"Dynamic zeroing" equals city-wide sealing? Wu Zunyou posted in response to four major misunderstandings

On the evening of April 18, 2022, Wu Zunyou, chief expert of epidemiology of the Chinese Center for Disease Control and Prevention, posted on social media to explain the main connotations and implementation measures of "dynamic zeroing" and clarify various misunderstandings from the outside world. The following is the full text of Wu Zunyou's article:

Over the past two years, the mainland has not only successfully controlled the COVID-19 epidemic, but also provided an environmental guarantee for social stability and economic construction. The mainland's achievements in the phased prevention and control of the new crown are due to the strong leadership of the Party Central Committee, the second is due to the general strategy of "external defense import, internal defense and rebound" and the general policy of "dynamic zero clearance", and the third is due to the broad masses of the people actively participating in the anti-epidemic struggle.

With the changes in the global epidemic situation, especially the rapid transmission speed, hidden transmission and difficulty of the Omi Kerong mutant strain, the prevention and control effect abroad is not ideal, and many countries have helplessly chosen to "lie flat". Recently, the mainland has also experienced a complex epidemic situation with many points and a wide range. Some people in China have no confidence in continuing to adhere to "dynamic clearance", and even some people confuse "dynamic clearance" with "zero infection", believing that at this stage, for the new epidemic situation, "dynamic clearance" is impossible to achieve. To this end, with the help of the Weibo platform, the basic principle of "dynamic zero clearance" playing a role in the prevention and control of the new crown epidemic is introduced, as well as a variety of misunderstandings in society.

1. Dynamic zeroing meaning

"Dynamic zeroing" consists of two words, "zeroing" and "dynamic".

"Zero clearance" is the process from existence to nothing, that is, the process of eliminating the epidemic. However, this eradication only refers to a certain epidemic that occurs at a certain time in a certain place, and does not refer to the general epidemic situation nationwide in a broad sense.

"Dynamic" means that the outbreak and zeroing are constantly changing. For example, if an epidemic in place A is extinguished, another epidemic may occur in place B; if the epidemic in place B is extinguished, there may be an epidemic in place C. In other words, the epidemic in A was extinguished, and after a while, there was another outbreak in A, or a new outbreak in the third, or even fourth or more times, but there was no direct transmission relationship between these outbreaks. After each outbreak, it can be extinguished in a relatively short period of time, so that the epidemic is zero.

The fundamental purpose of "dynamic zero clearance" is to find an epidemic, extinguish an epidemic, and prevent the epidemic from "taking root" in the local area.

2. Conditions for dynamic zeroing

After a person is infected with the new crown virus, after about 1-2 days of virus replication and growth, the virus begins to be excreted from the body (that is, a positive nucleic acid test) and lasts for about 7-12 days. When an infected person expels the virus from the body, it is contagious and can transmit the virus to others.

The coronavirus can only survive in the long run if it continues to spread from person to person. If an infected person is past their maximum detoxification time and cannot transmit the virus to others, the virus will be destroyed by the body's immune function.

All infected people in an epidemic are found, physical isolation is adopted, contact with others is restricted, the virus is prevented from spreading to others, and a maximum detoxification time is maintained, and the virus is eliminated at the location of the epidemic.

In the absence of a local ongoing spread of COVID-19 and the fact that local COVID-19 is mainly imported from abroad, the "dynamic zeroing" strategy is the best choice.

After the control of the new crown epidemic in Wuhan, the new crown virus epidemic in the mainland has been basically eliminated. The subsequent outbreak of the new crown virus spread locally and was imported from abroad. In other words, in the vast majority of the mainland, for the vast majority of times, the mainland's territory is clean and free of the new crown virus. Therefore, the "dynamic zero clearance" strategy is the best choice for the prevention and control of the new crown in the mainland.

Generally speaking, the earlier the epidemic is detected, the smaller the scope of its impact, the easier it is to achieve "dynamic clearance". Even if a certain proportion of community transmission occurs, with the county (district) as the basic unit, as long as the number of counties (districts) where the new crown epidemic occurs, the proportion of the total number of counties (districts) in the country is very small, it can be dynamically cleared. If these counties (districts) where community transmission occurs are scattered in 31 provinces, autonomous regions, and municipalities directly under the central government, "dynamic zeroing" is relatively easy to achieve; if these counties (districts) with community transmission are concentrated in a few provinces, autonomous regions, and municipalities directly under the central government, the difficulty of "dynamic zeroing" will be greater, and the time required will be longer.

3. Dynamically clear the soul

The soul of "dynamic zero clearance" is to discover early, control early, and eliminate every epidemic in the bud. Don't let the epidemic take root in place. Minimize the threat of the epidemic to people's health and life safety, as well as the impact on social stability and economic development.

4. The main measures of dynamic zeroing

The core of "dynamic zero clearance" is to cut off the propagation chain.

The main measures of "dynamic zero clearance" include early detection, early reporting, early isolation, and early treatment, which is the so-called "four early" measures.

