First-wave COVID-19 Transmissibility and Severity in China Outside Hubei After Control Measures, and Second-Wave Scenario Planning: A Modelling Impact Assessment

Lancet. 2020 Apr 25;395(10233):1382-1393. doi: 10.1016/S0140-6736(20)30746-7. Epub 2020 Apr 8.

Abstract

Background: As of March 18, 2020, 13 415 confirmed cases and 120 deaths related to coronavirus disease 2019 (COVID-19) in mainland China, outside Hubei province-the epicentre of the outbreak-had been reported. Since late January, massive public health interventions have been implemented nationwide to contain the outbreak. We provide an impact assessment of the transmissibility and severity of COVID-19 during the first wave in mainland Chinese locations outside Hubei.

Methods: We estimated the instantaneous reproduction number (Rt) of COVID-19 in Beijing, Shanghai, Shenzhen, Wenzhou, and the ten Chinese provinces that had the highest number of confirmed COVID-19 cases; and the confirmed case-fatality risk (cCFR) in Beijing, Shanghai, Shenzhen, and Wenzhou, and all 31 Chinese provinces. We used a susceptible-infectious-recovered model to show the potential effects of relaxing containment measures after the first wave of infection, in anticipation of a possible second wave.

Findings: In all selected cities and provinces, the Rt decreased substantially since Jan 23, when control measures were implemented, and have since remained below 1. The cCFR outside Hubei was 0·98% (95% CI 0·82-1·16), which was almost five times lower than that in Hubei (5·91%, 5·73-6·09). Relaxing the interventions (resulting in Rt >1) when the epidemic size was still small would increase the cumulative case count exponentially as a function of relaxation duration, even if aggressive interventions could subsequently push disease prevalence back to the baseline level.

Interpretation: The first wave of COVID-19 outside of Hubei has abated because of aggressive non-pharmaceutical interventions. However, given the substantial risk of viral reintroduction, particularly from overseas importation, close monitoring of Rt and cCFR is needed to inform strategies against a potential second wave to achieve an optimal balance between health and economic protection.

Funding: Health and Medical Research Fund, Hong Kong, China.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Betacoronavirus / isolation & purification
  • China / epidemiology
  • Coronavirus Infections / epidemiology*
  • Coronavirus Infections / transmission*
  • Disease Transmission, Infectious*
  • Humans
  • Infection Control / methods
  • Models, Statistical*
  • Pandemics
  • Pneumonia, Viral / epidemiology*
  • Pneumonia, Viral / transmission*

Supplementary concepts

  • COVID-19
  • severe acute respiratory syndrome coronavirus 2