Estimation of infection density and epidemic size of COVID-19 using the back-calculation algorithm
Tóm tắt
The novel coronavirus (COVID-19) is continuing its spread across the world, claiming more than 160,000 lives and sickening more than 2,400,000 people as of April 21, 2020. Early research has reported a basic reproduction number (R0) between 2.2 to 3.6, implying that the majority of the population is at risk of infection if no intervention measures were undertaken. The true size of the COVID-19 epidemic remains unknown, as a significant proportion of infected individuals only exhibit mild symptoms or are even asymptomatic. A timely assessment of the evolving epidemic size is crucial for resource allocation and triage decisions. In this article, we modify the back-calculation algorithm to obtain a lower bound estimate of the number of COVID-19 infected persons in China in and outside the Hubei province. We estimate the infection density among infected and show that the drastic control measures enforced throughout China following the lockdown of Wuhan City effectively slowed down the spread of the disease in two weeks. We also investigate the COVID-19 epidemic size in South Korea and find a similar effect of its “test, trace, isolate, and treat” strategy. Our findings are expected to provide guidelines and enlightenment for surveillance and control activities of COVID-19 in other countries around the world.
Tài liệu tham khảo
Li Q, Guan X, Wu P, et al. Early transmission dynamics in Wuhan, China, of novel coronavirus-infected pneumonia. N Engl J Med. 2020;. https://doi.org/10.1056/NEJMoa2001316.
Imai N, Cori A, Dorigatti I, et al. Report 3: Transmissibility of 2019-nCoV. 2020; www.imperial.ac.uk/mrcglobal-infectious-disease-analysis/news--wuhan-coronavirus/.
Read JM, Bridgen JR, Cummings DA, et al. Novel coronavirus 2019-nCoV: early estimation of epidemiological parameters and epidemic predictions. medRxiv. 2020; https://doi.org/10.1101/2020.01.23.20018549
Zhao S, Lin Q, Ran J, et al. Preliminary estimation of the basic reproduction number of novel coronavirus (2019-nCoV) in China, from 2019 to 2020: a data-driven analysis in the early phase of the outbreak. Int J Infect Dis 2020;92:214–7.
Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19) - World Health Organization, Feb. 28, 2020. https://www.who.int/docs/default-source/coronaviruse/who-china-joint-mission-on-covid-19-final-report.pdf
McEvoy M, Tillet HE. Some problems in the prediction of future numbers of cases of the acquired immunodeficiency syndrome in the U.K. Lancet. 1985;2:541–2.
Morgan WM, Curran JW. Acquired immunodeficiency syndrome: current and future trends. Public Health Rep. 1986;101:459–64.
Bailey N. The mathematical theory of infectious diseases. 2nd ed. London: Charles Griffin & Co.; 1975.
Brookmeyer R, Gail MH. Minimum size of the acquired immunodeficiency syndrome (AIDS) epidemic in the United States. Lancet. 1986;328(8519):1320–2.
Brookmeyer R, Gail MH. A method for obtaining short-term projections and lower bounds on the size of the AIDS epidemic. J Am Stat Assoc. 1988;83(402):301–8.
Ferguson NM, Donnelly CA, Woolhouse MEJ, et al. The epidemiology of BSE in cattle herds in Great Britain. II. Model construction and analysis of transmission dynamics. Philos Trans R Soc Lond Ser B. 1997;352(1355):803–38.
Qin J, You C, Lin Q, et al. Estimation of incubation period distribution of COVID-19 using disease onset forward time: a novel cross-sectional and forward follow-up study. medRxiv. 2020; https://doi.org/10.1101/2020.03.06.20032417.