Wu Zunyou's interpretation of epidemic prevention and control: how to treat asymptomatic infection? When is the turning point in the global epidemic?
Author: Zhang Nepal
The new crown pneumonia epidemic is raging around the world and has caused tens of thousands of deaths. In the face of this global public health emergency, while the public is actively preventing and controlling, it is also worried about the future trend of the epidemic.
How infectious is an asymptomatic person? When is the turning point in the global epidemic? Will the virus disappear from human society?
In response to a series of issues of concern to the outside world, Wu Zunyou, chief expert of epidemiology at the Chinese Center for Disease Control and Prevention, visited the Chinanews video interview on April 1 to answer questions and doubts of the public.
Wu Zunyou is a guest in the video interview
On April 1st, Wu Zunyou was a guest at Chinanews.com connected to the "European Times" and Japan's "Oriental News" for video interviews.
How infectious is an asymptomatic person?
From April 1, the National Health Commission began to publish data on asymptomatic infections in daily outbreak reports.
Recently, more and more asymptomatic people have appeared, making the public nervous again. How infectious is an asymptomatic person? Will it trigger a rebound in the domestic epidemic?
Regarding the above problems, Wu Zunyou analyzed that the location of the asymptomatic infection is firstly an infected person, and the infected person carries the new crown virus, which may cause transmission.
However, he emphasized that the infectivity of the infected person depends on the amount of virus, and the more the virus is replicated in the body, the greater the possibility of symptoms. The absence of symptoms is also related to the low virus content. With less virus, there is less risk of transmission.
Previous studies have found that the contribution rate of asymptomatic infection to second-generation cases is about 2% to 4%, that is, the overall contribution rate of asymptomatic infection transmission to the epidemic is very small, less than 5%.
In addition, Wu Zunyou believes that if he has not been to a place where neo-coronary pneumonia is endemic, and has not been in contact with others at home for the past two weeks, he can be determined to be an asymptomatic person. In addition, the chance that a person will encounter an asymptomatic infected person on the street is basically zero.
Wu Zunyou emphasized that the global epidemic situation is now on the rise, and the imported epidemic situation is now the most important challenge for China. After several months of accumulated experience in prevention and control, a more comprehensive prevention and control system has been constructed, which enables close contacts to be found in time and tracked and observed.
"We have a complete set of prevention and control measures, even if there are asymptomatic infections, they are still under control, and even if there are individual ones, they will not cause transmission and spread," he said.
Wu Zunyou was a guest at Chinanews.com connected to the European Times and Japan's Oriental Newspaper for video interviews.
When is the turning point in the global epidemic?
The latest data from Johns Hopkins University in the United States shows that the number of confirmed cases of new coronary pneumonia in the world has exceeded 930,000 and the cumulative deaths have exceeded 46,000.
"In the past 5 weeks, we have witnessed an almost exponential increase in newly diagnosed cases. The number of deaths has more than doubled in the past week. Newly diagnosed cases of new pneumonia will exceed one million in a few days and 50,000 people will die. "World Health Organization Director-General Tan Desai said at a press conference on the 1st.
The epidemic is raging around the world. Faced with the huge number of confirmed infections, people are most concerned about when the inflection point of the epidemic will appear.
In this regard, Wu Zunyou analyzed that at present, it is still difficult to investigate and judge the global epidemic inflection point, and the difficulties are reflected in two aspects: First, only the number of confirmed cases reported in each country is known, but the specific onset time of these reported patients Second, the measures and policies adopted by each country are different, and the implementation of policies is also different. It is difficult to judge when the policy measures will have an effect.
"Predicting the overall global epidemic situation is much more difficult than predicting the epidemic situation in a country, but we can also make a basic short-term judgment. In the coming week, the epidemic situation will continue to rise globally." Wu Zunyou emphasized.
Data map: There are very few guests at the outdoor cafe in Vittorio Square, Turin, Italy.
How to do good epidemic prevention and control overseas?
The spread of the domestic epidemic has been contained, but for a large number of overseas Chinese, the surge in the number of confirmed cases abroad has made them worry.
How to prevent and control overseas?
