Published time: 02 April 2020
Authors: Andrew S Azman, Francisco J Luquero
Keywords: COVID-19, Epidemics
Juanjuan Zhang and colleagues use detailed, publicly available data to explore key epidemiological features of the coronavirus disease 2019 (COVID-19) pandemic in China. Outside the original epicentre of Hubei province, they found that the effective reproduction number dropped below the critical threshold of 1 by the end of January, 2020, for nine heavily affected Chinese provinces or cities. This finding suggests significant slowing of local transmission. Importantly, these reductions were achieved in a matter of weeks from the first signs of local transmission in most provinces. Although the true causal nature of these transmission reductions is not addressed in Zhang and colleagues’ analyses, it is probably due to the strict government-imposed restrictions on movement of people and social gatherings, widespread symptom screening, testing and quarantine programmes, and the strong emphasis on personal behaviour change (eg, hand hygiene, mask use, and physical distancing) to reduce the risk of transmission. The authors also found, as others have shown,2 that the mean incubation period and serial interval were of similar length (5·2 days [95% CI 1·8–12·4] and 5·1 days [1·3–11·6], respectively), suggesting an important role of transmission before or soon after symptoms have developed. Although this study has a number of limitations, it illustrates the power of rapid openly available data for providing important insights to guide complex policy decisions in the coming months.
From China; hope and lessons for COVID-19 control