The spread of SARs-CoV-2

The spread of SARs-CoV-2. Spencer EA, Heneghan C, Jefferson T.

Published on June 8, 2020

Reference Sanche S, Lin YT, Xu C et al High Contagiousness and Rapid Spread of Severe Acute Respiratory Syndrome Coronavirus 2 [published online ahead of print, 2020 Apr 7]. Emerg Infect Dis. 2020;26(7):10.3201/eid2607.200282. 2020
Study type
Country China, Wuhan provinces other than Hubei
Setting Community transmission, any transmission
Funding Details Defense Advanced Research Projects Agency and the Laboratory Directed Research, Development Rapid Response Program through the Center for Nonlinear Studies at Los Alamos National Laboratory, and National Institutes of Health (grant no. R01AI135946).
Transmission mode Person to person
Exposures Travel, human contact

Bottom Line

Rapid spread may have been facilitated by significant numbers travelling outside of Hubei before lockdown.

Evidence Summary

The time from symptom onset to hospitalization showed evidence of time dependence: Before January 18th, the time from symptom onset to hospitalization was 5.5 days (95% CI 4.6 to 6.6 days); after January 18th, the duration shortened significantly to 1.5 days (95% CI 1.2 to 1.9 days)

The time from initial hospital admission to discharge was 11.5 days (95% CI 8.0 to 17.3 days) and admission to death was 11.2 days (95% CI 8.7 to 14.9 days).

Before the January 23rd lockdown of the city, approximately 40,000 to 140,000 people in Wuhan travelled to destinations outside Hubei Province.

What did they do?

This study looked at the post-initial phase of the epidemic in China, from the 15th to the 30th of  January 2020. It used publicly available reports of 140 confirmed COVID-19 cases (mostly outside Hubei Province) published by the Chinese Centers for Disease Control and Prevention (China CDC) and provincial health commissions.

Study reliability

This is a small study based on early cases in Wuhan and is unlikely to be fully representative of later wider stages of the epidemic. Early  phase resting practices would have missed many community cases.

Clearly defined setting Demographic characteristics described Follow-up length was sufficient Transmission outcomes assessed Main biases are taken into consideration
Unclear No Yes Yes Unclear

What else should I consider?

This is data from the early stage of the epidemic and should be considered along with later data. The time dependence data suggest other factors impact on the timing of presentation to hospital. These factors might include a growing awareness amongst the public and clinicians of a pathogen that may cause severe disease. The Lunar New Year travel may have played a role in the rapid spread in early and mid-January 2020

About the authors

Carl Heneghan

Carl is Professor of EBM & Director of CEBM at the University of Oxford. He is also a GP and tweets @carlheneghan. He has an active interest in discovering the truth behind health research findings

Elizabeth Spencer

Dr Elizabeth Spencer; MMedSci, PhD. Epidemiologist, Nuffield Department for Primary Care Health Sciences, University of Oxford.

Tom Jefferson

Tom Jefferson, epidemiologist.