The author of this article: Zhang Zuofeng
Professor Yu Shunzhang is a well-known epidemiologist in China and my graduate tutor.
During the SARS epidemic in 2003, Yu Shunzhang, deputy head of the Shanghai Expert Advisory Group, professor of the School of Public Health, Shanghai Medical University, and Weng Xinhua, director of the Department of Infectious Diseases of Huashan Hospital, suggested that the Shanghai citation should be different from the national standard. The more stringent diagnostic criteria for the diagnosis include adding the exposure history of other provinces and cities to the diagnostic criteria.
Professor Yu Shunzhang (Photo source: Shanghai Medical Alumni Association official website)
After discussion by the expert group, a set of Shanghai standards was formed. At that time, Shanghai Health Minister Liu Jun, Weng Xinhua and Yu Shunzhang all insisted. The Ministry of Health stated that if Shanghai insists on its opinion, it needs to submit a statement of the situation and sign it, and it will bear future responsibilities.
Liu Jun asked Weng and Yu for their opinions. Both of them expressed their willingness to take responsibility. Professor Yu and Professor Weng signed on the spot to explain the situation. Explain the responsibilities of the experts at that time and dare to take responsibility.
Finally, the Ministry of Health revised the diagnostic criteria in accordance with expert recommendations. This diagnostic standard once attracted media attention, and there were voices of suspicion that “Shanghai continues to use its own harsh standards to diagnose SARS, keeping the number of suspected patients at a low level.” Later, a serological study by Professor Jiang Qingwu, former dean of the School of Public Health at Shanghai Medical University, found that if the new diagnostic criteria were not adopted, about half of the patients would be misdiagnosed.
When encountering a major epidemic at that time, Shanghai experts used their professional knowledge to make important contributions to many large-scale epidemics and epidemic control.
Mr. Yu has made some contributions to the development of epidemiology in China. Under the guidance of Professor Su Delong, he participated in the research and control of schistosomiasis control. He participated in a survey of hepatitis A prevalence among 3000 people in Ningbo in 1983. Participated in controlling 30,000 hepatitis A epidemics in Shanghai two years later.
In the mid-1990s, a major outbreak of O157 hemorrhagic E. coli infection occurred in Japan. Tens of thousands of people were infected and dozens died. Professor Yu’s team developed a rapid and sensitive method for the detection of hemorrhagic E. coli infection O157. At the same time, he also made some contributions to the development of tumor epidemiology and trained a large number of epidemiologists.
Mr. Yu is nearly 90 years old this year. During his stay at home, he always took the new crown epidemic in Shanghai to heart. He has edited 64 episodes of epidemiological progress clips for research. Staff, CDC experts, epidemiology teachers and graduate students provided useful information and provided many technical supports for prevention and control.
He reviewed many epidemics in Shanghai, and in the end, he always found the main cause and solved it after he caught it. For example:
1. Diphtheria, measles, and influenza are all respiratory epidemics, all of which are spread through nearby air droplets. Isolation, wearing a mask, and using some drugs (globulin, oral anti-influenza drugs) were quickly resolved, and their transmission routes were simple and controllable.
2. Dysentery, cholera intestinal infectious diseases, although there are many transmission routes, food contamination (aquatic products on the market), flies are also positive, and human hands also play a role in transmission. But the main cause of the epidemic is always the main one. Dysentery is most closely related to hand pollution, and cholera is most closely related to drinking water. After being controlled, it subsided quickly.
3. Malaria, Japanese encephalitis, etc. are related to vectors. After controlling mosquitoes, the disease also decreased quickly.
5. Schistosomiasis catches snails, treats sick and sick animals, and soon the epidemic declines.
6. Liver cancer has taken drinking water, aflatoxin-contaminated food, and vaccinated against hepatitis B. After 10 years, the cancer rate has decreased significantly.
