What if China "opens up" like the U.S. and Britain on COVID?
Very bad, says PKU paper published on China CDC Weekly
Shortly before the very recent Omicron variant which has spooked the world, there were many Western press reports and opinions exploring Why China Is the World’s Last ‘Zero Covid’ Holdout and warning China’s self-isolation is a global concern.
This week, the Chinese Center for Disease Control and Prevention Weekly published a paper (PDF) (Web version) by Peking University researchers to evaluate the corresponding potential consequences if pandemic response strategies in the aforementioned countries (the United States, the United Kingdom, Israel, Spain, and France) were to be adopted in China.
Long story short, they say it’s very bad:
We found that even in a highly underestimated outbreak scenario under the most optimistic assumptions, once China adopts the control and prevention strategies of some typical western countries, the number of the daily new confirmed cases in China would likely rise up to hundreds of thousands of cases, and among which >10,000 cases would present with severe symptoms. Particularly, the number of standing severe cases would exceed the peak number nationwide in early 2020 within 1–2 days, which would have a devastating impact on the medical system of China and cause a great disaster within the nation.
The authors used the real-world pandemic scenario in the following countries: the United States, the United Kingdom, Israel, Spain, and France, as a reference group to evaluate the corresponding potential consequences if pandemic response strategies in the aforementioned countries were to be adopted in China. In order to obtain a conservative estimation/lower bound.
The population of the mainland of China is 1.4 billion, which yields a countrywide population density of 147 people/km2. In particular, the population of the eastern region, which accounts for 39.9% of the total population and yields a much higher population density of 661 people/km2
A population of 777 million has been fully vaccinated in the mainland of China, which represents a full vaccination ratio of roughly 55.04%. Natural immunity ratio is negligible in China.
Each country in the reference group, their vaccination coverage together with natural immunity ratio are higher than in China. As for the population density, the United States, Spain, and France all have population densities lower than China. At the same time, none of these reference countries have their population densities as high as that of the eastern region in China.
It is based on elementary arithmetic calculations to provide quick estimates on the lower bound of the daily new infections and severe cases should China adopt coexistent or open-up policies seen in the reference countries.
In order to depict the combined effect from vaccine coverage rate, vaccine protection efficiency, and the characteristics of the Delta strain on the current rate of severe cases, we used real-world data in the most recent outbreak in Yangzhou, China and modified it based on nationwide age structure.
The results, meaning if China adopts the respective reference country’s current situation
In plain English, the paper basically says:
If you copy and paste the United States to China, there will be 637,155 cases and 22,364 severe cases a day here.
If you copy and paste Britain to China, there will be 275,793 cases and 9,680 severe cases a day here.
In the authors’ own words,
We can see if strategies in these reference countries were adopted, the number of severe cases might exceed the peak of standing severe cases nation-wide in early 2020 [11,977, on February 18, 2020] within 1–2 days, and thus would pose an unaffordable burden to the medical system in this country.
The paper is based on this assumption
For now, we assumed that the immunity induced by inactivated vaccines used in China is as strong as the one induced by vaccines used in the reference countries and also as strong as natural immunity in terms of providing protection against infection/symptoms.
Important caveats that make the authors repeatedly underline they were only producing a conservative estimate:
1) the vaccination rate in China is as high as the reference countries;
2) the population density of China or China’s eastern region is as low as the reference countries if pandemic response strategies and community activity patterns in the reference countries were adopted in China, the ratio of infection would be similar to these countries. While in reality, such a rate should be much higher.
The authors’ discussion (NPIs=non-pharmaceutical interventions)
Foo et al. proposed four insightful key tenets for the safe transition from elimination strategies to open-up strategies: 1) retain flexible NPIs based on the changing epidemiology and hospital capacities; 2) maximize vaccination coverage; 3) shield industries and vulnerable groups from the unintended consequences resulting from NPIs; and 4) detect and isolate COVID-19 promptly using extensive surveillance and stronger community social responsibility. However, due to the large population and relatively scarce health resources per capita in China, it is difficult to fully achieve tenets 1, 3, and 4, especially during a large-scale outbreak; therefore, China needs to be cautious about the decision on the open-up. Nevertheless, our suggestions towards China might not necessarily be applicable to other countries.
limitations in our study, for example: 1) the estimates here were only the conservative lower bounds of, and not the actual number of cases, which is not possible to predict, but the order of magnitude seems reasonable; and 2) the effects on different vaccination strategies were not able to be incorporated into the estimations. More sophisticated dynamic models are needed to study the evolution of the pandemic and the risk if travel restrictions were lifted, various vaccination strategies were implemented together, different levels of NPI containment intensities, all of which are works in progress.
To summarize, in this article we estimated a plausible lower bound on the outbreak size and sickbed demands if the pandemic response strategies in the reference countries were applied in China. The estimates revealed the real possibility of a colossal outbreak which would almost certainly induce an unaffordable burden to the medical system. Our findings have raised a clear warning that, for the time being, we are not ready to embrace “open-up” strategies resting solely on the hypothesis of herd immunity induced by vaccination advocated by certain western countries. More efficient vaccinations or more specific treatment, preferably the combination of both, are needed before entry-exit quarantine measures and other COVID-19 response strategies in China can be safely lifted.
Lastly, your Pekingnologist wishes to add the paper apparently was written before the very recent Omicron variant which has spooked the world. The paper (PDF) (Web version) is in English so you can read it for yourself.
Online discussions of the paper have been seen by your Pekingnologist circulating on Chinese social media this weekend (November 27).