This wave of local epidemic was caused by the previous infection of Han. It may have been transmitted to Cao by sharing the polluted environment. The virus has been spread for several rounds, and finally more than 40 people were directly or indirectly transmitted through the 87-y

Southern Metropolis Daily reported that the local epidemic in Harbin is still spreading, with 4 new confirmed cases on April 18.

This wave of locally transmitted epidemics that have continued from April 9 to the present day, except for the 13th, there have been new confirmed cases and asymptomatic infections of in recent days.

As of 24:00 on April 18, there have been 54 infected people in Harbin (36 confirmed cases and 18 asymptomatic infections) related to Han, a 22-year-old female international student who returned to Harbin from the United States. A total of 17,325 close contacts have been traced, 16,493 people have been released from medical observation, and 832 are still under medical observation.

This wave of local epidemic was caused by the previous infection of Han. He may have been transmitted to Cao by sharing the polluted environment. After several rounds of transmission, the virus finally directly or indirectly transmitted more than 40 people through the 87-year-old hospitalized man, including 6 nurses and 1 doctor, and the virus is still spreading.

There is no doubt that there is insufficient prevention and control over the spread of the local epidemic. The Harbin Municipal Party Committee and Municipal Government have made a written and in-depth review to the Heilongjiang Provincial Party Committee and Provincial Government. The Heilongjiang Provincial Commission for Discipline Inspection and Supervision held 18 party members, cadres and public officials who failed to effectively prevent and control the epidemic, including the deputy mayor, director of the Municipal Health Commission, deputy district mayor and leading cadres of the three hospitals. The notice stated that the responsibilities were not fulfilled properly and there were loopholes in epidemic control measures.

However, besides poor prevention and control, is there any lessons worth learning for this wave of local epidemic?

has two points worth paying attention to: 1. Sharing the virus transmission caused by the polluted environment cannot be underestimated. 2. The new coronavirus is so contagious that it is beyond imagination. There are still unknown factors that need us to explore in epidemic prevention and control.

As of 24:00 on April 18, the epidemic transmission chain.

After 4 tests in 23 days of entry, Han did not identify the confirmed case. Why did it become the source of transmission?

Looking back at the beginning of this wave of epidemic, the public will focus on Han, a 22-year-old female international student.

Han is not a confirmed case, so why has it become the source of transmission?

Unlike some overseas personnel in some areas who secretly returned to China and concealed their whereabouts with illness, which led to the spread of the epidemic, Han met the epidemic control regulations from returning to China to quarantine at home.

According to the Harbin Health Commission's notice, Han arrived from the United States from March 19 and transferred it to his home in Jiangwan Community, Duoli District, Harbin City by "hand-handing" and implemented home quarantine observation in accordance with the policy regulations at the time.

The so-called "hand-handed hand" means that from the airport to the entrance of the community, there is health control throughout the entire process. This means that after Han returned to China, he made a health declaration in accordance with regulations, and the local disease control department also implemented control measures in accordance with regulations.

Some netizens questioned why overseas personnel did not have centralized quarantine when they returned to China? The official reply was that Han returned from the United States on March 19. According to the policy at that time, he only quarantined people returning from Japan, South Korea, , Iranian , and Italy. All incoming personnel will be quarantined on the spot only from the 21st.

During Han's home isolation observation period, the nucleic acid test was negative on March 31, and the antibody tests were both negative. On April 3, Han was isolated for 14 days, and the nucleic acid test was negative again and he was released from home quarantine.

Harbin Center for Disease Control and Prevention investigated and found that Cao and Han were neighbors upstairs and downstairs, and they didn’t know each other. The notice stated that on April 10 and 11, the Centers for Disease Control and Prevention conducted two antibody tests on Han, of which both IgM were negative and IgG were positive. They were diagnosed as a previous infection with the new coronary pneumonia (imported from abroad).

