Infectious diseases: Comments
Accurately estimating infected population is a key for making epidemic preventing policies.
Based on the SIR model and new information, I estimated the infectious population of Wuhan Coronavirus in China and project the possible policy consequence.
I find some data inconsistencies in the official data, while the reported data by Imai et al. (2020) is more reliable. Follow the data by Imai et al. the infected population is about 10000 on Jan. 23.
Government started to take strong measures in response to the epidemic of new coronavirus, we assume different scenarios。
My main findings include:
1, If the quarantine rate of infectious population is below 90%, the epidemic of Coronavirus can not be controlled. A stricter quarantine policy should be taken as soon as possible.
2, The basic reproduction number R0=3.5, a very high number indicating powerful infectivity.
3, (a) In the case of 100% quarantine, at the end of January, the infected population and death will be projected to reach 13250 and 102 respectively; while the end of February, the numbers will be 20421 and 525 as well. Final infected population could be 26,000. and the final death would be more than 700.
(b) In the case of 90% quarantine, at the end of January, the infected population and death will be projected to reach 14475 and 102 respectively; while the end of February, the numbers will be 29561 and 671 as well. Final infected population could be 59,000, and the final death would be more than 1,500.
(d) In the case of 80% quarantine, at the end of January, the infected population and death will be projected to reach 15842 and 102 respectively; while the end of February, the numbers will be 45572 and 872 as well. Final infected population could be 19,0000, and final death will be more than 4000.
(d) In the case of 50% quarantine, at the end of January, the infected population and death will be projected to reach 20951 and 102 respectively; while the end of February, the numbers will be 215048 and 2192 as well. Final infected population could be 4,694,000, and the final death would be more than 100,000.
As the whole society has been mobilized and realized the importance and difficulty of the epidemic prevention, the epidemic will be controlled in 2-3 months.
Appendix :excel data for SIR model
English Executive Summary:
There is a hot debate on the impact of the Coronavirus epidemic on China economy? Many experts compared it with the economic development of China after SARS, and the predictions are relative optimistic. I have slightly different opinions.
First of all, China just entered the WTO in 2003 and had a relatively friendly international economic environment, and its economic momentum was full. However, the international environment is relatively hostile now. Particularly, it is now facing serious Sino-US trade war.
Second, Domestic economic structure is different from 2003: (1) The share of tertiary industry in GDP has increased from 42% to 54%, while the epidemic has and will mainly hit the service industries; (2) the secondary industry is very strong in China, but it must be linked to world value chains. If the quarantine and fight again the epidemic took more than 2 months, many companies will go bankrupt to liquidity depletion. (3) In the primary industry, due to the impact of quarantine, the feed supply of livestock products has received a certain level of negative impact, and the supply of fresh products has decreased. Food prices will further increase in addition to the effect of African Swine Flu las year. 4) From the financial perspective, the leverages of residents and enterprises are very high. If social production is stopped for too long, it will cause leverages to break. (5) From a policy perspective, the economic downturn will lead to a decline in the revenue, an economic stimulus package is very likely to come out soon. Due to the rigidity of expenditure, monetary policy may dominate. 52 weeks make a year, a week of closedown will roughly cost 2% of GDP.
In short, the growth in this year is not pessimistic. There is a high probability to observe a low or even negative growth rate and high inflation this year in China.
Appendix: Paper can be downloaded below.