local time on January 31, "The Lancet" once again published a paper on the novel pneumonia epidemic, this time the authors are all from the University of Hong Kong WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health.
This is a paper that uses a transmission model to review and predict the trend of new pneumonia. The main conclusion is: according to the model estimation, as of January 25, 2020, the actual number of people infected with new pneumonia in Wuhan is 75815, and R0 is 2.68. The doubling time (epidemic doubling time) is 6.4 days, and predicts that major cities in China will experience the peak of the epidemic 1-2 weeks later than Wuhan.
"The Lancet" published a new pneumonia epidemic trend estimation paper at the University of Hong Kong:
In addition, the paper constantly mentioned a problem at the forefront of public opinion: Wuhan's closure of the city has little effect on national prevention and control, because before the closure of the city Large cities across the country have already harvested dozens or even hundreds of infection sources from Wuhan.
The University of Hong Kong estimates the best, not the worst,
. The baseline data used by the University of Hong Kong researchers when modeling is entirely derived from the data reported by the Chinese Center for Disease Control and Prevention (CCDC), especially in December 2019 The initial case report from January to early January 2020.
, that is, the baseline data used for evaluation is already the most conservative data confirmed by CCDC, and the possible missed diagnosis is not taken into consideration at all.
In addition, the researchers also adopted the most ideal conditions for the data evaluated by other impact models. For example, under the premise of the South China Seafood Market as the source of infection, the researchers chose to default to the official closure of the South China Seafood Market and no more contact with the market. Source of infection. In another example, the best control effect of non-drug interventions such as community isolation and health education and publicity on influenza is to reduce the infection rate by 50%. When considering the intervention effects of community isolation and health education, researchers adopted the most effective The parameter that can reduce the infection rate by 50%.
At the same time, taking into account the action of Wuhan's lockdown, the researchers also pushed the effect of the lockdown to the extreme when calculating-that is, from January 23 onwards, there was no inflow or outflow of Wuhan.
To sum up, this assessment of the University of Hong Kong is based on the most ideal situation, that is, it is assumed that the early data given by CCDC is rarely missed and missed, and the South China seafood market is perfectly closed (regardless of the complexities such as continued online sales by vendors) Situation) , the ability of intervention measures such as community isolation and health education across the country is perfectly utilized to the most efficient, and there is no movement of people after the closure of Wuhan (not counting those who drive away).
Under this ideal premise, the model estimates that as of January 25, the actual number of people infected with pneumonia in Wuhan was 75,815, with an R0 of 2.68 (that is, one patient can infect 2.68), and the epidemic doubling time was 6.4 days.
(estimated data published in the original text)
Of course, there is a huge gap between this estimated data and the current statistical data released by the local health commission-as of 24:00 on January 31, 2020, a total of new coronavirus infections have been reported in Hubei Province There were 7153 cases of pneumonia in Wuhan and 3215 cases in Wuhan.
Not to mention that 6 days have passed from January 25 to January 31, and R0 did not drop significantly, the data calculated according to the model should have skyrocketed again, even if we look at the estimated data on January 25, The confirmed cases announced on January 31 are less than 5% of the estimated data on January 25...
There are too many “exports” infected people, and the effect of the lockdown is poor.
Based on the assumption of population mobility, researchers at the University of Hong Kong estimated based on previous traffic data in Wuhan that before the closure of the city, Chongqing had “imported” 461 infected people from Wuhan, Beijing had 113 people, Shanghai had 98 people, and Guangzhou had 111 people. Shenzhen gets 80 people...
(estimated data published in the original text)
Of course, there are other cities, such as Changsha, Nanchang, Hefei, Nanjing, Hangzhou, Wenzhou, Kunming, etc., which have also received a considerable number of infections. Refer to the figure below-
(The number of infected people who flowed to the country and the city before the closure of the city is estimated by the paper, the city is marked on the abscissa, and the number of infected people is indicated by the column icon. The figure shows that the lockdown of Wuhan
is one in the study. It has been mentioned many times as an important evaluation factor, but the researchers regret to find that even if the effect of the lockdown is pulled to the most ideal limit, has already sent a large number of "seed" infected people to the country when the city was closed. Closing the city is of little significance to national epidemic prevention. (However, our simulation suggested that wholesale quarantine of population movement in Greater Wuhan would have had a negligible effect on the forward trajectories of the epidemic because multiple major Chinese cities had already been seeded with more than dozens of infections each.) The follow-up of
depends on whether the spread of the virus has decreased
According to this speculation, it is not clear how the epidemic will end in the end-it depends entirely on the work done by the people across the country to stop the epidemic. How.
estimates show that if R0 is maintained at 2.68, if the flow between cities is not reduced or only reduced by 50%, the impact on the epidemic dynamics of the disease will be minimal. If the virus transmission capacity does not decline, the peak of the Wuhan epidemic will appear in 2020 In April 2008, other cities will be delayed by 1-2 weeks from Wuhan.
If the spread of the virus decreases, the situation will be significantly improved. If R0 can be reduced by 25%, the peak of the epidemic will be greatly reduced, if R0 can be reduced by 50 % (Ie fell to 1.3), The peak of the epidemic will not even appear in the first half of 2020... The specific results of
are shown in the following figure-
This figure is an estimate of the future direction of the epidemic after a variety of factors are superimposed. The first row of the graph represents no inter-city flow. Estimates of the restricted epidemic trend, and the second line of icons represents a 50% decline in inter-city mobility.
As shown in the figure, with the virus R0 unchanged, regardless of whether the flow between cities is controlled, the peak virus infection rate will come around April, exceeding 30/1000 per day. If R0 drops by 25%, that is, the virus transmission capacity decreases, and the peak value drops significantly. If R0 can fall by 50%, it is obviously the situation we most expect now-the epidemic will not rise.
However, the forecast is based on current limited knowledge. During the discussion, the researchers mentioned that little is known about the seasonal properties of the new coronavirus, that is, if the new pneumonia has a strong seasonality, then their current predictions of future trends will become very unreliable.
References
1.https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30260-9/fulltext%20
2.https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30212-9/fulltext
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on duty丨Wang Lina
Coordinator丨Wang Jiayi
editor丨Liu Guanghui
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source of this article: medical endocrine channel