In other words, from Han’s return to China on March 19 to April 11, he received four tests in 23 days, but none of them were identified as confirmed cases.

However, Han may be the source of infection.

Harbin Center for Disease Control and Prevention investigated that the unit is one elevator and one household, and the entire unit shares an elevator, and there is a common space that may be contaminated; due to the house structure and other reasons, there is also the possibility of virus transmission between the two adjacent floors, and the two have the conditions for contagion.

shared the environment that has caused the spread of the epidemic, SARS has learned a lesson!

This is not an isolated case.

Beijing's first imported related case was also accused of sharing a contaminated environment and causing infection.

Liu developed symptoms such as fever on March 10, and took medication during the period and was diagnosed as a confirmed case of new coronary pneumonia on March 23. The epidemiological investigation found that Liu's neighbor Li arrived in Beijing from the UK on March 5 and was quarantined at home. He took the stairs to the community to apply for an entry and exit permit and went to the hospital for treatment. On March 12, he was diagnosed as a confirmed case.

The investigation believes that both of them have been taking stairs recently, and Liu may have been exposed to the stair environment polluted by Li before March 11, causing illness.

In fact, due to the pollution of the environment, it existed when the SARS epidemic broke out 17 years ago.

At the end of March 2003, a large number of people and sudden SARS epidemic broke out in , Hong Kong. On March 26, 7 people were infected in 5 households in Block E, Taoda Garden, and there have been family infections one after another. As of April 15, the number of infections reached 321. After investigation, the patient at the source of the incident was a 33-year-old man. After developing SARS, he went to his brother's residence in Block E, Taoda Garden, and used the toilet due to diarrhea. Later, his younger brother and his wife and two nurses who were caring for him in the hospital were confirmed to be infected with SARS.

There are 321 infected people in Taoda Garden, 40% are concentrated in Block E. Finally, after investigation, experts concluded that the culprits of the SARS outbreak in Taoda Garden were sewer pipes and floor drains. Most of the U-shaped water collectors in the floor drains of the home bathroom have failed to play a role in air isolation due to drying up.

At that time, relevant Hong Kong departments conducted tests in a unit in Building E and found that when the bathroom's exhaust fan is started, the air would flow backwards from the sewage pipe through the floor drain into the bathroom. These airflows may distribute aerosol stored in the sewage pipe into the bathroom, and the bathroom's air pumping fan may also discharge these aerosols to the patio, and finally the virus-containing aerosols enter other houses through the windows. This is the fundamental reason for the SARS outbreak in Hong Kong Taoda Gardens back then.

The spread of the new coronavirus is beyond our imagination!

Return to the spread of the epidemic, that is, Han, who had been infected with the new coronavirus, may have spread the new coronavirus through the environment to his unfamiliar neighbor Cao.

Another question is here.

After four tests, Han was not identified as a confirmed case (not yet). The virus in the body may not be detected or is weak during the test period. Why can the virus be transmitted through the shared environment?

According to the transmission chain, Cao was diagnosed as an asymptomatic infected person (later revised as a confirmed case), and transmitted the new coronavirus to his boyfriend Li (asymptomatic infected person), his mother Wang Mouling (asymptomatic infected person) and his mother's boyfriend Guo Mouming (confirmed case). It can be confirmed that these people are familiar with each other and have face-to-face contact with each other.

After, Guo Mouming and Wang Mouling had a dinner with Chen Mou's family. 87-year-old Chen Mou and two sons participated in the dinner and were diagnosed with infection. Chen visited the Second Hospital of Harbin City and the First Hospital of Harbin Medical University due to stroke, causing many patients, accompanying staff and medical staff in the same ward of both hospitals to be infected.

As of 24:00 on April 18, there have been 54 infections in this wave of epidemic in Harbin, including 36 confirmed cases and 18 asymptomatic infections. Except for the 8 infected cases, Cao, Li, Wang, Guo, Chen’s father and son, and Chen’s second daughter-in-law, the other 46 infected cases were all related to the infection during Chen’s hospitalization.

