Evolving epidemiology and transmission dynamics of coronavirus disease 2019 outside Hubei province, China: a descriptive and modelling study - PubMed (original) (raw)

. 2020 Jul;20(7):793-802.

doi: 10.1016/S1473-3099(20)30230-9. Epub 2020 Apr 2.

Maria Litvinova 2, Wei Wang 1, Yan Wang 1, Xiaowei Deng 1, Xinghui Chen 1, Mei Li 1, Wen Zheng 1, Lan Yi 1, Xinhua Chen 1, Qianhui Wu 1, Yuxia Liang 1, Xiling Wang 1, Juan Yang 1, Kaiyuan Sun 3, Ira M Longini Jr 4, M Elizabeth Halloran 5, Peng Wu 6, Benjamin J Cowling 6, Stefano Merler 7, Cecile Viboud 3, Alessandro Vespignani 8, Marco Ajelli 9, Hongjie Yu 10

Affiliations

Evolving epidemiology and transmission dynamics of coronavirus disease 2019 outside Hubei province, China: a descriptive and modelling study

Juanjuan Zhang et al. Lancet Infect Dis. 2020 Jul.

Abstract

Background: The coronavirus disease 2019 (COVID-19) epidemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), began in Wuhan city, Hubei province, in December, 2019, and has spread throughout China. Understanding the evolving epidemiology and transmission dynamics of the outbreak beyond Hubei would provide timely information to guide intervention policy.

Methods: We collected individual information from official public sources on laboratory-confirmed cases reported outside Hubei in mainland China for the period of Jan 19 to Feb 17, 2020. We used the date of the fourth revision of the case definition (Jan 27) to divide the epidemic into two time periods (Dec 24 to Jan 27, and Jan 28 to Feb 17) as the date of symptom onset. We estimated trends in the demographic characteristics of cases and key time-to-event intervals. We used a Bayesian approach to estimate the dynamics of the net reproduction number (Rt) at the provincial level.

Findings: We collected data on 8579 cases from 30 provinces. The median age of cases was 44 years (33-56), with an increasing proportion of cases in younger age groups and in elderly people (ie, aged >64 years) as the epidemic progressed. The mean time from symptom onset to hospital admission decreased from 4·4 days (95% CI 0·0-14·0) for the period of Dec 24 to Jan 27, to 2·6 days (0·0-9·0) for the period of Jan 28 to Feb 17. The mean incubation period for the entire period was estimated at 5·2 days (1·8-12·4) and the mean serial interval at 5·1 days (1·3-11·6). The epidemic dynamics in provinces outside Hubei were highly variable but consistently included a mixture of case importations and local transmission. We estimated that the epidemic was self-sustained for less than 3 weeks, with mean Rt reaching peaks between 1·08 (95% CI 0·74-1·54) in Shenzhen city of Guangdong province and 1·71 (1·32-2·17) in Shandong province. In all the locations for which we had sufficient data coverage of Rt, Rt was estimated to be below the epidemic threshold (ie, <1) after Jan 30.

Interpretation: Our estimates of the incubation period and serial interval were similar, suggesting an early peak of infectiousness, with possible transmission before the onset of symptoms. Our results also indicate that, as the epidemic progressed, infectious individuals were isolated more quickly, thus shortening the window of transmission in the community. Overall, our findings indicate that strict containment measures, movement restrictions, and increased awareness of the population might have contributed to interrupt local transmission of SARS-CoV-2 outside Hubei province.

Funding: National Science Fund for Distinguished Young Scholars, National Institute of General Medical Sciences, and European Commission Horizon 2020.

Copyright © 2020 Elsevier Ltd. All rights reserved.

PubMed Disclaimer

Figures

Figure 1

Figure 1

Geographical distribution and temporal dynamics of confirmed COVID-19 cases (A) Geographical distribution of confirmed COVID-19 cases (including clinically diagnosed cases for Hubei province), officially reported as of Feb 17, 2020 (n=72 436), in each province of mainland China (left) and in each city of Hubei province (right). Provinces or cities with a blue contour indicate those selected for analysis of the net reproduction number. (B) Time series of COVID-19 cases for which we had individual records in provinces outside Hubei province, divided into cases with travel history to Wuhan or Hubei and cases of local transmission. If no information about the travel history of a patient was reported in the individual records, we assumed that the patient acquired the infection locally. This graph refers to 5683 cases with available symptom onset date (out of 8579 individual cases available in our individual records). The decline in the number of cases in the last few days of February is in part due to the delay between the date of reporting of cases and the date of symptom onset. The first period ran from Dec 24 to Jan 27. Dec 24 is the earliest symptom onset date of the cases reported outside Hubei. COVID-19=coronavirus disease 2019. PHEIC=public health emergency of international concern.

Figure 2

Figure 2

Distributions of the incubation period and serial interval (A) Comparison between the best-fitting distributions of the incubation period and of the serial interval; the vertical dashed lines represent the means of the two distributions. (B) Cumulative density function of the best-fitting distributions of the incubation period and the serial interval.

Figure 3

Figure 3

Temporal dynamics of _R_t in three Chinese locations outside Hubei Period 1 ran from Dec 24 to Jan 27, and period 2 from Jan 28 to Feb 8. (A) Daily number of new cases in Shenzhen city (Guangdong province), Hunan province, or Shandong province, divided into cases with travel history to Wuhan or Hubei and cases resulting from local transmission. The insets show maps of China highlighting Hubei province (dark colour) and the analysed location (lighter colour). (B) Estimated _R_t over a 4-day moving average. We excluded the last 9 days of data (ie, data after Feb 8) to account for reporting delays. We estimated the 90th percentile of the distribution of the time from onset to reporting in mainland China outside Hubei province during period 2 of the epidemic to be 9·0 days. _R_t=net reproduction number.

Comment in

Similar articles

Cited by

References

    1. Chinese Center for Disease Control and Prevention Epidemic update and risk assessment of 2019 novel coronavirus 2020. 2020. http://www.chinacdc.cn/yyrdgz/202001/P020200128523354919292.pdf
    1. National Health Commission of the People's Republic of China Update on COVID-19 as of 24:00 on March 10, 2020. 2020. http://www.nhc.gov.cn/xcs/yqfkdt/202003/b4abcf83e53d4284b2981c75917385eb... - PMC - PubMed
    1. World Health Organization Coronavirus disease 2019 (COVID-19) situation report–47. 2020. https://www.who.int/docs/default-source/coronaviruse/situation-reports/2...
    1. World Health Organization Statement on the second meeting of the International Health Regulations (2005) Emergency Committee regarding the outbreak of novel coronavirus (2019-nCoV) 2020. https://www.who.int/news-room/detail/30-01-2020-statement-on-the-second-...
    1. Li Q, Guan X, Wu P. Early transmission dynamics in Wuhan, China, of novel coronavirus-infected pneumonia. N Engl J Med. 2020 doi: 10.1056/NEJMoa2001316. published online Jan 29. - DOI - PMC - PubMed

Publication types

MeSH terms

LinkOut - more resources