Study on the COVID-19 epidemic in mainland China between November 2022 and January 2023, with prediction of its tendency

Abstract

The prediction system EpiSIX was used to study the COVID-19 epidemic in mainland China between November 2022 and January 2023, based on reported data from December 9, 2022, to January 30, 2023, released by The Chinese Center for Disease Control and Prevention on February 1, 2023. Three kinds of reported data were used for model fitting: the daily numbers of positive nucleic acid tests and deaths, and the daily number of hospital beds taken by COVID-19 patients. It was estimated that the overall infection rate was 87.54% and the overall case fatality rate was 0.078%-0.116% (median 0.100%). Assuming that a new COVID-19 epidemic outbreak would start in March or April of 2023, induced by a slightly more infectious mutant strain, we predicted a possible large rebound between September and October 2023, with a peak demand of between 800,000 and 900,000 inpatient beds. If no such new outbreak was induced by other variants, then the current COVID-19 epidemic course in mainland China would remain under control until the end of 2023. However, it is suggested that the necessary medical resources be prepared to manage possible COVID-19 epidemic emergencies in the near future, especially for the period between September and October 2023.

Keywords: COVID-19; Case fatality rate; Epidemic; Infection rate; Prediction.

Fig. 1

Modeling and prediction of the COVID-19 epidemic by EpiSIX from November 2022 in mainland China using data from Dec. 9, 2022, to Jan. 30, 2023 (53 days) released by CCDC. The red line is the instant transmission rate (i.e., effective reproductive number Reff). When its value is less than the threshold 1.0 (yellow line), the epidemic is “under control.” Otherwise, it is “out of control.” The dark blue column is the daily number of reported new cases, and the gray curve is its model fitting. The dark blue solid line is the model fit for the cumulative total number of cases. The abscissa is the date. Assuming that a new outbreak starts on Mar. 1, 2023, the simulation shows that the peak future rebound will appear around Sept. 5, 2023.

Fig. 2

Inpatient demand simulated by EpiSIX from Dec. 9, 2022, to Jan. 30, 2023. The blue histogram is the actual daily number of inpatient beds from Dec. 9, 2022, to Jan. 30, 2023, and the red dotted line is its fitting. Estimation results: 0.483% and 6.39% of patients (after testing positive) would be transferred to ICU and general wards, respectively. Assuming a new outbreak starting from Mar. 1, 2023, the simulation shows that the peak demand for inpatient beds will reach 818,000 around Sept. 20, 2023.

Fig. 3

Modeling and prediction of in-hospital deaths by EpiSIX, using in-hospital death data from Dec. 9, 2022, to Jan. 30, 2023 (53 days) released by CCDC. Up to Jan. 30, 2023, the total number of in-hospital deaths was about 81,000. The predicted total number of in-hospital deaths ranges from 82,806–84,546 up to Mar. 31, 2023.

Fig. 4

Illustration of control efficacies calculated by EpiSIX for the COVID-19 epidemic course from November 2022 to December 2023 in mainland China (with an assumed new outbreak starting from Mar. 1, 2023). The purple line is the overall control efficacy generated by natural immunity. No vaccination program is assumed to start, and thus the overall vaccine efficacy vEff remains at zero. sEff and iEff are efficacy against susceptibility and infectivity, generated by all control measures including NPIs, vaccination, and natural immunity. All except vEff oscillate according to the loss of antibody protection and the emergence of new outbreaks. The blue line ctrEff is the combined control efficacy of sEff and iEff. The red line is the instant transmission rate Rt (i.e., effective reproductive number Reff). Finally, the gray line is the GDD. For the epidemic course under study, the GDD drops from 100% to 93.0%.