Individual-level data on 25,961 laboratory-confirmed Covid-19 cases reported through February 18, 2020 were extracted from the municipal Notifiable Disease Report System. 

Based on key events and interventions, the epidemic was divided into four periods: before January 11, January 11-22, January 23 - February 1, and February 2-18. 

They then compared epidemiological characteristics across periods and different demographic groups, and developed a susceptible-exposed-infectious-recovered model to study the epidemic and evaluate the impact of interventions

Methods for Effects of Countermeasures on the Reproductive Number in Wuhan

Considerable countermeasures effectively controlled the COVID-19 outbreak in Wuhan. 

Special efforts are needed to protect vulnerable populations, including healthcare workers, elderly and children. 

Estimation of unascertained cases has important implications on continuing surveillance and interventions.

Conclusions from the Study on Effects of Countermeasures on the Reproductive Number in Wuhan

In Wuhan, aggressive implementation of nonpharmaceutical interventions (NPIs), including a cordon sanitaire of the city, suspension of public transport, school, and most work, and cancellation of all public events reduced the reproductive number from 3.86 to 0.32 over a 5-week period 

University of Michigan - Ann Arbor

- Reproductive number Wuhan (December 31 2019 to January 28 2020)
- Reproductive number Wuhan (December 8 2019 to January 26 2020)
- Reproductive number Wuhan (January 18 2020)
- Effects of Countermeasures on the Reproductive Number in Wuhan

Studies on COVID-19 Reproductive Number in Wuhan, Hubei, China

Frieden, Thomas R., and Christopher T. Lee. “Identifying and Interrupting Superspreading Events—Implications for Control of Severe Acute Respiratory Syndrome Coronavirus 2.” Emerging Infectious Diseases, vol. 26, June 2020.

Identifying and Interrupting Superspreading Events—Implications for Control of Severe Acute Respiratory Syndrome Coronavirus 2

Method: Stochastic Markov Chain Monte Carlo (MCMC) 

Approaches: MCMC methods with Gibbs sampling and non-informative flat prior, using the posterior distribution 

Estimate of Reproductive number: 2.68 (95% CI 2.47-2.86)

Reproductive number Wuhan (December 31, 2019, to January 28, 2020)

Method: Mathematical Incidence Decay and Exponential Adjustment (IDEA) model 

Approaches: Adopted mean serial interval lengths from SARS and MERS ranging from 6 to 10 days to fit the IDEA model

Estimate of Reproductive number: 2.0-3.1 (2.55)

Reproductive number Wuhan (December 8, 2019, to January 26, 2020)

Method: Computational modeling of potential epidemic trajectories 

Approaches: Assume SARS-like levels of case-to-case variability in the numbers of secondary cases and a SARS-like generation time with 8.4 days, and set number of cases caused by zoonotic exposure and assumed total number of cases to estimate R0 values for best, median, and worst cases.

Estimate of Reproductive number: 1.5-3.5 (2.5)

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