The Omicron new coronavirus strain in the current round of epidemic in Shanghai has the characteristics of rapid spread, insidious disease, mild clinical symptoms and low fatality rate. Mr. Yu took the initiative to give me the test paper and discussed with me the question of “Why the epidemic in Shanghai remains high”.
Why is the epidemic in Shanghai so high?
The number of cases in Shanghai has risen rapidly this time, mainly due to the strong contagiousness of the Omicron BA.2 variant (R0: 8～10), and the virus spread much faster than dynamic clearing speed.
Author’s drawing
Omicron BA.2 has the following main features: it is more infectious than BA.1; after being infected with BA.2, the hospitalization and severe rates are similar to those of BA.1; Reduced protection, but reinfection rates for people who have been infected with BA.1 are currently low; BA.2The main symptoms after infection are similar to colds, mainly runny nose, headache, fatigue, sneezing and sore throat; BA.2 basically does not attack the lungs, and is less likely to cause severe illness and death.
According to the principle, through the static management of the population, the infection should be properly controlled within the 3-4 incubation period of the virus, and the epidemic curve will shift back to the sudden peak.
But why is the daily number of new infections in Shanghai still around 20,000? We conjecture that irregular operations and exposure during population nucleic acid sampling may be important reasons.
The risk may come from the non-standard sampling process itself, not paying attention to the disinfection measures in each sampling, such as changing gloves. When sampling, the social distance between people is too small. When sampling, open your mouth and inhale. Considering that the virus may be transmitted through aerosols, if the first one is positive, the second one may be infected.
More importantly, the organizers or volunteers responsible for maintaining order may have a higher infection rate due to their extensive contacts and lack of strict disinfection training, thus becoming possible potential sources of infection.
Secondly, there was the frenzied purchase before the blockade, there was no obvious social distancing, and few people wore masks. Coupled with multiple rounds of nucleic acid sampling, it has become an accelerator for the spread of infection. However, the above reasons can only explain the continued increase in the incidence during the incubation period after static management, and cannot explain the continuous increase observed so far.
What is different from Shenzhen is that although Shenzhen is under lockdown, social services remain as usual, and food and drug supply channels are unobstructed, which effectively avoids the possibility of crazy purchases and mail orders, and reduces the risk of transmission. risk.
In Shanghai, because the food and drug supply chain is basically unconnected, residents order online and are delivered by neighborhood committees, volunteers, and riders. These groups of people have not received personal protection training, which may lead to infection The risk increases and becomes the main source of infection for further outbreaks.
Why are Shanghai suburbs less affected than urban areas? Population densities are different, and low population densities can reduce exposure and transmission coefficients in population nucleic acid sampling.
In summary, the reason why the new crown epidemic in Shanghai remains high is mainly that the preventive measures against the high contagiousness of the Omicron BA.2 variant have not been dynamically cleared. Make timely and targeted improvements.
On March 27, the first day of Pudong’s closure, I put forward 4 suggestions for the control of the new crown epidemic in Shanghai based on the characteristics of the virus mutation: including self-nucleic acid sampling or self-antigen determination (follow-up Shanghai has already carried out), self-isolation at home if conditions permit, enhanced vaccination of elderly at-risk groups, and early treatment of patients.
These suggestions are all adjustments to preventive measures based on the new characteristics of virus mutation under the premise of dynamic clearing. If there are improvements in preventive measures against the characteristics of the virus, the Shanghai epidemic will ease.
In addition, it is recommended to vaccinate the elderly and high-risk groups urgently; allow the public to self-sample nucleic acid and antigen tests; and require antigen-positive persons at an early stage to have their families sampled at home to obtain deep throat The diagnosis was confirmed after the saliva sample collection bottle was re-tested for nucleic acid. This approach can avoid cross-infection caused by crowd gathering.
