifically, and then we can achieve good results at a relatively small cost.
Facing the epidemic, it has been nearly two years. Human beings are like walking through a dark tunnel, and now it seems to be able to see the light. When will we reach the end of the tunnel?
There has been a lot of good news recently. First, China has received more than 2.4 billion doses of vaccination, and vaccination has begun for people aged 3 to 5, and the coverage rate will further increase.
At the same time, both foreign and domestic research and development of new crown specific drugs have taken relatively large steps. The two are integrated. It seems that the moment of human farewell to the dark is not far away, but the epidemic is not over yet, and personal protection is still Is the top priority.
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