Among the 46 infected people, Chen’s two daughters had accompanied his father in the hospital or had direct contact with two brothers, resulting in infection; while many of the other 44 infected people may not have direct contact with Chen.

Analysis of these 44 infected patients has three characteristics: 1. There are all ages, with a large age span. The youngest is a 13-year-old middle school student and the oldest is 81 years old. 2. There are 13 people over 60 years old, most of whom have underlying diseases. After being infected with the new coronavirus, it brings difficulties to subsequent treatment. 3. A small number of people have direct contact with Chen, and most of them have indirect contact with Chen, and are infected only because of the same ward.

According to reports, Chen was first hospitalized in the Second Hospital of Harbin City, in a single ward. Later, he was transferred to the Department of Respiratory Medicine of the First Hospital of Harbin Medical University due to fever. He was transferred to the isolation ward of the Fever Clinic of the First Hospital of Harbin Medical University three days later, and was later diagnosed.

Currently, among the confirmed cases, there are 6 nurses (4 asymptomatic infections, 2 confirmed cases) and 1 doctor, and most of the rest are patients and accompanying patients in the same ward. Some may have direct contact with Chen, such as individual nurses or patients; but some patients, accompanying nurses and nurses are infected just because of the same ward.

For example, there were 4 new confirmed cases on the 18th: Xu's husband Yu, who had been hospitalized at the First Hospital of Harbin Medical University. Yu was a patient in the same ward in Chen. He was first diagnosed with infection, and now she is also infected; Zhang is a patient in the same ward in the Second Hospital of Harbin City, accompanied by Chen; Yan and Wang are both patients in the same ward on the same floor and ward during the hospitalization of Chen in the Second Hospital of Harbin City.

In addition, these infected people were infected mainly in early April, when the epidemic alarm has not been lifted. Most Harbin citizens wear masks when going out, especially when visiting hospitals. In this case, so many people are infected through indirect contact. You can imagine how powerful the virus is spreading.

Of course, it is not ruled out that some infected people may not wear masks, but among the confirmed cases, 6 nurses and 1 doctor, must have worn masks even if they are not "fully armed" at work, and they may even be N95 masks with better protective performance than ordinary citizens, but they are still caught.

This is not January when the COVID-19 epidemic just broke out. Some hospitals in Wuhan were in short supply of protective materials, and some medical staff were short of protective equipment, so they were also careless and were infected. Harbin had already experienced the epidemic test in April, but medical staff were still diagnosed with infection.

In addition to the hospital's own prevention and control loopholes, the relevant responsible persons are careless, and the virus's ability to spread is beyond our imagination.

None of the four tests were identified as confirmed cases. As a former infected person, Han may have transmitted to Cao by sharing the polluted environment. After several rounds of transmission, the virus finally directly or indirectly transmitted 43 people through the 87-year-old man, and the virus is still spreading.

The ability of the new coronavirus to spread is so strong, let me give you another example.

Beijing Center for Disease Control and Prevention reported on April 16 that a Chinese student studying in Miami, USA was quarantined after returning to Beijing from the United States on March 24, and all three nucleic acid test results were negative. After the 14-day quarantine period expires, the quarantine will be lifted. But on the third day of returning home, I developed symptoms of fever and coughing sputum. After two days, I went to the hospital for treatment and the nucleic acid test was positive! After the family was examined, his mother, younger brother and grandfather were all diagnosed. The international student lived alone while at home and did not go out.

The virus in this international student tested negative for three nucleic acids, and he immediately returned to the sun after being released from isolation, and also infected three family members.

At a press conference held by the Beijing Municipal Government Information Office, experts lamented, "This warns us that the new coronavirus is a newly discovered virus, and there are still unknown factors that we need to explore in epidemic prevention and control."