The fifth round of the epidemic in Hong Kong has accumulated 1.18 million cases of new crown infection. It is estimated that 180,000 infected people who were diagnosed through antigen self-test from February 26 to March 6 implemented home self-isolation, At least not aggravating the epidemic. Self-isolation at home for those who are infected has also reduced the possibility of cross-infection in the cabins, so as to reduce the probability of producing new variants of the virus.
Estimated case fatality rate
Shanghai should not have the same high fatality rate as Hong Kong. According to Hong Kong data, 92% of the 8,735 deaths had long-term underlying diseases (deaths with Covid-19), and only 8% (699 cases) were classified as deaths from Covid-19.
At the same time, Hong Kong’s COVID-19 fatality rate is significantly overestimated. Its denominator should include a large number of unreported potentially infected people, and if included, the new crown case fatality rate may be close to 0.1%.
Hong Kong data also shows that vaccination rates among those over 80 are less than 20%, and a high percentage of deaths are among those over 80. This also underscores the need to urgently strengthen the vaccination of high-risk groups in the elderly population to reduce the case fatality rate.
The median age of death cases in Hong Kong’s fifth wave of the epidemic was 86 years old, and 95% were aged 60 and over. The male to female ratio was 1.47, about 55% were elderly people living in nursing homes, and about 90% had a history of chronic diseases. (Source: Hong Kong Government)
More than 70% of deaths] were vaccinated (including those who received one shot but less than 14 days ago), 14% received one shot, and 11% received two shots , 1% received three doses of the vaccine. (Source: Hong Kong Government)
Under the big goal of dynamic clearing, for non-fatal infectious diseases with relatively high asymptomatic or mild symptoms, the hospitalization rate, serious illness rate, and case fatality rate (the number of deaths/ The number of sick people) mortality is used as a measure of the degree of dynamic zeroing and control, rather than the number of cases and morbidity.
According to the current situation: Shanghai Omicron BA.2 belongs to this example. At present, the fatality rate of the Omicron BA.2 variant is close to 0.1% in France and other places, and the localInfluenza has a similar case fatality rate.
Among the more than 500,000 infections in Shanghai, there are very few severe cases and fatalities, and there are no direct deaths from new coronary pneumonia, which also reflects the epidemic characteristics of BA.2.
According to the laws of epidemiology, I made a prediction on the fatality rate of the new crown infection in Shanghai. My assumptions are: an average of two weeks from the onset of severe cases to death, the fatality rate of this virus is similar to that of the flu, and the accuracy of the data reported in Shanghai is assumed to be high (see figure below).
Author’s drawing
It turns out that as of April 10, Shanghai has reported 138 deaths from COVID-19 (zero deaths directly from COVID-19), and I predict the corresponding expected death toll is 202. Although the actual number of deaths is currently lower than I predicted, I estimate that there may be a lag in reporting and the possibility of underreporting.
Meanwhile I predict a total of 370 deaths by May 1 and a total of 505 deaths by May 8. If my prediction is accurate, then it may be estimated based on the data: the case fatality rate of the new coronavirus BA.2 is comparable to the average case fatality rate of the local influenza, and it can be considered that the new crown infection has been transformed into an endemic disease. In this case, it is recommended to consider adjusting the prevention and control measures of category B infection of new coronavirus pneumonia to category C prevention and control measures of infectious disease C.
Under the premise of dynamic clearing, we can reduce social isolation, ease hospital runs, strengthen vaccination and personal protection, reduce deaths, and effectively control the new crown epidemic in Shanghai.
This article was first published on Professor Zhang Zuofeng’s personal beauty editor account, authorized to publish by Lilac Garden. Source of title map: Visual China｜Planning: gyouza
Conflict of Interest Statement:
1. This article was written by the author in his spare time and has not received any financial support.
2. The vaccines and therapeutic drugs introduced in this article are based on three conditions: one is that they are supported by large-scale Phase III clinical trial data, and the other is that they are the most effective in terms of prevention and treatment. 3. Compared with other foreign medicines, it is easy to obtain in China.
3. The author has no investment in pharmaceutical companies.
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