Abstract

Background: The outside input COVID-19 epidemic is an important issue for studying the prevention and disease control measures and the spread of the COVID-19 epidemic. Following our previous study for the mainland China epidemic during December 31st 2021 to December 6^th 2022, this paper studies the foreign input epidemics in Shanghai and Mainland China during this period.

Methods: Using differential equations and real word data modelings and simulates COVID-19 epidemic in Shanghai and mainland China during December 31, 2021 to December 06, 2022, estimates the input transmission rates and the recovery rates to the symptomatic and the asymptomatic infections.

Results: The simulation results were in good agreement with the real word data on the end point days of investigated time-intervals. One month before December 6th 2022, the symptomatic foreign input transmissions both in mainland and Shanghai were under control. After day 135, the numbers of the cumulative foreign input asymptomatic individuals both in mainland and Shanghai had been increasing in wave ways. During the first 170 days, the average input transmission rates of the foreign input symptomatic and asymptomatic individuals in mainland were much lower than the average input transmission rates of the symptomatic and asymptomatic individuals in Shanghai, respectively. During the last 170 days, the average input transmission rates of the foreign input symptomatic and asymptomatic individuals in mainland were similar to and much higher the average input transmission rates of the symptomatic and asymptomatic individuals in Shanghai, respectively.
Discussion: During the first 170 days, the average recovery rates of the foreign input symptomatic and asymptomatic individuals in mainland were lower and similar to the average recovery rates of the symptomatic and asymptomatic individuals in Shanghai, respectively. During the last 170 days, the average recovery rates of the foreign input symptomatic and asymptomatic individuals in mainland were lower and much higher than the average recovery rates of the symptomatic and asymptomatic individuals in Shanghai, respectively. Foreign Input Mainland Epidemic Virtual Simulations show that that if kept the input transmission rates and the recovery rates on day 99, the numbers of the current symptomatic and asymptomatic individuals would reduce to about 1 and 41 on day 215, respectively. Foreign Input Shanghai Epidemic Virtual Simulations show that if kept the input transmission rates and the recovery rates on day 120, the numbers of the current symptomatic and asymptomatic individuals would reduce less than 1 and about 5 on day 132, respectively.

Conclusion: For the foreign input epidemic in mainland, keeping the input transmission rates of under 0.07 to the symptomatic and asymptomatic infections, and the recovery rates of over 0.125 and 0.099 to the symptomatic and asymptomatic individuals may make the numbers of the current symptomatic and asymptomatic infected individuals to decrease to very low levels in four months. For the foreign input epidemic in Shanghai, keeping the input transmission rates of under 0.04 and 0.11 to the symptomatic and asymptomatic infections, and the recovery rates of over 0.18 and 0.13 to the symptomatic and asymptomatic individuals may make the numbers of the current symptomatic and asymptomatic infected individuals to decrease to very low levels in two weeks. The low recovery rate to the foreign input asymptomatic individuals in Shanghai is the reason that the number of the cumulative asymptomatic individuals charged in medical observation increased rapidly after day 120. In a region appearing new COVID-19 variant infection, this paper recommends: (1) Administrations report timely the COVID-19 epidemic, in particularly the numbers of symptomatic and asymptomatic individuals. (2) Administrations act quickly to discover and extinguish together, cut off quickly the transmission chain until the community transmission of COVID-19 has been initially blocked. (3) Using more accuracy SARS-CoV-2 nucleic acid testing (CT value >40) discovers potential foreign input infected individuals. (4) Individual who do not have symptoms but have had close contact with someone who is, or may be, infected may take COVID-19 antigen detection at least one time every week. (5) Individuals take SARS-CoV-2 antibody detection regularly.

Keywords: COVID-19; Recovery rates; Modelings; Simulations; Foreign input infection transmission rates; Nucleic