First Wave of COVID-19 Abated With Control Measures in China

Relaxing the interventions when epidemic size still small would increase cumulative case count


TUESDAY, April 14, 2020 (HealthDay News) -- Interventions implemented in China interrupted coronavirus disease 2019 (COVID-19) transmission in all areas outside of Hubei, and low transmissibility can be maintained by monitoring the instantaneous effective reproduction number (Rt), according to a study published online April 8 in The Lancet.

Kathy Leung, Ph.D., from the University of Hong Kong, and colleagues estimated the Rt of COVID-19 in Beijing, Shanghai, Shenzhen, Wenzhou, and the 10 Chinese provinces with the highest number of confirmed COVID-19 cases. In addition, the confirmed case-fatality risk (cCFR) was assessed in Beijing, Shanghai, Shenzhen, and Wenzhou and all 31 Chinese provinces. The potential effect of relaxing containment measures after the first wave of infection was demonstrated using a susceptible-infectious-recovered model.

The researchers found that the Rt decreased substantially following implementation of control measures on Jan. 23, 2020, in all selected cities and provinces and has since remained less than 1. Outside Hubei, the cCFR was 0.98 percent (95 percent confidence interval, 0.82 to 1.16), which was much lower than in Hubei (5.91 percent; 95 percent confidence interval, 5.73 to 6.09). With the epidemic size still small, the model showed that relaxing the interventions (resulting in an Rt >1) would increase the cumulative case count exponentially as a function of the duration of relaxation, although disease prevalence could subsequently be pushed back to the baseline level with aggressive interventions.

"As economic activity continues to resume in the coming weeks, real-time assessment by monitoring the instantaneous effective reproduction number could allow policy makers to tune relaxation decisions to maintain transmissibility to below the self-sustaining threshold of 1," the authors write.

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