"First is to respect the law of disease prevention, respect the overall arrangements of local governments and health administration departments for prevention and control, and actively cooperate with local governments."
Wu Zunyou said that it is not recommended or encouraged to return to China in order to avoid the epidemic, because the risks faced during travel are not lower than staying in the local area.
In addition, he also emphasized that during the epidemic prevention and control, it should be implemented in accordance with some of the experiences and control measures already summarized. For example: keep enough food and supplies, try not to go out, work at home or isolate at home; if you have to go out, wear a mask; keep away from other people; ventilate at home; try not to use public transportation, if you must Avoid peak periods as much as possible; wash your hands frequently and bring some alcohol-based hand sanitizer.
"At the same time, pay close attention to your physical condition. If you have abnormal temperature and symptoms, you must go to the doctor in time and don't carry it at home."
Wu Zunyou emphasized that when there are mild symptoms, if you do not go to the doctor in time, you must wear a mask at home to observe, and remind everyone in the family to wear a mask to prevent transmission within the family.
"Wearing a mask is not only to prevent yourself from being infected, but also to prevent transmission to others if you become infected. This is to fulfill social responsibilities. To do this, it should be said to be relatively safe." Wu Zunyou said.
Data Figure: Researchers are demonstrating the experimental process of developing a new coronavirus mRNA vaccine. Photo by Tang Yanjun
When will vaccines and drugs come out?
As countries struggle to deal with the epidemic, they are pinning their hopes on the successful development of drugs and vaccines that will ultimately help humans overcome the disease.
But in the eyes of experts, the market for drugs and vaccines still requires patience.
Wu Zunyou believes that, from the perspective of drugs, even if there are candidate drugs for clinical trials, most of these drugs are drugs for treating other diseases, and "old drugs are new." This situation can only be determined after clinical evaluation.
He said that if it was a drug previously used in other diseases in the clinic, a phase III clinical trial could be conducted directly, and the process would be relatively faster. For drugs that have never been used for patient treatment, they need to go through clinical phase I, phase II, and phase III trials, which will take longer.
"An optimistic estimate is that a new drug proves that it is effective and can be used after it is approved by the FDA. The shortest time is 6 months to 1 year."
For vaccines, he emphasized that if all the links were green, the research would be very smooth, and it would take 6 months at the earliest. And these are idealized conditions. The problem.
"If there is a new vaccine for the prevention of new coronary pneumonia within this year, or a new drug proven to be effective through clinical trials, there are still great challenges," said Wu Zunyou.
The staff of Shanghai Pudong Airport arrived at the baggage carousel at the T2 terminal and placed their luggage according to the place of departure. Photo by China Press Agency reporter Yin Liqin
Where will the epidemic eventually go?
"New crown pneumonia will become a 'large flu'", "the epidemic will spread throughout the world", "the epidemic will disappear like SARS" ...
There are many speculations about the final direction of this epidemic.
For various claims, Wu Zunyou also gave his own analysis.
"For now, it's less likely that SARS will disappear soon, like SARS, and the term 'large flu' isn't accurate because it creates a misunderstanding."
Wu Zunyou believes that if New Crown Pneumonia is "large flu", it will make everyone feel that the flu is nothing and will not pay attention to it. However, there is a fundamental difference between new crown pneumonia and influenza.
He emphasized that the biggest difference between the two is that the proportion of patients with influenza that actually causes lung inflammation is very small, mainly those who do not seek medical treatment in a timely manner. Pneumonia will occur when the condition develops seriously.
However, for new coronary pneumonia, if the mild patients are excluded, 60% of them are mainly pneumonia, and 20% are severe or critically ill, and the mortality rate is much higher than that of influenza.
"New crown pneumonia is new crown pneumonia, it's not flu, nor SARS."
So, will the epidemic pattern of new coronary pneumonia coexist with humans for a long time like the flu?
Wu Zunyou said that this possibility is possible, but how much the possibility is still to be determined by observation in the next few months.
He emphasized that only 3 months have passed since the epidemic of new coronary pneumonia, and humans have not yet understood enough about the disease. The information they have now is very limited to make such a judgment.