Beijing Health Commission emphasized that some infected people have other symptoms for a long time, which may cover up similar symptoms of new coronavirus pneumonia. A few infected people have long incubation period, positive nucleic acid tests and onset time appear late, and early symptoms are atypical, which brings new challenges to prevention and control work.

Harbin Center for Disease Control and Prevention also stated that at present, since the understanding of the new coronavirus is not deep enough and the law of transmission is not accurate enough, the investigation into the infection between Han and Cao is still continuing.

Screenshot on the official website of Harbin Municipal Government.

Find all direct and indirect contacts to get the transmission path

How can we end this wave of local epidemic that has lasted for more than a week?

At the provincial video conference on April 17, Heilongjiang Provincial Party Secretary Zhang Qingwei gave a clear measure: carry out the epidemic investigation in a strict and meticulous manner, find all direct and indirect contacts, and cut off the transmission path.

Judging from the current epidemic situation, Cao and Guo Ming have no longer transmitted to third parties. The increased cases after April 10 are all related to 87-year-old Chen. Moreover, all transmission sites may be brought to other public places with these infected patients and accompanying them.

For example, a new asymptomatic infection case on April 17 was added, a commuter car driver. His mother was diagnosed with hospitalization in the first hospital of Harbin Medical University. She belonged to Chen’s patient. Her father was later infected, and he was also diagnosed as an asymptomatic infection. What is worrying is that he has picked up and dropped off employees from two units to and from get off work every day for 10 consecutive days. According to regulations, these employees will undergo nucleic acid tests.

In addition, there were also cross-provincial cases. Zhang, a new confirmed case of COVID-19, was confirmed to have intersections with the confirmed cases in Harbin. Liu, a suspected case in Inner Mongolia, was also found out during the epidemiological investigation and issued a letter of cooperation through the province.

All these indicate that Harbin’s epidemic investigation and investigation have achieved great results, but due to objective conditions, degree of cooperation, etc., there are still certain hidden dangers of missed investigation.

For this reason, on April 17, Harbin City issued a notice to the public on "an urgent search for people who had had intersections with confirmed cases from April 2 to April 9", and urgently searched for close contacts of Chen. The notice stated that although most of the close contacts have been found, a small number of them have not been contacted. It is hoped that those who have had intersections with the time and place of the notice should take necessary measures in a timely manner and take the initiative to conduct inspections in a timely manner.

At present, Harbin has expanded the scope of epidemic investigation, investigated "six categories" of personnel, and strengthened the prevention and control of asymptomatic infections; strive to find close contacts and risk groups of close contacts and close contacts as soon as possible, and all nucleic acid testing are implemented;

opens social third-party testing institutions to mobilize citizens to self-screen;

Level 2 and above medical institutions conduct nucleic acid and serum antibody testing for all admitted patients and accompanying personnel, and those who have not been tested are not allowed to be hospitalized and transferred to the hospital to prevent cross-infection in the hospital;

"scan the code, measure temperature, wear a mask", and outsiders are prohibited from entering the community, and preventing gatherings of people, etc.; those who fail to implement responsibilities in epidemic prevention and control will be strictly held accountable.

In response to the possible transmission caused by the shared polluted environment, Harbin has taken terminal disinfection measures for hotels, supermarkets and other public places that have been found in the trajectory of confirmed cases and asymptomatic infected persons. After the terminal disinfection of the original ward of the hospital involved is currently closed, the patient will be admitted to other wards.

With a large-scale investigation and investigation, close contacts who "lost the network" will still be tested and confirmed. In the next few days, local confirmed cases will not come to an abrupt end. We don’t need to panic too much, because only by finding all direct and indirect contacts and being isolated and treated can the epidemic be eliminated.

Original title: Disassembly the powerful contagiousness of the new coronavirus: Four tests have not been confirmed, how can Han spread 154?

Source: Southern Metropolis Daily Editor: Wang Qian