Among the prevention and control measures of "foreign prevention and importation", one is to emphasize the isolation and observation of inbound personnel in order to timely discover infected people entering abroad; the other is to emphasize the daily monitoring of people involved in overseas cold chain or cargo transportation, and timely discover the "human-to-human transmission" that occurs after "material transmission". Both of these measures aim to detect first-generation cases of epidemics imported from abroad and control the first-generation cases. This is the highest state of "dynamic zeroing".

Among the prevention and control measures of "internal prevention and rebound", the first is to strengthen the control of the flow of people in the new crown epidemic areas, strictly prevent the outflow of infected people, and bring the new crown epidemic into non-epidemic areas, causing a new epidemic. The second is to strengthen the monitoring of outpatients, and conduct nucleic acid testing for patients with fever, cough and other suspected new crown or cold; those who do not have the conditions to do nucleic acid can use antigen screening in order to detect early cases in time. Third, people with symptoms such as throat redness or pain, cough, etc., can use antigen screening methods to do self-testing, and if they find positive, they should report to the local epidemic prevention department in time for proper disposal. These three measures are all effective methods for early detection of the epidemic and provide a guarantee for early detection of the epidemic to achieve "dynamic clearance".

5. Dynamic ZeroIng Myth 1: Zero Infection

"Dynamic zeroing" does not mean zero infection, which is essentially different from zero infection. "Dynamic zeroing" means that for the occurrence of the new crown epidemic, it is found together and eliminated together, which not only prevents the new crown virus from circulating in the place where the epidemic is located, but also prevents the virus from spreading from the epidemic area to other areas.

Although "dynamic zero clearance" does not pursue zero infection, in order to eliminate an epidemic, it is also required to block the transmission in time at the location of the epidemic, and no new infections occur. In other words, there is no requirement that the whole country be free of COVID-19 infection at any one point, but for each outbreak that occurs, it is required to be extinguished in a shorter period of time.

"Dynamic zeroing" emphasizes the zeroing of infected people at the social level, and does not require that there be no infected people in the location of the epidemic. The so-called zero at the social level means that there are no infected people in the group of free social activities, even if there is a certain number of infected people in the isolated management group, it does not matter, because they are in isolation and will not spread to society. For example, in A, 100 people with COVID-19 were found in nucleic acid screening, of which 50 were from outpatient screening and community screening, and the other 50 were from close contacts under isolation and observation. Then, A land has not reached the social level of zero. B, in the nucleic acid screening found 200 new crown infected people, but all infected people are from the isolation of the observation of the population, and in the community screening and outpatient screening did not find infected people, then, B has achieved no infection at the social level, as long as the continuous community screening and outpatient screening did not find infected people for a longest detoxification period (with nucleic acid testing as an indicator) or a longest incubation period (with confirmed cases as an indicator), it achieved "dynamic clearance".

6. Dynamic Zero Misunderstanding 2: Sealing

Some people equate the measures of "dynamic zeroing" with the sealing and control measures, and when they mention "dynamic zeroing", they think of the city-wide sealing and control. The measures taken by "dynamic zeroing" depend on the stage of epidemic detection, if it is found early, only need to isolate and treat patients, plus isolation and observation of close contacts, can achieve zero clearance. For example, in the past two years, there have been 12 new crown epidemics in Shanghai, and the maximum number of cases in each epidemic has not exceeded 25, which has been controlled and zeroed, and no sealing measures have been taken at all. Containment measures are used only when the outbreak is detected late, or if decisive measures are not taken to control it in time, although it is detected earlier, and there is more community transmission.

7. Dynamic zeroing misunderstanding three: nucleic acid testing for all employees

There are also some people who equate the "dynamic zeroing" measures with the nucleic acid screening measures for all employees, and when they mention "dynamic clearance", they think of the nucleic acid screening of all employees in the city. Similarly, as long as the epidemic is detected early, the transmission chain is clear, and the close contacts are found along the transmission chain, there is no need to do nucleic acid screening for all employees.

Nucleic acid screening measures are used only when the outbreak is detected late, or if decisive measures are not taken to control it in time, there is more community transmission, and the transmission chain is not clear.

8. Dynamic Zero Misconception 4: Affecting the Economy

When some people mention "dynamic zeroing", they think of the great impact on the economy. In fact, dynamic zeroing can escort economic construction to the greatest extent.

If the epidemic is found in the first generation, controlled in the first generation, and eliminated in the first generation, it will have no impact on economic construction, but can only provide a safe environment.

If the outbreak is detected earlier, such as in the second or third generation of the epidemic, it will not have an impact on economic development.

If the development of the epidemic situation is more severe, it is necessary to take a large range of nucleic acid screening and sealing and control measures for all employees, and the "dynamic zeroing" strategy does have a certain impact on economic development. According to the preliminary analysis of mathematical model experts, the impact of the "dynamic zeroing" strategy on local GDP is only half of the economic impact of the non-"dynamic zeroing" strategy.

Source/@Wu Zunyou ChinaCDC

Editor/Tao Yinsheng

Review/Qiao Hong

Producer/Xi Shujun